[Current Topics in Microbiology and Immunology] Current Topics in Microbiology and Immunology Volume 99 __ The Biol

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[Current Topics in Microbiology and Immunology] Current Topics in Microbiology and Immunology Volume 99 __ The Biol

The Biology and Pathogenesis of Coronaviruses H. WEGE*, ST. SIDDELL*, AND V. TER MEULEN* 1 Introduction.............

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The Biology and Pathogenesis of Coronaviruses H. WEGE*,




1 Introduction.................. 2 Biology................... 2.1 Members of the Coronavirus Group and Their Relationships 2.1.1 Antigenic Relationships. . . . . 2.1.2 Nucleic Acid Homologies . . . . 2.2 Host Range and Organ Tropism. . 3 Coronaviruses and Disease Spectrum 3.1 Murine Coronaviruses 3.1.1 Murine Hepatitis Virus Hepatitis. . . . . Encephalomyelitis. . Enteritis . . . . . 3.2 Human Coronaviruses 3.3 Avian Coronaviruses. . . 3.3.1 Infectious Bronchitis Virus. 3.3.2 Turkey Coronavirus . . . 3.4 Feline Coronaviruses . . . . . 3.4.1 Feline Infectious Peritonitis Virus 3.5 Other Coronaviruses. . . . . 3.5.1 Bovine Coronavirus . . . . . 3.5.2 Canine Coronavirus . . . . . 3.5.3 Hemagglutinating Encephalomyelitis Virus 3.5.4 Transmissible Gastroenteritis Virus. . . 3.5.5 Rat Coronavirus . . . . . . . . . 4 Pathogenetic' Aspects. . . . . . . . . . . . . 4.1 The Role of Resistance in the Development of Disease . 4.1.1 Acute Infections . . . . . Murine Hepatitis Virus Type 2 . . . . . Murine Hepatitis Virus Type 3 . . . . . . . . Murine Hepatitis Virus JHM . . . . . . . . . 4.1.2 Chronic Infections . . . . . . . . . . . . 4.2 Pathogenicity Associated with Viral Gene Sequences . 5 Conclusions . References. . .

165 166 166 166 168 168 171 171 171 171 173 174 175 176 176 177 178 178 179 179 180 181 181 182 183 183 183 183 184 185 186 187 188 189

1 Introduction The coronaviruses were frrst recognized and morphologically defmed as a group by Tyrrell and co-workers (1968, 1975, 1978). Biochemical studies have recently provided

* Institute ofVrrology and Immunobiology, Versbacher StraBe 7, 0-8700 Wuerzburg, Federal Republic of Germany

M. Cooper et al. (eds.), Current Topics in Microbiology and Immunology © Springer-Verlag Berlin Heidelberg 1982

166 H. Wege et al.

additional information which allows better characterization of these agents. Presently, coronaviruses are defmed as being particles which are pleomorphic to rounded with a diameter of 60-220 nm, surrounded by a fringe or layer oftypical club-shaped spikes. The virion is composed ofabout four to six proteins and possesses a lipid bilayer. The genome consists of a single-stranded polyadenylated RNA which is infectious and of positive polarity. During maturation these viruses are released by internal budding into vesicles derived from the endoplasmatic reticulum. These viruses are widespread in nature and are associated with a great variety of diseases with an acute, subacute, or subclinical disease process. Several reviews have been published describing aspects of the physicochemical and biological properties and the clinical significance of coronaviruses (Mdntosh 1974; Kapikian 1975; Pensaert and Callebaut 1978, Robb and Bond 1979). During the past years new data on the biology of these viruses and on the pathogenesis of diseases, in particular murine-induced coronavirus diseases, have also become available. These recentfmdings are the basis for this review.

2 Biology 2.1 Members of the Coronavirus Group and Their Relationships Table 1lists the coronaviruses described to date, their natural hosts, and the predominant disease type as caused by these viruses. 2.1.1 Antigenic Relationships Our knowledge of the antigenic relationships between the different coronaviruses is

incomplete. The relationships shown in Table 2 are based on results obtained by enzyme-linked immunoassay (Macnaughton 1981; Kraaijeveld et a1. 1980a, b), immunofluorescent and immunoelectron microscopic studies (Pedersen et al. 1978, Pensaert et al. 1981), other serological methods (Reynolds et a1.1980; Gema etal.1981), and the data summarized by Robb and Bond (1979). As shown, the avian and the nonavian coronaviruses each appear to fall into two distinct and unrelated groups. In the case of infectious bronchitis virus (lBV) at least eight different serotypes are at present known (Hopkins 1974) and these again fall into two groups by cluster analyses based on neutralization assays (Darbyshire et al. 1979). Also, comparison of the protein patterns of mv isolates suggested that two groups exist which differ in the electrophoretic migration of the virion glycoproteins (Nagy and Lomniczi 1979; Collins and Alexander 1980). The location of antigenic sites on coronavirion structural proteins has been investigated. Coronaviruses basically contain three major antigens, as has been shown by immunodiffusion experiments (Hajer and Storz 1978; Yaseen and Johnson-Lussenburg 1981) and by the analysis of monospecific antisera prepared against purified coronavirus structural proteins (Schmidt and Kenny 1981). In human, porcine, and murine systems the antigenic sites responsible for the induction ofneutralizing antibodies are associated with the surface glycoproteins (peplomers). Immunological studies with subcomponents prepared from purified virions ofTGEV (Garwes et al. 1978), HCV 229E and MIN-3 (Macnaughton et al. 1981; Hasony and Macnaughton 1981), and HCV-OC43 and 229E (Schmidt

Pig Pig Rat Rat Turkey


Porcine transmissible gastroenteritis virus Porcine hemagglutinating encephalomyelitis virus (vomiting and wasting disease virus) Parker's rat coronavirus c Rat sialodacryoadenitisvirusc Thrkey coronavirus (turkey bluecomb disease coronavirus, turkey coronaviral enteritis virus, coronavirus enteritis of turkeys)


Runde tick coronavirus e

Seabird, tick

Parrot Pig

No data on disease in natural host

Hirai et al. 1979 Pensaert and Debouck 1978 Horvath and Mocsari 1981 Traavik et al. 1977

Bass and Sharpee 1975 Caul et al. 1975 Burks et al. 1980

Parker et al. 1970 Jonas et al. 1969 Adams and Hofstad 1971

Doyle and Hutchings 1946 Roe and Alexander 1958

1Y"e/l and Bynoe 1965 Cheever et al. 1949

Binn et al. 1975 Holzworth 1963

&halkand Hawn 1931 Mebus et al. 1973a

First description


In brackets, synonyms used in literature, b Abbreviations used in literature, C Both viruses might be serotypes of the rat coronaviruses, d Probably serotype(s) of human (respiratory) coronaviruses, e Probably a bunyavirus


Parrot coronavirus Porcine CV-777 and other isolates

Foal enteritis coronavirus Human enteric coronavirus d Isolates SD and SK

Diarrhea Diarrhea Demyelinating encephalomyelitis in mice Diarrhea Diarrhea

Man Mouse


Human coronavirus Murine hepatitis virus

Horse Man Mouse, man

Dog Cat



Diarrhea Peritonitis, granulomatous inflammations in multiple organs Common cold Encephalomyelitis, hepatitis, diarrhea Diarrhea Vomiting and wasting, encephalomyelitis Pneumonitis, rhinitis Adenitis Enteritis


Questionable or unclassified members

Respiratory disease Diarrhea



Avian infectious bronchitis virus Bovine coronavirus (neonatal calf diarrhea coronavirus, enteropathogenic bovine coronavirus, bovine enteric coronavirus) Canine coronavirus Feline infectious peritonitis virus

Predominant clinical disease

Natural host



Table 1. Coronaviruses - designations, natural host and predominant clinical disease


0\ -.I


'" '"




..., g









168 H. Wege et al. Table 2. Antigenic cross-reactions between coronaviruses

Mammalian Group 1

Group 2

HCV-229 E and other isolates TGEV one serotype CCV one serotype illV one serotype

HCV-OC43 and other isolates MHV many serotypes, also related to RCV andSDAV BCV one serotype HEV one serotype


Group 3

Group 4

mv at least 8 serotyes

TCV one serotype No cross-reactions with other strains

No cross-reactions with other strains

Unclassified isolates: Several isolates ofHCV (and HECV), porcine coronavirus CV-777 and others, FECV, RTV

and Kenny 1981) support this conclusion. A similar conclusion was reached by immunoelectron microscopy of bovine coronaviruses (StolZ and Rott 1981). The surface glycoproteins are also involved in complement fIxation and hemagglutinin inhibition. 2.1.2 Nucleic Acid Homologies Some preliminary data on the nucleic acid sequence homology between a few coronaviruses is available. Hybridization with MHV-specific cDNA, representative ofthe entire genome, shows that a close relationship exists between the murine strains MHV-A59, MHV-3 and JHM. Using the same probe no homology between the murine viruses and the human coronavirus 229E could be detected (Weiss and Leibowitz 1981). Using the technique ofT} oligonucleotide fingerprinting Lai and Stahlman (1981a), Weiss and Leibowitz (1981), and Wege et al. (1981a) have shown variation in the genome RNA of murine hepatitis viruses of different neurovirulence (Sect 4.2). This variation seems to be independent of the serological relationships of these strains. In the avian coronavirus group such an analysis also revealed considerable variation within serotypes (Clewley et al.1981). Studies such as these might be useful in characterizing the origin, evolution and spread of both new isolates and live vaccine strains.

2.2 Host Range and Organ Tropism Most coronaviruses cause clinical diseases only in the species from which they were isolated and replicate predominantly in cell lines derived from that host However, transmission to other species can be achieved either experimentally or for some virus strains by a natural route of infection (Table 3). The natural infection of dogs by the porcine strain transmissible gastroenteritis virus (TGEV) and a single case of diarrhea transmitted from cattle to man may indicate a possibly wider host range for enteric infections. The experimental intracerebral inoculation of several coronaviruses into suckling rats, mice,


Cat and other feline species






MHV-2and 3



Only one accidental case report;

Mouse Mouse



Monkeys Rats Hamsters


and Beaudette MHV-JHM


Intracerebral Intracerebral Intracerebral

Intracerebral Intracerebral Intracerebral and intranasal Intranasal Intracerebral


Intracerebral Oral

Intracerebral Oral (natural infection) Intracerebral Intracerebral and intracutaneous Oral

Virus shedding

Asymptomatic infection Hydrocephalus and encephalitis Clinically inapparent hepatitis, encephalitis Encephalitis

Encephalomyelitis Encephalomyelitis Encephalomyelitis

Woods et al. 1981

Inapparent intestinal infection Inapparent CNS infectio?, inapparent intestinal infection Encephalitis

McIntosh et al. 1969 Estola 1967 Kersting and Pette 1956 Cheever et al. 1949 Cheever et al. 1949 Bailey et al. 1949 Taguchi et al. 1979a Hirano et al. 1980 Takahashi et al. 1980 Wege et al. 1981a (Wege et al. unpublished) Jonas et al. 1969 Bhatt et al. 1972 Haelterman 1962 Reynolds and Garwes 1979

Osterhaus et al. 1978a, b. Woods et al. 1981

Kaye et al. 1975a Akashi et al. 1981

Kaye et al. 1977 StolZ and Rott 1981

McIntosh et al. 1967 McIntosh et al. 1969 Larson et al. 1979


Encephalitis Encephalitis

Inapparent intestinal infection Encephalitis Diarrhea


Effect on experirnental host

Other strains not transmissible to mice (Dea et al. 1980a)

Dogs, foxes, cats

Adult rats Suckling rats Suckling mice

Suckling rats Suckling rats

Suckling mice

Newborn mice, rats, and hamsters, piglets



Cattle Cattle

BCV Nebraska BCV Kakegawa

mv Massachusetts

Pig Cattle

HEV-67N BCVLY-138 Suckling mice b Suckling mice, rats, and hamsters Piglets

Suckling mice Mana





Suckling mice, suckling hamsters Dogs



Route of inoculation

Transmissible to

Natural host

Virus strain

Table 3. Host range of coronaviruses





'" '"



n 0 .... 0




1:1 (l)





















++ +

+ +* ++ ++*

+* +









++ + ++* +* +

++* +*







TGEVand HEV others

Murine Porcine

Symbols: ++ main target for infection; + organs less frequently involved; * involvement in persistenUchronic disease







Target organs Central nervous system Blood vessels Ependym Gonad Intestine Kidney Liver Lymphoid organs Pancreas Parotid gland Peritoneum Respiratory tract


Host species

Table 4. Target organs involved in coronavirus infections


















The Biology and Pathogenesis of Coronaviruses 171

or hamsters often induces an infection (Table 3). The brain ofsuckling mice is highly susceptible for viruses of avian, human, and mammaljan origin. However, infection under these experimental conditions is not representative for the clinical disease in the natural host A survey of the organs involved in coronavirus infections is summarized in Table 4. Some coronaviruses reveal relatively restricted organ tropism leading to diseases of the respiratory system (HCV, mY, RCV) and gastrointestinal tract only (BCV, CCV, TGEV, TCV). In other coronavirus infections, for example with feline and murine coronaviruses, several organs are involved. The murine coronaviruses represent a group containing many strains with different organ tropism. In addition, feline, murine, and avian coronavirus strains have a strong tendency to establish persistent and chronic diseases.

3 Coronaviroses and Disease Spectrum 3.1 Murine Coronaviruses 3.1.1 Murine Hepatitis Virus

The frrstmurine coronavirus described was MHV-JHM, which was isolated from a spontaneously paralyzed mouse (Cheever et al. 1949). Subsequently, other strains were isolated from different disease conditions and different organs of mice (Table 5). Murine coronavirus infections are often subclinical or inapparent, but clinical disease can be activated by coinfection with leukemia viruses or protozoal agents. These viruses can be transmitted by feces or urine to susceptible strains (Table 5). Vertical transmissio~ by intrauterine infection can also occur with MHV-JHM (Katami et al. 1978) and the respiratory route is important in natural transmission (Carthew and Sparrow 1981; Taguchi et al. 1979c). The prevalent diseases resulting from MHV infection are hepatitis, encephalomyelitis, and enteritis. A strict classification, of all MHVs into hepatotropic, neurotropic, and enterotropic strains is not possible, however, since under certain conditions several organs are affected (Table 4) and the type of disease varies to a great extent with the age and genetic background of the host (Sect 4.1). The role of murine coronaviruses as pathogens of the respiratory tract must also be taken into consideration (Carthew and Sparrow 1981). Variants which differ in organ tropism are easily selected in tissue culture or by animal passages. Hepatitis

Several murine coronavirus strains replicate predominantly in liver tissue and induce an acute fatal-hepatitis by destruction of parenchymal and Kupffer cells (Table 5; Piazza 1969; Hirano et al. 1981a). The highly virulent strains MHV-2, MHV-3, and MHV-A 59 cause hepatitis in adult mice. MHV-1 andMHV-S are less virulent butlead eventually to a similar disease. MHV-8 is enteropathogenic for young mice whereas most of the other strains (Table 5) cause hepatitis only in newborn mice. MHV-N is virulent only for mice which have been immunosuppressed by cortisone treatment Viruses isolated from nude mice (MHV-NuU, NuA and Nu66) cause chronic hepatitis in athymic mice (Sect 4.1.2). However, tissue-culture-adapted MHV-Nu66 and NuA are also hepatotropic for normal mice, indicating an increase in virulence.

Hirano et aI. 1975 Sebesteny and Hill 1974 Tamura et aI. 1976 Ward et aI. 1977 Hirano et aI. 1979 Sabesin et aI. 1972

Cheever et aI. 1949 Broderson et aI. 1976 Krajt1962 Sato et aI. 1976 Ishida et aI. 1978

Burks et aI. 1980

Burks et aI. 1980

MHV-NuU, NuA, Nu66, and other isolates

MHV-JHM MHV-S/CDC b LIVIM MHV-DVlM MHV-D Unclassified isolates Isolate SD

Isolate SK

Demyelinating encephalomyelitis in mice

Encephalomyeltits, hepatitis Enteritis Enteritis Enteritis Enteritis, hepatitis

Hepatitis in mice treated with cortisone Hepatitis

Hepatitis, encephalitis

Hepatitis, enteritis

Hepatitis Hepatitis, ascites Hepatitis,encephalitis

probably the same strain

a The strains H747, EHF 210 and EHF 120 mentioned in earlier reports (McIntosh 1974) have not been described further; b MHV-S/CDC and LIVIM are

Balb/c mice inoculated with human brain (multiple sclerosis) 2-6 months before isolation Subcultures of 17 CI-1 cells originally inoculated with human brain (multiple sclerosis)

Feces of healthy carrier mice Latent infection of cultured mouse liver cells (NCTC 1469) Spontaneous paralyses of Swiss mice Fatal diarrhea in ICR mice Fatal diarrhea Diarrhea of infant mice Fatal diarrhea in suckling mice

Rowe et aI. 1963



Nelson 1952 Dick et aI. 1956 Manaker et aI. 1961




Spontaneous hepatic disease (albino mouse, Parkes strain) Associated with mouse leukemia (Princeton strain) Inoculation of human serum into Swiss mice Inoculation of organ suspensions from mice with Moloney leukemia into Balb/c Acute diarrhea of newborn CD-1 mice housed with other strains Wasting syndrome in nude mice

Gledhill and Andrewes 1951




Conditions of isolation

First isolation

Straina Predominant effect on host



Table 5. Origin and characteristics of murine coronavirus strains

The Biology and Pathogenesis of Coronaviruses 173 Encephalomyelitis Mureine coronaviruses can cause encephalitis is suckling and adult mice (Table 5;

Hirano et al. 1981a). The strain MHV-JHM is especially neurotropic (Cheever et al. 1949; Bailey et al. 1949), causing acute and chronic demyelinating diseases. By the natural intranasal route of infection the virus invades the central nervous system via the olfactory nerve (Goto et al. 1977, 1979), initially replicating in the nasal mucosa and spreading within 6 days to the spinal cord. The outcome of experimental intracerebral infection is similar and necrotic lesions are localized in the hippocampus, olfactory lobes, and periependymal tissues. Demyelination is prevalently confmed to the brain stem and spinal cord. In mice which do not develop an acute disease involvement of grey matter is minimal and viral antigen is detectable in white matter up to 28 days post infection (Pj.) (Weiner 1973). Electron microscopic studies demonstrated that oligodendrocytes are the main target cells for JHM virus (Lampert 1973; Powe1l1975), but especially in young mice virus can also be detected in neurons and ependymal and endothelial cells, indicating the pantropic nature of this infection (Fleury et al. 1980). Infectious virus can be isolated from animals with acute encephalomyelitis at any time during the disease process. Mice which do not show clinical signs within the ftrst weeks pj. or which recover from disease can develop a chronic infection of the central nervous system. Herndon etal. (1975, 1977) observed small foci of active demyelination in Balb/c mice surviving JHM infection for 16 months. Their studies on remyelination in these mice indicated that some of the oligodendroglia cells active in remyelination might be newly generated cells. No information is available about the presence ofviral antigens in the central nervous system or the isolation of infectious virus from these animals. In recent experiments Stohlman and Weiner(1981) induced a chronic infection by intracerebral inoculation of JHM virus into 3-month-old C57 BLl6 mice. No clinical diseases were observed, but during the frrst 12 days pj. infectious virus was recoverable from liver, brain, and spinal cord. Three months pj. small foci of viral antigen were detectable in 70010 of the animals and by elec-. tron microscopy demyelinated lesions were found. At this point immunosuppression did not lead to clinical disease and no infectious virus could be activated or isolated. These results are in contrast to earlier studies by Weiner (1973) who showed that immunosuppression shortly after infaction modilled a nonfatal infection to an acute encephalomyelitis. This indicates, that the virus-host interactions differ signiftcantly between the acute disease and the chronic infection Experiments using cloned JHM virus and temperature-sensitive (TS) mutants of this strain were reported by Haspel et al. (1978). This collection of genetically stable mutants was tested forneurovirulence in Balb/c mice infected at an age of4 weeks. Whereas wildtype virus was lethal for most animals within 6 days, many TS mutants were found to be less neurovirulent Fatal diseases were caused only after the inoculation of about 10 000 times higher doses of infectious virus than was needed for the wild-type virus. Some of the mutants induced demyelination in the spinal cord of survivors, and only very few animals died of an acute encephalomyelitis. Further studies revealed that the wild-type virus replicates in both neuronal cells and oligodendrocytes, whereas a TS mutant selectively replicates in oligodendrocytes of the spinal cord (Knobler et al. 1981a, b). This selective tropism of mutants within the central nervous system is probably an important parameter for the ability to induce demyelination without resulting in fatal encephalomyelitis. Similar observations of different neurovirulence between wild-type

174 H. Wege et al.

and mutant viruses, obtained by mutagens or isolated from persistent infections, have been reported by Robb et al. (1979) and Hirano et al. (1981b). Cheever et al. (1949) described a delayed course of encephalomyelitis with marked demyelination in rats after inoculation of wild-type JHM virus. These original observations have been recently enlarged upon (Nagashima et al. 1978a, b; 1979). The infection of outbred rats (strain Thomae/Chbb) with uncloned JHM virus results in acute or subacute to chronic demyelinating encephalomyelitis which is dependent on the age of the animals, the time of infection, and the virus preparation used. In suckling rats an acute panencephalitis characterized by necrotic lesions in all parts of the central nervous system is found. In weanling rats (age 3-4 weeks), however, a subacute demyelinating encephalomyelitis can occur after an incubation time of several weeks. Demyelinating plaques are sharply demarcated and distributed in the white matter of the central nervous system. A similar disease picture is also found in other rat strains (Sorensen et al. 1980). Preliminary results indicate that the susceptibility of inbred rat strains is dependent on genetic traits (Sorensen et al. 1981). Kinetic studies during the development of subacute demyelinating encephalomyelitis in weanling rats infected with JHM virus suggest a biphasic course of the disease (Wege et al. 1981b). Within 2 weeks p.i. most of the rats develop a clinically silent acute encephalomyelitis in parallel to the replication of the virus in the central nervous system. After this period virus cannot be recovered from these animals, but histologically marked demyelinating lesions are found prior to the development of a subacute encephalomyelitis. By the time a clinically recognizable disease appears JHM virus is again isolatable. Occasionally remissions after acute disease are observed (Sorensen et al. 1980), and surviving rats sometimes develop a late demyelinating encephalomyelitis after an incubation time of up to 8 months (Nagashima et al. 1979). Brain sections of these animals reveal viral antigen and with conventional techniques virus can be isolated. These observations indicate a persistent infection of the brain tissue which is reponsible for a chronic disease process. Whereas wild-type JHM virus varies in its ability to induce subacute and late diseases in weanling rats, TS mutants cause high rates of subacute to chronic diseases. Moreover, suckling rats from immunized mothers can also develop chronic demyelinating diseases if inoculated with TS mutants (Wege et al. 1981b). These observations suggest that the development of acute or subacute to chronic demyelinating disease is dependent on the virulence of the virus and host factors such as age, immune status, and genetic background. Enteritis Several enteropathogenic strains of murine coronaviruses have been isolated during the last few years (Table 5). The fIrst agent of this type was investigated by Kraft (1962) and termed lethal intestinal virus for infant mice (LIVIM). This agent is probably identical with an enterotropic variant of MHV-S described by Rowe et al. (1963) which was later designated MHV-S/CDC by Broderson et al. (1976). These viruses cause an acute intestinal disease with a high mortality rate during the fIrst 3 weeks of life. Intestinal contents from moribund mice contain typical coronavirus particles and the virus spreads by contact infection via the nasal or oral route in newborn mice. Diseased animals are dehy-

The BiolQgy and Pathogenesis of Coronaviruses 175

drated by severe diarrhea. Multinucleated giant cells are found especially in the villi of the small intestines (Biggers et al. 1964). By electron microscopy large numbers of coronavirus particles are detectable in intestinal epithelial cells and in macrophages of the lamina propria of the lower intestines (Hierholzeret al. 1979). The mothers ofaffected litters are clinically healthy but necrotic foci are found in the liver. Orally infected adult animals do not develop dermed clinical signs and shed virus for about 15 days. Intranasal infection by cell-adapted virus leads to a mild diarrhea without mortality. These mice show no evidence of liver or brain disease. Litters from immune mothers are protected against both natural and experimental infection. Strain MIN-S/CDC is serologically related to other MIN prototype strains, especially to MIN-S, and to the human strain OC43 (Hierholzeret al. 1979). Endemics ofLMM disease were reported by Carthew (1977) and a similar virus-designated MIN D-was isolated during a natural outbreak of diarrhea (Ishida et al. 1978; Ishida and FUjiwara 1979). MIN-D tends to produce a more systemic infection with the involvement of liver, brain, lung, and lymphoid organs. Another isolate, MIN-DVIM, causes diarrhea in infant mice and is remarkable for its ability to agglutinate red blood cells from rats and mice (Sato et al. 1976; Sugiyama and Amano 1980).

3.2 Human Coronaviruses Human coronaviruses are often responsible for common colds and are associated with lower respiratory tract diseases and probably enteric diseases. Essentially two groups of isolates can be distinguished. One group grows in tissue cultures of human origin and is related to the prototype strain 229E; the other group can only be maintained in organ cultures, for example strain OC43. The antigenic relationships are summarized in Table 2. These viruses are distributed worldwide and antibodies are present with high prevalence (Monto 1974; Kaye et al. 1975; Gerna et al. 1978). The antibody response to 229E and OC43 appears to have a cycle of several years, with peaks against each strain every 2-3 years. About 15% of common colds are attributed to coronaviruses (Mdntosh et al. 1970; Larson et al. 1980). In children pneumonia and other respiratory distress can be caused by coronaviruses (Mdntosh et al. 1973, 1974). Results of a seroepidemiological survey (Riski and Hovi 1980) indicate a possible association of coronaviruses with more severe diseases such as pneumonia, pleurodynia, myocarditis, and meningitis. An agent termed Tettnang virus has been isolated by inoculation of cerebrospinal fluid from patients with various neuropathies and fever into suckling mice (Malkova et al. 1980). This virus and similar isolates probably respresent MIN strains which naturally infect these mice (Bardos et al. 1980). The development of the common cold was studied in human volunteers inoculated with HCV (Bradbume et al.1967; Beare and Reed 1976, Mdntosh etal. 1978). Virus inoculated by nasal drops causes predominantly coryza, but in contrast to rhinoviruses no cough or mucopurulent nasal discharge occurs. Virus shedding decreases sharply within 3-4 days pj. No evidence for involvement of the lower respiratory tract or intestinal organs was found under experimental conditions. The cilial epithelium is selectively infected and shedding ofantigen-containing cells coincide withe coryza. Rechallenge of volunteers with homologous and heterologous virus 8-12 months pj. revealed that no crossprotection occurs against the heterologous strain but immunity against homologous virus exists (Larson et al. 1980).

176 H. Wege et at.

The systemic immune response against purified HCV 229E and subcomponents have been quantitated by an enzyme-linked immunoassay (Kraaijeveld et al.1980b; Macnaughton et al. 1981) and the results indicate that most of the antibodies produced during infection react with the peplomer protein of the virus. Only small amounts of antibodies recognize the matrix and nucleocapsid protein. No data on the role oflocal immunity in protection against respiratory disease are available. In addition to respiratory diseases some human coronaviruses may be associated with enteric infections (Caul et al.1975; Caul and Clarke 1975; Moore et al. 1977; Caul and Egglestone 1977; Schnagl et al. 1978; Moscovici et al.1980). However, no information exists on the characterization of these agents and their serological relationships to other human coronaviruses (reviewed by Macnaughton and Davies 1981). Coronaviruses have also been associated with an endemic nephropathy (Apostolov et al. 1975), but there are no studies revealing an etiological link between nephropathy and coronaviruses. Two coronavirus strains were recently isolated from mice or mouse tissue culture cells during attempts to isolate viruses from patients with multiple sclerosis (Burks et al. 1980). The frrstisolate, designated SD virus, was isolated after intracerebral inoculation of human brain material into weanling Balb/c mice. Within 2-6 months p.i., mice developed neurological signs and died. From these animals a coronavirus was isolated which replicated in the 17 Cl-l mouse cell line. The second isolate, designated SK virus, was obtained after 12 subcultures of 17 Cl-l cells which had been incubated with brain material from a second patient These isolates are antigenically related to both murine and human coronaviruses and reveal related structural polypeptides as shown by immunoprecipitation (Gerdes et al. 1981a, b). At the present time it cannot be decided whether these isolates have been derived from human or mouse tissue, since it is known that murine coronaviruses establish latency in mouse colonies as well as in mouse tissue cultures (Sabesin 1972). Additionally, serological studies by Leinikki et al. (1981) could not demonstrate any correlation between coronavirus antibody titers and patients with multiple sclerosis or other neurological diseases. Further studies are necessary to show if there is an association of coronaviruses SD and SK with multiple sclerosis.

3.3 AvianCoronaviruses 3.3.1 Infectious Bronchitis Virus Avian mv infects young chickens, causing an acute respiratory disease leading to high mortality and a decrease in yield and quality of egg production. The disease was fIrst described by Schalk and Hawn (1931) and is a very common and worldwide infection in poultry flocks. The virus spreads by both air and the fecal-oral route. At least eight mv serotypes have been described (Dawson and Gough 1971; Hopkins 1974). These serotypes fall into two main groups, the Massachusetts and Connecticut types, which differ in their antigenic relatedness (Sect 2). The virulence of many different isolates and attenuated vaccine strains differs widely. The primary target tissue for infection is the trachea (Purcell and McFerran 1972; Darbyshire et al. 1975). The virus replicates also in bronchial tissue, lung, kidneys, ovaries, and oviduct A strong tendency to produce a prolonged infection which results in shedding of virus of several months via the feces has been observed (Alexanderand Gough 1977). Per-

The Biology and Pathogenesis of Coronaviruses 177

sistent infection in the presence of high antibody titers is often accompanied by severe nephritis and infectious virus can be reisolated from cecal lymph nodes up to 8 months p.i. (Alexander et al. 1978). Both age and genetic factors influence the outcome of the diseases. In addition, infections by bacteria, mycoplasmas, or infectious bursal disease virus (Rosenberger and Gelb 1978) increase the susceptibility of chickens to my. Resistance to natural infection or experimental challenge after vaccination is probably mediated by the local immune response in the trachea, the nasal mucosa, and the Harderian gland. Detailed knowledge of the humoral or cellular immune mechanisms is not yet available (reviewed by Darbyshire 1981). No correlation between serumneutralizing antibodies and resistance to reinfection has been shown, but protection seems to be correlated to resistance of the tracheal epithelium to challenge virus and the presence of high titers of hemagglutinin-inhibiting serum antibodies (Gough and A lexander 1979). Secretion of local antibodies can also be demonstrated in organ cultures (Gomez and Raggi 1974; Darbyshire 1980). Cross-protection against challenge by homologous and heterologous virus strains can be measured by observation of the ciliary activity of tracheal explants from vaccinated chickens. The local antibody response is quite independent of the kinetics of the serum antibody development (Holmes 1973; Leslie and Martin 1973; Watanabe et al.1975; Chhabra and Goel 1980). Whereas antibodies were frrst detected 3 days p.i. in the trachea and the titers fall again several weeks later, serum antibodies maintain a persistently high titer. IgG, IgA, and IgM are all detectable in tracheal washings. However, it should be noted that the antibody patterns detected by neutralization tests and enzymelinked immunoassay (Mockett and Darbyshire 1981) are not identical, indicating that antibodies with different specificity and avidity might be detected by the two techniques. Cell-mediated immunity is demonstrable by specific lymphoblast transformation, but the role in pathogenesis is not yet known (Timms et at 1980). Maternal antibodies are transferred to chicks during development and may contribute to protection early after hatching (Darbyshire 1981). Under experimental conditions respiratory symptoms are observed between 2 and 8 days p.i, accompanied by complete absence of ciliary activity. Maximum virus titers are obtained 3 days p.i. The morphology of epithelial cells changes and thickening of mucosa, edema, and lylnphocytic infIltration are observed (Hawkes et at personal communication). Using immunofluorescence small groups of fluorescent cells can still be demonstrated 6 weeks p.i., but the regenerated tracheal epithelium seems to be restistant to destruction by virus infection. 3.3.2 Turkey Coronavirus

In the 1950s a virus was suspected to induce a transmissible enteritis of turkeys in Minnesota. By electron microscopic studies, a coronavirus-like agent was identifIed (Ritchie et al. 1973; Panigrahy et al. 1974) and characterized by physiochemical and morphological criteria (Deshmukh and Pomeroy 1974; Naqui et al. 1975). By immunoelectron-microscopy no cross-reaction of this virus to other coronaviruses was found (Ritchieetal.1973), but different isolates ofTCV are probably antigenically identical (Pomeroy et al. 1975). No tissue culture system is available for propagation of the virus but the virus grows in embryonated eggs (Adams and Hofstad 1971).

178 H. Wege et al.

The onset of the clinical disease caused by this virus is characterized by depression, loss ofappetite, weightloss, and watery diarrhea. The mortality, especially in older poults, is very low. The lesions in experimental and field cases are very similar to the changes caused by mammalian enterotropic coronaviruses and consist in a marked shortening of the villi, loss of microvilli, epithelial desquamation, and hemorrhage in the jejunum, ileum, and cecum. The number of goblet cells decreases, and the appearance of epithelial cells changes from columnar to cuboidal form (Adams et al. 1972; Desmukh et al. 1976; Gonder et al. 1976). The lesions appear within 1 day pj., and recovery and healing begins after about 5 days. No pathological changes are observed in other organs. The number of lymphoid cells in the lamina propria increases and the villus to crypt ratio remains depressed for 10 days. Despite an early regression of histopathological changes, viral antigen can be found by immunofluorescence up to 28 days pj. Turkeys that recover are immune throughout their lives (Pomeroy et al. 1975). This lifelong immunity is mediated by the secretory IgA antibody barrier (Nagaraja and Pomeroy 1978, 1980, 1981). Serum-neutralizing antibody titers are very low, but intestinal secretions and bile contain virusspecific IgA antibodies for at least 6 months p.i. By immunofluorescence, antibody-secreting cells can be localized in the intestines 4-5 months after recovery from disease. In addition to local immunity, peripherallymphocytes are specifically stimulated by virus antigen. These lymphocytes probably migrate from the intestinal lamina propria to the peripheral blood. Circulating IgA and IgM antibodies appear only during the acute phase of the disease (Carson et al. 1972).

3.4 Feline Coronaviruses 3.4.1 Feline Infectious Peritonitis Virus Feline infectious peritonitis virus (FIPV) normally causes widespread inapparent infections of wild and domestic cats, but the infection can also lead to a fatal disease. The disease syndrome was first described by Holzworth (1963) and experimentally transmitted from field cases to other cats by Wolfe and Griesemer (1966). A coronavirus was identified as the cause of this disease by both morphological and physiochemical criteria (Ward 1970; Osterhaus et al. 1976; Pedersen 1976a; HOlZinek et al. 1977). Serologically this agent reveals an antigenic relationship to the TGEV of pigs (Witte et al. 1977; Reynolds et al. 1977; Pedersen et al. 1978) and to CCV (Everman et al. 1981). Recently a tissue culture system was found which supports the growth of FIPV, and several isolates from field cases are now available (O'Reilly et al. 1979; Black etal.1980; Everman et al. 1981; McKeirnan et al. 1981). It is unknown, whether these isolates are serologically and biologically identical or represent different strains of FIPV. In nature the virus infects cats and other feline species. Randomly collected sera from wild cats and catteries are often up to 90% positive, indicating a wide distribution of the virus (Pedersen 1976b; Osterhaus et al. 1977; Loif.fler et al. 1978). However, the incidence of clinical disease is rather low, usually up to 10%. The virus probably causes a high rate of inapparent infections as coronavirus-like particles have been demonstrated in feces of normal cats. Furthermore, the virus replicates in organ cultures of both small intestines and trachea, causing only small ultrastructural changes of absorptive epithelial cells (Hoshino and Scott 1978, 1980a, b). Under epizootic conditions, the incubation time of clinical disease ranges from

The Biology and Pathogenesis of Coronaviruses 179

several weeks to 4 months (Hardy and Hurvitz 1971; Robison et al. 1971). Experimentally transmitted disease occurs after a much shorter incubation time, which may last only 2-3 days from oral inoculation (Pedersen and Boyle 1980; Everman et al. 1981). The clinical onset of disease is rather unspecific and characterized by fever, loss of appetite, and general depression. In typical cases swelling of the abdomen is observed as a result of peritonitis, but this effusive form is not always clinically detectable. In the noneffusive (dry) form localized granulomatous lesions are found. Both the effusive and noneffusive forms are caused by the same virus inoculum (Hayashi etal.1980; Everman et al. 1981). In addition, both neurological symptoms and pleuritis are observed. After onset of disease, several pathophysiological changes indicate damage to the reticuloendothelial system, liver, and kidneys (Gouffoux et al. 1975; Weiss et al. 1980). A depression of several plasma factors and an increase of fibrin-fibrinogen degradation products is accompanied by anemia, neutrophilia, and leukopenia. The amount of gammaglobulins increases significantly and the urine contains elevated levels of proteins, bilirubin, and urobilinogen. The level of liver-specific enzymes is very high. In the effusive form, fibrin is deposited on abdominal organs. Granulomatous inflammatory reactions, vasculitis, and plaques of focal necrosis are scattered through the parenchyma of the liver, kidneys, lung, spleen, and lymph organs. Central nervous system and ocular lesions can also occur, depending on the route of inoculation (Ward etal.1974). Virus can be isolated from peritoneal exudate, organ homogenates, and blood. Several observations support the concept that FIP might be an immunopathologically mediated disease (HolZinek et al. 1979). High levels of antibodies are often detected in field cases, but do not prevent disease (Pederson et al. 1976b; HOlZineket al. 1978). Experimentally infected seronegative kittens survive significantly longer and develop a less fulminant disease than seropositive kittens (Weiss et al. 1980; Pedersen and Boyle 1980). Moreover, treatment of seronegative kittens with purified anti-FIP IgG results in an aggravation of the disease. In addition, lesions in the liver and serosa of seropositive kittens contain viral antigen, IgG bound to antigen, and complement. In these animals immune complexes can be demonstrated in renal glomeruli tissue (Jacobse-Geels et al. 1980). These fmdings indicate that the immune response against FIPV infections does not have a protective but maybe a destructive effect. In this context it is of interest that the disease often occurs in association with other virus infections such as feline leukemia, feline panleukopenia (a parvovirus), and feline syncytial virus (Cotter et al. 1973; Black 1980; McKeiman et al. 1981). In such cases an enhancement of the FIPV-induced disease process is observed. It is possible that a preexisting persistent viral infection either leads to a higher susceptibility to FIPV or supports the manifestation of a disease state.

3.5 Other Coronaviruses 3.5.1 Bovine Coronavirus Rotaviruses, parvoviruses and coronaviruses are the main causes of bovine viral diarrhea. Mebus et al. (1973a, b) described a coronavirus-like agent associated with diarrhea in young calfs (neonatal calf diarrhea coronavirus), which was identified by morphological and physicochemical criteria (Stair et al. 1972; Sharpee et al. 1976; Dea et al. 1980a, b). This agent has been adapted to grow in tissue cultures and can easily be transmitted by the oral route.

180 H. Wege et al.

Other BCV strains cannot be grown on tissue culture and must be maintained by passage in vivo (Doughri et al. 1976; Doughri and StolZ 1977). Both these and the tissue-culture-adapted strains (Mebus et al. 1975) cause clinical signs of diarrhea within 24-30 h of inoculation. These symptoms last for 4-5 days and can be letha1. The most severe lesions develop in the small intestines, but the large intestines are also infected. The experimental observation that the addition of trypsin to culture media results in a significant enhancement of virus growth in vitro (Dea et al. 1980b; StolZ et al. 1981) suggests that the initiation of infection might be promoted by the action of proteolytic enzymes in the intestinal tract. Virions derived from such trypsin-treated in vitro cultures show shorter surface projections than usual (StolZ et al. 1981). The destruction of the intestinal absorptive epithelium leads rapidly to pathophysiological changes followed by extensive loss of water, sodium, chloride, bicarbonate, and potassium. Metabolism of glucose and lactate becomes severely disturbed and hypoglycemia, lactic acidosis, and an elevated effiux of potassium to the hypovolemic plasma consequently lead to acute shock, heart failure, and death (summarized by Lewis and Phillips 1978; Phillips and Case 1980). Maternal antibodies (IgA and IgM) are transmitted via colostrum to calves and reduce the severeness of disease (Mebus et a1. 1976). More than 50% of bovine sera contain antibodies againstthe BCV strain L Y -138 (Hajer and StolZ 1978; StolZ and Rott 1980). Furthermore, high percentages of human sera from different sources cross-react with BCV antigens in immunodiffusion, neutralization, and electron microscopic tests (StolZ and Rott 1981). The common reactive antigenes) responsible for neutralization is associated with the virion peplomers, but other studies indicate that additionally internal antigens may be responsible for cross-reactivity (Gema et a1. 1981). A single case of diarrhea caused in man by infection with a BCV has been observed (StolZ and Rott 1981), and could indicate that the high degree of reactive antibodies in human sera may result from infection with bovine strains. 3.5.2 Canine Coronavirus Canine coronaviruses usually induce a self-limiting mild gastroenteritis in dogs. CCV has been isolated during an epizootic outbreak of diarrheal disease in military dogs in 1971 (Binn et at. 1975) and during two outbreaks of a highly contagious vomiting and diarrheal disease in the USA (Appel et al. 1979). CCV often occurs in association with canine parvoviruses, which cause a similar but more severe enteric disease (Appel et a1. 1979; Helfer-Baker et al. 1980). Serologically, CCV is more predominant among kennel dogs than among family dogs (62%-87% vs 22%) and the incidence of animals seropositive against coronavirus in combination with parvovirus is also much higher in kennel dogs than in family dogs (55.6% vs 7.4%). Epizootic fatal canine enteritis caused by both viruses can also occur among captive coyote populations (Everman et al. 1980). Canine coronavirus cross-reacts strongly with the porcine TGEV, although it can be serologically differentiated (Reynolds et a1. 1980; Gmwes and Reynolds 1981). It is also serologically related to FIPV (Everman et al.1981). CCV cannot infect piglets, but TGEV can be transmitted to dogs without causing clinical signs (Larson et al. 1979). The oral inoculation of beagle pups leads within 1-7 days to enteritis and diarrhea (Keenan et a1. 1976; Takeuchi et a1. 1976; Nelson et al. 1979). The lesions, which consist of atrophy and fusion of intestinal villi, are most predominant in the ileum. Virus can be recovered from duodenum, jejunum, ileum, colon, and mesenteric lymph nodes, but no

The Biology and Pathogenesis of Coronaviruses 181

further spread of virus is detectable. Within 1-2 weeks the diarrhea and histopathological changes disappear and antibodies are detectable. The disease has a more severe course in very young pups than in older pups.

3.5.3 Hemagglutinating Encephalomyelitis Virus Hemagglutinating encephalomyelitis virus (HEV) selectively infects neuronal tissue of pigs and causes a vomiting and wasting disease. The disease was fIrst described as an epizootic outbreak in Canadian swine herds leading to high morbidity in suckling pigs (Roe and Alexander1958). Clinical symptoms consist of vomiting and depression which can lead to death after emaciation and starvation. Additionally, neurological signs of encephalomyelitis appear (Werdin et al.1976). The mortality in young pigs is very high: older litters often survive but remain permanently stunted. Clinical outbreaks are now not so predominant but high percentages of sera contain antibodies, indicating a wide distribution of the virus. The virus exists as a subclinical infection in the presence of maternal antibodies. After the weaning period an active immunity develops (Andries and Pen-

saert 1981). Greig et al. (1962) were the fIrst to isolate HEV. Mengeling and Cutlip (1976) demon-

strated that both the vomiting disease and encephalomyelitis are caused by the same virus. Pathogenetic studies reveal that after oronasal infection of newborn colostrum-deprived pigs the virus replicates in the respiratory tract, the tonsils, and small intestines and spreads via nerve tracts to the peripheral ganglia nearest to the sites of primary infection (Andries and Pensaert 1980a, b; Andries et al. 1978). Vomiting starts 4 days pj. at the time when the virus is detected in neurons of peripheral ganglia. In the central nervous system the viral antigen is fIrst detected in the sensory nuclei of the trigeminal and vagal nerve located in the medulla oblongata, and then spreads to the brain stem and occasionally to the cerebrum, cerebellum, and spinal cord. The infection of other organs or viremia doesnot play a signiftcant role in the pathogenesis of the disease. The local inoculation of the virus intragastrically, intraintestinally, intramuscularly, or into the cerebrosllinal fluid always leads to the same clinical signs. However, the distribution of viral antigens is very different depending on the route of inoculation. Thus it seems probable that infection of neurons in different locations could lead to vomiting due to a disturbance of regulatory mechanisms. A further consequence of the infection of neuronal cells is paralysis of the ileum, which leads to emaciation and death by starvation. 3.5.4 Transmissible Gastroenteritis Virus Transmissible gastroenteritis (TGE) is an acute disease affecting pigs of all ages. Especially in pigs under 2 weeks of age, the infection leads after a short incubation period to diarrhea and vomiting, resulting frequently in death within 3-6 days. Older pigs are less severely affected. The targets for virus replication after oral transmission are absorptive cells of the small intestine (Pensaert et al. 1970). However, respiratory infection can also occur, and viruses can persist for prolonged times in lung tissue of older pigs (Underthal et al. 1974, 1975; Watt 1978). In the infected intestinal cells necrotic lesions develop and lead to pro-

182 H. Wege et at.

gressive shortening of the villi. Replacement of the villous epithelial cells begins 18-72 h pj. by migration of undifferentiated cells from the crypts. These crypt cells are resistant against infection. The epithelial cells of microvilli are important for the digestion of disaccharides and the absorption ofmonosaccharides and contribute to osmoregulation. Their destruction leads consequently to diarrhea, acidosis, and dehydration (Moon et al. 1978; Shepherd et al. 1979a, b). A key role in the defence against TGE is played by the local immune response of secretory IgA and IgM production (Stone et at. 1977; Kodama et al. 1980). Recovery from infection might also be enhanced by a strong cell-mediated local immune response (Frederickand BohI1976; Shimizu and Shimizu 1979). Interferon (type 1) also appears early in the disease process and is probably secreted by local enterocytes. However, intestinal and serum interferon appear to have little protective effect, since up to 100% of newborn pigs die after infection (La Bonnardiere and Laude 1981). The transfer of antibodies via colostrum and milk is of practical importance for protection of suckling pigs. Several attenuated virus strains with low virulence are now available for vaccination of pregnant sows (Hess et al. 1977; Saifand BohI1979). IgA-secreting lymphocytes are locally stimulated in the lamina propria and invade the mammary glands. The pathological changes after oral infection are strongly dependent on the virulence of the TGEV inoculated, since attenuated strains infect only short parts of the intestines and cause only little atrophy of microvilli (Hess et al. 1977). However, the advantage of restricted growth of attenuated virus is counterbalanced by only a weak stimulation ofIgA-secreting cells. Recently, a coronavirus designated CV-777 was isolated in epizootic diarrhea outbreaks (Pensaert and Debouck 1978). No antigenic relationships to other coronaviruses were detected (Pensaert etal. 1981). The disease course is slower than in TGE andaccompanied by less cell destruction (Debouck and Pensaert 1980). CV-777 also replicates to a certain extent in the duodenum and colon and infects crypt cells without destroying their regenerative potential. Another porcine virus unrelated to TGEV was recently described by Horvath and Mocsori (1981). . 3.5.5 Rat Coronavims

Two different coronavirus strains have been isolated from rats. Parker's rat coronavirus (RCV) is pathogenic for the respiratory system of rats, whereas the sialodacryoadenitis virus (SDAV) has a pronounced tropism for salivary and lacrimal glands. These viruses replicate on primary rat kidney cells but not on cells susceptible to MHV infection. Isolation ofRCV was achieved by inoculation oflung tissue homogenates of rats into specific pathogen-free animals (Parker et al. 1970). Newborn rats infected intranasally with RCV develop respiratory disease and die within 6-U days pj. Rats older than 21 days remain clinically healthy. Histopathological lesions are typical for an interstitial pneumonitis. Virus replication is confmed to the mucosal epithelium and lungs. Virus was only exceptionally recovered from salivary and submaxillary glands (Bhatt and Jacoby 1977). Initially was SDAV detected by electron microscopy in the salivary glands of rats. Infectious virus was subsequently isolated by inoculation of organ homogenates into newborn mice (Jonas et al. 1969). The virus is pathogenic for newborn mice by intracerebral inoculation and causes neuronal degradation. Mouse passaged virus induces lesions

The Biology and Pathogenesis of Coronaviruses 183

of the salivary and lacrimal glands in rats (Bhatt et al. 1972). After intranasal inoculation the virus spreads from the respiratory tract via cervical lymph nodes to submaxillary and parotid salivary glands (Jacoby et al. 1975). Within 2 days a rhinitis develops and necrotic lesions spread, especially in the ductal epithelium of the affected glands. The disease is self-limiting and no spread to other organs is detectable. Antibodies are demonstrable within 7 days. In addition to the infection of salivary glands, a keratoconjunctivitis and ophthalmic lesions can be associated with the disease (Lai et al. 1976; Weisbroth and Peress 1977). These lesions may be a secondary phenomenon due to bacterial invasion and impediment of the lacrimal glands.

4 Pathogenetic Aspects The development of a disease process depends not only on the biological properties of the infectious agent but also on the host. Such factors as susceptibility, spread of virus through the body, type and severity of disease, and control and elimination of the infectious virus are all host-dependent. In this context, experiments carried out with MHVs have provided important information on the pathogenic mechanisms of coronavirus infections.

4.1 The Role of Resistance in The Development of Disease 4.1.1 Acute Infectious Murine Hepatitis Virus Type 2 The fIrst evidence for an association of host genes with resistance to MHV infection was reported for MHV-2, which causes a fulminant hepatitis with high lethality in PRI mice but no clinical disease in adult C3H mice. Bang and Wmwick (1960) observed that peritoneal macrophages derived from PRI mice and cultured in vitro are able to replicate MHV-2, whereas novirus growth was detected in cultures ofC3H macrophages. Breeding experiments indicated that resistance is inherited by a single recessive gene. These observations suggested that the result of virus infection may depend on the genetically determined ability of cells from the macrophage lineage to replicate the virus. A difference in susceptibility of macro phages was also observed by Taguchi etal. (1976) who compared the mouse strains DDD and CDP 1. However, as the following experiments illustrate, a complex network of interactions with other cells of the immune system also influences and modifIes the outcome of infection (Bang 1981). Shif and Bang (1970a, b) demonstrated that macrophages of PRI and C3H mice absorb and take up the virus equally well although macrophage cultures derived from resistant C3H mice did not produce detectable amounts of infectious virus. The ability of macrophages from both strains to replicate equally well a variant virus which arose during high multiplicity of infection indicates, however, that this genetically determined resistance is not absolute and can be overcome by strain variation. Weiser and Bang (1976) bred a mouse strain (C3HSS) which contains the gene for MHV-2 susceptibility from PRI mice but is in all other respects congenic with the resistant C3H strain. Cotijl et al. (cit Bang 1981) used this new strain to show that whilst MHV-2 can replicate under single-

184 H. Wege et al.

cycle conditions in macrophage cultures from both resistant and susceptible strains, the virus produced in resistant macrophages is relatively much less infectious for the genetically incompatible system. Additional experiments have also shown that the resistance of adult C3H mice to hepatitis induced by MHV-2 can be modulated by procedures affecting T-cell functions. Whilst normal mice develop transitory hepatic lesions which do not lead to clinical signs, thymectomized animals are no longer resistant and die with an acute hepatitis (Sheets et a1. 1978). Macrophage cultures derived from thymectomized animals are, however, still relatively resistant This indicates that in addition to macrophage resistance, thymus-dependent functions are involved in preventing the disease. Also treatment of C3H mice with hydrocortisone, a steroid which suppresses T-cell functions, abolishes the resistance of C3H mice to MHV-2 (Gallily et al. 1964). On the other hand, polyclonal stimulation of lymphocytes by inoculation of concanavalin A into normally susceptible PRI mice induces resistance, again suggesting the involvement of T cell-mediated factors ( Weiser and Bang 1977). These in vivo observations were further supported by experiments with cultured macrophages in vitro (Weiser and Bang 1976, 1977; Taylor et al. 1981). These authors showed that macrophages from resistant mice can be modulated in their susceptibility by the addition of soluble mediators (lymphokines and interferon) which have been secreted by stimulated lymphocyte cultures. Murine Hepatitis Virus Type 3 In the MHV-3 system, the resistance or susceptibility of animals is correlated with the degree of virus growth in macrophage cultures (Virelizierand Allison 1976; Macnaughton and Patterson 1980; reviewed by Virelizier 1981). Whilst little or no virus replication occurs in macrophage cultures from AIJ mice, a resistant strain (Table 6), the degree ofvirus replication in macrophage cultures from susceptible and semiresistant strains reflects the pathogenicity ofMHV-3 for the particular host Resistant and susceptible macrophage cultures absorb and incorporate virions to the same extend (Krzystyniak and Dupuy,

Table 6. Different diseases induced by MHV-3 in inbread strains of mice. (Virelizier et al. 1975; Le

Prevost et al. 1975a; Yamada et al. 1979) Type of disease

Mouse strain inoculated

Age at time of intraperitoneal infection

Lethal, fulminant hepatitis 5-8 days pj., systemic infection Lethal hepatitis 6-10 days pj., selective destruction of T cells Chronic vasculitis 2-12 months pj. Chronic chorioependyrnitis 2-12 months pj. Clearance of virus within 7 days, survival Inapparent hepatitis, clearance of virus within 7 days pj.

C57 BLl6, Balb/c, DBA2, and others C3H1He

6-8 weeks


5-8 months 6-8 weeks Over 10 weeks 4 weeks

4 weeks

The Biology and Pathogenesis of Coronaviruses 185

1981). The restriction may affectlater stages in virus replication. LelYetal. (1981) observed that infection of macrophages from susceptible mouse strains leads to a significant stimulation of the blood coagulation system. This may be an additional parameter which contributes to the development of disease. The genetically determined degree of susceptibility is not only restricted to peritoneal macrophages, since hepatocyte cultures obtained by perfusion ofliver also reveal the same type of genetic restriction (A mheiter and Haller 1981). LeIY-Leblond et al. (1979) have shown that at least two recessive genes are responsible for resistance and that they are associated with the histocompatibility (H2) genes. This suggests that antigen recognition by T -lymphocytes plays a role in virus elimination. Further evidence that impairment of virus replication in macrophages and cooperation with cells of the T-cell lineage are both required for resistance is the observation that resistance can only be transferred if peritoneal cells and adherent spleen cells are inoculated together (LeIY-Leblond and Dupuy 1977). Additionally, bone marrow cells enhance the protection transferred by spleen cells (Tardieu et al. 1980). The host-cell gene functions which regulate the susceptibility for MIN-3 are apparently not important for the replication of other viruses (Amheiter and Haller 1981). The interferon system represents another important line of defence against MIN-3 infection. Interferon is released by macrophages during the fIrst cycles of virus replication and is induced in both resistant and susceptible mouse strains, with peak titers 1-2 days pj. (Virelizieret al.1976). Application of an antiserum against virus-induced (type 1) interferon amplifles the disease course in susceptible mice and abolishes resistance if inoculated into resistant strains shortly before virus infection (Virelizierand Gresser 1978). No enhancement of disease by anti-interferon globulin can be found in chronically diseased animals (Sect 4.1.2). As in the MIN-2 system, inlrnunosuppressive treatments such as thymectomy or treatment with anti Thy-1 serum aggravate the disease - induced b-y MIN-3 and indicate that T cell-mediated immune mechanisms contribute to resistance (Dupuy et al. 1975). SpecifIc antibodies are not of major importance, since transfer of serum from immunized, resistant mice to susceptible mice gives no protection (LePrevostetal.1975). It should also be noted, however, that immunosuppressive treatments impair not only T-cell functions but also the production of virus-induced interferon (Virelizieretal.1979). Interperitoneal inoculation of inactivated Corynebacterium parvum together with MIN-3 suppresses the development of disease (Schindleret al. 1981). This type of resistance may be due to a nonspecifIc immune stimulation and activation of macrophages. This situation is still further complicated by the influence of age of the mouse at the time ofMIN-3 infection. For example, in young C3H mice T cells and not macrophages are the primary target for MIN-3 replication (Yamada et al. 1979). Thus although C3H mice infected at 4 weeks of age are susceptible, whilst D D D mice are relatively resistant, (Table 6), peritoneal macrophages from both strains support virus growth to the same extent and serum interferon titers are very similar. However, in cultured spleen cells ofC3H mice virus growth is associated only with Thy-1-antigen-positive cells. Murine Hepatitis Virus JHM The third MIN strain that has been studied in some detail is MIN-JHM. Stohlman and Frelinger(1978) showed that resistance to JHM virus is a recessive genetic trait, not strongly associated with the H2 complex. The interaction of at least two host genes may be re-

186 H. Wege et a1.

quired. A similar result was reported by Knobler et al. (1981b). It seems most important that in infections with MHV-JHM the development of resistance correlates with the maturation of the macrophage cell population. This is indicated by the results of cell transfer experiments (Stohlman et al. 1980, Stohlman and Frelinger 1981). SJL/J mice at an age of6 weeks are relatively susceptible compared to older mice ofthe same strain and resistance can be transferred from old to young mice by peritoneal exudate cells. Depletion of cells bearing markers for Tor B cells does not influence the transfer ofprotection. Virus replication in macrophage cultures ofboth young and old mice is poor, andmacrophages have the ability to suppress virus growth in another susceptible cell culture which is permissive for the virus. This type of suppression is not mediated by interferon. When comparing resistant and susceptible strains, Knobleretal. (1981b) found a correlation between virus replication in cultured macrophages and the outcome of disease in vivo. A similar age-dependent resistance associated with the IIl8;turation of macrophages was observed by Taguchi et al. (1977, 1979b, c, 1980) for MHV-S. Pickel etal. (1981) also studied the development of resistance to MHV-JHM infection during host maturation and found that a mature immune system is not the only requirement for protection. Intraperitoneal infection ofC3H mice withJHM virus up to 20 days of age results in an acute fatal disease, whilst mice older than 20 days rapidly acquire resistance. Suckling mice can be rendered resistant by transferring spleen cells from adult mice immunized against JHM virus. Nonimmune spleen cells from adult mice, however, cannot protect after transfer. The transferred normal spleen cells were able to mediate a normal immune response in the immature host 4.1.2 Chronic Infections

The infection ofsemiresistant strains (C3H1He andA2G) withMHV-3 results ina persistent infection associated with a chronic neurological disease (Virelizier et al. 1975; LePrevost et al. 1975b). The majority of animals survive the acute stage of infection and develop a progressive chronic disease characterized by incoordination and paresis ofone or more limbs (Table 6). The pathological fmdings in A2G mice consist mainly of a chronic chorioependymitis resulting in hydromelia and hydrocephalus, whereas C3H mice reveal a diffuse vasculitis in kidney, liver, spleen, brain, and spinal cord. Perivascular infiltrations by polymorphonuclear lymphocytes and fibrinoid necrosis develop around veins and arteries. In the central nervous system destruction of myelin and axons can be found, but in contrast to neurotropic MHV strains virus antigen has never been demonstrated in neuronal cells. Antigens and immunoglobulin are, however, detectable in the walls of affected vessels. Inoculation of susceptible mouse strains with organ suspensions from chronically diseased animals induces a fatal acute hepatitis in the recipient Therefore, persistency in semisusceptible mice is a consequence of the host response and not due to the biological properties of the virus. The infection of host macrophages by MHV-3 results in modification of the immune response (Virelizier et al. 1976; Lahmy and Virelizier 1981). Application of antigen (sheep red blood cells) at the time of virus infection results in an immunostimulation against this antigen. However, an immunosuppression occurs if the antigen is inoculated later in infection. In persistent infection, a chronic immunosuppression is observed and may be associated with the continuous release of circulating (type 2) interferon. Furthermore,

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prostaglandin(s) produced by stimulated macrophages contribute to immunosuppression. This modification might be one of the mechanisms in the pathogenesis of chronic disease in semisusceptible mice. Athymic nude mice are another host in which a chronic MHV infection occurs. Several MHVs have been isolated from nude (nu/nu) mice (Table 5). The strain termed MHV-NuU is oflow virulence and causes a persistent infection with progressive necrotizing hepatitis and perivascular infiltrations in the lung (Furuta et a1.1979). It is not pathogenic for heterozygote nul+ mice with a Balbic background. Interestingly, Tamura et al. (1977, 1978, 1980) found in infected athymic nulnu mice an immune response normally not detectable in these animals. After inoculation with thymus-dependent antigen (sheep red blood cells), chronically infected nulnu mice produce neutralizing antibodies (lgM and IgG) and also produce a secondary response (Tamura and Fujiwara 1979). This immunostimulation is thought to involve the differentiation ofT-cell precursors. Humoral immunity alone however is not sufficient to prevent disease. Especially the functions ofT cells are required for protection (Kai et al. 1981). Additionally, during the early phase of disease; the phagocytic activity and number of macrophages is enhanced. Impairment of macrophage functions by the toxic effects of silica inoculation aggravates the disease course and leads to a lethal acute hepatitis (Tamura et al. 1979, 1980).

4.2 Pathogenicity Associated with Viral Gene Sequences In the preceeding sections the importance of both viral and host factors in determining the outcome of coronaviral infection have been discussed. As a flrst step in attempting to defme the viral gene sequences which might playa major role in the pathogenicity of a particular virus strain, Lai and co-workers have compared the genomes of several MHV strains and variants by oligonucleotide fmgerprinting (Lai and Stohlman 1981ab; Lai et al. 1981). Most interesting is their comparison oflarge- and small-plaque variants ofMHVJHM (Stohlman et al. 1981). The large-plaque variant (DL) is highly virulent for mice, whereas the small-plaque variant is less virulent and might induce a more extensive demyelination (Fleming et al., personal communication). Each variant contains one unique oligonucleotide sequence which is missing in its counterpart. The unique oligonucleotide of the large-plaque variant is located on the genome about 14-15 kb from the 3' end, whilst the small-plaque variant oligonucleotide maps about 3-5 kb from the 3' end. The respective mRNAs for these oligonucleotides have been tentatively identifled. Assuming that the same genes are associated with tropism in tissue culture and pathogenicity in animals, these studies, in conjunction with biochemical studies on viral replication (see Siddell et al. pp 131-165), could eventually indicate which protein(s) are important for the different biological properties of such mutant pairs. A similar approach is based on the observation that MHV-3 is more hepatotropic in comparison to MHV-A59. The genomic RNAs of these two virus strains have been compared by T 1 oligonucleotide mapping and are very similar except for two oligonucleotide sequences. The mRNAs encoded by these sequences are known. Consequently, when the proteins encoded by these mRNAs are identilled it may be possible to determine the proteins which are associated with the different pathogenicity of these virus strains.

188 H. Wege et aI.

5 Conclusions It is evident that the framework of host age and genetic background, biological properties of the virus strain, and dose and route of inoculation are the major factors which determine the result of coronavirus infection. The respiratory and intestinal tract may be the site of primary replication for all coronavirus infections under natural conditions, although the involvement of other target organs is important for the manifestation of disease in most cases. These target cells are hepatocytes and macrophages in the case of different MHV strains and FIPV, ependymal and endothelial cells for MHV-3 in semiresistant hosts, T cells in MHV-3 infection of young C3H mice, ductus cells in the salivary glands for SDAV infection, neurons in the case of infections with HEV and some MHV strains, and oligodendroglia cells for infection with MHV-JHM mutants. For most viruses causing enteric diseases (BCV, CCV, some MHV strains, TGEV, and TCV) and respiratory diseases (!BV, HCV, and RCV) the pathophysiological events leading to clinical symptoms are almost certainly due to the acute cytocidal infection of the target cells (epithelial cells of intestines or respiratory epithelium). These infections can be limited by the local immune response resulting in production of secretory antibodies. In enteric infections, maternal antibodies supplied by colostrum and milk are an additional important defence mechanism. In contrast, many coronaviruses are maintained and spread in the population as inapparent and subclinical infections. Many murine strains have been isolated from clinically healthy animals, and chronic infection by mv can result in prolonged virus shedding. TGEV can also be carried for a prolonged time. In the case ofFIPV, although only a low percentage of animals develop disease there is good reason to believe that many more animals may be infected. In central nervous system infections with MHV-JHM a clinically silent acute encephalitis develops, which may later become a subacute to chronic demyelinating disease. The sequence of events leading to chronic diseases is unknown. During the pathogenesis of chronic and acute diseases stages of viral persistency can be involved. The result depends on the expression of viral genes, the functional impairment of host cells and the interaction with the host immune response. At the present stage, no experimental data are available on the molecular mechanisms important in the development and maintenance of persistent infections. However, the use of permanent cultures of differentiated cells may be of great use in this respect. For example, neurotropic and nonneurotropic MHV viruses behave very differently in certain neuroblastoma lines (Lucas et al. 1977) and viral mutants exist which selectively replicate in oligodendroglia cells (Knobler et al. 1981a). Also, persistent infected neuroblastoma cell lines can harbor the virus without any indication of viral antigen expression and other lines can shed virus variants with altered pathogenicity (Stahlman et al. 1979a, b; Holmes and Behnke 1981; Hirano et al. 1981b). Such systems will be of value in investigating the physiological impairment of cell functions by virus persistence and as model systems to evaluate mechanisms of viral persistence. For several murine systems the host genetic background is an essential parameter determining resistance and the outcome of disease. A valuable system for investigating the mechanism of genetic resistance is formed by inbred mice, which are congenic with the exception of the gene(s) responsible for different susceptibility. Many results indicate

The Biology and Pathogenesis of Coronaviruses 189

that macrophages playa key role in this genetic restriction. The detailed mechanisms for this restriction are as yet difficult to defme and cannot be generalized, and the effect of genes which influence the susceptibility may change during host maturation. Mutations within the virus population also have to be considered during prolonged virus-host relationships. Additionally, infection of macrophages and other cells of the immune system clearly modulates the host immune response and influences the outcome of the infection. The ftrst attempts to defme viral genes which influence pathogenicity have been reported. If strain differences are defmed in biochemical terms, it may be possible to describe the role of these gene products in pathogenesis. Further work on variants which differ in only few mutations and show clear differences in biological properties can help to elucidate the function of viral genes in pathogenesis. Coronaviruses are pathogens of economic and clinical importance. Defmed experimental systems have been established, especially for murine coronaviruses, which are valuable disease models representative for coronaviral and other diseases of man and animals. We may expect rapid progress to be made in the next few years. Acknowledgements. We gratefully acknowledge the help of many colleagues who provided manuscripts and information. Data were also made available by the WHO Collaborating Centre for Collection and Evaluation of Data on Comparative Virology, University of Munich, Germany. We thank Helga Kriesinger for typing the manuscript The authors were supported by the Deutsche Forschungsgemeinschaft

References Adams NR, Ball RA, Hofstad MS (1970) Intestinal lesions in transmissible enteritis of turkeys. Avian Dis 14:392-399 Adams NR, Hofstad MS (1971) Isolation of transmissible enteritis agent of turkeys in avian embryos. Avian Dis 15:426-433 Adams NR, Hofstad MS, Gough PM (1972) Physical and morphological characterization of transmissible enteritis virus of turkeys. Avian Dis 16:817-827 Akashi H, Inaba Y, Miura Y, Sato K, Tokuhisa S, Asagi M, Hayashi Y (1981) Propagation of the Kakegawa strain of bovine coronavirus in suckling mice, rats and hamsters. Arch Virol 67: 367-370 Alexander DJ, Gough RE (1977) Isolation of infectious bronchitis virus from experimentally infected chickens. Res Vet Sci 23:344-347 Alexander DJ, Gough RE, Pattison M (1978) A long-term study of the pathogenesis of infection of fowls with three strains of avian infectious bronchitis virus. Res Vet Sci 24:228-233 Andries K, Pensaert MB (1980a) Virus isolation and immunofluorescene in different organs of pigs infected with hemagglutinating encephalomyelitis virus. Am J Vet Res 41:215-218 Andries K, Pensaert MB (1980b) Immunofluorescence studies on the pathogenesis of hemagglutinating encephalomyelitis virus infection in pigs after oronasal inoculation. Am J Vet Res 41:1372-1378 Andries K, Pensaert M (1981) Vomiting and wasting disease. In: ter Meulen V, Siddell S, Wege H (eds) Biochemistry and biology of coronaviruses. Plenum Press, New York, pp 399-408 Andries K, Pensaert M, Callebaut P (1978) Pathogenicity of hemagglutinating encephalomyelitis (vomiting and wasting disease) virus of pigs, using different routes of inoculation. Zentralbl Veterinaermed [B]25:461-468 Apostolov K, Spasic P, Bojanic N (1975) Evidence of a viral aetiology of endemic (Balkan) nephropathy. Lancet ll:1271-1273 Appel MJG, Cooper BJ, Greisen H, Scott F, Carmichael LE (1979) Canine viral enteritis. I. Status report on corona- and parvo-like viral enteritides. Cornell Vet 69:123-133

190 H. Wege etal.


Arnheiter H, Haller (1981) Inborn resistance of mice to mouse hepatitis virus type 3 (MHV3). In: ter Meulen V, Siddell S, Wege H (eds) Biochemistry and biology of coronaviruses. Plenum Press, New York, pp 409-417 Bailey OT, Pappenheimer AM, Cheever FS, Daniels JB (1949) A murine virus (JHM) causing disseminated encephalomyelitis with extensive destruction of myelin. ll. Pathology. J Exp Med 90:195-212 Bang FB (1981) The use of a genetically incompatible combination of host and virus (MHV) for the study of mechanisms of host resistance. In: ter Meulen V, Siddell S, Wege H (eds) Biochemistry and biology of coronaviruses. Plenum Press, New York, pp 359-373 Bang FB, Warwick A (1960) Mouse rnacrophages as host cells for the mouse hepatitis virus and the genetic base of their susceptibility. Proc Nat! Acad Sci USA 46:1065-1075 Bardos V, Schwanzer V, Pesko J (1980) Identification of Tettnang virus (possible arbovirus) as mouse hepatitis virus. Intervirol13:275-283 Bass EP, Sharpee RL (1975) Coronavirus and gastroenteritis in foals. Lancet ll:822 Beare AS, Reed SE (1977) The study ofantiviral compounds in volunteers. In: Oxford JS (ed) Chemoprophylaxis and virus infections of the respiratory tract CRC Press, Cleveland, pp 27-35 Bhatt PN, Jacoby RC (1977) Experimental infection of adult axenic rats with Parker's rat coronavirus. Arch Virol 54:345-352 BhattPN, Percy DH, Jones AM (1972) Characterization of the virus ofsialodacryoadenitis of rats: a member of the coronavirus group. J Infect Dis 126:123-130 Biggers DC, Kraft LM, Sprinz H (1964) Lethal intestinal virus infection of mice (LIVIM). Am J PathoI45:413-422 Binn LN, Lazar EC, Keenan KP, Huxson DL, Marchwicki RM, Strano AJ (1975) Recovery and characterisation of a coronavirus from military dogs with diarrhoea. Proc. 78th Ann. Meeting U.S. Anim. Health Assoc. Roanoke, Va., Oct 1974, pp 366-459 Black JW (1980) Recovery and in vitro cultivation of a coronavirus from laboratory induced cases offeline infectious peritonitis (FIP). Vet Med Small Anim Clin 75:811-814 Bradburne AF, Bynoe ML, Tyrrell DAJ (1967) Effects of a "new" human respiratory virus in volunteers. Br Med J 3:767-769 Broderson JR, Murphy FA, Hierholzer JC (1976) Lethal enteritis in infant mice caused by mouse hepatitis virus. Lab Anim Sci 26:824-827 Burks JS, DeVald BL, Jankovsky LD, Gerdes JC (1980) Two coronaviruses isolated from central nervous system tissue of two multiple sclerosis patients. Science 209:933-934 Carson CA, Naqi CA, Hall CF (1972) Serologic response, of turkeys to an agent associated with infectious enteritis (bluecomb). Appl Environ Microbiol23:903-907 Carthew P (1977) Lethal intestinal virus of infant mice is mouse hepatitis virus. Vet Rec 101:465 Carthew P, Sparrow S (1981) Murine coronaviruses: the histopathology of disease induced by intranasal inoculation. Res Vet Sci 30:270-273 Caul EO, Clarke SKR (1975) Coronavirus propagated from patient with non bacterial gastroenteritis. Lancet ll:953-954 Caul EO, Egglestone SI (1977) Further studies on human enteric coronaviruses. Arch VITol 54: 107-117 Caul EO, Paver WK, Clarke SKR (1975) Coronavirus particles in faeces from patients with gastroenteritis. Lancet 1:1192 Cheever FS, Daniels JB, Pappenheimer AM, Bailey OT (1949) A murine virus OHM) causing disseminated encephalomyelitis with extensive destruction of myelin. I. Isolation and biological properties of the virus. J Exp Med 90:181-194 Chhabra PC, Goel MC (1980) Normal proftle of immunoglobulins in sera and tracheal washings of chickens. Res Vet Sci 29:148-152 Clewley JP, Morser J, Avery RJ, Lomniczi B (1981) Oligonucleotide fIngerprinting of the RNA of different strains of infectious bronchitis virus. Infect Immun 32:1227-1233 Collins MS, Alexander DJ (1980) The polypeptide composition of isolated surface projections of avian infectious bronchitis virus. J Gen ViroI48:213-217 Cotter SM, Gilmore CE, Rollins C (1973) Multiple cases of feline leukemia and feline infectious peritonitis in a household. J Am Vet Med Assoc 162:1054-1058 Darbyshire JH (1980) Assessment of cross-immunity in chickens to strains of avian infectious bronchitis virus using tracheal organ cultures. Avian PathoI9:179-184

The Biology and Pathogenesis of Coronaviruses 191 Darbyshire JH (1981) Immunity to avian infectious bronchitis virus. In: Rose ME, Payne LN, Freeman BM (eds) Avian Immunology. Poultry Science Symposium Series 16, Edinburgh, Brit Poult Science Ltd, pp 205-226 Darbyshire JH, Cook JKA, Peters RW (1975) Comparative growth kinetic studies on avian infectious bronchitis virus in different systems. J Comp Pathol 85:623-630 Darbyshire JH, Rowell JG, Cook JKA, Peters RW (1979) Taxonomic studies on strains of avian infectious bronchitis virus using neutralisation tests in tracheal organ cultures. Arch Virol 61:227-238 Dawson PS, Gough RE (1971) Antigenic variation in strains of avian infectious bronchitis virus. Arch Ges Virusforsch. 34:32-39 Dea S, Roy RS, Begin ME (1980a) Physicochemical and biological properties of neonatal calf diarrhea coronaviruses isolated in Quebec and comparison with the Nebraska calf coronavirus. Am J Vet Res 41:23-29 Dea S, Roy RS, Begin ME (1980b) Bovine coronavirus isolation and cultivation in continuous cell lines. Am J Vet Res 41:30-38 Debouck P, Pensaert M (1980) Experimental infection of pigs with a new porcine enteric coronavirus CV 777. Am J Vet Res 41:219-223 Deshmukh DR, Pomeroy BS (1974) Physicochemical characterization of a bluecomb coronavirus of turkeys. Am J Vet Res 35:1549-1552 Deshmukh DR, Sautter JH, Patel BL, Pomeroy BS (1976) Histopathology offasting and bluecomb disease in turkey poults and embryos experimentally infected with bluecomb disease coronavirus. Avian Dis 20:631-640 Dick GWA, Niven JFS, Gledhil1A W (1956) A virus related to that causing hepatitis in mice (MHV). Br J Exp PathoI37:90-97 Doughri AM, Storz J (1977) Light and ultrastructural pathologic changes in intestinal coronavirus infection of newborn calves. Zentralbl Veterinii.rmed [B]24:367-385 Doughri AM, Storz J, Hajer I, Fernando HS (1976) Morphology and morphogenesis of a coronavirus infecting intestinal epithelial cells of newborn calves. Exp Molec PathoI25:355-370 Doyle LP, Hutchings LM (1946) A transmissible gastroenteritis in pigs. J Am Vet Assoc 108: 257-259 Dupuy 1M, Levy-Leblond E, Le Prevost C (1975) Immunopathology of mouse hepatitis virus type 3 infection. II. Effects of immunosuppression in resistant mice. J Immunol114:226-230 Estola T (1967) Sensitivity of suckling mice to various strains of infectious bronchitis virus. Acta Vet Scand 8:86-87 Evermann JF, Foreyt W, Maag-Miller L, Leathers W, McKeirnan AJ, Leamaster B (1980) Acute hemorrhagic enteritis associated with canine coronavirus and parvovirus infections in a captive coyote population. J Am Vet Med Assoc 177:784-786 Evermann JF, BaumEartener L, Ott RL, Davis EV, McKeirnan AJ (1981) Characterization of a feline infectious peritonitis isolate. Vet PathoI18:256-265 Fleury HJA, Sheppard RD, Bomstein MB, Raine CS (1980) Further ultrastructural observations of virus morphogenesis and myelin pathology in JHM virus encephalomyelitis. Neuropath Appl Neurobiol 6:165-179 Frederick GT, Bohl E (1976) Local and systemic cell-mediated immunity against transmissible gastroenteritis, an intestinal viral infection of swine. J Immunol116:1000-1004 Furuta T, Goto Y, Tamura T, Kai Ch, Ueda K (1979) Pulmonary vascular lesions in nude mice persistently infected with mouse hepatitis virus. Jpn J Exp Med 49:423-428 Gallily A, Warwick A, Bang FB (1964) Effect of cortisone on genetic resistance to mouse hepatitis virus in vivo and in vitro. Proc Natl Acad Sci USA 51:1158-1164 Garwes DJ, Reynolds DJ (1981) The polypeptide structure of canine coronavirus and its relationship to porcine transmissible gastroenteritis virus. J Gen Virol 52:153-157 Garwes DJ, Lucas MR, Higgins DA, Pike BV, Cartwright SF (197811979) Antigenicity of structural components from porcine transmissible gastroenteritis virus. Vet MicrobioI3:179-190 Gerdes JC, J ankovsky LD, DeVald BL, Klein I, Burks JS (1981a) Antigenic relationships of coronaviruses detectable by plaque neutralization, competitive enzyme linked immunoabsorbent assay and immunoprecipitation. In: ter Meulen V, Siddell S, Wege H (eds) Biochemistry and biology of coronaviruses. Plenum Press, New York, pp 29-41

192 H. Wege et a1. Gerdes JC, Klein I, DeVald B, Burks JS (1981b) Coronavirus isolates SK and SD from multiple sclerosis patients are serologically related to murine coronavirus A59 and JHM and human coronavirus OC43 but not to human coronavirus 229E. J ViroI38:231-238 Gerna G, Cattano E, Cereda P, Revello MG (1978) Seroepidemiological study on human coronavirus OC43 infections in Italy. Boll Inst Sieroter. Milan. 57:535-542 Gerna G, Cereda PM, Revello MG, Cattaneo E, Battaglia M, Gerna MT (1981) Antigenic and biological relationships between human coronavirus OC43 and neonatal calfdiarrhoea coronavirus. J Gen ViroI54:91-102 Gledhill AW, Andrewes CA (1951) A hepatitis virus of mice. Br J Exp Pathol 32:559-568 Gomez L, Raggi LG (1974) Local immunity to avian infectious bronchitis in tracheal organ culture. Avian Dis 18:346-368 Gonder E, Patel BL, Pomeroy BS (1976) Scanning electron, light and immunofluorescent microscopy of coronaviral enteritis of turkeys (bluecomb). Am J Vet Res 37:1435-1439 Goto N, Hirano N, Aiuchi M, Hayasl¥ T, Fujiwara K (1977) Nasoencephalopathy of mice infected intranasally with a mouse hepatitis virus, JHM strain. Jpn J Exp Med 47:59-70 Goto N, Takahashi K, Huang KJ, Katami K, Fujiwara K (1979) Giant cell formation in the brain of suckling mice infected with mouse hepatitis virus, JHM strain. Jpn J Exp Med 49:169-177 Gouffaux M, Pastoret PP, Henroteaux M, Massip A (1975) Feline infectious peritonitis proteins of plasma and ascitic fluid. Vet Pathol12:335-348 Gough RE, Alexander DJ (1979) Comparison of duration of immunity in chickens infected with a live infectious bronchitis vaccine by three different routes. Res Vet Sci 26:329-332 Greig AS, Mitchell D, Comer AH (1962) A hemagglutinating virus producing encephalomyelitis in baby pigs. Can J Comp Med 26:49-56 Haelterman EO (1962) Epidemiological studies of transmissible gastroenteritis of swine. Proc. 66th Annual Meeting US Livestock San. Assoc., pp 305-315 Hajer I, Storz J (1978) Antigens ofbovine coronavirus strain LY-138 and their diagnostic properties. Am J Vet Res 39:441-444 Hardy WD, Hurvitz AI (1971) Feline infectious peritonitis: experimental studies. J Am Vet Med Assoc 158:994-1002 Hasony HJ, Macnaughton MR (1981) Antigenicity of mouse hepatitis strain 3 subcomponents in C57 strain mice. Arch Virol 69:33-41 Haspel VM, LampertPW, Oldstone MBA (1978) Temperature-sensitive mutants ofmouse hepatitis virus produce a high incidence of demyelination. Proc Natl Acad Sci USA 75:4033-4036 Hayashi T, Utsumi F, Takahashi R, Fujiwara K (1980) Pa,thology of non-effusive type feline infectious peritonitis and experimental transmission. Jpn J Vet Sci 42:197-210 Helfer-Baker C, Evermann JF, McKeiman AJ, Morrison WB, Slack RL, Miller CW (1980) Serological studies on the incidence of canine enteritis viruses. Canine Pract 7:37-42 Herndon RM, Griffm DE, McCormick U, Weiner LP (1975) Mouse hepatitis virus-induced recurrent demyelination. Arch Neurol 32:32-35 Herndon RM, Price DL, Weiner LP (1977) Regeneration of oligodendroglia during recovery from demyelinating disease. Science 195:693-694 Hess RG, Bachmann PA, Hiinichen T (1977) Versuche zur Entwicklung einer Immunprophylaxe gegen die iibertragbare Gastroenteritis (TGE) der Schweine. I. Pathogenitat des Stammes Bl im Verlaufe von Serienpassagen. Zentralbl Veterinarmed [B) 24:753-763 Hierholzer JC, Broderson JR, Murphy FA (1979) New strain of mouse hepatitis virus as the cause oflethal enteritis in infant mice. Infect Immun 24:508-522 Hirai K, Hitchner SB, Calnek BW (1979) Characterization of a new coronavirus like agent isolated from parrots. Avian Dis 23:515-525 Hirano N, Tamura T, Taguchi F, Ueda K, Fujiwara K (1975) Isolation of low virulent mouse hepatitis virus from nude mice with wasting syndrome and hepatitis. JpnJ Exp Med 45:492-496 Hirano N, MiyajimaH, Fujiwara K (1979) Isolation oflow virulent mouse hepatitis virus from feces in infected mouse breeding colony. Jpn J Vet Sci 41:31-40 Hirano N, Goto N, Ogawa T, Ono K, Murakami T, Fujiwara K (1980) Hydrocephalus in suckling rats infected intracerebrally with mouse hepatitis virus, MHV A59. Microbiol Immuno124: 825-834 Hirano N, Murakami T, Taguchi F, Fujiwara K, Matumoto M (198la) Comparison of mouse hepatitis strains for pathogenicity in weanling mice infected by various routes. Arch ViroI70:69-73

The Biology and Pathogenesis of Coronaviruses 193 Hirano N, Goto N, Makino S, Fujiwara K (1981b) Persistent infection with mouse hepatitis virus JHM strain in DBT cell culture. In: ter Meulen V, Siddell S, Wege H (eds) Biochemistry and biology of coronaviruses. Plenum Press, New York, pp 301-308 Holmes HC (1973) Neutralizing antibody in nasal secretions of chickens following administration of avian infectious bronchitis virus. Arch Ges Virusforsch 43:235-241 Holmes KV, Behnke IN (1981) Evolution of a coronavirus during persistent infection in vitro. In: ter Meulen V, Siddell S, Wege H (eds) Biochemistry and biology of coronaviruses. Plenum Press, New York, pp 287-300 Holzworth J (1963) Some important disorders of cats. Cornell Vet 53:157-160 Hopkins SR (1974) Serological comparisons of strains of infectious bronchitis virus using plaquepurified isolants. Avian Dis 18:231-239 Horvath I, Mocsari E (1981) Ultrastructural changes in the small intestinal epithelium of suckling pigs affected with a transmissible gastroenteritis (TGE)-like disease. Arch Virol 68: 103-113 Horzinek MC, Osterhaus ADME, Ellens DJ (1977) Feline infectious peritonitis virus. Zentralbl Veterinaermed [B]24:398-405 Horzinek MC, Osterhaus ADME (1978) Feline infectious peritonitis: a coronavirus disease of cats. J Small Anim Pract 19:561-568 Horzinek MC, Osterhaus ADME (1979) The virology and pathogenesis of feline infectious peritonitis. Arch Virol 59:1-15 Hoshino Y, Scott FW (1978) Replication of feline infectious peritonitis virus in organ cultures of feline tissue. Cornell Vet 68:411-417 Hoshino Y, Scott FW (1980a) Immunofluorescent and electron microscopic studies offeline small intestinal organ cultures infected with feline infectious peritonitis virus. Am J Vet Res 41: 672-675 Hoshino Y, Scott FW (1980b) Coronavirus-like particles present in the feces of normal cats. Arch Viro163:147-152 Ishida T, Fujiwara K (1979) Pathology of diarrhea due to mouse hepatitis virus in the infant mouse. Jpn J Exp Med 49:33-41 Ishida T, Taguchi G, Lee Y, Yamada A, Tamura T, FujiwaraK (1978) Isolation of mouse hepatitis virus from infant mice with fatal diarrhea. Lab Anim Sci 28:269-276 Jacobse-Geels H, Daha MR, Horzinek M (1980) Isolation and characterization of feline C3 and evidence for the immune complex pathogenesis of feline infectious peritonitis. J Immunol 125:1606-1610 . Jacoby RO, Bhatt PN, Jonas AM (1975) Pathogenesis of sialodacryoadenitis in gnotobiotic rats. Vet PatholI2:196-206 Jonas AM, Craft J, Black CL, Bhatt PN, Hilding D (1969) Sialodacryoadenitis in rats. A light and electron microscope study. Arch Pathol 88:613-622 Kai C, Tamura T, Fujiwara K (1981) Effect of immune heterozygous spleen cell transfer on resistance to mouse hepatitis virus infection in nude mice. Microbiol Immuno125:1011-1018 Kapikian AZ (1975) The coronaviruses. Dev BioI Stand 28:42-64 Katami K, Taguchi F, Nakayama M, Goto N, Fujiwara K (1978) Vertical transmission of mouse hepatitis virus infection in mice. Jpn J Exp Med 48:481-490 Kaye HS, Dowdle WR (1975) Seroepidemiologic survey of coronavirus (strain 229E) infections in a population of children. Am J Epidemiol101:238-244 Kaye HS, Yarbrough WE, Reed CV (1975) Calf diarrhoea coronavirus. Lancet 11:509 Kaye HS, Yarbrough WE, Reed CJ, Harrison AK (1977) Antigenic relationship between human coronavirus strain OC43 and hemagglutinating encephalomyelitis virus strain 67N of swine: antibody response in human and animal sera J Infect Dis 135:201-209 Keenan KP, Jervis HR, Marchwicki RH, Binn LN (1976) Intestinal infection of neonatal dogs with canine coronavirus 1-71: studies by virologic, histologic, histochemical and immunofluorescent techniques. Am J Vet Res 37:247-256 Kersting G, Pette E (1956) Zur Pathohistologie und Pathogenese der experimentellen JHM-Virusencephalomyelitis des Affen. Dtsch Zeitschr fNervenheilkd 174:283-304 Knobler RL, Dubois-Dalcq M, Haspel MY, Claysmith AP, Lampert PW, Oldstone MBA (1981a) Selective localization of wild type and mutant mouse hepatitis virus (JHM strain) antigens in CNS tissue by fluorescence, light and electron microscopy. J Neuroimmunoll:81-92

194 H. Wege et al. Knobler RL, Haspel MY, Oldstone MBA (1981b) Mouse hepatitis virus type-4 (JHM strain) induced fatal nervous system disease, part I (Genetic control and the murine neuron as the susceptible site of disease). J Exp Med 133:832-843 Kodama Y, Ogata M, Shimizu Y (1980) Characterization of immunoglobulin A antibody in serum of swine inoculated with transmissible gastroenteritis virus. Am J Vet Res 41:740-745 Kraaijveld CA, Madge MH, Macnaughton MR (1980a) Enzyme-linked immunosorbent assay for coronaviruses HCV 229E and MHV 3. J Gen Virol 49:83-89 Kraaijveld CA, Reed SE, Macnaughton MR (1980b) Enzyme-linked immunosorbent assay for detection of antibody in volunteers experimentally infected with human coronavirus 229E group viruses. J Clin Microbiol12:493-497 Kraft LM (1962) An apparently new lethal virus disease of infant mice. Science 137:282-283 Krystyniak K, Dupuy JM (1981) Early interaction between mouse hepatitis virus 3 and cells. J Gen ViroI57:53-61 La Bonnardiere C, Laude H (1981) High interferon titer in newborn pig intestine during experimentally induced viral enteritis. Infect Irnmun 32:28-31 Lahmy C, Virelizier JL (1981) Role of prostaglandins in the suppression of antibody production by mouse hepatitis virus infection. Ann Immunol (Paris) 132C:I01-105 Lai MMC, Stohlman SA (1981a) Comparative analysis of RNA genome of mouse hepatitis viruses. J ViroI38:661-670 Lai MMC, Stohlman SA (198Ib) Genome structure of mouse hepatitis virus: comparative analysis by oligonucleotide mapping. In: ter Meulen V, Siddell S, Wege H (eds) Biochemistry and biology of coronaviruses. Plenum Press, New York, pp 69-82 Lai MMC, Brayton PR, Armen RC, Patton CD, Stohlman SA (1981) Mouse hepatitis virus A59 messenger RNA structure and genetic localization of the sequence divergence from the hepatropic strain MHV -3. J Virol 39:823-834 Lai YL, Jacoby RO, Bhatt PN, Jonas AM (1976) Keratoconjunctivitis associated with sialodacryoadenitis in rats. Invest OphthalmoI15:538-541 Lampert PW, Sims JK, KniazefT AJ (1973) Mechanism of demyelination in JHM virus encephalomyelitis. Electron microscopic studies. Acta Neuropathol (Berlin) 24:76-85 Larson DJ, Morehouse LG, Solorzano RF, Kinden DA (1979) Transmissible gastroenteritis in dogs: Experimental intestinal infection with transmissible gastroenteritis virus. Am J Vet Res 40:477-486 Larson HE, Reed SE, Tyrrell DAJ (1980) Isolation of rhinoviruses and coronaviruses from 38 colds in adults. J Med Virol 5:221-229 Leinikki PO, Holmes KV, Shekarchi J, Iivanainen M, Madden D, Sever JL (1981) Coronavirus antibodies in patients with multiple sclerosis. In: ter Meulen V, Siddell S, Wege H (eds) Biochemistry and biology of coronaviruses. Plenum Press, New York, pp 323-326 Le Prevost C, Levy-Leblond B, Virelizier JL, Dupuy JM (1975a) Immunopathology of mouse hepatitis"virus type 3 infection. I. Role of humoral and cell-mediated immunity in resistance mechanism. J ImmunoI117:221-225 Le Prevost C, Virelizier JL, Dupuy JM (1975b) Immunopathology of mouse hepatitis virus type 3 infection. III. Clinical and virologic observation of a persistent viral infection. J Immunol 115:640-645 Leslie GA, Martin LN (1973) Studies on the secretory immunologic system of fowl. III. Serum and secretory 19A of the chicken. J Immunol110:1-9 Levy GA, Leibowitz JL, Edgington TS (1981) Induction of monocyte procoagulant activity by murine hepatitis type 3 parallels disease susceptibility in mice. J Exp Med 154:1150-1163 Levy-Leblond E, Dupuy JM (1977) Neonatal susceptibility to MHV-3 infection in mice. I. Transfer of resistance. J IrnmunoI118:1219-1222 Levy-Leblond E, Oth D, Dupuy JM (1979) Genetic study of mouse sensitivity to MHV-3 infection: Influence of the H-2 complex. J ImmunoI122:1359-1362 Lewis LD, Phillips RW (1978) Pathophysiologic changes due to coronavirus induced diarrhea in the calf. J Am Vet Med Assoc 173:636-641 Loeffler DG, Ott RL, Evermann JF, Alexander JE (1978) The incidence of naturally occurring antibodies against feline infectious peritonitis in selected cat populations. Feline Pract 8:43-45 Lucas A, FlintofTW, Anderson R, Percy D, Coulter M, Dales S (1977) In vivo and in vitro models

The Biology and Pathogenesis of Coronaviruses 195 of demyelinating diseases: tropism of the JHM strain of murine hepatitis virus for cells of glial origin. Cell 12:553-560 Macnaughton MR (1981) Structural and antigenic relationships between human, murine and avian coronaviruses. In: ter Meulen V, Siddell S, Wege H (eds) Biochemistry and biology of coronaviruses. Plenum Press, New York, pp 19-28 Macnaughton MR, Davies HA (1981) Human enteric coronaviruses. Arch Virol 70:301-313 Macnaughton MR, Hasony HJ, Madge H, Reed S (1981) Antibody to virus components in volunteers experimentally infected with human coronaviruses 229E group viruses. Infect Immun 31:845-849 Macnaughton MR, Patterson S (1980) Mouse hepatitis virus strain 3 infection of C57, A/Sn and AIJ strain mice and their macrophages. Arch Virol 66:71-75 MAlkovA D, HolubovA I, Kolman JM, Lobkovic F, PohlreichovA L, ZikmundovA L (1980) Isolation of Tettnang coronavirus from man. Acta Virol 24:363-366 Manaker RA, Piczak CV, Miller AA, Stanton MF (1961) A hepatitis virus complicating studies with mouse leukemia. I Natl Cancer Inst 27:29-44 McIntosh K (1974) Coronaviruses: a comparative review. Curr Top Microbiol ImmunoI63:85-129 McIntosh K, Becker WB, Chanock RM (1967) Growth in suckling mouse brain of ''IBV-like" viruses from patients with upper respiratory tract disease. Proc Natl Acad Sci USA 58:2268-2273 McIntosh K, Kapikian AZ, Hardison KA, Hartley JW, Chanock RM (1969) Antigenic relationships among coronaviruses of man and between human and animal coronaviruses. I Immunol102: 1109-1118 McIntosh K, Kapikian AZ, Turner HC, Hartley JW, Parrot RH, Chanock RM (1970) Seroepidemiologic studies of coronavirus infection in adults and children. AmI Epidemiol 91:585-592 McIntosh K, Ellis EF, Hoffman LS, Lybass TG, Eller JJ, Fulginiti VA (1973) The association of viral and bacterial respiratory infections with exacerbations of wheezing in young astmatic children. I Pediatr 82:578-593 McIntosh K, Chao RK, Krause HE, Wasil R, Mocega HE, Mufson MA (1974) Coronavirus infection in acute lower respiratory tract disease of infants. I Infect Dis 139:502-507 McIntosh K, McQuillin I, Reed SE, Gardener PS (1978) Diagnosis of human coronavirus infection by immunofluorescence: method and application to respiratory disease in hospitalized children. I Med Viro12:341-346 McKeirnan AI, Evermann IF, Hargis A, Miller LM, Ott RE (1981) Isolation of feline coronaviruses from two cats with diverse disease manifestations. Feline Pract 11:16-20 Mebus CA, Stair EL, Rhodes MB, Twiehaus MJ (1973a) Pathology of neonatal calf diarrhoea induced by a coronavirus-like agent Vet Patholl0:45-64 Mebus CA, Stair EL, Rhodes MB, Twiehaus MJ (1973b) Neonatal calf diarrhoea: propagation, attenuation, and characteristics of a coronavirus-like agent Am I Vet Res 34:145-150 Mebus CA, Newman LE, Stair EL (1975) Scanning electron, light and immunofluorescent microscopy of intestine of gnotobiotic calf infected with calf diarrhea coronavirus. Am I Vet Res 36:1719-1725 Mebus CA, Torres-Medina A, Twiehaus MI (1976) Immune response to orally administered calf reovirus-like agent and coronavirus vaccine. Dev BioI Stand 33 :396-403 Mengeling WL, Cutlip RC (1976) Pathogenicity of field isolates of hemagglutinating encephalomyelitis virus for neonatal pigs. I Am Vet Med Assoc 128:236-239 Mockett A, Darbyshire IH (1981) Comparative studies with an enzyme-linked immunosorbent assay (ELISA) for antibodies to avian infectious bronchitis virus. Avian Patholl0:l-1O Monto AS (1974) Medical Reviews: Coronaviruses. Yale I BioI Med 47:234-251 Moon HW (1978) Mechanisms in the pathogenesis of diarrhea: a review. I Am Vet Med Assoc 172:443-448 Moore B, Lee P, Hewish M, Dixon B, Mukherjee T (1977) Coronaviruses in training centre for intellectually retarded. Lancet 1:261 Moscovici 0, Chany C, Lebon P, Rousset S, Laporte (1980) Association d'infection acoronavirus avec l'enterocolite hemorragique du nouveau-ne. CR Acad SC [DJ (Paris) 290:869-872 Nagaraja KV, Pomeroy BS (1980) Cell-mediated immunity against turkey coronaviral enteritis (bluecomb). Am I Vet Res 41:915-917 Nagaraja KV, Pomeroy BS (1978) Secretory antibodies against turkey coronaviral enteritis. Am I Vet Res 39:1463-1465

196 H. Wege et al. NagarajaKV, Pomeroy BS (1981) Immunofluorescent studies on localization ofsecretory immunoglobulins in the intestines of turkeys recovered from turkey coronaviral enteritis. Am J Vet Res 41:1283-1284 Nagashima K, Wege H, ter Meulen V (1978a) Early and late CNS-effects of coronavirus infection in rats. Adv Exp Med BioI 100:395-409 Nagashima K, Wege H, Meyermann R, ter Meulen V (1978b) Corona virus induced subacute demyelinating encephalomyelitis in rats. A morphological analysis. Acta Neuropathol (Berlin) 44:63-70 Nagashima K, Wege H, Meyermann R, ter Meulen V (1979) Demyelinating encephalomyelitis induced by a long-term corona virus infection in rats. Acta Neuropathol (Berlin) 45: 205-213 Nagy E, Lomniczi B (1979) Polypeptide patterns of infectious bronchitis virus serotypes fall into two categories. Arch ViroI61:341-345 Naqui SA, Panigrahy B, Hall CF (1975) Purification and concentration of viruses associated with transmissible (coronaviral) enteritis of turkeys (bluecomb). Am J Vet Res 36:548-552 Nelson DT, Eustin SL, McAdarach JP, Stotz I (1979) Lesions of spontaneous canine viral enteritis. Vet PathoI16:680-686 Nelson JB (1952) Acute hepatitis associated with mouse leukemia. I. Pathological features and transmission of the disease. J Exp Med 96:293-303 O'Reilly KJ, Fishman B, Hitchcock LM (1979) Feline infectious peritonitis. Isolation of a coronavirus. Vet Rec 104:348 Osterhaus ADME, Horzinek MC, Ellens DJ (1976) Untersuchungen zur Atiologie der felinen infektiosen Peritonitis. Bed Miinch Tieraerztl Wochenschr 89:135-137 Osterhaus ADME, Horzinek MC, Reynolds DJ (1977) Seroepidemiology offeline infectious peritonitis virus infections using transmissible gastroenteritis virus as antigen. Zentra1bl Veterinaermed [B] 24:835-841 Osterhaus ADME, Horzinek MC, Wirahadiredja RMS (1978a) Feline infectious peritonitis (FIP) virus. II. Propagation in suckling mouse brain. Zentra1bl Veterinaermed [B] 25:301-307 Osterhaus ADME, Horzinek MC, Wirahadiredja RMS, Kroo A (1978b) Feline infectious peritonitis (FIP) virus. IV. Propagation in suckling rat and hamster brain. Zentra1bl Veterinaermed [B] 25:816-825 Panigrahy B, Naqi SA, Hall CE (1973) Isolation and characterization of viruses associated with transmissible enteritis (bluecomb) of turkeys. Avian Dis 17:430-438 Parker JC, Cross SS, Rowe WP (1970) Rat coronavirus (ReV): a prevalent, naturally occurring pneumotropic virus of rats. Arch Ges Virusforsch 31:293-302 Pedersen NC (l976a) Morphologic and physical characteristics offeline infectious peritonitis virus and its growth in autochthonous peritoneal cell cultures. Am J Vet Res 37:567-572 Pedersen NC (1976b) Serological studies of naturally occuring feline infectious peritonitis. Am J Vet Res 37:1449-1453 Pedersen NC, Boyle BS (1980) Immunologic phenomena in the effusive form offeline infectious peritonitis. Am J Vet Res 41:868-876 Pedersen NC, Ward J, Mengeling WL (1978) Antigenic relationship of the feline infectious peritonitis virus to coronaviruses of other species. Arch Virol 58:45-53 Pensaert M, Callebaut P (1978) The coronaviruses: clinical and structural aspects with some practical implications. Ann M6d Vet 122:301-322 Pensaert M, Haelterman EO, Burnstein T (1970) Transmissible gastroenteritis of swine: virus-intestinal cell interactions. Arch Ges Virusforsch 31:321-334 PensaertMB, Debouck P (1978) A new coronavirus-like particle associated with diarrhoea in swine. Arch Virol 58:243-247 Pensaert MB, Debouck P, Reynolds DJ (1981) An immunelectron microscopic and immunofluorescent study on the antigenic relationship between the coronavirus like agent, CV777, and several coronavirus. Arch ViroI68:45-52 Phillips RW, Case GL (1980) Altered metabolism, acute shock and therapeutic response in a calf with coronavirus induced diarrhea. Am J Vet Res 41:1039-1044 Piazza M (1969) Experimental viral hepatitis. Thomas, Springfield Illinois Pickel K, Miiller MA, ter Meulen V (1981) Analysis of age-dependent resistance to murine coronavirus JHM infection in mice. Infect Immun 34:375-387

The Biology and Pathogenesis of Coronaviruses 197 Pomeroy BS, Larsen CT, Deshmukh DR, Patel BL (1975) Immunity to transmissible (coronaviral) enteritis of turkeys (bluecomb). Am J Vet Res 36:553-555 Powell HC, LampertPW (1975) Oligodendrocytes and their myelin-plasma membrane connections in JHM mouse hepatitis virus encephalomyelitis. Lab Invest 33:440-445 Purcell DA, McFerran JB (1972) The histopathology of infectious bronchitis in the domestic fowl. Res Vet Sci 13:116-122 Reynolds DJ, Garwes DJ (1979) Virus isolation and serum antibody responses after infection of cats with transmissible gastroenteritis virus. Arch Virol60:161-166 Reynolds DJ, Garwes DJ, Gaskell CJ (1977) Detection of transmissible gastroenteritis virus neutralizing antibody in cats. Arch Virol 55:77-86 Reynolds DJ, Garwes DJ, Lucey S (1980) Differentiation of canine coronavirus and porcine transmissible gastroenteritis virus by neutralization with canine, porcine and fetina sera. Vet Microbioi 5:283-290 Riski H, Hovi T (1980) Coronavirus infections of man associated with diseases other than the common cold J Med Virol 6:259-265 Ritchie AE, Deshmukh DR, Larsen CT, Pomeroy BS (1973) Electron microscopy of coronaviruslike particles characteristic of turkey bluecomb disease. Avian Dis 17:546-558 Robb JA, Bond CW (1979) Coronaviridae. In: Fmenkel-Conrat H, Wagner RR (eds) Comprehensive virology. Plenum Press, New York 14:193-247 Robb JA, Bond CW, Leibowitz JL (1979) Pathogenic murine Coronaviruses ill. Biological and biochemical characterization of tempemture sensitive mutants of JHMV. Virol 94:385-399 Robison RL, Holzworth J, Gilmore CE (1971) Natumlly occurring feline infectious peritonitis: signs and clinical diagnosis. J Am Vet Med Assoc 158:981-986 Roe CK, Alexander TJL (1958) A disease of nursing pigs previously unreported in Ontario. Can J Comp Med 22:305-307 Rosenberger JK, Gelb J (1978) Response to several avian respimtory viruses as affected by infectious bursal disease virus. Avian Dis 22:95-105 Rowe WP, Hartley JW, Capps VJ (1963) Mouse hepatitis virus infection as a highly contagious, prevalent, enteric infection of mice. Proc Soc Exp BioI Med 112:161-165 Sabesin SM (1972) Isolation of a latent murine hepatitis virus from cultured mouse liver cells. Am J GastroenteroI58:259-274 SaifU, Bohl EH (1979) Passive immunity in transmissible gastroenteritis of swine. Am J Vet Res 40:115-117 Sato K, Maru M, Wata T (1976) Some characteristics of corona-like virus isolated from infant mice with diarrhea and inflammatory submaxillary gland ofmts (in Japanese). Virus 26:97 Sato K, Inaba Y, Kurogi H, Takahashi E, Ito Y, Goto Y, Omori T, Matumoto M (1977) Physicochemical properties of calf coronavirus. Vet Microbiol 2:73-81 Schalk AE, Hawn MC (1931) An apparently new respiratory disease of baby chicks. J Am Vet Med Assoc 78:413-422 Schindler L, Streissle H, Kirchner H (1981) Protection of mice against mouse hepatitis virus by Corynebacterium parvum. Infect Immun 32:1128-1131 Schmidt OW, Kenny GE (1981) Immunogenicity and antigenicity of human coronavirus 229E and OC43. Infect Immun 32:1000-1006 Schnagl RD, Holmes IH, Mackay-Scollay EM (1978) Coronavirus-like particles in aboriginals and non-aboriginals in Western Australia. Med J Australia 1:307-310 Sebesteny A, Hill AC (1974) Hepatitis and bmin lesions due to mouse hepatitis virus accompanied by wasting in nude mice. Lab Anim 8:317-326 Sharpee RL, Mebus CA, Bass EP (1976) Characterization of a calf diarrheal coronavirus. Am J Vet Res 37:1031-1041 Sheets P, Shah KV, Bang FB (1978) Mouse hepatitis virus (MHV) infection in thymectomized C3H mice. Proc Soc Exp BioI Med 159:34-38 Shepherd RW, Butler DG, Cutz E, Gall DG, Hamilton JR (1979a) The mucosal lesion in viral enteritis: extent and dynamics of the epithelial response to virus invasion in transmissible gastroenteritis in piglets. GastroenteroI75:770-777 Shepherd RW, Gall DG, Butler DG, Hamilton JR (1979b) Determinants of diarrhea in viral enteritis. The role of ion transport and epithelial changes in the ileum in transmissible gastroenteritis in piglets. Gastroenterol 76:20-24

198 H. Wege et at. Shif I, Bang FB (1970a) In vitro interaction of mouse hepatitis virus and macrophages from genetically resistant mice. I. Absorption of virus and growth curve. J Exp Med 131:843-850 Shif I, Bang FB (1970b) In vitro intemction of mouse hepatitis virus and macrophages from genetically resistant mice. n. Biological characterization of a variant virus (MHV C3H) isolated from stocks ofMHV (PRI). J Exp Med 131:851-862 Shimizu M, Shimizu Y (1979) Demonstration of cytotoxic lymphocytes to virus infected target cells in pigs inoculated with transmissible gastroenteritis virus. Am J Vet Res 40:208-213 Sorensen 0, Percy D, Dales S (1980) In vivo and in vitro models of demyelinating diseases. m. JHM virus infection of mts. Arch NeuroI37:478-484 Sorensen 0, Coulter-Mackie M, Percy D, Dales S (1981) In vivo and in vitro models of demyelinating diseases. In: ter Meulen V, Siddell S, Wege H (eds) Biochemistry and biology of coronaviruses, Plenum Press, New York, pp 271-286 Stair EL, Rhodes MB, White RG (1972) Neonatal calf diarrhea: purification and electron microscopy of a coronavirus-like agent Am J Vet Res 33:1147-1156 Stohlman SA, Frelinger JA (1978) Resistance to fatal central nervous system disease by mouse hepatitis virus strain JHM. I. Genetic analysis. Immunogen 6:277-281 Stohlman SA, Weiner LP (1981) Chronic central nervous system demyelination in mice after JHMV virus infection. Neurology 31:38-44 Stohlman SA, Sakaguchi A, Weiner LP (1979a) Rescue of a positive stranded RNA virus from antigen negative neuroblastoma cells. Life Sci 24:1029-1036 Stohlman SA, Sakaguchi AY, Weiner LP (1979b) Chamcterization of the cold-sensitive murine hepatitis virus mutants rescued from latently infected cells by cell fusion. Virology 98:448-455 Stohlman SA, Frelinger JA, Weiner LP (1980) Resistance to fatal central nervous system disease by mouse hepatitis virus, strain JHM. n. Adherent cell mediated protection. J Immuno1124: 1733-1739 Stohlman SA, Frelinger JA (1981) Macrophages and resistance to JHM virus. In: ter Meulen V, Siddell S, Wege H (eds) Biochemistry and biology of coronaviruses. Plenum Press, New York, pp 387-398 Stone SS, Kemeny LS, Woods RD, Jensen MT (1977) Efficacy of isolated colostral '1~, IgG, IgM(A) to protect neonatal pigs against the coronavirus of transmissible gastroenteritis. Am J Vet Res 38:1285-1288 Storz J, Rott R (1980) Uber die Verbreitung der Coronavirusinfektion bei Rindem in ausgewiihlten Gebieten Deutschlands: Antikorpernachweis durch Mikroimmundiffusion und Neutralisation. Dtsch Tieriirztl Wochenschr 87:252-254 Storz J, Rott R (1981) Reactivity ofantibodies in human serum with antigens ofan enteropathogenic bovine coronavirus. MMI 169:169-178 Storz J, Rott R, Kaluza G (1981) Enhancement of plaque formation and cell fusion of an enteropathogenic coronavirus by trypsin treatment Infect Immun 31:1214-1222 Sugiyama K, Amano Y (1980) Hemagglutination and structural polypeptides of a new coronavirus associated with diarrhea in infant mice. Arch Virol66:95-105 Taguchi F, Hirano N, Kiuchi Y, Fujiwam K (1976) Difference in response to mouse hepatitis virus among susceptible mouse strains. Jpn J Microbiol 20:293-302 Taguchi F, Aiuchi M, Fujiwara K (1977) Age-dependent response of mice to a mouse hepatitis virus, MHV-S. Jpn J Exp Med 47:109-115 Taguchi F, Yamada A, Fujiwam K (1979a) Asymptomatic infection of mouse hepatitis virus in the mt Arch ViroI59:275-279 Taguchi F, Yamada A, Fujiwara K (1979b) Factors involved in the age-dependent resistance of mice infected with low-virulence mouse hepatitis virus. Arch Virol 62:333-340 Taguchi F, Goto Y, Aiuchi M, Hayashi T, Fujiwara K (1979c) Pathogenesis of mouse hepatitis virus infection. The role of nasal epithelial cells as a primary target of low-virulence virus, MHV-S. Microbiol ImmunoI23:249-262 Taguchi F, Yamada A, Fujiwara K (1980) Resistance to highly virulent mouse hepatitis virus acquired by mice after low-virulence infection: enhanced antiviral activity of macrophages. Infect Immun 29:42-49 Takahashi K, Hirano N, Goto N, Fujiwara K (1980) Massive cerebral cortical necrosis in suckling mts inoculated intracerebrally with mouse hepatitis virus, A59 strain. Jpn J Vet Sci 42: 311-321

The Biology and Pathogenesis of Coronaviruses 199 Takeuchi A, BinnLN, Jervis HR, KeenanKP, HildebrandtPK, Valas RB, BlandFF (1976) Electron microscope study of experimental enteric infection in neonatal dogs with a canine coronavirus. Lab Invest 34:539-549 Tamura T, Fujiwara K (1979) IgM and IgG response to sheep red blood cells in mouse hepatitis virus infected nude mice. Microbiol ImmunoI23:177-183 Tamura T, Ueda K, Hirano N, Fujiwara K (1976) Response of nude mice to a mouse hepatitis virus isolated from a wasting nude mouse. Jpn J Exp Med 46:19-30 Tamura T, Taguchi F, U eda K, Fujiwara K (1977) Persistent infection with mouse hepatitis virus of low virulence in nude mice. Microbiol Immunol 21:683-691 Tamura T, Machii K, U eda K, Fujiwara K (1978) Modification of immune response in nude mice infected with mouse hepatitis virus. Microbiol Immunol 22:557-564 Tamura T, Kai Ch, Sakaguchi A, Ishida T, Fujiwara K (1979) The role of macrophages in the early resistance to mouse hepatitis virus infection in nude mice. Microbiol ImmunoI23:965-974 Tamura T, Sakaguchi A, Kai Ch, Fujiwara K (1980) Enhanced phagocytic activity of macrophages in mouse hepatitis virus infected nude mice. Microbiol ImmunoI24:243-247 Tardieu M, Hery C, Dupuy lM (1980) Neonatal susceptibility to MHV-3 infection in mice. II. Role of natural effector marrow cells in transfer of resistance. J Immunol124:418-423 Taylor CE, Weiser WY, Bang FB (1981) In vitro macrophage manifestation of cortisone induced decrease in resistance to mouse hepatitis virus. J Exp Med 153:732-737 Timms LM, Bracewell CD, Alexander DJ (1980) Cell mediated and humoral immune response in chickens infected with avian infectious bronchitis. Br Vet J 136:349-356 Traavik T, Mehl R, Kjeldsberg E (1977) "Runde" virus, a coronavirus-like agent associated with seabirds and ticks. Arch ViroI55:25-38 Tyrrell DAJ, Bynoe ML (1965) Cultivation of a novel type of common cold virus in organ cultures. Br Med J 1:1467-1470 Tyrrell DAJ, Almeida JD, Berry DM, Cunningham CH, Hamre D, Hofstad MS, Malluci L, McIntosh K (1968) Coronaviruses. Nature 220:650 Tyrrell DAJ, Almeida JD, Cunningham CH, Dowdle WR, Hofstad MW, McIntosh K, Tajima M, Zastelskaya LY, Easterday BC, Kapikian A, Bingham RW (1975) Coronaviridae. Intervirol 5:76-82 Tyrrell DAJ, Alexander JD, Almeida JD, Cunningham CH, Easterday BC, Garwes DJ, Hierholzer JC, Kapikian AZ, Macnaughton MR, McIntosh K (1978) Coronaviridae: second report InterviroI1O:321-328 Underdahl NR, Mebus EL, Stair EL, Rhodes MB, McGill LD, Twiehaus MJ (1974) Isolation of transmissible gastroenteritis virus from lungs of market-weight swine. Am J Vet Res 35:12091216 Underdahl NR, Mebus CA, Torres-Medina A (1975) Recovery oftransmissible gastroenteritis virus from chronically infected experimental pigs. Am J Vet Res 36:1473-1476 Virelizier JL (1979) Effects of immunosuppressive agents on leucocyte interferon production in normal or thymus-deprived mice. Transplantation 27:353-355 Virelizier JL (1981) Role of macrophages and interferon in natural resistance to mouse hepatitis virus infection. Curr Top Microbiol Immunol 92:51-64 Virelizier JL, Allison AC (1976) Correlation of persistent mouse hepatitis virus (MHV-3) infection with its effect on mouse macrophage cultures. Arch Virol 50:279-285 Virelizier JL, Gresser I (1978) Role of interferon in the pathogenesis of viral diseases of mice as demonstrated by the use of anti-interferon serum. V. Protective role in mouse hepatitis virus type 3 infection of susceptible and resistant strains of mice. J Immunol120:1616-1619 Virelizier JL, Dayan AD, Allison AC (1975) Neuropathological effects of persistent infection of mice by mouse hepatitis virus. Infect Immun 12:1127-1140 Virelizier JL, Virelizier AM, Allison AC (1976) The role of circulating interferon in the modifications of immune responsiveness by mouse hepatitis virus (MHV-3). J Immunol117:748-753 Ward lM (1970) Morphogenesis of a virus in cats with experimental feline infectious peritonitis. ViroI41:191-194 Ward lM, Gribble DH, Dungworth DL (1974) Feline infectious peritonitis: experimental evidence for its multiphasic nature. Am J Vet Res 35:1271-1275 Ward lM, Collins MJ, Parker JC (1977) Naturally occurring mouse hepatitis virus infection in the nude mouse. Lab Anim Sci 27:372-376

200 H. Wege et al. Watanabe H, Kobayashi K, Isayama Y (1975) Peculiar secretory IgA system identified in chickens. ll. Identification and distribution of free secretory component and immunoglobulins ofIgA, IgM and IgG in chicken external secretions. J ImmunoI115:998-100l Watt RG (1978) Virological study of two commercial pig herds with respiratory disease. Res Vet Sci 24:147-153 Wege H, Stephenson JR, Koga M, Wege Hanna, ter Meulen V (1981a) Genetic variation of neurotropic and non neurotropic murine coronaviruses. J Gen ViroI54:67-74 Wege H, Koga M, Wege Hanna, ter Meulen V (1981b) JHM infections in rats as a model for acute and subacute demyelinating disease. In: ter Meulen V, Siddell S, Wege H (eds) Biochemistry and biology of coronaviruses. Plenum Press, New York, pp 327-349 Weiner LP (1973) Pathogenesis of demyelination induced by a mouse hepatitis virus (JHM virus). Arch NeuroI28:293-303 Weisbroth SH, Peress N (1977) Ophthalmic lesions and dacryoadenitis: a naturally occurring aspect ofsialodacryoadenitis virus infection of the laboratory rat Lab Animal Sci 27:466-473 Weiser WY, Bang FB (1976) Macrophages genetically resistant to mouse hepatitis virus converted in vitro to susceptible macrophages. J Exp Med 143:690 Weiser WY, Bang FB (1977) Blocking of in vitro and in vivo susceptibility to mouse hepatitis virus. J Exp Med 146:1467 Weiser W, Vellisto I, Bang FB (1976) Congenic strains of mice susceptible and resistant to mouse hepatitis virus. Proc Soc Exp Bioi Med 152:499 Weiss RC, Dodds JW, Scott FW (1980) Disseminated intravascular coagulation in experimentally induced feline infectious peritonitis. Am J Vet Res 41:663-671 Weiss SR, Leibowitz JL (1981) Comparison of the RNAs of murine and human coronaviruses. In: ter Meulen V, Siddell S, Wege H (eds) Biochemistry and biology of coronaviruses. Plenum Press, New York, pp 245-259 Werdin RE, Sorensen DK, Stewart MS (1976) Porcine encephalomyelitis caused by hemagglutinating encephalomyelitis virus. J Am Vet Med Assoc 168:240-246 Witte KH, Tuch K, Dubenkropp H, Walther C (1977) Untersuchungen iiber die Antigenverwandtschaft der Viren derfelinen infektiOsen Peritonitis (FIP) und der transmissiblen Gastroenteritis (TGE) des Schweines. Berl Miinch Tieraerztl Wochenschr 80:396-401 Wolfe LG, Griesemer RD (1966) Feline infectious peritonitis. Pathol Vet 3:255-270 Woods RD, Chevi1le NF, Gallagher JE (1981) Lesions in the small intestine of newborn pigs inoclated with porcine, feline and canine coronaviruses. Am J Vet Res 42:1163-1169 Yamada A, Taguchi F, Fujiwara K (1979) T-Iymphocyte dependent difference in susceptibility between DDD and C 3H mice to mouse hepatitis virus, MHV 3. Jpn J Exp Med 49:413-421 Yaseen SA, Johnson-Lussenburg M (1981) Antigenic studies on coronavirus. I. Identification of the structural antigens of human coronavirus, strain 229E. Can J MicrobioI27:334-342