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1、Research in Veterinary Science 1991, 51, 11-18 Canine coronavirus infection in the dog following oronasal inoculation B. J. TENNANT, R. M. GASKELL, D. F. KELLY, S. D. CARTER, Department of Veterinary Pathology, C. J. GASKELL, Department of Veterinary Clinical Science, University of Liverpool, Liverp
2、ool, L69 3BX The pathogenesis of canine coronavirus (ccv) infection in 10-week-old puppies was studied up to 14 days after oronasal inoculation. Mild diarrhoea was seen from three to 11 days after inoculation, approx- imately coincident with faecal virus shedding. Virus was initially isolated from t
3、he tonsils on day 3, and then from both small and large intestinal tissues up to 14 days after inoculation. Virus was also isolated from liver and lung. Histological changes were not seen in any tissues, but ccv antigen was detected, using a peroxidase antiperoxidase staining technique, mainly in ep
4、ithelium overlying gut-associated lymphoid tissue. Virus neutralising antibody was first detected on day 10. Specific anti-ccv IgM was first detected in plasma three days after inoculation and IgG on days 4 to 7. Small amounts of anti-ccv IgG, IgM and IgA were detected in duodenal secretion, but non
5、e in bile. ALTHOUGH canine coronavirus (ccv) has been recognised since 1971 (Binn et al 1974) in association with moderate to severe disease in dogs (Binn et al 1974, Vandenberghe et al 1980, Williams 1980, Carmichael and Binn 1981), it is generally considered to induce only mild enteritis (Appel 19
6、87). Clinical signs are considered to be difficult to reproduce experimentally (Appel 1987), although little work has been reported on this. Moderate signs of disease have been induced experimentally in neonatal pups but in- contact bitches showed no clinical signs (Binn et al 1974, Keenan et al 197
7、6). In naturally occurring infections, pups of six to 12 weeks old appear to be more susceptible to disease (Cartwright and Lucas 1972, Vandenberghe et al 1980, Carmichael and Binn 1981). This may be related to the decline in maternal antibody. There are few reports on the pathogenesis of ccv infect
8、ion in dogs. In neonatal dogs the virus appears to replicate primarily in enterocytes on the villus tips of the small intestine (Binn et al 1974, Keenan et al 1976, Takeuchi et al 1976). Following natural infection, virus has been reported in the epithelium of the small and large intestine (Vandenbe
9、rghe et al 1980). 11 Systemic spread of ccv has not been well studied although there are some, often anecdotal, reports of virus having been demonstrated in various tissues including mesenteric lymph nodes, liver, spleen, meninges and lung (Keenan et a11976, Binn et a11979, Greene 1984, Acree et al
10、1985). ccv has also been implicated in a pancreatitis/meningitis syndrome following live ccv vaccination (Martin 1985, Wilson et al 1986) and ccv has also been shown to cause systemic infection in the cat (McArdle et al 1991). Other coronaviruses, including the closely related feline infectious peri
11、tonitis virus and transmissible gastroenteritis virus of pigs, have also been found to affect various organ systems in addition to the gut (Hooper and Haelterman 1969, Mebus et al 1973, Underdahl et al 1974, Pedersen et al 1984, Weiss and Scott 1981, Thomas et al 1982, Childs et al 1983). As the pub
12、lished work on the pathogenesis of ccv infection is mainly based on experimental infection of neonatal pups, the present work was undertaken in older, 10-week-old pups, in order to reproduce more closely the naturally occurring disease. A recent UK isolate was used in these studies. Since mucosal im
13、munity is considered important in other closely related coronavirus infections, such as transmissible gastroenteritis virus (Bohl et al 1972), clinical and virological findings were related to local and systemic antibody responses. Materials and methods Experimental animals Six six-week-old pups, wh
14、elped and reared in isolation with their dam, were maintained in isolation under strict barrier conditions until they were used at 10 weeks old. They remained seronegative to ccv during this time and no virus was isolated from their faeces. Virus cfv-c54, isolated from a dog presented with enteritis
15、 to the Small Animal Hospital at the Uni- versity of Liverpool, was used in this experiment at 12 B.J. Tennant, R. M. Gaskell, D. the sixth passage with a titre of 10 6.3 TCID50 ml-l. The original isolation was made in feline embryo A (FEA) cells (Jarrett et al 1973) but the isolate was passaged in
16、A-72 cells (Binn et al 1980). A-72 cells, used in attempts at virus isolation in this study, were grown in Wellcome minimum essential medium (Gibco), with antibiotics and 10 per cent fetal calf serum for growth and 4 per cent fetal calf serum for maintenance. Experimental design Five dogs were inoculated oronasally with 1 ml of ccv-c54. A control dog was given A-72 tissue culture fluid oronasally 14 days before the start of the experiment and killed on day 0 restricted animal acc
