Experimental infection of young rabbits with a rabbit enteric coronavirus.
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The clinical signs and lesions caused by the rabbit enteric coronavirus (RECV) were studied in young rabbits orally inoculated with a suspension containing RECV particles. The inoculated animals were observed daily for evidence of diarrhea. Fecal samples and specimens from the small intestine and from the gut associated lymphoid tissue (GALT) were collected from 2 h to 29 days postinoculation (PI) and processed for immune electron microscopy (IEM) and light microscopy. Coronavirus particles were detected in the cecal contents of most inoculated animals from 6 h to 29 days PI. Lesions were first observed 6 h PI and were characterized by a loss of the brush border of mature enterocytes located at the tips of intestinal villi and by necrosis of these cells. At 48 h PI, short intestinal villi and hypertrophic crypts were noted. In the GALT, complete necrosis of the M cells as well as necrosis of the enterocytes lining the villi above the lymphoid follicules with hypertrophy of the corresponding crypts were observed in all the animals. Five inoculated rabbits had diarrhea three days PI. The presence of RECV particles in the feces of the sick animals and the microscopic lesions observed in the small intestine suggested that the virus was responsible for the clinical signs. A few inoculated rabbits remained free of diarrhea. Fecal material collected at postmortem examination contained RECV particles. The results suggest that the virus could also produce a subclinical infection. (+info)
Detection of alpha and betacoronaviruses in multiple Iberian bat species.
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Rabbit cardiomyopathy associated with a virus antigenically related to human coronavirus strain 229E.
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A new disease of rabbits is described. Following an acute febrile course, animals die or recover by the 11th day postinoculation. The characteristic pathologic finding is multifocal myocardial degeneration and necrosis. The disease can be transmitted by various routes with tissue filtrates or with infectious sera diluted to 10(-6) and passed through 0.1 micron filters. Virus particles with morphologic features characteristic of a coronavirus are present in infectious but not in normal rabbit serums. The antigen(s) in the infectious serums cross-reacts with the 229E and the OC43 strains of human coronavirus. Antigen cross-reacting with the 229E virus is detectable by immunofluorescent staining in frozen sections of heart tissue from sick but not from healthy animals. Animals surviving infection seroconvert to coronavirus specificity, as demonstrated by the presence in convalescent serums of antibody capable of reacting with the 339E virus. Susceptibility to infection has not been demonstrated in mice, hamsters, or guinea pigs, and the virus was not adapted for growth in tissue culture. It is uncertain whether the agent is a natural pathogen of rabbits or a coronavirus contaminant from another species, possibly human. The name rabbit infectious cardiomyopathy is suggested for this disease. (+info)
ORF23 of murine gammaherpesvirus 68 is non-essential for in vitro and in vivo infection.
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Discovery of seven novel Mammalian and avian coronaviruses in the genus deltacoronavirus supports bat coronaviruses as the gene source of alphacoronavirus and betacoronavirus and avian coronaviruses as the gene source of gammacoronavirus and deltacoronavirus.
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Counterimmunoelectroosmophoresis for detection of neonatal calf diarrhea coronavirus: methodology and comparison with electron microscopy.
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A counterimmunoelectroosmophoresis (CIE) technique is described for the detection of calf diarrhea coronavirus antigens in intestinal contents. The antibody reagent was prepared in rabbits against the Nebraska calf diarrhea coronavirus adapted to Vero cells and purified by density gradient centrifugation. The method was applied to intestinal contents of diarrheic and normal calves and compared with electron microscopy (EM). Calf coronavirus antigens were detected in intestinal contents of 44% (21/48) of the diarrheic calves and 24% (4/17) of the normal calves. Two precipitin lines could be observed in the majority of the positive samples. When compared with EM, CIE detected more positive animals. In only two cases (2/20) CIE was negative despite the visualization of coronavirus particles by EM. (+info)
Functional analysis of the murine coronavirus genomic RNA packaging signal.
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