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| Canine coronavirus highly pathogenic for dogs |
Canine coronavirus (CCoV) is usually responsible for mild, self-limiting infections restricted to the enteric tract. We report an outbreak of fatal disease in puppies caused by a pathogenic variant of CCoV that was isolated from organs with severe lesions.
Coronaviruses are large, enveloped, positive-stranded RNA viruses
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(1). Three different coronaviruses have been identified in dogs
(2,3). Canine coronavirus (CCoV) type I and type II are included in group 1 coronaviruses, and their evolution is related to that of feline coronavirus (FCoV) type I and type II. FCoV type II originated by heterologous recombination between CCoV type II and FCoV type I, while CCoV type I is genetically more similar to FCoV type I than to CCoV type II
(3). In addition, 2 FCoV biotypes that differ in pathogenicity have been observed in cats.
The onset of acute fatal disease (feline infectious peritonitis) is caused by pantropic variants (able to disseminate throughout the organism) of enteric FCoVs with deletions or recombinations in the 3c and 7b genes at the 3' end of the FCoV genome
(4). Similarly, changes in tissue tropisms in porcine and murine coronaviruses
(5, 6) and adaptation of the recently recognized severe acute respiratory syndrome-associated coronavirus
(7) to humans have been related to mutations or deletions. A third canine coronavirus, CRCoV, detected in the respiratory tract, has [less than or equal to] 96.0% amino acid (aa) conservation in the spike (S) protein with bovine coronavirus within group 2 coronaviruses, which provides strong evidence for a recent host-species shift (2).
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