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Feline Coronavirus Persistence in Healthy Cats

Kipar A, Meli ML, Baptiste KE, et al. Sites of feline coronavirus persistence in healthy cats. J Gen Virol March 17, 2010.

Feline coronavirus (FCoV), the agent of FIP, is transmitted by the fecal-oral route. Some cats infected with FCoV do not clear the virus, and shed the virus either persistently or intermittently. These cats are important sources of the virus in cat populations. These investigators examined the tissues of infected cats in order to identify the organ site of viral persistence in healthy carriers. Overall, the colon tested positive for virus more than any other tissue over time. Interestingly, all organs, including brain and skin, tested positive for virus in at least one cat during the investigatory period, indicating that FCoV infection disseminates to many organs during infection, even in healthy cats. Cats shedding the virus were found to be infected not only in the colon, but also in the small intestine (jejunum and ileum); in addition, the amount of virus present was an important determinant of shedding in feces, with higher amounts leading to viral shedding as one would expect. While the colon was the primary site for viral persistence and the source of continued shedding over the long-term, spread of the virus to the small intestines appears to be necessary for detectable fecal shedding. This would explain the intermittent nature of virus shedding in carrier cats. In addition, it was found that other tissues outside the gut may remain persistently infected as well, and could serve as a source for recurrent viremia. Most commonly, the mesenteric, or abdominal lymph nodes, and liver were sites of viral persistence. In these tissues, it appears that the resident macrophages are the specific cells involved. Thus, even cats that clear the virus from the intestines may remain virus-infected. [MK]

Related articles:
Goodson TL, Randell SC, Moore LE. Feline infectious peritonitis. Compend Contin Educ Vet 2009;31.