Pederson N, Liu H, Dodd K, Pesavento P. Significance of coronavirus mutants in feces and diseased tissues of cats suffering from feline infectious peritonitis. Viruses. 2009;1(2):166-184.
This article describes viral characterization of the feline coronavirus found in feces versus diseased tissues of cats with feline infectious peritonitis (FIP). The researchers found that within a single cat, the viruses found in the intestinal tract and diseased tissue were almost 100% identical genetically. Minor differences were found in several of the genes of feline coronaviruses. Notably, the gene encoding a virus protein whose function remains unknown, the 3c protein, was almost always mutated in viruses found in FIP lesions. These mutations, while minor, are predicted to lead to a dysfunctional protein product. Viruses from the feces of these same cats however, almost always had intact, functional 3c genes. While the 3c mutation is not universal among FIP virus isolates, it does occur in the majority, and is speculated to play a significant role in FIP development. From this study, it also appears that the FIP mutants arose separately in each affected cat, rather than spreading cat-to-cat. Thus, horizontal transmission of FIP does not readily occur. More research into the function of the 3c gene product is needed to define its role in FIP. [MK]
Pedersen NC. A review of feline infectious peritonitis virus infection: 1963-2008. Journal of Feline Medicine & Surgery. 2009;11(4):225-258.
Vennema H, Poland A, Foley J, Pedersen NC. Feline infectious peritonitis viruses arise by mutation from endemic feline enteric coronaviruses. Virology. Mar 30 1998;243(1):150-157.