Pedersen NC, Liu H, Scarlett J, et al. Feline infectious peritonitis: Role of the feline coronavirus 3c gene in intestinal tropism and pathogenicity based upon isolates from resident and adopted shelter cats. Virus Research 2012;165:17-28.
Feline infectious peritonitis (FIP) is a complex disease involving a mutant coronavirus. The specific mutation that occurs allowing this normally innocuous virus to cause a fatal disease remains unclear. A particular virus protein, the 3c protein, has been investigated as a possible viral mutational site contributing to disease development. These investigators found that this protein appears to be involved with the ability of the virus to replicate in the intestines. Mutations in the gene for this protein lead to the virus being unable to replicate in the intestinal tract and thus unable to be shed in feces. More than half of the FIP viruses they analyzed had a mutation in the 3c gene. This may explain why FIP outbreaks with cat-to-cat transmission of the mutant virus rarely occurs – it is simply no longer shed in feces once this mutation occurs. While we still don’t know what makes the FIP virus so nasty, we have gained a better understanding of its strange epidemiology. [MK]