The Winn Foundation just released information about some new FIP research: A particular virus protein, the 3c protein, has been investigated as a possible viral mutational site contributing to disease development.
Basically, it looks like this protein is 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 then they cannot be shed via feces. What’s more, they found that more than half of the FIP viruses analyzed had a mutation in the 3c gene.
This helps explain why it doesn’t spread from cat to cat: it isn’t airborne, and now it appears that it isn’t fecal-borne, either. We still aren’t sure how cats get this mutated virus, but we’re finding out more about how it isn’t spread, and that’s useful information.
The paper’s abstract is here; I haven’t been able to find a free copy of the entire paper online yet.