Meredith A. Brown
, Jennifer L. Troyer, Jill Pecon-Slattery, Melody E. Roelke, and Stephen J. O’Brien
Figure 1. Alternative phylogenetic predictions of the in vivo mutation hypothesis versus the dual circulating virulent/avirulent hypothesis. A) The in vivo mutation transition hypothesis predicts paraphyly of feline infectious peritonitis (FIP) cases and feline enteric coronavirus (FECV) asymptomatic feline coronavirus (FCoV) isolates). B) The circulating virulent/avirulent strain hypothesis predicts reciprocal monophyly of FIV-cases versus FECV asymptomatic. Numbers represent individual cat (or locale), which is either FIPV case (red) or FECV asymptomatic (blue). Evidence presented in this article supports the circulating dual virulent and avirulent strains.