Molecular Detection and Genotype Differentiation of Feline Coronavirus Isolates from Clinical Specimens in Thailand

Feline coronavirus (FCoV) infection manifests a wide magnitude of clinical symptoms from nonpathogenic mild enteric infection to pathogenic fatal feline infectious peritonitis (FIP). Based on the in vitro properties and antigenic relationship to canine coronavirus (CCoV), FCoVs are classified into type I and II with different continent preference. To investigate the incidence of FCoV infection among cat populations in Thailand during 2010-2011, clinical specimens (103 bodily fluids from 95 FIP clinically suspected cats and 17 feces from 7 healthy cats living in groups and 10 healthy cats living singly) were analyzed by amplification of the 3’UTR gene. Among them, 46% (47/103), 100% (7/7) and 50% (5/10) were positive, respectively. After that, the amplification of the 3’ end of S gene was performed to differentiate the genotypes of FCoV. Among the 3’UTR positive cats, genotype I predominated with the percentage of 29-60%. Genotype II was 15-29% and mixed genotype was 0-13%. Phylogenetic analysis of S gene revealed that type I FCoV were more genetically divergent (80-100%) than type II FCoV (100%) and closely related to Malaysia and Taiwan isolates based on 3’UTR analysis. Taken together, the 3’UTR RT-PCR could be applicable to confirm FIP infection in addition with the S RT-PCR to differentiate its genotype. Feces is a suitable specimen for monitoring the FCoV carrier condition in healthy cat.