Feline Coronavirus in Northern Vietnam: Genetic Detection and Characterization Reveal Predominance of Type I Viruses

This study was conducted to identify the molecular and biological characteristics of the collected feline coronavirus (FCoV) strains in northern Vietnam. A total of 166 fecal samples were collected from domestic cats in Hanoi, Bacgiang, Hungyen, and Hanam in northern Vietnam. Conventional polymerase chain reaction (PCR) was used to detect the FCoV genome in the field samples. Results indicated that 19 (11.45%) out of 166 fecal samples were positive for the FCoV genome using PCR. Insignificant differences in positive rates were detected according to breed, age, sex, and health status of the cats. By using nested PCR, all 19 FCoV strains obtained belonged to type I. Analysis of the partial S gene sequences indicated that the nine Vietnamese FCoV strains in this study shared high nucleotide identity, ranging from 88.5% to 99.16%. Phylogenetic analysis supported that the Vietnamese FCoV strains obtained were type I viruses, which are divided into several clades. The nine Vietnamese FCoV strains were genetically close to viruses from the Netherlands, France, and China and differed from the vaccine strain. No mutation was detected among the nine Vietnamese FCoV strains at sites 23,531 and 23,537 in the S gene sequences. The S1/S2 cleavage site on the S protein of FCoV of the nine viral strains indicated an R/G-R-S/A-R-R-S motif, which was typical for feline enteric coronavirus strains. The sequences found were consistent with FECV/low-path viruses, and that it was healthy cats (not FIP cats) that were sampled.