Molecular Investigation of Feline Calicivirus Infection in China, 2019-2020

Abstract

Feline calicivirus (FCV) is a highly contagious viral pathogen of upper respiratory infections and oral disease in cats. To investigate the prevalence and gene characteristic of FCV in China, a total of 1739 clinical swabs of cat eyes and nasal were collected from 19 cities in China from 2019 to 2020. The FCV from clinical samples were isolated in F81 cells, and the gene sequences of the isolated FCV’s capsid proteins were phylogenetically analyzed by constructing the phylogenetic tree with the FCV vaccine strain F9 and reference strains of other countries. Results revealed a prevalence of 13.0% (226/1739) for FCV in China in this study, and samples from Langfang showed the highest prevalence in the cities. The 74 FCV strains isolated from clinical samples shared the nucleotide identity of 73.4%-79.1% and the amino acid identity of 83%-90% comparing with the F9 strain. Phylogenetic analysis reveals two branches of these FCV strains from China, which distinct from the vaccine strains of F9 and 255, and other reference strains. Structurally, the highly variable sites of capsid protein were exposed on the protein surface between circulating strains in China and the vaccine strain F9. Overall, this study would promote the understanding of the FCV prevalence and gene characteristics in China.