Detection of Feline Cupripoxvirus and Variation Analysis of Its VP1 Gene in Chengdu from 2020 to 2023

Abstract

Feline calicivirus (FCV) is an important pathogen causing infectious diseases in the oral cavity and upper respiratory tract of cats. Research on its prevalence and genetic variations contributes to the prevention and treatment of related diseases, as well as the development of new vaccines. In this study, a total of 113 samples of eye, nose, and throat secretions were collected from cats with respiratory and oral inflammation symptoms in Chengdu area from 2020 to 2023. The samples were tested using the RT-PCR method. The VP1 gene region was then cloned, sequenced, and subjected to homology analysis and phylogenetic analysis with domestic and foreign FCV reference strains. The results showed that among the 113 samples, 24 tested positive for FCV, with a positive rate of 21.24%. The nucleotide homology between the 5 FCV VP1 genes obtained in this study and the reference strains ranged from 72.6% to 84.1%, while the amino acid homology ranged from 84.0% to 95.9%. Phylogenetic analysis showed that the strains obtained in this study clustered into two gene groups (GⅠ and GⅡ) in the domestic and foreign FCV strain evolution tree. Strains SMU-M2, SMU-M7, SMU-M13, and SMU-M71 belonged to the GⅡ subtype, while strain SMU-M8 belonged to the (GⅠ subtype. The FCV vaccine strain had a distant genetic relationship with the prevalent FCV strains in Chengdu. The study revealed that FCV is prevalent in the cat population of Chengdu, and there is a low genetic homology and significant sequence differences between the prevalent strains and vaccine strains. This suggests the need to evaluate the actual protective efficiency of existing commercial FCV vaccines and promote the development of new vaccines with better cross-protection against prevalent strains.