Genomic and phylogenetic analysis of the ORF7b gene from a Chinese feline infectious peritonitis virus isolate

Abstract

FCoV viruses exhibit great genetic diversity, leading to the presence of FIPV-causing variants. Current molecular evolution analysis and genetic variation studies of FCoV in China are predominately focused on gene encoding the spike protein or other structural proteins, while few studies have evaluated genetic variations in nonstructural FCoV genes, which can play an important role in disease pathogenesis. In this study, the gene encoding the open reading frame (ORF) 7b nonstructural FCoV protein of the Chinese Fujian strain FJLY20201 was amplified from the ascitic fluid of a Chinese domestic cat infected with FIPV and compared with ORF 7b from previously published FCoV strains. Multiple sequence alignment revealed that FJLY20201 exhibited high identity with other Chinese FCoV strains. Phylogenetic analyses indicated that the Chinese strains did not differentiate between type I and type II serotypes of FCoV based on S proteins. In addition, they formed clades and differed genetically from strains originating outside China. This study provides the molecular epidemiology data about the ORF 7b genes of FCoV strains in China. Our results show that the identity of ORF 7b genes was closer between the Chinese isolates, and suggest that variation in ORF 7b is more dependent on geographical origin.