Sequencing analysis of N and G gene of rabies viruses from Sichuan province of China in 2011- 2017

Abstract

Objective To analyze molecular feature of rabies virus (RABV) epidemic strains in Sichuan province during 2011 to 2017, and explore differences at nucleotide, amino acid and protein modification between these street strains and vaccine strains. Methods Nucleoprotein(N) and glycoprotein(G) genes were amplified by RT-PCR using specific primers for 23 antigen-positive canine brain specimens collected from 2011 to 2017. The evolutionary relationship and immune antigenicity of N and G genes was analyzed. Bioinformatics software was used to analyze and organize data. Results We obtained the N and G genes sequences of 23 RABV strains by sequencing. Genetic evolution relationship analysis showed that all the 23 RABV strains belonged to rabies virus species and could be divided into three branches, which had apparent geographically specific characteristics but some Sichuan strains co-circulated with the epidemic strains in the eastern and northern regions of China.The N genes of Sichuan strains had nucleotide and amino acid homology of 97.4% to 100% and 99.6%-100%. The nucleotide and amino acid homology between Sichuan strains and reference strains were 72.1%-99.8% and 81.6%-100%, respectively. There were some differences in antigenic sites, cell epitopes and signal peptide sequences between vaccine strain and Sichuan strains but no significant change was found in antigenicity, organizational preference and virulence. Conclusions The 23 strains of RABV of Sichuan belonged to rabies virus species and had no obvious differences. There were few differences between Sichuan strain and vaccine strain in amino acid sequences of G, but the virulence did not change. Key words: Rabies virus; Nucleoprotein; Glycoprotein; Phylogenetic analysis; Immunogenicity