Genetic evolution and biological characteristics of the human H3N2 influenza virus isolate

Abstract

Objective To analyse the genome sequences of the human influenza A virus A/Guangdong/SKLRD01/2017 (SKLRD01) , so as to elucidate its evolution status, molecular evolution and biological characteristics. Methods The genome sequences of influenza strains required for analysis were collected from Global Initiative on Sharing All Influenza Data (GISAID) and National Center for Biotechnology Information (NCBI) . The gene segments of SKLRD01 were compared with the referenced influenza viruses by BioEdit7.0.9 software. The phylogenetic trees of hemagglutinin (HA) and neuraminidase (NA) were constructed by the neighbor-joining method and Mega 5.0 software. The characteristics of gene sequence, virus evolution, pathogenicity, infectivity, drug susceptibility and antigenicity of the virus strain were analyzed. Results SKLRD01 was typical seasonal influenza virus according to the genome sequences. The HA gene belonged to the 3C.2a clade of H3 subtype, which had been widely spread in Southern China. The NA gene was closely related to the human H3N2 strain which was prevalent worldwide, and this kind of NA genes were dominant in the epidemic strains. SKLRD01 could spread from person to person effectively and possessed a partially high pathogenicity. The virus was sensitive to oseltamivir, but resistant to amantadine. Compared with the vaccine strain, only 3 amino acid mutations involving two epitopes in the A and C regions appeared in the antigen region of SKLRD01, that indicated the existing vaccine remained effective. Conclusions SKLRD01 is H3N2seasonal influenza virus with no major variation. It only has a small antigenic drift. Vaccination is currently the best preventive measures. Meanwhile, surveillance of such virus variants needs to be strengthened for updating vaccine strains in time and preventing an outbreak of influenza pandemic. Key words: Influenza A virus; Subtype H3N2; Genetic evolution; Biological characteristics