Gene analysis of influenza B Yamagata lineage viruses in Fangshan district of Beijing in 2015

Abstract

Objective To analyze the genetic characteristics of influenza B Yamagata lineage in Fangshan district of Beijing in 2015. Methods A total of 13 strains of influenza B Yamagata lineage viruses were randomly selected from the strains had isolated in 2015. HA1 gene of B influenza Yamagata lineage viruses was amplified by reverse transcription-poly-merase chain reaction (RT-PCR) and sequenced. The seauences were used for gene evolution analysis compared with vaccine strain sequence recommended by WTO with phylogenetic analysis in MEGA6 software. Homologous was calculated on-line in the BLAST website. Results The length of the nucleotide sequence of HA1 gene obtained by sequencing was 1059bp, encoding 353 amino acids. Compared with the vaccine strain B/Massachusetts / 02/2012 in 2014-2015, the amino acids sequences of the 13 strains were different at poisitions 123, 131, 165, 180, 187, 196, 211, 217, 244, 313 and 327. Compared with the vaccine strain B/Wisconsin/01/2010 in 2012-2013, the amino acids sequences of the strains were different at the positions 187, 313 and 327. Phylogenetic tree of HA1 gene sequences showed the influenza B Yamagata lineage vruses in Fangshan District of Beijing in 2015 were close to the vaccine strain B / Wisconsin/1/2010 and they are on the same branch. Conclusions HA1 gene of influenza B Yamagata virus in Fangshan District of Beijing has been mutated in the region of antigenic determinant in 2015, but the vaccine strain B/Wisconsin/01/2010 had a protective effect. We should continue to pay attention to amino acid replacements. Key words: Influenza B virus; HA1; Phylogenetic tree