Characterization of HA1 gene of the victoria lineage influenza B virus in Mentougou district of Beijing during 2015-2016.

Abstract

Objective To understand the genetic variantion of HA1 gene from the Victoria like strain of infienza B virus isolated in Mentougou District of Beijing during 2015-2016, and to compare the genovariation with current vaccine stains, so as to provide the basis for the efficacy assessment of influenza B vaccine. Methods The nucleic acid was extracted from influenza B virus cultured and isolated from madin-darby canine kidney (MDCK), and HA1 gene was amplified by reverse transcription polymerase chain reaction (RT-PCR). The PCR products were sequenced and phylogenetic trees were constructed with the neighbor-joining method. Results The Victoria lineage of influenza B virus was the predominanted in Mentougou Ddistrict of Beijing. The 14 isolated strains of influenza B virus were closer to the vaccine strain B/Brisbane/60/2008 (FJ766842) recommended by WHO for 2016-2017, and to the representative circulating strain B/JilinNanguan/1223/2016 (EPI768805). Comparing to the amino acid sequences of HA1 gene in the above 2 strains, all 14 strains had substitutions occured in two positions. There were some other mutations in certain strains but the antigenic determinants remained intact. The isolated stains were distant in relationship with the vaccine strain B/Phuket/3073/2013 which was recommended by WHO for 2015- 2016. Conclusions The Victoria lineage of influenza B virus was predominant in Mentougou district of Beijing in 2015-2016 while the vaccine stain recommended by WHO belonged to the Yamagata lineage, indicating a poor matching of local stains with the vaccine strain. Key words: Influenza B virus; Victoria lineage; Sequence analysis; Genetic characteristics