两株B型流感病毒的基因组序列分析

目的 了解两株B型流感病毒的基因组序列特征。方法 对两株B型流感病毒进行全基因组序列测定和基因进化特性的分析。结果 成功扩增出两株B型流感病毒的全基因组序列,并且两毒株的基因组均属于Yamagata系类似株Ⅱ系。两株病毒的基因组序列与疫苗株B/Florida/4/2006(Yamagata系)以及Victoria系代表株B/Brisbane/60/2008、B/Malaysia/2506/2004相比,HA基因同源性为89.7%～97.3%,NB基因同源性则为95.4%～98.4%。两株病毒的HA蛋白与WHO推荐的疫苗株B/Florida/4/2006(Yamagata系)相比,存在11处氨基酸突变,其中HA的N131K氨基酸位点突变,可能对抗原性产生影响。NB的S198N氨基酸位点突变可能影响神经氨酸酶抑制剂的灵敏度。结论 两株B型流感病毒的遗传进化状态稳定,但是与同分支中的毒株基因序列部分位点存在差异。

Genome sequence analysis on two strains of influenza B virus

To investigate genetic characterization of two influenza B virus strains, the complete genomes were sequenced and analyzed. Phylogenetic analysis of the whole genomes revealed that two strains were classified into the Yamagata-like clade. Comparison of genome sequences of strain CX1, CX2 and other vaccines (B/Florida/4/2006, B/Brisbane/60/2008, and B/Malaysia/2506/2004) showed that these influenza B viruses shared higher homology. The HA gene was 89.7% to 97.3% in homology, and NB gene was 95.4% to 98.4% in homology. However, phylogenetic analysis of these two strains with a WHO recommended vaccine strain (B/Florida/4/2006) showed that 11 variations in amino acid occurred on its HA protein. Meanwhile, the N131K mutation in HA may impact its antigenicity, and the S198N mutation in NB may affect the sensitivity of NA inhibitor. These data indicated a close evolutionary relationship between these two influenza B virus strains despite minor variations on certain genes of strains in the same clade.