北京地区2009-2010年流感监测季乙型流感病毒HA基因特征分析

Analysis on the characteristics of HA gene of influenza virus B circulated in Beijing area from 2009 to 2010

目的了解2010年1~4月间北京地区流感病原学监测中分离到的乙型流感病毒株血凝素（HA）基因的特征,探讨2009-2010年流感监测季乙型流感病毒的分子流行病学特征。方法采用一步法RT-PCR方法,随机抽取32株本监测季分离到的乙型流感病毒毒株进行血凝素基因的扩增,将扩增产物进行序列测定,采用相应的生物信息软件进行核酸及氨基酸序列比对以及进化树分析。结果 2009-2010年流感监测季期间,北京地区人群中乙型流感病毒以Victoria系的活动占优势,其间分离的32株病毒的HA基因与2009-2011年北半球的疫苗株B/Brisbane/60/2008相比,31株在HA1区发生I73P的变化,32株发生I161V的变化,氨基酸的替换均发生在抗原决定簇A区。绘制的种系发生树显示这些毒株与B/Brisbane/60/2008亲缘关系最近,而与B/Malaysia/2506/2004以及B/Hong Kong/330/2001差异较大。结论 2010年1~4月间北京地区人群中Victoria系乙型流感病毒的HA基因发生变化,导致其抗原性发生改变,表明北京地区人群中流行的乙型流感病毒的抗原性和基因特性在逐渐发生变异,今后在流感监测工作中要加强流感病原学的监测,及时发现新的乙型流感病毒变异株。

Objective To study the characteristics of HA gene of influenza virus B circulated in Beijing area during January to April 2010,and investigate the molecular epidemiological characteristics of influenza virus B circulated in Beijing area during 2009-2010 seasonal influenza surveillance.Methods The HA gene of 32 isolated influenza viruses B were amplified through one-step RT-PCR method.The PCR products were sequenced and the sequence alignment was carried out using bioinformatics software.The mutation of HA gene was analyzed and the evolutionary trees were generated.Results Influenza virus B,Victoria linage was the dominant pathogen in Beijing area during January to April in 2010,comparing with 2009-2011 Northern Hemisphere influenza B vaccine strain B/Brisbane/60/2008,the amino acid at position 73 was changed from I to P in 31 influenza viruses B,the amino acid at position 161 was changed from I to V in 32 influenza viruses B,all these changes were located at the antigenic determinant domain.The evolutionary tree showed that the genetic relationship of these 32 influenza B viruses with B/Brisbane/60/2008 was the closest,but the difference between these 32 influenza viruses B and B/Malaysia/2506/2004 or B/Hong Kong/330/2001 were larger.Conclusions The HA gene of Victoria linage influenza viruses B circulated in Beijing area during January to April in 2010 was changed,leading to the change of antigenicity of virus,the influenza surveillance should be strengthened to find the new mutant of virus in time.