上海地区2004-2008年流行性感冒病毒亚型分布及血凝素基因进化研究

目的 了解上海地区近几年的流行性感冒(简称流感)病毒型与亚型分布及甲亚型流感病毒血凝素(HA)基因的进化.方法 采集2004-2008年上海地区5个流感监测哨点流感样患者和聚集性流感暴发患者的962份咽拭子标本进行流感病毒分离鉴定,确定病毒型及亚型.对上海市不同年份、不同区域的甲型流感病毒散发、聚集性暴发分离株进行HA基因全片段测序,并与近几年世界卫生组织(WHO)疫苗推荐株进行比对分析,绘制基因进化树.结果 A/H3N2是近几年季节性流感的主要亚型,占阳性标本构成比为54.9%(162/295),但在2005年末至2006年夏季流行强度低,仅占阳性标本构成比分别为0%(0/16)和23.5%(8/34);A/H1N1在2005-2006年3个流行季节活跃,占阳性标本构成比分别达到21.4%(12/56)、43.8%(7/16)、76.5%(26/34),近2年分离株明显减少,占阳性标本构成比仅分别为0%(0/44)和5.0%(7/139);B型在2004年至2005年季节性流感中活动强度较高,占阳性标本构成比分别为42.9%(24/56)和56.2%(9/16),在2006-2007年季节性流感中未分离到,2008年流行强度又有增加,占阳性标本构成比为34.5%(48/139).2005-2008年,A/H1N1 HA基因进化树显示,同一年份HA基因成簇分布,序列相近;2004-2008年,A/H3N2 HA基因进化树显示,虽然同一年份序列相近,但相近序列进化枝插有相近年份的分离株,并且同一年份存有变异较大的序列.A/H1N1、A/H3N2流行株的序列与当年WHO的疫苗推荐株序列相似.结论 各年份流感流行的型与亚型分布不同,A/H3N2是近几年季节性流感的主要亚型.同一年份的A/H1N1、A/H3N2 HA基因序列成簇分布,但在A/H3N2同一年份的进化枝中插有相近年份的分离株序列,并且存在变异较大的序列.近年,WHO疫苗推荐株HA序列与当年流行株序列相近.

Type and subtype distribution of influenza virus and genetic evolution of hemagglutinin in Shanghai area in duration of 2004-2008

Objective To analyze the type and subtype distribution of influenza virus and the genetic evolution of hemngglutinin (HA) in Shanghai area during 2004 to 2008. Methods All 962 throat swabs were collected from influenza-like patients in 5 influenza sentry hospitals and influenza outbreaks. Influenza viruses were isolated in MDCK cell lines, and then viral types and subtypes were identified. The HA of influenza Aisolates selected by outbreak or sporadic patients in different areas and epidemic seasons were sequenced and analyzed by phyiogenetic trees. Results A/H3N2, accounting for 54.9% (162/295),was the dominate subtype in recent years, but less popular in the end of 2005 to the middle of 2006 with 0% (0/16)and 23.5% (8/34)of positive specimen,respectively. There were more A/ H1N1 isolates in 2005-2006 with 21.4% (12/56),43.8% (7/16)and 76.5% (26/34)of positive specimen, respectivly, but declined obviously in 2007-2008 accounting for only 0% (0/44)and 5.0% (7/ 139). Influenza B virus was more popular in 2004 to 2005 with 42.9% (24/56)and 56. 2% (9/16), respectively,and not isolated from 2006 to 2007,then increased in 2008 accounting for 34. 5% (48/139). Phylogenetic tree of HA showed that A/H1N1 isolates in the same year clustered from 2005 to 2008, and most A/H3N2 isolated were homologous in the same year during 2004-2008 while some were inserted to the clusters of near years and more distinguished sequences appeared. A/H1N1 and A/H3N2 isolates were all similar to the vaccine strains recommended by WHO. Conclusion The distribution of influenza type and subtype kept on changing each year, but A/H3N2 dominated in most years. A/H1N1 and A/H3N2 in the same year clustered ,but some A/H3N2 of near years were and evolved faster with more distinguished strains appeared in same interval Generally, HA of influenza A isolates in Shanghai during 2004 to 2008 were similar to the WHO reference strains.