【关键词】 流感病毒a型; h1n1亚型; 系统发育; 基因重排
2009年3月底，墨西哥流感样疾病(ili)病例异常增加，2009年4月17～28日期间，共报道1 551例严重肺炎流感疑似病例(其中7例确诊死亡病例)[1]，随后与之毗邻的美国也相继出现类似病例。2009年4月25日，世界卫生组织(who)宣布本次疫情为国际关注的突发公共卫生事件(pheic)[2]，并于4月30日将流感大流行警戒级别从4级提高到5级[3]，此举意味着该疾病随时可能以人人之间的传播方式大规模流行[4]。
流感病毒属正粘病毒科a型流感病毒属，为单股负链rna病毒，其基因组由大小不等的8个独立片段组成[5]，自然条件下极易发生基因重排形成新的病毒并因此表现出极强的流行趋势[6，7]。本文分析此次流行的h1n1亚型流感病毒的各基因序列，旨在探讨新型流感病毒的起源演化规律，为防控流感提供理论依据。
1 材料和方法
1.1 本文毒株的命名方法 本文对甲型流感病毒的8个非断裂基因片段进行分析，参与对比的基因序列数量庞大，如以表格方式一一列举基因的毒株信息，势必占据大量篇幅，流感病毒有着严格的命名原则，本文参照该原则对文中所涉及的毒株以“gene bank access no./region/host/strain or isolate/subtype”方式命名，未指明宿主(host)类型者，其初始分离宿主为人类。www.11665.cOm
1.2 本次流行h1n1甲型流感病毒基因序列的选取 序列选自美国国立生物技术信息中心网站(
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