Dating the emergence of pandemic influenza viruses
Dating the emergence of pandemic influenza viruses
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DOI：
10.1073/pnas.0904991106
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发表时间：
2009-07-14
影响因子：
11.1
通讯作者：
Guan, Yi
中科院分区：
文献类型：
--
作者：
Smith, Gavin J. D.;Bahl, Justin;Guan, Yi
大流行性流感病毒在人类中引起显著死亡。在20世纪世纪，三种流感病毒引起了大流行：1918年H1N1病毒、1957年H2 N2病毒和1968年H3 N2病毒。这些大流行是由一种新的血凝素亚型从动物源引入并成功适应人类引发的，导致抗原性转变。尽管全球关注新的大流行性流感，但大流行性毒株的出现途径仍然未知。在这里，我们估计了所有世纪大流行流感毒株的进化历史，并推断了每个基因引入人类的日期。我们的研究结果表明，1918年H1N1大流行病毒的遗传成分在哺乳动物宿主中传播，即，猪和人类，早在1911年，不太可能是最近引入的禽流感病毒。系统发生关系表明，A/Brevig使命/1/1918病毒（BM/1918）是由哺乳动物病毒和先前在猪或可能在人类中传播的人毒株之间的重配产生的。此外，季节性和经典的猪H1N1病毒不是直接来自BM/1918，而是它们的前体在大流行期间共同传播。对最近共同祖先时间的平均估计也表明，H2 N2和H3 N2大流行毒株可能是通过未知哺乳动物宿主中的重配事件产生的，并涉及大流行识别之前的多种禽类病毒。在大流行确认之前的数年内，哺乳动物中可能通过一系列重配事件产生大流行毒株，这表明检测前体病毒的适当监测策略可能会阻止未来的大流行。
Pandemic influenza viruses cause significant mortality in humans. In the 20th century, 3 influenza viruses caused major pandemics: the 1918 H1N1 virus, the 1957 H2N2 virus, and the 1968 H3N2 virus. These pandemics were initiated by the introduction and successful adaptation of a novel hemagglutinin subtype to humans from an animal source, resulting in antigenic shift. Despite global concern regarding a new pandemic influenza, the emergence pathway of pandemic strains remains unknown. Here we estimated the evolutionary history and inferred date of introduction to humans of each of the genes for all 20th century pandemic influenza strains. Our results indicate that genetic components of the 1918 H1N1 pandemic virus circulated in mammalian hosts, i.e., swine and humans, as early as 1911 and was not likely to be a recently introduced avian virus. Phylogenetic relationships suggest that the A/Brevig Mission/1/1918 virus (BM/1918) was generated by reassortment between mammalian viruses and a previously circulating human strain, either in swine or, possibly, in humans. Furthermore, seasonal and classic swine H1N1 viruses were not derived directly from BM/1918, but their precursors co-circulated during the pandemic. Mean estimates of the time of most recent common ancestor also suggest that the H2N2 and H3N2 pandemic strains may have been generated through reassortment events in unknown mammalian hosts and involved multiple avian viruses preceding pandemic recognition. The possible generation of pandemic strains through a series of reassortment events in mammals over a period of years before pandemic recognition suggests that appropriate surveillance strategies for detection of precursor viruses may abort future pandemics.