Reid Ann H, Taubenberger Jeffery K
Division of Molecular Pathology, Department of Cellular Pathology and Genetics, Armed Forces Institute of Pathology, 1413 Research Blvd, Building 101, Room 1057, Rockville, MD 20850-3125, USA.
J Gen Virol. 2003 Sep;84(Pt 9):2285-2292. doi: 10.1099/vir.0.19302-0.
Influenza A virus is a major public health threat, killing more than 30,000 per year in the USA alone, sickening millions and inflicting substantial economic costs. Novel influenza virus strains emerge periodically to which humans have little immunity, resulting in devastating pandemics. The 1918 pandemic killed nearly 700,000 Americans and 40 million people worldwide. Pandemics in 1957 and 1968, while much less devastating than 1918, also caused tens of thousands of deaths in the USA. The influenza A virus is capable of enormous genetic variability, both by continuous, gradual mutation and by reassortment of gene segments between viruses. Both the 1957 and 1968 pandemic strains are thought to have originated as reassortants, in which one or both human-adapted viral surface proteins were replaced by proteins from avian influenza virus strains. Analyses of the surface proteins of the 1918 pandemic strain, however, suggest that this strain may have had a different origin. The haemagglutinin gene segment of the virus may have come directly from an avian source different from those currently circulating. Alternatively, the virus, or some of its gene segments, may have evolved in an intermediate host before emerging as a human pathogen. Determining whether pandemic influenza virus strains can emerge via different pathways will affect the scope and focus of surveillance and prevention efforts.
甲型流感病毒是对公众健康的重大威胁，仅在美国每年就导致超过3万人死亡，使数百万人患病并造成巨大经济损失。新型流感病毒毒株会定期出现，而人类对这些毒株几乎没有免疫力，从而引发毁灭性的大流行。1918年的大流行导致近70万美国人死亡，全球死亡人数达4000万。1957年和1968年的大流行虽然破坏力远不及1918年，但在美国也造成了数万人死亡。甲型流感病毒具有极大的基因变异性，这既源于持续的渐进突变，也源于病毒基因片段的重配。1957年和1968年的大流行毒株被认为都是重配体，其中一种或两种适应人类的病毒表面蛋白被禽流感病毒株的蛋白所取代。然而，对1918年大流行毒株表面蛋白的分析表明，该毒株可能有不同的起源。该病毒的血凝素基因片段可能直接来自与目前流行的毒株不同的禽类来源。或者，该病毒或其一些基因片段可能在中间宿主中进化，然后才成为人类病原体。确定大流行性流感病毒毒株是否能通过不同途径出现，将影响监测和预防工作的范围与重点。
