Pusch Elizabeth A, Suarez David L
Southeast Poultry Research Laboratory, US National Poultry Research Center, Agricultural Research Service, US Department of Agriculture, 934 College Station Road, Athens, GA 30605, USA.
Vet Sci. 2018 Sep 21;5(4):82. doi: 10.3390/vetsci5040082.
Poultry-adapted H9N2 avian influenza viruses (AIVs) are commonly found in many countries in Asia, the Middle East, Africa, and Europe, and although classified as low pathogenic viruses, they are an economically important disease. Besides the importance of the disease in the poultry industry, some H9N2 AIVs are also known to be zoonotic. The disease in humans appears to cause primarily a mild upper respiratory disease, and doesn't cause or only rarely causes the severe pneumonia often seen with other zoonotic AIVs like H5N1 or H7N9. Serologic studies in humans, particularly in occupationally exposed workers, show a large number of people with antibodies to H9N2, suggesting infection is commonly occurring. Of the four defined H9N2 poultry lineages, only two lineages, the G1 and the Y280 lineages, are associated with human infections. Almost all of the viruses from humans have a leucine at position 226 (H3 numbering) of the hemagglutinin associated with a higher affinity of binding with α2,6 sialic acid, the host cell receptor most commonly found on glycoproteins in the human upper respiratory tract. For unknown reasons there has also been a shift in recent years of poultry viruses in the G1 and Y280 lineages to also having leucine instead of glutamine, the amino acid found in most avian viruses, at position 226. The G1 and Y280 poultry lineages because of their known ability to infect humans, the high prevalence of the virus in poultry in endemic countries, the lack of antibody in most humans, and the shift of poultry viruses to more human-like receptor binding makes these viruses a human pandemic threat. Increased efforts for control of the virus, including through effective vaccine use in poultry, is warranted for both poultry and public health goals.
适应家禽的H9N2禽流感病毒（AIVs）在亚洲、中东、非洲和欧洲的许多国家普遍存在，尽管被归类为低致病性病毒，但它们仍是一种具有经济重要性的疾病。除了该疾病在家禽业中的重要性外，一些H9N2 AIVs也为人畜共患病原体。人类感染该疾病似乎主要引起轻度上呼吸道疾病，不会引发或仅偶尔引发其他禽流感病毒（如H5N1或H7N9）常见的严重肺炎。针对人类的血清学研究，特别是针对职业暴露工人的研究表明，大量人群具有针对H9N2的抗体，这表明感染普遍发生。在四个已确定的H9N2家禽谱系中，只有两个谱系，即G1和Y280谱系，与人类感染有关。几乎所有来自人类的病毒在血凝素的第226位（H3编号）都有一个亮氨酸，这与α2,6唾液酸具有更高的结合亲和力，α2,6唾液酸是人类上呼吸道糖蛋白中最常见的宿主细胞受体。由于未知原因，近年来G1和Y280谱系中的家禽病毒在第226位也发生了变化，由大多数禽流感病毒中发现的谷氨酰胺变为亮氨酸。G1和Y280家禽谱系因其已知的感染人类的能力、流行国家家禽中该病毒的高流行率、大多数人缺乏抗体以及家禽病毒向更类似人类受体结合的转变，使其成为人类大流行的威胁。为实现家禽和公共卫生目标，有必要加大对该病毒的控制力度，包括在家禽中有效使用疫苗。
