MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.
Viruses. 2022 Mar 30;14(4):726. doi: 10.3390/v14040726.
The H9N2 subtype avian influenza viruses (AIVs) have been circulating in China for more than 20 years, attracting more and more attention due to the potential threat of them. At present, vaccination is a common prevention and control strategy in poultry farms, but as virus antigenicity evolves, the immune protection efficiency of vaccines has constantly been challenged. In this study, we downloaded the hemagglutinin (HA) protein sequences of the H9N2 subtype AIVs from 1994 to 2019 in China-with a total of 5138 sequences. The above sequences were analyzed in terms of time and space, and it was found that h9.4.2.5 was the most popular in various regions of China. Furthermore, the prevalence of H9N2 subtype AIVs in China around 2006 was different. The domestic epidemic branch was relatively diversified from 1994 to 2006. After 2006, the epidemic branch each year was h9.4.2.5. We compared the sequences around 2006 as a whole and screened out 15 different amino acid positions. Based on the HA protein of A/chicken/Guangxi/55/2005 (GX55), the abovementioned amino acid mutations were completed. According to the 12-plasmid reverse genetic system, the rescue of the mutant virus was completed using A/PuertoRico/8/1934 (H1N1) (PR8) as the backbone. The cross hemagglutination inhibition test showed that these mutant sites could transform the parental strain from the old to the new antigenic region. Animal experiments indicated that the mutant virus provided significant protection against the virus from the new antigenic region. This study revealed the antigenic evolution of H9N2 subtype AIVs in China. At the same time, it provided an experimental basis for the development of new vaccines.
H9N2 亚型禽流感病毒（AIVs）在中国已经流行了 20 多年，由于它们潜在的威胁，引起了越来越多的关注。目前，疫苗接种是家禽养殖场常用的预防和控制策略，但随着病毒抗原性的演变，疫苗的免疫保护效率不断受到挑战。在本研究中，我们从 1994 年到 2019 年在中国下载了 H9N2 亚型 AIV 的血凝素（HA）蛋白序列，共 5138 个序列。对上述序列进行了时空分析，发现 h9.4.2.5 在中国各个地区最为流行。此外，2006 年前后中国 H9N2 亚型 AIV 的流行情况有所不同。1994 年至 2006 年期间，国内流行分支相对多样化。2006 年后，每年的流行分支均为 h9.4.2.5。我们对 2006 年前后的序列进行了整体比较，筛选出 15 个不同的氨基酸位置。基于 A/chicken/Guangxi/55/2005（GX55）的 HA 蛋白，完成了上述氨基酸突变。根据 12 质粒反向遗传系统，使用 A/PuertoRico/8/1934（H1N1）（PR8）作为骨架完成了突变病毒的拯救。交叉血凝抑制试验表明，这些突变位点可以将亲本株从旧抗原区转变为新抗原区。动物实验表明，突变病毒对来自新抗原区的病毒提供了显著的保护作用。本研究揭示了中国 H9N2 亚型 AIV 的抗原进化，同时为新型疫苗的开发提供了实验依据。
