H6N1亚型禽流感病毒体外感染猪和人呼吸道组织的基因特征

H6N1 avian influenza viruses have been circulating in multiple poultries and infecting humans，posing a significant threat to human health and public health potential. Therefore, it is important to explore avian influenza virus H6N1 how to cross interspecies barriers from avians to humans and screen these key gene markers. In ecosystems of influenza viruses，pigs act as a “mixing vessels” to facilitate reassortment events and generate an influenza virus with pandemic potential. Our previous study showed that SAα-2,3Gal species was prevalent in lung alveolar epithelium in human. These results suggest that the human lung, to some extent, is infected by avian influenza viruses. On the basis of previous study,respiratory tract tissues of swines were infected by H6N1 virus isolated from poultry and respiratory tract tissues of humans were infected by H6N1 virus that capable of binding to human SAα-2,6Gal receptor in vitro in our study.Then pathological changes and infection of H6N1 viruses in respiratory tract tissues of swines and humans were observe. Also, the gene changes of all gene segments of H6N1 viruses were compared and then key gene markers with infecting swines and humans potential were screened. These results might provide useful basis for exploring the key factors of influenza A viruses H6N1 cross interspecies barriers from avians to swines and humans and monitoring influenza viruses with pandemic potential. At the same time, human respiratory tissues can serve as an efficient model for screening infection potential of newly emerging H6N1 viruses.

H6N1亚型禽流感病毒在多种禽类流行并感染人，其对人类健康和公共卫生安全呈潜在巨大威胁，故探讨H6N1病毒如何跨种间屏障传播人，筛选病毒跨种间传播的关键基因标记具有重要意义。在流感病毒生态系统中，宿主猪有助于病毒基因重配演变成感染人的潜能，我们前期研究人呼吸道流感病毒受体的分布,结果显示肺泡细胞表达禽型SAα-2，3Gal受体，表明禽流感病毒可感染人。本项目在此研究基础上，应用体外感染试验，将家禽分离的H6N1病毒感染猪呼吸道组织,能与人型α-2,6Gal受体结合的H6N1病毒感染人呼吸道组织，依据病毒在猪和人呼吸道复制情况，结合基因测序法分析H6N1病毒在猪和人呼吸道复制的基因特点，最终筛选H6N1病毒感染猪和人的关键基因标记。此研究结果为探索流感病毒H6N1跨种间屏障感染猪和人的关键因素以及流感病毒的监测提供基础。同时建立体外感染人呼吸道试验充当筛选H6N1病毒感染人潜能的模型。

H6亚型禽流感病毒在多种禽类流行并感染人，其对人类健康和公共卫生安全呈潜在巨大威胁，故探讨H6病毒如何跨种间屏障传播人，筛选病毒跨种间传播的关键基因标记具有重要意义。在流感病毒生态系统中，宿主猪有助于病毒基因重配演变成感染人的潜能，我们前期研究人呼吸道流感病毒受体的分布,结果显示肺泡细胞表达禽型受体，表明禽流感病毒可感染人。本项目在此研究基础上，应用体外感染试验，将家禽分离的H6病毒感染猪呼吸道组织,能与人型受体结合的H6病毒感染人呼吸道组织，依据病毒在猪和人呼吸道复制情况，结合基因测序法分析H6病毒在猪和人呼吸道复制的基因特点，最终筛选H6病毒感染哺乳动物和人的关键基因标记。取得的研究成果如下：(1)水禽鸭H6N1病毒接种BABL/c小鼠后出现感染症状，病毒分离和血清抗体阳性，小鼠肺组织出现炎症反应并检测出病毒抗原。因此，水禽H6N1病毒具有可跨种属间屏障从水禽直接感染哺乳动物小鼠的能力。(2)H6N1病毒在人和猪呼吸道组织有效复制，提示H6N1病毒具有跨越种间屏障从禽直接感染猪及人的潜能，病毒在人和猪呼吸道组织中持续复制有助于病毒进化演变成具有感染人以及人际传播能力的新型流感病毒的可能。(3)H6N1病毒为低致病性禽流感病毒，但也存在与病毒毒力、宿主嗜性相关的基因突变，病毒的HA出现S158T、P186S双联突变、NA颈部基因缺失，结合该病毒均可在人和猪呼吸道有效复制的结果，提示这些突变和缺失有利于陆禽H6N1病毒感染猪和人的潜能。(4)鸡源性H6N6病毒株ZZ346HA的P186T、H156R、S263G突变，158位点氨基酸缺失，NA出现氨基酸缺失，该病毒同时与人型和禽型受体结合。感染实验显示ZZ346病毒株对小鼠具有致病性，在人肺和猪呼吸道有效复制。因此，鸡源H6N6病毒无需适应可跨种属间屏障直接感染哺乳动物和人，基于ZZ346病毒株可有效感染小鼠以及在人和猪肺组织有效复制，提示H156R突变、S263G、158位点氨基酸缺失，NA序列中出现11个氨基酸缺失有助于H6N6病毒感染哺乳动物和人。因此，本项目的研究成果推动了禽流感病毒H6跨种间传播基础理论的发展，为禽流感病毒的监测提供依据。