College of Animal Science and Technology, Shandong Agriculture University, Taian, China.
Shanghai Veterinary Research Institute, CAAS, Shanghai, China.
Transbound Emerg Dis. 2018 Jun;65(3):904-910. doi: 10.1111/tbed.12805. Epub 2018 Jan 14.
H9N2 is one of the major subtypes of influenza virus circulating in poultry in China, which has a wide host range from bird to mammals. Two H9N2 viruses were isolated from one mink farm in 2014. Phylogenetic analysis showed that internal genes of the H9N2 viruses have close relationship with those of H7N9 viruses. Interestingly, two H9N2 were separated in phylogenetic trees, indicating that they are introduced to this mink farm in two independent events. And further mice studies showed that one H9N2 caused obvious weight loss and 20% mortality in infected mice, while another virus did not cause any clinical sign in mice infected at the same dose. Genetic analysis indicated that the virulent H9N2 contain a natural mutation at 701N in PB2 protein, which was reported to contribute to mammalian adaptation. However, such substitution is absent in the H9N2 avirulent to mice. Circulation of H9N2 in mink may drive the virus to adapt mammals; continual surveillance of influenza virus in mink was warranted.
H9N2 是在中国禽类中流行的主要流感病毒亚型之一，其宿主范围广泛，从鸟类到哺乳动物。2014 年从一个水貂养殖场分离到两株 H9N2 病毒。系统进化分析显示，H9N2 病毒的内部基因与 H7N9 病毒密切相关。有趣的是，两株 H9N2 在系统进化树上分离，表明它们是在两个独立的事件中引入这个水貂养殖场的。进一步的小鼠研究表明，一株 H9N2 在感染的小鼠中引起明显的体重减轻和 20%的死亡率，而另一株病毒在相同剂量感染的小鼠中没有引起任何临床症状。遗传分析表明，毒力 H9N2 在 PB2 蛋白的 701N 位含有一个天然突变，据报道该突变有助于病毒适应哺乳动物。然而，这种突变在对小鼠无毒的 H9N2 中不存在。H9N2 在水貂中的流行可能促使病毒适应哺乳动物；有必要持续监测水貂中的流感病毒。
