两株野鸟源H9N2亚型禽流感病毒的进化分析和对小鼠的感染性研究

Evolution and infectivity in mice of two wild bird-origin H9N2 subtype avian influenza viruses

为了解2015年分离自我国四川省野鸟粪便中的两株H9N2亚型禽流感病毒(AIV)Wild Bird/SC/S1264/2015(H9N2)(WB/SC/264/15)和Wild Bird/SC/S1411/2015(H9N2)(WB/SC/411/15)的生物学特性,本研究对其进行了全基因组序列测定和BALB/c小鼠的感染性试验。序列分析结果显示:两个分离株的HA裂解位点基序均为333PSRSSR↓GL340,符合低致病性AIV(LPAIV)的氨基酸序列特征,HA蛋白受体结合位点处的第226以及228位氨基酸残基分别为谷氨酰胺(Q)和甘氨酸(G),具有结合禽源AIV受体的分子特征。内部基因片段来源复杂,呈现明显的基因多样性。BALB/c小鼠的感染性试验结果显示,这两个分离株只在小鼠的上呼吸道鼻甲中有效复制,小鼠体重变化轻微,未见明显临床症状。

To investigate the biological characteristics of two wild bird-origin H9N2 subtype avian influenza virus（AIV）, Wild Bird/SC/S1264/2015（H9N2） （WB/SC/264/15） and Wild Bird/SC/S1411/2015（H9N2） （WB/SC/411/15）, which were isolated from wild bird feces in Sichuan province in 2015, the two H9N2 subtype AIV were sequenced and the infectivity of the isolates were evaluated in BALB/c mice. Sequence analysis showed that both of the isolates had a HA cleavage site of 333PSRSSR GL 340, a feature of low pathogenic avian influenza virus （LPAIV）. The two H9N2 viruses had residues Q226 and G228 at the HA receptorbinding pocket, suggesting the binding preference of these viruses favors α-2,3 avian-type receptors. The internal genes of the two H9N2 viruses showed distinct diversity. The infectious experiments in mice showed that the isolates were able to replicate only in the nasal turbinate of mice and mice had slight body weight change without apparent clinical disease.