一株野鸟源H9N2亚型禽流感病毒的全基因组序列分析及致病性研究

Whole genomic sequence and pathogenicity analysis of a wild bird-derived H9N2 subtype avian influenza virus

为进一步了解2014年分离自我国南方野鸟粪便中的一株H9N2亚型禽流感病毒(AIV)Wide Bird/Hu N/SC1400/2014(H9N2)(WB/400/14)的生物学特性,本研究对其进行全基因组序列测定、进化分析及SPF鸡、SPF鸭和BALB/c小鼠的感染性试验。序列分析显示:该分离株的HA裂解位点基序为333PAASDR↓GL340,其中不存在多个连续的碱性氨基酸,符合低致病性禽流感病毒(LPAIV)氨基酸序列特征。该分离株不同基因片段来源较复杂,分别与H9、H6、H4、H1、H11、H10、H3等多种亚型的LPAIV同源性较高,呈现明显的多样性。感染性试验显示,WB/400/14不能够在SPF鸡和小鼠体内有效复制,但病毒感染SPF鸭后能够在部分脏器中检测到病毒的存在,并且感染鸭能通够过咽喉和泄殖腔同时向外排毒,而同居感染鸭仅通过泄殖腔向外排毒,表明分离株在SPF鸭群中具有良好的水平传播能力。本研究为AIV的监测和防控提供实验依据。

To investigate the biological characteristics of a H9N2 subtype avian influenza virus （AIV） Wide Bird/HuN/ SC1400/2014（H9N2） （WB/400/14） that isolated from wild bird droppings collected in north of Hunan area, the whole genome of the isolate was sequenced and the pathogenicity of the isolate was evaluated in SPF chicken, SPF ducks and BALB/c mice. Sequence analysis showed that the isolate had a HA cleavage site of 333pAASDR ↓ GL340, which was identity to the sequence characters of low pathogenic AIV （LPAIV）. The different gene segments of the isolate showed a complicated source, which had the high homology with H9, H6, H4, HI, Hll, H10 and H3 subtype LPAIVs, respectively. The infectious experiments demonstrated that the isolate had no ability to duplicate in chicken and mice. However, the virus was able to be detected in partial organs of artificially infected ducks. In addition, the infected ducks were able to shed through throat and cloaca, while the contacting infected ducks only shed through cloaca, which illustrated that the isolate had the ability of horizontal transmission.