中国首株H13N6亚型禽流感病毒遗传进化分析及致病性和传播性评估

Phylogenetic analysis and assessment of the pathogenicity and transmissibility of the H13N6 subtype AIV firstly isolated from China

为了解我国首次分离的H13N6亚型禽流感病毒(AIV)生物学特性,本研究对该分离株进行全基因序列测定和分析,并对其进行BALB/c小鼠和SPF鸡致病性试验以及豚鼠传播试验。序列分析表明HA碱性裂解位点序列为PAISNR↓G,为低致病性AIV。遗传进化分析表明NA基因属于北美谱系,其余7个基因均属于欧亚谱系;其中NA、NP、M、NS基因来源于鸥类,而HA、PB2、PB1、PA基因来源于野鸭类。动物致病性和传播试验结果显示,该病毒株在鸡和小鼠体内不能进行有效复制,在豚鼠和鸡体内也不能进行排毒和有效传播。基因序列分析结合致病性和传播性试验表明H13N6亚型AIV分离株可能是通过候鸟迁徙而传入我国的新型重组AIV,但该病毒株仍只能感染野生水禽尚未获得跨越种间屏障感染陆生家禽和人的能力,尚不具备哺乳动物间和家禽间的传播能力。

The emergence of a new serotype of H13N6 avian influenza virus （AIV） in China was firstly isolated from mallard environmental samples in Dalian and the biological characteristics of the H13N6 isolate were identified. The sequence analysis indicated that the H13N6 isolate showed a cleavage site （PAISNR .↓ G） consistent with a low pathogenic AIV characterization. The phylogenetic analysis of all eight viral genes revealed that NA segment of H13N6 belonged to the North American lineage, the remaining segments were grouped with the Eurasian lineage; In addition, the NA, NP, M and NS segments were similar to AIVs from gulls and the HA, PB2, PB1, PA segments showed highly similarity with the A1Vs isolated fxom waterfowl. Furthermore, the pathogenicity and transmissibility experiments showed that the isolate was unable to efficiently replicate in chicken and mice, and also unable to shed and efficiently transmit in guinea pigs and chicken. The study indicated that the novel reassortant H13N6 isolate probably had already spreaded into China through wild birds migratory. The H13N6 isolate seems to be transmitted exclusively in wild waterfowl and still do not aquired the ability of crossing the species barrier to transmitting in mammals and domestic avian.