新发高致病性禽流感H5N1病毒的致病性、传播力研究及进化分析

Research on the pathogenicity,transmission,and phylogenetic analysis of the new emerging infectious avian influenza H5N1 virus

目的对2011年底导致香港红嘴鸥死亡、并与深圳死亡患者分离株高度同源的新发高致病性禽流感H5N1病毒的致病性及传播力进行预警,同时对其序列进行遗传进化分析。方法对新发H5N1病毒进行感染性评价,证实其是否确实具有在人类细胞中增殖的能力,并对新发毒株在细胞及小鼠中的感染性进行评价,并对其在小鼠群体中的传播力进行研究。同时,还基于HA蛋白序列对新发病毒进行遗传分析,确定其进化地位。结果新发H5N1病毒在体外对人源肺细胞具有一定程度的感染性,对小鼠的致病性相比目前毒力最强H5N1毒株及WHO推荐的禽流感疫苗制备株较弱,可在小鼠群体间进行有效传播,但诱发机体体液免疫保护程度较弱。结论新病毒进化地位属于Clade 2.3.2.1,为近年来的国内主流流行株,其进化的过程中暂未发生导致致病性增强的正向选择事件。

Objective To evaluate the pathogenicity, transmission ability, and phylogenesis of the dead black headed gull isolated new emerging infectious H5NI virus which was existed in the end of 2011. Methods To verify whether the dead black headed gull isolated H5N1 could infect human source cells, and investigate the replication ability, virulence and pathogenicity in MDCK cells and BALB/c mouse model. Meanwhile, the transmission ability of the new emerging infectious HSN1 will be tested using mouse model. Meanwhile, phylogenetic analysis was done based on HA protein sequence. Results The new emerging H5N1 virus could replicate in some human lung cell lines, and the pathogenicity to BALB/c mice is weaker than the most virulent H5N1 strain and the vaccine preparation strain. However, the new virus could be efficiently transmitted among mice, but the protective antibody could not be detected in mice. Conclusion Phylogenetic analysis based on HA amino acid sequences showed it belong to clade 2. 3.2. 1, which is themain epidemic group in recent years.