流感病毒A/广州/333/99(H9N2)毒株基因组特性的研究

Chracterization of genome of A/Guangzhou/333/99(H9N2)virus

目的 了解一株再次从流感患儿中分离出禽H9N2流感毒株的基因组特性 ,并弄清它的来源。方法 病毒在鸡胚中传代 ,从收获的尿囊液中提取RNA ,通过逆转录合成cDNA ,cDNA用PCR扩增。PCR产物用纯化试剂盒纯化 ,接着做核苷酸序列测定 ,然后用MegAlign(Version 1 0 3)和Editseg(Version 3 69)软件进行基因进化树分析。结果 A 广州 333 99(H9N2 )毒株的基因组属于禽流感病毒 ,但它明显不同于A Duck HongKong Y439 97毒株。同时不含有任何人流感病毒基因节段 ,其基因组中有 4个基因节段 (分别编码HA、NA、NP和NS蛋白 )来自G9毒株基因系 ,而其余 4个基因节段 (分别编码PB2、PB1、PA和M蛋白 )来自G1毒株基因系。结论 A 广州 333 99(H9N2 )病毒是G9和G1毒株通过基因重配而来的重配株 ,它最大可能性直接来自禽。进一步证实了禽H9N2毒株能感染人 ,同时首次证实了H9N2不同基因系毒株间 。

Objective To understand the characterization of genome of a strain of avian influenza A H9N2 virus repeatedly isolated from a child with influenza illness.Thereafter to reveal the origin of this H9N2 virus.Methods Viruses were passed in embryonated hen eggs and virion RNA was extracted from allantoic fluid and reverse transcribed to syntehsize cDNA.cDNA was amplified by PCR and the PCR product was purified with a purification kit.Afterwards RNA sequence analysis was performed by dideoxynucleotide chain termination and a cloning method.Finally,phylogenetic analysis of the sequencing data was performed with MegAlign (Version 1.03) and Editseg (Version 3.69) softwares.Results Genome of A/Guangzhou/333/99 (H9N2) virus was closely related to avian influenza A H9N2 virus,but obvious difference from that of A/Duck/Hong Kong/Y439/97(H9N2) virus,as well as,its genome did not include any RNA segment derived from human influenza A virus.However,the genes encoding the HA,NA,NP and NS proteins of A/Guangzhou/333/99 virus wer derived from those of G9 lineage virus,the rest genes encoding the M and three plymerase (PB2,PB1 and PA) proteins were derived from G1 lineage strain.Conclusion A/Guangzhou/333/99 virus was a reassortant derived from reassortment between G9 and G1 lineages of avian influenza A (H9N2) viruses.Therefore,the most possibility is that it is derived from avian influenza A virus directly.The results do not only emonstrated that avian influenza A (H9N2) viruse could infect men,but also firstly prove that the genetic reassortment could be occurred between different genetic lineages of avian influenza A (H9N2) viruses in the nature.