Research Of Molecular Epidemiology Of H9N2 Avian Influenza Virus In Guangxi

In this study,HA,NA,M,NS,NP,PB2,PB1 and PA genes of 16 H9N2 avian influenza viruses isolated in Guangxi were cloned and sequenced completely(except WB/GX/63/05,which only sequenced HA,NA,M and NS gene).The results indicated that 16 HA genes of Guangxi isolates shared 91.4% to 99.9%nucleotide homology and 93.6%to 100%deduced amino acid homology;NA genes shared 90.8%to 100%nucleotide homology and 89.9%～100%deduced amino acid homology;The nucleotide homology of M genes were 92.8%to 100%,M1 and M2 protein shared 93.3%to 100%and 80.8%to 99.0%deduced amino acid homology;The nucleotide homology of NS genes were 94.0%to 100%,NS1 and NS2 protein shared 90.5%to 100%and 91.8%to 99.2%deduced amino acid homology;NP genes shared 91.6%to 99.9% nucleotide homology and 96.4%to 99.6%deduced amino acid homology;PB2 genes shared 85.4%to 99.9%nucleotide homology and 94.1%to 99.9% deduced amino acid homology;PB1 genes shared 89.0%to 99.7%nucleotide homology and 94.1%to 99.7%deduced amino acid homology;PA genes shared 88.9%to 99.8%nucleotide homology and 94.8%to 99.5%deduced amino acid homology.Analyse those important amino acids which correlate with pathogenicity and host specificity,we can find that Guangxi isolates exist three types of amino acid sequence on HA cleavage site,PARASR*G,PARSSR*G and PSRSSR*G, respectively,which satisfy the molecular charasteristic of low pathogenicity to avian species.Five Guangxi isolates,CK/GX/37/05,DK/GX/51/05,CK/GX/55/05,WB/GX/63/05 and WB/GX/H1/06 have amino acid change of Gln to Leu at position 226 in the HA1 protein,which have the characteristic of human influenza virus receptor.The phylogenetic analysis of HA gene indicated that all Guangxi isolates belonged to Eurasian lineage.With the exclusion of HA,NA and NS gene originated from BeiJing sublineage,represented by CK/BJ/1/94,other genes derived from ancestor.Genotype analysis which according to the phylogenetic trees revealed that Guangxi isolates have undergone extensive reasortment to generate multiple novel genotypes.There are eight genotypes in Guangxi isolates.A,C,D,G and H genotype contain only one isolate,B and F genotype include two isolates.E genotype is the prevailing genotype,eight Guangxi isolates included.The genotype of Guangxi isolates are of timeliness to some extent but not of the character of host and region.