[Genetic evolution analysis of matrix protein 2 gene of avian influenza H5N1 viruses from boundary of Yunnan province].

OBJECTIVE: To elucidate the variation in characterizations and genetic evolution of the matrix protein 2 or ion channel protein(M2) genes of avian influenza subtype H5N1 viruses in the boundary region of Yunnan province from 2008 to 2012. METHODS: A total of swab samples were collected from foreign poultry such as the junction between Yunnan and Vietnam, Laos,myanmar and wild birds in boundary region of Yunnan province from 2008 to 2012 and screened by H5N1 subtype-specific multiplex RT-PCR. The M genes of H5N1 virus from the positive samples were amplified by RT-PCR and cloned into pMD18-T vectors for sequencing. The alignment and phylogenetic analysis of M2 genes were performed with sequences of the known reference strains. RESULTS: A total of 71 positive samples were found out of 1240 samples and the positive rate was 5.72%. A total of 14 different M2 sequences were obtained from 30 positive samples and were divided into 3 distinct clades or sub-clades(1.2.1, 1.2.2 and 2) by phylogenetic analysis, 5, 7 and 2, respectively. The M2 genes and Hemagglutinin(HA) genes of H5N1 viruses from the boundary region of Yunnan province had showed different relationship of genetic evolution. The substitution or mutation of key amino acids sites had been found among the domains of epitope, adamantane-resistance, and poultry or human original viral strains. CONCLUSION: The M2 genes of H5N1 subtype viruses in boundary region of Yunnan province from 2008 to 2012 showed genetic divergence and the virus of clade 1.2.2 had become dominant epidemic strain in this region.

[Genetic evolution of non-structural gene among avian influenza H5N1 viruses isolated from the boundary of Yunnan province].

OBJECTIVE: To elucidate the characteristics of variation and the genetic evolution of non-structural protein (NS1, NS2) genes related to avian influenza subtype H5N1 viruses isolated from the boundary region of Yunnan province. METHODS: Swab samples were collected from foreign poultry and wild birds in the boundary regions of Yunnan province and screened by H5/N1 subtype-specific multiplex RT-PCR. The NS segment of H5N1 virus from the positive samples were amplified by RT-PCR and cloned into pMD18-T vectors for sequencing. The alignment and phylogenetic analysis on those available NS1, NS2 genes were performed with sequences of the known reference strains. RESULTS: 71 positive samples were identified from 1240 samples, with the positive rate as 5.72%. Fourteen different NS segment sequences were obtained from 30 representative positive samples and could be divided into 3 distinct clades or sub-clades (I-1, I-2 and II), by phylogenetic analysis. The NS1/NS2 genes and Hemagglutinin (HA) genes of H5N1 viruses from the boundary regions of Yunnan province showed different relationships regarding the characteristics on genetic evolution. The substitution or mutation of key amino acids sites had been noticed in the nuclear location signal domains, effect domain, and other pathogenicity markers. CONCLUSION: NS genes of H5N1 subtype viruses in boundary region of Yunnan province showed genetic divergence and the virus of clade I-2 and II had become dominant epidemic strains in this region since 2010.

[Genetic diversification of avian influenza H5N1 virus in boundary areas of Yunnan province].

OBJECTIVE: To elucidate the genetic diversifications of avian influenza subtype H5N1 viruses in the boundary regions of Yunnan province during 2009 to July, 2011. METHODS: Swab samples were collected from foreign poultry and wild birds in boundary regions of Yunnan province during 2009 to July, 2011 and tested by H5/N1 subtype-specific multiplex RT-PCR. The HA genes of H5N1 virus from the positive samples were amplified by RT-PCR and cloned into pMD18-T vectors for sequencing. Both alignment and phylogenetic analysis were performed with sequences of the known reference strains. RESULTS: Fifteen different HA sequences were obtained from 36 representative positive samples and could be divided into 2 distinct Clades (2.3.2 and 2.3.4). Through phylogenetic analysis, Clade 2.3.2 and 2.3.4 could then be further divided into 3 (II-1 to II-3) and 2 smaller clades (I-1 and I-2), respectively. The viruses of Clade 2.3.2 II-1 and II-2 were new variant strains of H5N1 virus. The cleavage sites of HA from positive samples all possessed molecular characterization of highly pathogenic avian influenza virus. Mutation of key amino acids had been found among receptor binding sites, potential glycosylation sites, neutralizing epitopes and others. CONCLUSION: It seemed evident that the H5N1 subtype viruses showed genetic diversifications and had undergone the evolution progress of multi-clade (2.3.2, 2.3.4) to single calde (2.3.2) in the boundary regions of Yunnan province, during 2009 to July, 2011.