南京市首例甲型H1N1(2009)流感病毒分离及其血凝素基因遗传变异分析

对南京市首例甲型H1N1(2009)病毒进行细胞分离,获得一株具有较高血凝活性的病毒,命名为A/Nanjing/1/2009。在全基因组测序的基础上,对分离株的血凝素基因(haemagglutinin,HA)的遗传特征进行了详细研究。分离株HA蛋白不具有多碱基HA裂解位点,具有低致病性流感病毒特点。与参考株A/California/04/2009相比,分离株A/Nanjing/1/2009HA蛋白的有5个氨基酸发生了突变,其中一个位于Ca抗原位点208位氨基酸(R→K),这一突变虽然还不会影响抗原性的改变,但预示了新甲型H1N1(2009)抗原漂移的启动。分离株有5个潜在糖基化位点,这与近年来古典猪H1N1和北美三源重配猪H1病毒完全一致,保留了古典猪H1病毒的特点。与禽H1病毒相比,分离株HA蛋白受体结合位点上的190(E→D)和225(G→D)位点发生突变,这可能成为新甲型H1N1(2009)在人际间传播的一个重要分子基础。此外,其它受体结合位点上相关氨基酸同时具有人和猪流感病毒的特点。本研究对南京市早期流行的甲型H1N1(2009)流感病毒的HA蛋白的分子遗传特征进行了详细研究,对进一步监测病原变异具有重要指导意义。

Isolation of Influenza A H1N1(2009)Virus from the First Human Case in Nanjing City and Genetic Characterization of Its Haemagglutinin

A virus strain with hemagglutination activity was isolated from the clinical samples of the first influenza A H1N1 case in Nanjng city using both MDCK cells and embryonic eggs,and was designated as A/Nanjing/1/2009.In order to track the variation of the virus,we carried out whole-genome sequencing of the virus,and studied genetic characteristic of its hemagglutinin in detail.Based on the deduced amino acid sequence,the isolate did not contained the multibasic amino acid motif at its HA cleavage sites,the characteristic of low pathogenic avian influenza viruses.Compared with reference virus A/California/04/2009,the HA protein of the isolate had five amino acid mutation,one of which was located on the known antigenic Ca sites.Consistent with the triple-reassortant swine H1 viruses in recent years,the isolate contained five potential glycosylation sites,the features of classical swine H1N1 viruses.Compared with avian H1 viruses,two amino acid(E190D and G225D) were changed on receptor binding sites of HA of the isolate,which may be the important molecular mechanism of human-to-human transmission for the novel viruses.In this study,for the first time,we studied the molecular characteristics of the HA protein of the novel influenza A H1N1(2009) viruses in detail,providing guiding significance for further monitoring of virus mutations.