Jiangsu Provincial Center for Disease Prevention and Control, Nanjing 210009, China.
Virol Sin. 2012 Oct;27(5):292-8. doi: 10.1007/s12250-012-3262-9. Epub 2012 Oct 11.
Currently, three predominant subtypes of influenza virus are prevalent in pig populations worldwide: H1N1, H3N2, and H1N2. European avian-like H1N1 viruses, which were initially detected in European pig populations in 1979, have been circulating in pigs in eastern China since 2007. In this study, six influenza A viruses were isolated from 60 swine lung samples collected from January to April 2011 in eastern China. Based on whole genome sequencing, molecular characteristics of two isolates were determined. Phylogenetic analysis showed the eight genes of the two isolates were closely related to those of the avian-like H1N1 viruses circulating in pig populations, especially similar to those found in China. Four potential glycosylation sites were observed at positions 13, 26, 198, 277 in the HA1 proteins of the two isolates. Due to the presence of a stop codon at codon 12, the isolates contained truncated PB1-F2 proteins. In this study, the isolates contained 591Q, 627E and 701N in the polymerase subunit PB2, which had been shown to be determinants of virulence and host adaptation. The isolates also had a D rather than E at position 92 of the NS1, a marker of mammalian adaptation. Both isolates contained the GPKV motif at the PDZ ligand domain of the 3' end of the NS1, a characteristic marker of the European avian-like swine viruses since about 1999, which is distinct from those of avian, human and classical swine viruses. The M2 proteins of the isolates have the mutation (S31N), a characteristic marker of the European avian-like swine viruses since about 1987, which may confer resistance to amantadine and rimantadine antivirals. Our findings further emphasize the importance of surveillance on the genetic diversity of influenza A viruses in pigs, and raise more concerns about the occurrence of cross-species transmission events.
目前，全球猪群中流行的流感病毒主要有三种亚型：H1N1、H3N2 和 H1N2。1979 年首次在欧洲猪群中检测到的欧洲类禽流感 H1N1 病毒自 2007 年以来一直在中国东部的猪群中传播。本研究从 2011 年 1 月至 4 月在中国东部采集的 60 份猪肺样本中分离出 6 株甲型流感病毒。基于全基因组测序，确定了 2 个分离株的分子特征。系统进化分析表明，这两个分离株的 8 个基因与在猪群中流行的类禽流感 H1N1 病毒密切相关，与中国的病毒尤其相似。在两个分离株的 HA1 蛋白中观察到 4 个潜在的糖基化位点，分别位于 13、26、198 和 277 位。由于在 12 号密码子处存在终止密码子，分离株的 PB1-F2 蛋白发生了截断。在本研究中，分离株的聚合酶亚基 PB2 中含有 591Q、627E 和 701N，这些氨基酸已被证明是毒力和宿主适应性的决定因素。分离株的 NS1 蛋白第 92 位也含有 D 而不是 E，这是哺乳动物适应的标志。两个分离株的 NS1 蛋白 3'末端 PDZ 配体结构域都含有 GPKV 基序，这是自 1999 年左右以来欧洲类禽流感猪病毒的一个特征性标志，与禽、人及经典猪病毒不同。分离株的 M2 蛋白具有 1987 年左右以来欧洲类禽流感猪病毒的特征性标志（S31N）突变，这可能使其对金刚烷胺和金刚乙胺抗病毒药物产生耐药性。本研究结果进一步强调了监测猪流感病毒遗传多样性的重要性，并引起了对跨种传播事件发生的更多关注。
