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目的了解1例不明原因肺炎病例中甲型H1N1流感病毒的生物学特性和变异情况,为临床治疗与疫情防控提供依据。方法利用MDCK细胞分离不明原因肺炎病例中的甲型H1N1流感病毒,分离的毒株经全基因组测序后分析其抗原性、致病性和耐药性等特征。结果从该病例的咽拭子标本中分离得到1株甲型H1N1流感病毒并命名为A/FujianGulou/SWL64/2016(H1N1),其8个节段的核苷酸和氨基酸序列与A/California/07/2009(H1N1)疫苗株的相似性分别为96.9%~98.9%和96.7%~99.5%。氨基酸序列分析显示HA蛋白共有18个位点发生突变,其中K163Q、S185T、S203T和D222N变异涉及到3个不同的抗原位点,提示病毒发生抗原漂移;与受体结合位点相关的D222N突变还提示病毒感染下呼吸道的能力增强。耐药性分析显示该病毒对金刚烷胺耐药,对达菲仍然敏感。结论本次研究的甲型H1N1流感病毒具有抗原漂移现象,且具备引发重症肺炎的分子特征,应进一步加强监测,为疫情防控奠定基础。
Objective To understand the biological characteristics and variation of influenza A (H1N1) virus in one case of unexplained pneumonia and provide the basis for clinical treatment and epidemic prevention and control. Methods MDCK cells were used to isolate influenza A (H1N1) virus in patients with unexplained pneumonia. The isolated strains were sequenced and analyzed for their antigenicity, pathogenicity and drug resistance. Results One swine influenza A (H1N1) virus was isolated from throat swab specimens of this case and named A / FujianGulou / SWL64 / 2016 (H1N1). The nucleotide and amino acid sequences of the 8 segments were identical to those of A / California / The similarity of the 07/2009 (H1N1) vaccine strains was 96.9% -98.9% and 96.7% -99.5%, respectively. Amino acid sequence analysis revealed a total of 18 mutations in the HA protein, of which K163Q, S185T, S203T and D222N mutations involved three different antigenic sites, suggesting that the virus antigenic drift; D222N mutation associated with receptor binding sites also Suggesting that the virus’s ability to infect the lower respiratory tract. Resistance analysis showed that the virus is resistant to amantadine and is still sensitive to Tamiflu. Conclusion The influenza A (H1N1) virus in this study has antigenic drift and possesses the molecular characteristics of causing severe pneumonia. Therefore, surveillance should be further strengthened to lay the foundation for the prevention and control of the epidemic.