目的 分析甘肃省首例人感染H7N9禽流感病例的发现过程及病毒分子特征,为本省禽流感防控提供科学依据.方法 分析病例发现过程,对病例呼吸道标本进行实时荧光定量PCR检测并对分离毒株进行测序,分析该毒株血凝素(hemagglutinin,HA)和神经氨酸酶(neuraminidase,NA)基因特征.结果 该病例明确暴露于A(H7N9)禽流感病毒污染的环境,标本经核酸检测为A(H7N9)阳性.分离病毒的HA基因和NA基因均属于欧亚系的长三角株,并与山东省和江苏省禽间分离的A(H7N9)禽流感病毒相似度较高.该病毒HA蛋白发生了G186V、T160A和Q226L基因位点突变,HA基因165~167增加了一个糖基化位点NKS,HA序列糖基化22~24、38~40、240~242、411~413和483~445位点均未发生明显改变.结论 甘肃省首例人感染H7N9禽流感病毒与已报道的H7N9病毒亲缘关系较高,加强基因水平病毒变异的监测有助于疫情的科学防控.
Objective To analyze the discovery process and molecular characteristics of the first human case of influenza A (H7N9) virus infection in Gansu province, so as to provide scientific basis for the prevention and control of avian influenza in Gansu province. Methods For the case detection process, the respiratory tract samples from the patient were analyzed by real-time fluroscent PCR and the isolated strain was sequenced to analyze the genetic characteristics of hemagglutinin (HA) and neuraminidase (NA). Results The case had confirmed history of exposure to the environment contaminated by influenza A (H7N9) virus. The nucleic acids test results of the samples were positive for influenza A (H7N9) virus. The HA and NA genes of the isolated strain belong to the Yangtze River Delta strain of the Eurasian lineage and had high similarity with avian influenza A (H7N9) viruses isolated from poultry in Shandong provinceand Jiangsu province. Three mutations, G186V, T160A and Q226L occurred in HA protein. An additional glycosylation site NKS was observed at sites 165-167. Sequence glycosylation at sites 22-24, 38-40, 240-242, 411-413 and 483-445 showed no significant change. Conclusions The first human case of avian influenza A (H7N9) virus infection in Gansu province showed high homology with the reported avian influenza A (H7N9) virus strains. Strengthening monitoring for mutations of the virus at the genetic level may help scientific prevention and control of the epidemics.