广西猪源A(2009/H1N1)流感病毒的进化分析及其致病性研究

Evolutionary analysis and study of the pathogenicity of a swine-origin influenza A(2009/H1N1)virus from Guangxi,China in mice

目的对一株分离自广西兴安的猪源A(2009/H1N1)流感病毒进行遗传演化分析及致病性研究,为流感疫情防控提供科学依据。方法通过SPF鸡胚进行流感病毒分离,对8个基因进行RT-PCR扩增、测序及进化分析;以6周龄雌性BALB/c小鼠为感染模型进行病毒滴定,分析临床数据评估病毒致病性。结果分离的甲型H1N1病毒株A/swine/Guangxi/18/2013(H1N1)HA、NS和NP基因属于古典型H1N1,NA和M基因源于类禽型H1N1,PA和PB2基因归属禽源,PB1基因来自人源H3N2。HA裂解位点序列为PSIQSR↓GLF,具有低致病性特征。以50μl 106 TCID50感染小鼠后其体重发生明显变化,最高体重平均变化率为86.98%,死亡率为12.5%;感染第3 d测定肺、鼻甲病毒滴度(Log10 TCID50/ml)分别为5.25±0.28和3.89±0.47。结论A/swine/Guangxi/18/2013(H1N1)为2009/H1N1流感病毒,能感染小鼠而造成体重下降并产生明显的临床症状。该病毒能在小鼠肺与鼻甲中进行复制,具有低致病性特征。

Objective To analyze the genetic evolution and pathogenicity of a swine-origin influenza A(2009/H1 N1)virus isolated from Xing’an,Guangxi in order to provide a scientific basis for prevention and control of influenza epidemics Methods The influenza A(2009/H1 N1)virus was isolated from SPF chicken embryos,and 8 genes were amplified using RT-PCR,sequenced,and their evolution was analyzed.Six-week-old female BALB/c mice served as a model of infection.Virus titration and clinical data were analyzed to evaluate the pathogenicity of the virus.Results The HA,NS,and NP genes of the isolated influenza A/swine/Guangxi/18/2013(H1 N1)are from classic H1 N1,the NA and M genes are from avian H1 N1,the PA and PB2 genes are of avian origin,and the PB1 gene is from human H3 N2.The HA cleavage site sequence is PSIQSR↓GLF,and the isolate has low pathogenicity.The weight of mice infected with 50μl 106 TCID50 changed markedly.The average percent in maximum body weight was 86.98%,and the mortality rate was 12.5%.On day 3 of infection,the viral titer(Log10TCID50/ml)in the lungs was 5.25±0.28 and that in the turbinates was 3.89±0.47.Conclusion Influenza A/swine/Guangxi/18/2013(H1 N1)is the 2009/H1 N1 influenza virus,and it can infect mice and cause weight loss and produce obvious clinical symptoms.The virus can replicate in the lungs and turbinates of mice and it has low pathogenicity.