韶关市2006年B型流感病毒流行与HA1基因变异分析

Analysis of Influenza B Epidemic and the Mutation of Hemagglutinin HA1 in the Virus Isolated in Shaoguan City

目的了解2006年韶关市B型流感病毒的流行及基因变异情况。方法收集2006年韶关市流感监测及疫情资料,并随机选取流感疫情中分离的1株B型毒株,提取病毒RNA,RT-PCR扩增病毒HA1基因,纯化产物进行核苷酸序列测定,使用DNA Start MegAlign等生物软件包进行序列分析。结果 2006年流感监测与疫情中共分离到22株B型流感毒株,分离率为2.48%(22/887),发生的35起流感疫情中有9起检出B型流感病毒,爆发时间多集中在3～4月;B/SG/y139/2006与B型代表株B/HongKong/330/2001相比,同源性为96.3%,其中有7个氨基酸替换发生在抗原决定蔟,在第197位增加了1个糖基化位点。2005和2006年分离的两毒株之间有2个氨基酸发生了替换。结论韶关市整体人群的B型Victoria系抗体水平比较低,2006年分离的B型流感毒株与B/HongKong/330/2001相比基因特性发生了变异,是2006年B型Victoria系流感病毒在韶关市成为优势毒株的原因。

Objective To understand the epidemic of Influenza B virus and the mutation of hemagglutinin HA1 in the virus isolated in Shaoguan.Methods Data of influenza surveillance and the disease outbreaks in Shaoguan （2006） were collected.An Influenza B virus isolate was randomly selected and the HA1 gene was amplified using RT-PCR.The HA1 gene was then sequenced and analyzed using the DNA Start MegAlign software.Results Among the 887 samples,22 Influenza B isolates were obtained （2.48%） in 2006.Nine out of 35 influenza outbreaks were found to have influenza B infection.March and April were the peaks of epidemic.The isolate B/SG/y139/2006 had 96.3% homology with B/HongKong/330/2001.Mutation,as a result of 7 amino acids replacements,was observed in the epitopes.One additional glycosylation site at 197 was also found.Compared with the strains B/SG538/2005,changes in 2 amino acids were found in B/SGy139/2006.Conclusion The level of protective antibody against influenza B/Victoria was low in the population.Compared with the B/HongKong/330/2001 ,mutation of HA1 might be responsible for the epidemic outbreak of Influenza B/Victoria virus in 2006.