摘要目的 分析2010-2012年宁波市乙型流行性感冒(简称流感)病毒的流行状态及表面抗原基因血凝素(HA)和神经氨酸酶(NA)进化情况.方法 收集宁波市2010-2012年流感样患者的咽拭子和含漱液标本3440份,进行流感病毒分离鉴定;同时采集2010年正常人群血清628份,进行抗体滴度测定.选择不同时期乙型流感分离株进行HA和NA基因序列测定,分析病毒表面抗原基因的进化方向与流行规律的关系.结果 共计109份临床样本分离出乙型流感病毒,其中Victoria系102份(93.6％),Yamagata系7份(6.4％);在628份正常人群血清中,Victoria和Yamagata系乙型流感病毒抗体阳性率分别为321 (51.1％)和300 (47.8％),差异无统计学意义(x2=1.405,P＞0.05).进化分析显示,2010-2012年Victoria系HA基因均聚集在疫苗株Malaysia/2506/2004分支中,而NA基因则出现了不同方向的进化分支.Victoria系流行株与Brisbane/60/2008在HA基因中仅1～5个氨基酸位点的差异,而NA基因上有6～16个位点的差异.相比HA基因,Victoria系NA的进化速度更快.结论 2010-2012年宁波市Victoria系乙型流感的NA基因进化速度比HA基因快;综合HA与NA基因序列分析对观察流感病毒的基因变异更为灵敏可靠.

abstractsObjective To investigate the epidemiological characteristics of influenza B viruses and explore the genetic evolution characteristics of the hemagglutinin (HA) and neuraminidase (NA) genes of local isolated strains in Ningbo,Southeast China,during 2010 to 2012.Methods Respiratory specimens from 3440 cases of patients with influenza-like illness(ILI) during 2010 to 2012 were collected in for virus isolation.And the 628 sera samples were collected in 2010 from the healthy community population to detect the HI antibody level against the local isolated virus.For phylogenetic analysis,the fragments of HA and NA genes were amplified and sequenced from strains isolated in different years.The association between evolution of HA and epidemiological characteristics were analyzed.Results A total of 109 strains of influenza B virus were isolated,including 102 (93.6％) Victoria-lineage strains and 7 (6.4％) Yamagata-lineage strains.Positive rates of HI antibody against Victoria-lineage strains and Yamagata-lineage strains were 51.1％ (321) and 47.8％ (300),respectively (x2 =1.405,P ＞ 0.05) among the 628 sera samples.The phylogenetic analysis showed that all HA fragments of isolated strains clustered the same branch with Malaysia/2506/2004 while the NA genes formed different branches.Compared with Brisbane/60/2008 strain,there were 1 to 5 Amino acid mutations in HA domain,and more mutations were detected in NA domain,ranged from 6 to 16 sites.The genetic evolution of NA in Victoria-lineage strains were faster compared with HA.Conclusion The genetic evolution rates of NA genes were faster than that of HA genes in the local circulated Victoria-lineage viruses during 2010 to 2012;The comprehensive analysis of HA and NA fragments were more reliable and sensitive on surveillance of genetic evolution of influenza B viruses.