中国HCV 2a的分子流行病学研究

The study of molecular epidemiology of HCV 2a in China

目的对我国HCV 2a亚型的分子流行病学进行研究。方法收集全国18个省、直辖市HCV感染患者标本776份,逆转录巢式PCR扩增E1基因,通过比对得出HCV基因分型。从NCBI数据库中下载HCV 2a序列作参考序列,与此次的HCV 2a序列进行分析。在Exponential模型下进行进化树构建以及BSP曲线绘制。结果扩增E1基因664份,有8种亚型及HCV 6新亚型:1a、1b、1c、2a、3a、3b、6a、6n、6new的例数分别为10、392、3、127、28、48、44、6、6份。进化树分析显示HCV 2a于20世纪60年代早期分成了两簇,clusterⅠ全是来自中国的序列,主要是来自西北的序列,clusterⅡ包括了来自全球的序列,clusterⅤ、Ⅵ和Ⅶ显示日本与中国形成各自的传播网络,而clusterⅧ和Ⅸ均可以看出是由日本传到中国。BSP曲线显示1992—1996年增长速率明显较快。结论全国范围内,HCV 1b为最主要亚型,2a次之,HCV 2a尤其在我国北方、东北、西北等省、直辖市分布比较高,还是应该引起足够的重视。进化分析显示HCV 2a一部分序列是由日本传到中国。

Objective To study the molecular epidemiology of HCV 2a in China. Methods Totally 776 specimens of HCV infection patients were collected from 18 provinces/municipalities in China. The samples were subjected to detect the E1 gene area by RT - PCR. The resulting sequences were aligned with the reference sequences to get HCV genotyping. The corresponding HCV 2a sequences from National Center for Biotechnology Information （NCBI） were obtained for analyzing along with the sequences of HCV 2a in this study. The evolutionary tree was constructed and the BSP curve was drawn under Exponential model. Results A total of 664 isolates were amplified successfully for E1 gene. There were 8 known subtypes and a new HCV 6 subtypes. The case numbers of la, lb, lc, 2a, 3a, 3b, 6a, 6n and 6new were 10, 392, 127, 28, 48, 44, 6 and 6, respectively. Evolutionary analysis showed that all sequences for HCV 2a were divided into two clusters in the early 1960s, sequences in Cluster Ⅰ were all from China, mainly from Northwest China. However, sequences in Cluster Ⅰ were all over the world. Sequences in Cluster Ⅴ, Ⅵ and Ⅶ showed that HCV 2a form their own networks of transmission in Japan and China. However, sequences both in Cluster Ⅷ and IX was seen that HCV 2a transformed from Japan to China. The BSP curve showed that the growth rate accelerated from 1992 to 1996. Conclusion HCV lb is the most important gene subtype, followed by HCV 2a in nationwide. HCV 2a subtype is in relatively high prevalence in China, especially in the north, such as provinces/municipalities in northeast and northwest. Thus this subtype should be still received enough attention. Analysis of some sequences showed that HCV 2a spreads from Japan to China.