禽流感是一种由甲型流感病毒的一种亚型(也称禽流感病毒)引起的传染性疾病,被国际兽疫局定为甲类传染病。通常只感染鸟类,很少情况会感染猪。禽流感病毒高度针对特定物种,但在罕有情况下会跨越物种间障碍感染人。自从1997年在香港发现人类也会感染禽流感之后,此病引起全世界卫生组织的高度关注。其后,本病一直在亚洲区零星爆发,但在2003年12月开始,禽流感在东亚多国──主要在越南、韩国、泰国──严重爆发,并造成越南多名病人丧生。直到2005年中,该病不但未有平息的迹象,而且还不断扩散,远至东欧多个国家。
中国科学院动物研究所何宏轩研究组通过对215个人源的H5N1病毒株和5885个禽源的H5N1病毒株的HA序列进行分析,并结合地理信息学数据和鸟类迁徙动态数据,综合分析认为:(1)全球人源H5N1病毒株分为4个大分支,即Southern China cluster(华南分支,CN)、Indonesia cluster(印度尼西亚分支,ID)、Indo-China cluster(印支分支,IC)以及Middle Asia-north Africa cluster(中亚-北非分支,MN)。进一步的糖基化位点分析表明,这四大分支属于3大病毒类型,即广东196型或原始型(the GD196 type or original type),过渡性(the Transitional type)和印度尼西亚型(the Indonesia type)。这些结果表明,全球人源H5N1病毒株根据地域不同存在不同的进化亚型,而且在防控上也要选用同地域毒株制备疫苗。(2)在进化分支上,人源H5N1病毒株分散在禽源的H5N1病毒株中,这表明人源H5N1病毒株来源于禽源H5N1病毒株,不同地域病毒传播是通过鸟类来传播的,而人与人之间或人与鸟之间单项不能直接传播。(3)从病毒溯源上来看,本研究的结果推测华南很可能多个病毒支系的共同来源。综上所述,我们了解到,人感染H5N1禽流感病毒多是接触了感染H5N1病毒的病禽而感染,从发生的人病例的事实来看,符合这一说法。
该研究提出的对全球流感毒株的分型和分类的方法尚属首次,对于未来研究禽流感的进化具有重要的参考价值。(生物谷Bioon.com)
生物谷推荐英文摘要:
The Journal of Infectious Diseases 2010;202:452–458 doi: 10.1086/653709
New Evidence Suggests Southern China as a Common Source of Multiple Clusters of Highly Pathogenic H5N1 Avian Influenza Virus
Bin Wu,1,a Chengmin Wang,1,a Guoying Dong,1 Yunhai Guo,1 Dale Louis Nolte,4 Thomas Jude Deliberto,4 Jianguo Xu,3 Mingxing Duan,2 and Hongxuan He1
1National Research Center for Wildlife Borne Diseases, Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, and 2State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing, and 3Department of Respiratory, First Hospital, Jilin University, Changchun, China; 4National Wildlife Research Center, Wildlife Services, Animal and Plant Health Inspection Service, United States Department of Agriculture, Fort Collins, Colorado
Highly pathogenic H5N1 avian influenza is considered an avian disease, although there is some evidence of limited human‐ o‐human transmission of the virus. A global effort is underway to control or eradicate the highly pathogenic H5N1 avian influenza virus in poultry and prevent human exposure, both of which may also reduce the risk of pandemic emergence. Hemagglutinin gene sequences from 215 human H5N1 influenza viruses were used to trace the source and dispersal pattern of human H5N1 influenza viruses on a global scale. A mutation network and phylogenetic analyses of the hemagglutinin gene show that human H5N1 influenza viruses can be clearly divided among 4 clusters across geographic space. On the basis of analysis of the N‐glycosylation sites at positions 100 and 170 in the hemagglutinin protein, human H5N1 influenza viruses were also divided into 3 types. When we combined these analyses with geographic information system data analyses, we found that Southern China is often a common source of multiple clusters of H5N1 influenza viruses and that each cluster has different dispersal patterns and individual evolutionary features. In summary, the genetic evidence presented here provides clear evidence for multiple clusters of human H5N1 influenza viruses that initially originated in Southern China.