新发虫媒病毒- - 版纳病毒分子遗传进化及其与疾病关系的研究

Banna virus (BAV) is the prototype species of genus Seadornavirus within the family Reoviridae. BAV was initially isolated from patients with encephalitis and fever in Xishuangbanna, Yunnan Province of China in 1987. Since then, BAV isolates have been obtained from pigs, cattle, ticks and mosquitoes in China and Southeast Asia. The pathogenicity and molecular evolutionary of BAV,which is an emerging virus, are not well understood, and impact of BAV infection in Asia require further investigation.In order to elucidate the molecular genetic characteristics of Banna virus and its relationship with infectious diseases. 20 BAV strains isolated from various sources were sequenced for the first time in our lab. A Banna virus database will be created based on these 20 sequences with other publicly available full-length genome sequences to forme the current largest BAV genome database in the world.With this database, we will performed the first detailed evolutionary analysis of BAV by phylogenetic network, which is the advanced evoltionary analysis method that can depicting microevolutionary events, to investigate the molecular genetic characters of BAV and the phylogenetic relationship between BAV and other virus within the family Reoviridae. Meanwhile, the serum and CSF samples from acute and convalescent patients will be collacted to detect BAV antibodies to clarify the relationship between Banna virus and infectious disease. The results of this study would be helpful to elucidate the molecular origins and genetic characters as well as to understand the pathogenicity of BAV.

版纳病毒是呼肠孤病毒科新建立病毒属（Seadornavirus）的模式病毒。该病毒于1987年首次从我国病毒性脑炎病人中分离，此后相继在多种动物宿主和蚊虫媒介中分离，广泛分布在我国和东南亚地区。作为一种新发病毒，版纳病毒相关研究相对滞后。国际上该病毒基因组序列少、遗传进化特征不清楚，特别是版纳病毒与人群疾病的关系仍不明确。为了阐明版纳病毒分子遗传特征及其与疾病的关系。我课题组测定了具有代表性的20株版纳病毒全基因组序列。本研究将在此基础上构建版纳病毒基因数据库并采用国际最先进的可以综合处理复杂微进化遗传信息的系统进化网络分析法，进行版纳病毒基因重组、重配等微进化事件分析以及该病毒与其他呼肠孤病毒进化关系的研究以探明其分子起源。同时在版纳病毒最初分离地（云南省）采集不明原因发热和脑炎患者急性期及恢复期血清标本进行版纳病毒中和抗体滴度的检测，以真正明确该病毒和疾病的联系。

版纳病毒是呼肠孤病毒科新建立病毒属（Seadornavirus）的模式病毒。本研究在蚊虫、蜱、蜢标本中分离到11株版纳病毒，与原有的34株病毒合计共获得45株版纳病毒，形成了目前世界上数量最多的版纳病毒生物资源库。并构建了可以与GenBank完成对接的层次型呼肠孤病毒科病毒数据库，实现了快速稳定的呼肠孤病毒同源序列数据的比对搜寻和查找。版纳病毒微进化分析发现，该病毒各片段的基因组均可检测到碱基的缺失、插入、重组和重配以及基因倍增事件发生的信号，表明其在进化过程中通过不断的进化以适应不同类型的宿主环境。对全世界不同媒介宿主分离的版纳病毒开展系统的分子进化分析发现，版纳病毒为大约在1900年左右新出现的病毒，不存在种群屏障。病毒平均碱基替换率为2.467×10-2 /碱基替换/位点/年，高纬度地区版纳病毒为最新分化病毒且碱基替换率明显高于中低纬度病毒种群。毒株之间的亲缘关系与地域分布成正相关。新发的版纳病毒在30年左右时间变异出适应在热带地区，温带地区和北纬47度不同地域生存的病毒种群，快速的碱基突变率使得版纳病毒准种中蕴藏着丰富的基因多样性。本研究连续三年在我国云南省、山西省等地采集100余份不明原因发热和脑炎患者脑脊液和血清标本，检测到4份乙脑病毒阳性标本未检测到版纳病毒阳性标本，提示版纳病毒是否可以引起人类脑炎仍需开展进一步确证研究。