中东呼吸综合征(MERS)和严重急性呼吸综合征(SARS)间流行病学及其病原体间分子进化的比较研究

A comparative study of epidemiology and molecular evolution between MERS and SARS

目的比较中东呼吸综合征(Middle East respiratory syndrome,MERS)与严重急性呼吸综合征(severe acute respiratory syndrome,SARS)的流行特征差异,分析其病原体亲缘关系,探讨两者可能的不同起源。方法应用描述性方法研究MERS和SARS的病例分布。基于MERS冠状病毒(MERS coronavirus,MERS-Co V)和SARS冠状病毒(SARS Coronavirus,SARS-Co V)的部分保守区序列,使用MEGA 6.0软件构建进化树,并通过序列之间的距离和拓扑结构支持度分析比较两者进化差异。结果 MERS流行过程长于SARS,但病死率高于后者(P=0.001)。分子系统发育分析显示,人源MERS-Co V和SARS-Co V序列都有亲缘较近的动物来源序列,但MERS-Co V及其相近序列之间的聚类支持程度普遍高于SARS-Co V及其相近序列。结论 MERS-Co V是自然进化发生,可能是以中东为疫源地、骆驼和蝙蝠为传染源甚至贮存宿主之自然疫源性疾病;SARS-Co V是过客病毒,为非自然进化产生。

Objective To evaluate the differences of epidemic characteristics between Middle East respiratory syndrome（MERS） and severe acute respiratory syndrome（SARS）; analyze the relationship between the two pathogens; and explore the possible different origins.Methods Descriptive studies were applied to compare distribution of MERS and SARS cases.Phylogenetic tree of filtered sequences was constructed using the maximum likelihood method in MEGA 6.0 software based on conservative region.Results Despite the single transmission mode and low morbidity,the mortality rate of MERS was higher than that of SARS（P = 0.001）.Phylogenetic analysis showed that both MERS coronavirus（MERSCoV） and SARS coronavirus（SARS-CoV） sequences of human source had very close relations with animal origin,but the support degree of MERS-CoV-related sequences clustering was generally higher than that of SARS-CoV.Conclusions Camels and bats carrying MERS-CoV are the source of MERS infection,even the host reservoir.MERS is an evolutionary natural focus infection disease.SARS-CoV is passenger virus produced from non-natural evolution.