应用分子进化和流行病学方法对SARS CoV非自然起源和消失的进一步研究

The origin and the reservoir of SARS CoV are not yet found though with very extensive studies since SARS epidemic ten years ago. However, from an innovative macroscopic view, we have comprehensively re-examined and reanalyzed the major previous studies on SARS and SARS CoV with the combination of epidemiological and molecular evolution methods, and reverse evolution theory as a guide. Therefore, we have first illuminated that there is no direct ancestor and reservoir of the SARS CoV in nature, which came from Bat SARS- like CoV (Bt-SLCoV) by "non-natural (genetic modifying) " way, and the SARS CoV had always been under the strong continuing pressure from the new host group for unadaptative evolution and experienced the reverse evolution, and disappeared in nature at last. On this basis and with above theories and methods, the project is mainly to re-examine the epidemiological characteristics and evolution of SARS CoV during 2002-2004 epidemic, by controlling for confounding factors ,and using " Clinical database of SARS cases in the mainland of China " and the data in different countries and regions. Therefore, we absolutely recognize the "non-natural" origin and disappearance of SARS CoV and open up a new field to research the pathogenesis and epidemic of diseases with reverse evolution theory as a guide, in order to contribute to our country's security and to human health.

SARS暴发至今已10年, 虽进行了广泛深入研究,但SARS CoV的起源始终未突破。然而近两年,我们结合流行病学和分子进化技术, 以"逆向进化"理论为指导，从全新视角，重新研究了爆发以来主要工作和相关文献，得出结论：自然界根本不存在SARS CoV直接祖先和贮存宿主，其是从蝠SARS样冠状病毒(Bt-SLCoV) 经 "非自然（如基因改造）"方式产生，故引入人群后，遭到了新宿主群体强大持续而为其不能适应的压力，仅能以"逆向进化"应对，回到其"祖先状态（仅蝠具备）"，即从人群和自然界消失。在此基础上, 本项目仍以上述理论和方法, 用"中国内地SARS病例临床数据库"等不同国家地区资料,控制混杂因素,有重点地重新审视SARS 流行之特点及其病毒之进化历程, 以进一步完善SARS CoV非自然起源和消失过程，开辟 "逆向进化"理论应用于疾病研究的崭新领域，为我国安全和人类健康做出贡献。

本项目研究从不同流行时段，比较分析不同来源SARS CoV的分子系统发育进化发现，在全基因组水平，不同时期各种SARS CoV与SARSL CoV和/或Bt-SLCoV、以及其他冠状病毒间亲缘关系有明显差异，主要表现为2003-2004广州爆发毒株SARS-CoV与2002-2003流行晚期株遗传距离远，而与SARSL-CoV以及猫、狗、牛等其他冠状病毒遗传距离更接近，提示2003-2004广州爆发毒株SARS-CoV与2002-2003年流行晚期SARS-CoV遗传差异大，可能存在逆向/返祖进化。从核苷酸突变规律角度，对GenBank数据库所有SARS CoV相关的病毒全基因组序列进行比较分析发现，根据整个SARS CoV基因组的突变位点分布，可以将其分为突变密集区和突变稀疏区，其中重要基因S基因恰好位于突变稀疏区，但却呈现出高的突变频率；基因组的其他区域表现为突变密集区，但其突变频率却很低。突变稀疏区和突变密集区的核酸突变类型分布也表现出相反的特征。这些发现为探索SARS CoV的非自然起源和消失提供了新的证据。本研究应用SARS起源研究方法，探索了人H7N9禽流感的异常流行和起源。发现了人H7N9禽流感流行强度异常、流行地区和传染源栖居点分布异常、年龄分布异常、传染源分布的异常，深入探究新-H7N9 AIV在中国流行的自然史，研究认为不能排除其为人制新病毒基因武器的观点，为人H7N9 AIV流行的中国起源提供了不同的理论观点。