SARS-CoV-2溯源新进展

从2019年12月~2020年11月19日，COVID-19大流行已导致全球55 928 327例确诊病例，造成1 344 003人死亡。但是，我们对这次疫情的病原体-新型冠状病毒（SARS-CoV-2）的来源仍然未了解清楚。本综述总结和分析SARS-CoV-2溯源研究进展，为进一步的研究提供启示。现有证据表明SARS-CoV-2有可能是在40~70年前由蝙蝠冠状病毒分化而来；该病毒在进化过程中同时存在多种变异及自然选择现象，病毒基因不同区域可能发生不同变异并受到不同的选择压力，这些都增加了病毒溯源的困难性；有多种动物被认为可能是SARS-CoV-2的宿主，包括猫、狮子、老虎、狗、水貂等；SARS-CoV-2可能可由人类传播给动物，且该病毒也可以在动物间互相传播；现有证据不支持该病毒的源头是中国。我们仍未清楚该病毒如何传播到人类，仍然需要更多的研究去探索SARS-CoV-2的来源、宿主、中间宿主及其跨物种传播的机制。

Progress in source tracking of SARS-CoV-2

Coronavirus disease 2019 (COVID-19) pandemic has caused a total of 55 928 327 confirmed cases and 1 344 003 deaths as of November 19, 2020. But so far the origin of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes this pandemic has remained undetermined. The purpose of this study is to review the current research of SARS-CoV-2 and the existing problems therein, which may provide inspiration for further researches. Existing evidence suggested that SARS-CoV-2 may be derived from bat coronavirus 40-70 years ago. During the evolution, this virus underwent extensive variations in the process of mutations and natural selection. Different genomic regions of SARS-CoV-2 may have different selection pressures, but all of which increase the difficulty of tracing the origin of this virus. A wide variety of animals have been considered as potential hosts of SARS-CoV-2, including cats, lions, tigers, dogs and minks. SARS-CoV-2 has a chance to transmit from humans to animals and can be transmitted among animals. Current research evidence has shown that China is not the original source of SARS-CoV-2. It is still unclear how the virus spreads to human, and efforts are still need to be made to explore the origin of SARS-CoV-2, its hosts and intermediate hosts, and the mechanism of its transmission across different species of animals.