The analysis of variation and evolution of SARS CoV-2 genome/ 冠状病毒SARS CoV-2病毒变异进化的分析

Objective To analyze the evolution and variation of SARS CoV-2, which caused an epidemic in the end of 2019 Methods With the software of bioinformatics such as MEGA- X, BEAST, and TempEst, we downloaded the entire genome sequence of related viruses from database of GISAID and NCBI, constructed a genomic evolution tree, inferred the time evolution signal of the virus, calculated the tMRCA time of the virus and analyzed the virus selection pressure for evolution Results As shown in the phylogenetic tree, SARS CoV-2 belonged to the Sarbecovirus subgenus of b Coronavirus genus together with bat coronavirus BetaCoV/bat/Yunnan / RaTG13/2013, bat-SL-CoVZC45，bat-SL-CoVZXC21 and SARS CoV The current SARS CoV-2 genomic sequences have a weak time evolution signal, and the average time of tMRCA is 73 days, in the 95% interval (38 9- 119 3 days) There is no positive time evolution signal between SARS CoV-2 and BetaCoV/bat/Yunnan/ RaTG13/2013, but SARS CoV-2 has a strong positive temporal evolution relationship with bat- SL-CoVZC45 and SARS CoV The major cause of SARS CoV-2 mutations is the pressure of purification selection during an epidemic Conclusion SARS CoV-2 may emerge around November 2019 and most likely has originated from bat- associated coronavirus The results will contribute to the study of tracing the sources and evolution of the SARS CoV- 2, and be instructive for us to contain the epidemic