Mutation and Virulence of SARS-CoV-2 Strains Circulating in Anhui Province, China

Abstract

Background: The genome of SARS-CoV-2 has shown considerable variation during its spreading. Monitoring variations in the virus genome to understand the evolution and spread of the virus\xa0is extremely important.\xa0 \n \nMethods: Seven\xa0SARS-CoV-2 strains (BB127, BB183, HB030, MAS525, HF3028, FY1494, and SZ005) circulating in Anhui Province, China were isolated and\xa0sequenced for\xa0evolutionary analysis.\xa0Five strains were further cultured in vitro and were subjected to viral growth assay, TCID50 assay, and detection of spike protein expression. Next generation sequence (NGS) analysis\xa0were\xa0applied to investigate the\xa0mutation frequencies throughout the whole genome at different time gradients\xa0in vitro.\xa0 \n \nFindings: Our observations revealed that in vitro\xa0cultured SARS-CoV-2 virus had much higher mutation frequency (up to ~20 times) than that\xa0in infected patients, and the mutation in nonstructural protein\xa014 (nsp14) might increase the genomic mutation frequency. Different strains had various amount of spike protein which may positively correlated with\xa0the virus replication capacity but may be influenced by other viral factors.\xa0 \n \nInterpretation: Our study suggested that SARS-CoV-2 has the potential to diversify\xa0under\xa0favorable conditions.\xa0Monitoring viral mutations is not only\xa0helpful\xa0for better understanding of virus evolution\xa0and\xa0virulence change, but also the key to prevent virus transmission\xa0and disease progression. SARS-CoV-2 genomic variation analysis may also provide potential ideas for more efficient vaccine\xa0development\xa0and clinical treatment.\xa0 \n \nFunding: This work is funded by Special Project for Emergency Scientific and Technological Research on New Coronavirus Infection (YG,\xa0No. YD9110002001), Emergency Research Project of Novel Coronavirus Infection of Anhui Province (Grant numbers 202004a07020002; 202004a07020004), Postdoctoral Research Foundation of China (2020M670084ZX) and the Fundamental Research Funds for the Central Universities (WK9110000166; WK9110000167). \n \nDeclaration of Interests: We declare no competing interests. \n \nEthics Approval Statement: The study was conformed to the principles of the Declaration of \nHelsinki and approved by the Ethics Committee of the First Affiliated Hospital of USTC..