Are the original SARS-CoV-2 novel mutants from in vitro culture able to escape the immune response?

Monitoring variations in the virus genome to understand the SARS-CoV-2 evolution and spread of the virus is extremely important. Seven early SARS-CoV-2 isolates in China were cultured in vitro and were analyzed for their viral infectivity through viral growth assay, tissue culture infectious dose (TCID50) assay, spike protein quantification, and next generation sequencing analysis, and the resultant mutations in spike protein were used to generate the corresponding pseudoviruses for analysis of immune escape from vaccination and postinfection immunity. The results revealed that in vitro cultured SARS-CoV-2 virus had much higher mutation frequency (up to similar to 20 times) than that in infected patients, suggesting that SARS-CoV-2 diversify under favorable conditions. Monitoring viral mutations is not only helpful for better understanding of virus evolution and virulence change, but also the key to prevent virus transmission and disease progression. Compared with the D614G reference strain, a pseudovirus strain of SARS-CoV-2 was constructed with a high mutation rate site on the spike protein. We found some novel spike mutations during in vitro culture, such as E868Q, conferred further immune escape ability.

Automated summary

It is crucial to monitor variations in the virus genome to understand the evolution and spread of SARS-CoV-2. In this study, early isolates of SARS-CoV-2 from China were cultured in vitro and analyzed for viral infectivity and spike protein mutations. The results showed that in vitro cultured SARS-CoV-2 had a higher mutation frequency compared to infected patients, indicating diversification under favorable conditions. Monitoring viral mutations is essential for understanding virus evolution, virulence change, and preventing transmission and disease progression.