Spike protein D614G and RdRp P323L: the SARS-CoV-2 mutations associated with severity of COVID-19

The severity of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), greatly varies from patient to patient. In the present study, we explored and compared mutation profiles of SARS-CoV-2 isolated from mildly affected and severely affected COVID-19 patients in order to explore any relationship between mutation profile and disease severity. Genomic sequences of SARS-CoV-2 were downloaded from Global Initiative on Sharing Avian Influenza Data (GISAID) database. With the help of Genome Detective Coronavirus Typing Tool, genomic sequences were aligned with the Wuhan seafood market pneumonia virus reference sequence and all the mutations were identified. Distribution of mutant variants was then compared between mildly and severely affected groups. Among the numerous mutations detected, 14408C>T and 23403A>G mutations resulting in RNA-dependent RNA polymerase (RdRp) P323L and spike protein D614G mutations, respectively, were found predominantly in severely affected group (>82%) compared with mildly affected group (<46%, p < 0.001). The 241C>T mutation in the non-coding region of the genome was also found predominantly in severely affected group (p < 0.001). The 3037C>T, a silent mutation, also appeared in relatively high frequency in severely affected group compared with mildly affected group, but the difference was not statistically significant (p = 0.06). We concluded that spike protein D614G and RdRp P323L mutations in SARS-CoV-2 are associated with severity of COVID-19. Further studies will be required to explore whether these mutations have any impact on the severity of disease.