Analysis of the SARS-CoV-2 nsp12 P323L/A529V mutations: coeffect in the transiently peaking lineage C.36.3 on protein structure and response to treatment in Egyptian records.

SARS-CoV-2 nsp12, the RNA-dependent RNA-polymerase plays a crucial role in virus replication. Monitoring the effect of its emerging mutants on viral replication and response to antiviral drugs is important. Nsp12 of two Egyptian isolates circulating in 2020 and 2021 were sequenced. Both isolates included P323L, one included the A529V. Tracking A529V mutant frequency, it relates to the transience peaked C.36.3 variant and its parent C.36, both peaked worldwide on February-August 2021, enlisted as high transmissible variants under investigation (VUI) on May 2021. Both Mutants were reported to originate from Egypt and showed an abrupt low frequency upon screening, we analyzed all 1104 nsp12 Egyptian sequences. A529V mutation was in 36 records with an abrupt low frequency on June 2021. As its possible reappearance might obligate actions for a candidate VUI, we analyzed the predicted co-effect of P323L and A529V mutations on protein stability and dynamics through protein structure simulations. Three available structures for drug-nsp12 interaction were used representing remdesivir, suramin and favipiravir drugs. Remdesivir and suramin showed an increase in structure stability and considerable change in flexibility while favipiravir showed an extreme interaction. Results predict a favored efficiency of the drugs except for favipiravir in case of the reported mutations.