Endemic seasonal coronaviruses may lead to significant morbidity and mortality in some subgroups, yet no specific treatment is available. Molnupiravir emerges as an encouraging antiviral drug for treating SARS-CoV-2 infection since it acts upon RNA-dependent RNA polymerase (RdRp). 

A study investigated the prospect of repurposing molnupiravir for treating seasonal human coronavirus (HCoV) infections and found that-

• The active form of molnupiravir, β-D-N4-hydroxycytidine (NHC), has an identical binding affinity to RdRp of SARS-CoV-2 as seasonal HCoV-NL63, HCoV-OC43 and HCoV-229E. 
• Viral replication and production of infectious viruses of the three seasonal coronaviruses were effectively inhibited after treating the cell culture models with molnupiravir. 
• A time-of-drug-addition experiment showed the specificity of molnupiravir in impeding viral components. 
• Molnupiravir and the protease inhibitor GC376 combination enhanced the antiviral activity even more. 

Thus repurposing molnupiravir has a great potential for treating seasonal coronavirus infected patients.

Source- Virology, 2021; 564:33-38. https://doi.org/10.1016/j.virol.2021.09.009.