Letermovir for COVID-19

The rapidly enlarging COVID-19 pandemic caused by novel SARS-coronavirus 2 is a globalpublic health emergency of unprecedented level. Therefore the need of a drug or vaccine thatcounter SARS-CoV-2 is an utmost requirement at this time. Upon infection the ssRNA genomeof SARS-CoV-2 is translated into large polyprotein which further processed into differentnonstructural proteins to form viral replication complex by virtue of virus specific proteases:main protease (3-CL protease) and papain protease. This indispensable function of main proteasein virus replication makes this enzyme a promising target for the development of inhibitors andpotential treatment therapy for novel coronavirus infection. The recently concluded α-ketoamideligand bound X-ray crystal structure of SARS-CoV-2 Mpro (PDB ID: 6Y2F) from Zhang et al.has revealed the potential inhibitor binding mechanism and the determinants responsible forinvolved molecular interactions. Here, we have carried out a virtual screening and moleculardocking study of FDA approved drugs primarily targeted for other viral infections, to investigatetheir binding affinity in Mpro active site. Virtual screening has identified a number of antiviraldrugs, top ten of which on the basis of their bending energy score are further examined through molecular docking with Mpro. Docking studies revealed that drug Lopinavir-Ritonavir, Tipranavirand Raltegravir among others binds in the active site of the protease with similar or higheraffinity than the crystal bound inhibitor α-ketoamide. However, the in-vitro efficacies of the drugmolecules tested in this study, further needs to be corroborated by carrying out biochemical andstructural investigation. Moreover, this study advances the potential use of existing drugs to beinvestigated and used to contain the rapidly expanding SARS-CoV-2 infection.