Abstract
The COVID-19 pandemic continues to be a public health threat with emerging variants of SARS-CoV-2. Nirmatrelvir (PF-07321332) is a reversible, covalent inhibitor targeting the main protease (M pro ) of SARS-CoV-2 and the active protease inhibitor in PAXLOVID (nirmatrelvir tablets and ritonavir tablets). However, the efficacy of nirmatrelvir is underdetermined against evolving SARS-CoV-2 variants. Here, we evaluated the in vitro catalytic activity and potency of nirmatrelvir against the M pro of prevalent variants of concern (VOCs) or variants of interest (VOIs): Alpha (α, B.1.1.7), Beta (β, B.1.351), Delta (δ, B1.617.2), Gamma (γ, P.1), Lambda (λ, B.1.1.1.37/C37), Omicron (ο, B.1.1.529), as well as the original Washington or wildtype strain. These VOCs/VOIs carry prevalent mutations at varying frequencies in the M pro specifically for α, β, γ (K90R), λ (G15S), and ο (P132H). In vitro biochemical enzymatic assay characterization of the enzyme kinetics of the mutant M pros demonstrates that they are catalytically comparable to wildtype. We found that nirmatrelvir has similar potency against each mutant M pro including P132H that is observed in the Omicron variant with a Ki of 0.635 nM as compared to a Ki of 0.933 nM for wildtype. The molecular basis for these observations were provided by solution-phase structural dynamics and structural determination of nirmatrelvir bound to the ο, λ, and β M pro at 1.63 to 2.09 Å resolution. These in vitro data suggest that PAXLOVID has the potential to maintain plasma concentrations of nirmatrelvir many-fold times higher than the amount required to stop the SARS-CoV-2 VOC/VOI, including Omicron, from replicating in cells.
Keywords: Beta; Ki; Lambda; M(pro); Omicron; PF-07321332; SARS-CoV-2; VOC; crystal structure; nirmatrelvir.
【저자키워드】 SARS-CoV-2, VoC, omicron, M(pro), Beta, PF-07321332, crystal structure, Lambda, nirmatrelvir., Ki, 【초록키워드】 Efficacy, Mutation, B.1.351, COVID-19 pandemic, variant, Ritonavir, variants of concern, Delta, protease, in vitro, omicron, variants, Protease inhibitor, SARS-CoV-2 variants, cells, B.1.1.7, P.1, VOCs, Gamma, Alpha, variants of interest, Omicron variant, Beta, PF-07321332, B.1.1.529, mutant, VOIs, crystal structure, inhibitor, Nirmatrelvir, Lambda, Paxlovid, Frequency, Washington, observation, Tablet, plasma concentration, biochemical, enzyme, M pro, tablets, potency, molecular basis, plasma concentrations, wildtype, catalytic activity, enzymatic assay, public health threat, in vitro data, variants of SARS-CoV-2, prevalent, evaluated, required, provided, maintain, comparable, catalytically, the SARS-CoV-2, 【제목키워드】 Efficacy, SARS-CoV-2 variant, in vitro,