Maraviroc Inhibits SARS-CoV-2 Through Variant-Dependent Effects on Viral Entry and Mpro Activity Using Single-Round...

Maraviroc (MVC), a CCR5 antagonist, has been proposed as a potential antiviral agent against SARS-CoV-2; however, its mechanism of action across viral variants remains unclear. Here, we evaluated the antiviral activity of MVC against SARS-CoV-2 wild-type (WT) and Omicron BA.1 variants using single-round infectious particles (SRIPs), virus-like particles (VLPs), and cell-based assays, with a focus on its impact on viral entry and Mpro function. MVC potently inhibited infection of both WT and BA.1 SRIPs in Vero E6 cells, exhibiting EC₅₀ values of 0.0065 μM and 0.016 μM, respectively. Time-of-addition assays revealed that MVC primarily targets the early phase of infection, with the strongest inhibition observed at the viral entry stage, while moderate effects were detected during attachment and post-entry stages. Fluorescence-labeled VLP imaging demonstrated distinct entry pathways, with WT predominantly entering via plasma membrane fusion and BA.1 via endocytosis, independent of cell type. MVC altered WT-VLP trafficking by promoting internalization and lysosomal localization, whereas it had minimal impact on BA.1 internalization. In spike-mediated cell-cell fusion assays, MVC preferentially inhibited WT spike-driven syncytium formation but showed limited effects on BA.1 or BA.4 fusion, while more effectively reducing Omicron spike-mediated binding. At the post-entry stage, MVC inhibited SARS-CoV-2 main protease (Mpro) activity, with BA.1 Mpro (P132H) exhibiting greater sensitivity (IC₅₀ = 0.496 µM) than WT (1.869 µM). Collectively, these findings demonstrate that MVC exerts variant-dependent antiviral effects by targeting viral entry, modulating trafficking pathways, and inhibiting Mpro activity. This study highlights MVC as a multi-stage inhibitor with differential efficacy against SARS-CoV-2 variants, providing insights into its potential therapeutic application.