The Selective DHCR24 Blocker SH42 Inhibits ACE2 Binding and Cellular Entry of SARS-CoV-2 Spike Proteins More...

ACE2 binding of spike proteins and concomitant viral uptake are the first and most decisive membrane-coupled events of SARS-CoV-2 infection, which rely on cholesterol-rich lipid raft microdomains of the host cell plasma membrane. Therefore, lowering membrane cholesterol levels may combat the infection, potentially complementing specific, resistance-prone antiviral approaches such as vaccines. High-throughput flow cytometry and quantitative 3-dimensional microscopy reveal that SH42, a novel, extremely potent, and highly selective 24-dehydrocholesterol reductase (DHCR24) blocker, markedly inhibits ACE2 binding of SARS-CoV-2 spike receptor-binding domains and entry of spike trimers of Wuhan-Hu-1 (WT), Delta, and Omicron BA.1 variants into living cells. These effects are related to SH42-induced reduction of plasma membrane cholesterol abundance and subsequent lipid raft disruption, which are accompanied by decreased cell surface ACE2 expression and its lowered raft partitioning. SH42 exhibits superior efficacy and potency in all aspects compared to the reference atorvastatin. Furthermore, inhibitory effects of SH42 are also corroborated by reduced SARS-CoV-2 RNA copy numbers of replication-competent complete virions of WT-resembling D614G, Delta, and Omicron-derived JN.1 strains. These results suggest that selective DHCR24 blockers such as SH42 may be promising novel candidates for inhibiting initial membrane-coupled events of SARS-CoV-2 infection and serve as potential alternative therapeutic option for COVID-19.