SARS-CoV-2 exploits cellular RAD51 to promote viral propagation: implication of RAD51 inhibitor as a potential drug candidate against COVID-19

RAD51 is an important factor involved in the homologous recombination and repair of DNA breaks, which has also been implicated in various virus replication processes. We have previously reported that hepatitis C virus (HCV) exploits cellular RAD51 to promote viral propagation. Since severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is also an RNA virus, we interrogated whether SARS-CoV-2 could coopt RAD51 for its propagation. Here, we showed that silencing of RAD51 impaired SARS-CoV-2 propagation. We further demonstrated that RAD51 colocalized with SARS-CoV-2 RNA in Vero E6 cells. Interestingly, RAD51 interacted with SARS-CoV-2 3CL protease. This suggests that RAD51 inhibitors may block SARS-CoV-2 propagation. Hence, we evaluated multiple RAD51 inhibitors as potential drug candidates for coronavirus disease 2019 (COVID-19). Among these, B02, 4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), IBR2, and RI(dl)-2 significantly decreased RNA, protein, and infectious virion levels of Wuhan and variants of SARS-CoV-2. Antiviral activity of DIDS was further confirmed in the Syrian hamster model. Molecular docking model showed that these chemicals interfered with RAD51 through dimerization interface. These data suggest that SARS-CoV-2 exploits host RAD51 to facilitate viral propagation, and hence, RAD51 inhibitor may serve as a putative novel therapeutic agent for the treatment of COVID-19.IMPORTANCEViruses are constantly evolving to promote propagation in the host. Here, we show that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) utilizes host RAD51 for replication. Silencing of RAD51 impaired SARS-CoV-2 propagation. Viral RNA colocalized with RAD51 in the cytoplasm of SARS-CoV-2-infected cells, suggesting that both viral RNA and RAD51 may form a replication complex. We, therefore, evaluated RAD51 inhibitors as possible therapeutic agents against SARS-CoV-2. Indeed, RAD51 inhibitors exerted antiviral activities against not only Wuhan but also variants of SARS-CoV-2. Molecular docking model shows that RAD51 inhibitors impede SARS-CoV-2 propagation by interfering with dimerization of RAD51. These data suggest that RAD51 may represent a novel host-based drug target for coronavirus disease 2019 treatment. Viruses are constantly evolving to promote propagation in the host. Here, we show that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) utilizes host RAD51 for replication. Silencing of RAD51 impaired SARS-CoV-2 propagation. Viral RNA colocalized with RAD51 in the cytoplasm of SARS-CoV-2-infected cells, suggesting that both viral RNA and RAD51 may form a replication complex. We, therefore, evaluated RAD51 inhibitors as possible therapeutic agents against SARS-CoV-2. Indeed, RAD51 inhibitors exerted antiviral activities against not only Wuhan but also variants of SARS-CoV-2. Molecular docking model shows that RAD51 inhibitors impede SARS-CoV-2 propagation by interfering with dimerization of RAD51. These data suggest that RAD51 may represent a novel host-based drug target for coronavirus disease 2019 treatment.

Automated summary

This study reveals that SARS-CoV-2 utilizes host RAD51 for replication. Silencing RAD51 impairs the propagation of SARS-CoV-2. Viral RNA and RAD51 colocalize in the cytoplasm, hinting at the formation of a replication complex. RAD51 inhibitors show antiviral activities against both Wuhan and variants of SARS-CoV-2 by interfering with RAD51 dimerization. These findings suggest that RAD51 may be a potential therapeutic target for COVID-19 treatment.