Adenosylhomocysteinase like 1 interacts with nonstructural 5A and regulates hepatitis C virus propagation

Amuvatinib Blocks SARS-CoV-2 Infection at the Entry Step of the Viral Life Cycle

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019 (COVID-19). SARS-CoV-2 propagation is mediated by the protein interaction between viral proteins and host cells. Tyrosine kinase has been implicated in viral replication, and hence, it has become a target for developing antiviral drugs. We have previously reported that receptor tyrosine kinase inhibitor blocks the replication of hepatitis C virus (HCV). In the present study, we investigated two receptor tyrosine kinase-specific inhibitors, amuvatinib and imatinib, for their potential antiviral efficacies against SARS-CoV-2. Treatment with either amuvatinib or imatinib displays an effective inhibitory activity against SARS-CoV-2 propagation without an obvious cytopathic effect in Vero E6 cells. Notably, amuvatinib exerts a stronger antiviral activity than imatinib against SARS-CoV-2 infection. Amuvatinib blocks SARS-CoV-2 infection with a 50% effective concentration (EC50) value ranging from ~0.36 to 0.45 μM in Vero E6 cells. We further demonstrate that amuvatinib inhibits SARS-CoV-2 propagation in human lung Calu-3 cells. Using pseudoparticle infection assay, we verify that amuvatinib blocks SARS-CoV-2 at the entry step of the viral life cycle. More specifically, amuvatinib inhibits SARS-CoV-2 infection at the binding-attachment step. Moreover, amuvatinib exhibits highly efficient antiviral activity against emerging SARS-CoV-2 variants. Importantly, we demonstrate that amuvatinib inhibits SARS-CoV-2 infection by blocking ACE2 cleavage. Taken together, our data suggest that amuvatinib may provide a potential therapeutic agent for the treatment of COVID-19. IMPORTANCE Tyrosine kinase has been implicated in viral replication and has become an antiviral drug target. Here, we chose two well-known receptor tyrosine kinase inhibitors, amuvatinib and imatinib, and evaluated their drug potencies against SARS-CoV-2. Surprisingly, amuvatinib displays a stronger antiviral activity than imatinib against SARS-CoV-2. Amuvatinib blocks SARS-CoV-2 infection by inhibiting ACE2 cleavage and the subsequent soluble ACE2 receptor. All these data suggest that amuvatinib may be a potential therapeutic agent in SARS-CoV-2 prevention for those experiencing vaccine breakthroughs.

Inhibition of KIF20A suppresses the replication of influenza A virus by inhibiting viral entry

The influenza A virus (IAV) has caused several pandemics, and therefore there are many ongoing efforts to identify novel antiviral therapeutic strategies including vaccines and antiviral drugs. However, influenza viruses continuously undergo antigenic drift and shift, resulting in the emergence of mutated viruses. In turn, this decreases the efficiency of existing vaccines and antiviral drugs to control IAV infection. Therefore, this study sought to identify alternative therapeutic strategies targeting host cell factors rather than viruses to avoid infection by mutated viruses. Particularly, we investigated the role of KIF20A that is one of kinesin superfamily proteins in the replication of IAV. The KIF20A increased viral protein levels in IAV-infected cells by regulating the initial entry stage during viral infection. Furthermore, the KIF20A inhibitor significantly suppressed viral replication, which protected mice from morbidity and mortality. Therefore, our findings demonstrated that KIF20A is highly involved in the viral replication process and viral propagation both in vitro and in vivo, and could thus be used as a target for the development of novel antiviral drugs.

Asunaprevir, a Potent Hepatitis C Virus Protease Inhibitor, Blocks SARS-CoV-2 Propagation

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has become a global health concern. Various SARS-CoV-2 vaccines have been developed and are being used for vaccination worldwide. However, no therapeutic agents against coronavirus disease 2019 (COVID-19) have been developed so far; therefore, new therapeutic agents are urgently needed. In the present study, we evaluated several hepatitis C virus direct-acting antivirals as potential candidates for drug repurposing against COVID-19. Theses include asunaprevir (a protease inhibitor), daclatasvir (an NS5A inhibitor), and sofosbuvir (an RNA polymerase inhibitor). We found that asunaprevir, but not sofosbuvir and daclatasvir, markedly inhibited SARS-CoV-2-induced cytopathic effects in Vero E6 cells. Both RNA and protein levels of SARS-CoV-2 were significantly decreased by treatment with asunaprevir. Moreover, asunaprevir profoundly decreased virion release from SARS-CoV-2-infected cells. A pseudoparticle entry assay revealed that asunaprevir blocked SARS-CoV-2 infection at the binding step of the viral life cycle. Furthermore, asunaprevir inhibited SARS-CoV-2 propagation in human lung Calu-3 cells. Collectively, we found that asunaprevir displays broad-spectrum antiviral activity and therefore might be worth developing as a new drug repurposing candidate for COVID-19.