TMPRSS2 inhibitors with broad-spectrum efficacy against SARS-CoV-2 (JN.1) and influenza A (H1N1) viruses protect mice from influenza A infection

Human TMPRSS2 is a type II transmembrane serine protease and an essential host factor for SARS-CoV-2 and influenza A virus (IAV H1N1) infections. It facilitates the cleavage of viral surface glycoproteins, which are required for membrane fusion. This importance makes it an attractive target for host-directed antiviral therapies. We previously identified N-0385 and N-0920 as nanomolar TMPRSS2 inhibitors and demonstrated their antiviral potency against several SARS-CoV-2 variants. Here, we screened another twelve N-0385/N-0920 analogs with improved pharmacokinetics. Compounds 9 and 10 showed strong inhibition of TMPRSS2 activity and viral entry: they blocked pseudoviruses and authentic SARS-CoV-2 JN.1 and IAV H1N1 in Calu-3 cells. Compound 9 displayed a synergistic effect with baloxavir during IAV H1N1 infection. Both compounds highly reduced H1N1 infection in air–liquid interface cultures and mouse models, thus highlighting their broad antiviral potential. The discovery of broad-spectrum, host-directed antivirals against current and emerging human viruses is critical in preparing for future pandemics.