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 <b>9</b> and <b>10</b> 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 <b>9</b> 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.