An N-terminal heptad repeat trimer-based peptide fusion inhibitor exhibits potent anti-H1N1 activity.

Influenza viruses are susceptible to seasonal influenza, which has repeatedly caused global pandemics and jeopardized human health. Vaccines are only used as preventive medicine due to the extreme mutability of influenza viruses, and antiviral medication is the most significant clinical treatment to reduce influenza morbidity and mortality. Nevertheless, the clinical application of anti-influenza virus agents is characterized by the narrow therapeutic time window, the susceptibility to drug resistance, and relatively limited effect on severe influenza. Therefore, it is of great significance to develop novel anti-influenza virus drugs to fulfill the urgent clinical needs. Influenza viruses enter host cells through the hemagglutinin (HA) mediated membrane fusion process, and fusion inhibitors function antivirally by blocking hemagglutinin deformation, promising better therapeutic efficacy and resolving drug resistance, with targets different from marketed medicines. Previous studies have shown that unnatural peptides derived from Human Immunodeficiency Virus Type 1 (HIV-1) membrane fusion proteins exhibit anti-HIV-1 activity. Based on the similarity of the membrane fusion protein deformation process between HIV-1 and H1N1, we selected sequences derived from the gp41 subunit in the HIV-1 fusion protein, and then constructed N-trimer spatial structure through inter-helical isopeptide bond modification, to design the novel anti-H1N1 fusion inhibitors. The results showed that the novel peptides could block 6-HB formation during H1N1 membrane fusion procedure, and thus possessed significant anti-H1N1 activity, comparable to the positive control oseltamivir. Our study demonstrates the design viability of peptide fusion inhibitors based on similar membrane fusion processes among viruses, and furthermore provides an important idea for the novel anti-H1N1 inhibitors development.