ABSTRACT
Recent characterization of broadly neutralizing antibodies (bnAbs) against influenza virus identified the conserved hemagglutinin (HA) stem as a target for development of universal vaccines and therapeutics. Although several stem bnAbs are being evaluated in clinical trials, antibodies are generally unsuited for oral delivery. Guided by structural knowledge of the interactions and mechanism of anti-stem bnAb CR6261, we selected and optimized small molecules that mimic the bnAb functionality. Our lead compound neutralizes influenza A group 1 viruses by inhibiting HA-mediated fusion in vitro, protects mice against lethal and sublethal influenza challenge after oral administration, and effectively neutralizes virus infection in reconstituted three-dimensional cell culture of fully differentiated human bronchial epithelial cells. Cocrystal structures with H1 and H5 HAs reveal that the lead compound recapitulates the bnAb hotspot interactions.
Subject(s)
Antibodies, Neutralizing/chemistry , Biomimetic Materials/pharmacology , Influenza A Virus, H1N1 Subtype/drug effects , Influenza, Human/prevention & control , Piperazines/pharmacology , Pyridines/pharmacology , Tetrazoles/pharmacology , Viral Fusion Protein Inhibitors/pharmacology , Virus Internalization/drug effects , Administration, Oral , Animals , Biomimetic Materials/administration & dosage , Biomimetic Materials/pharmacokinetics , Bronchi/virology , Cells, Cultured , Dogs , Hemagglutinin Glycoproteins, Influenza Virus/genetics , Hemagglutinin Glycoproteins, Influenza Virus/metabolism , Humans , Madin Darby Canine Kidney Cells , Mice , Piperazines/administration & dosage , Piperazines/pharmacokinetics , Pyridines/administration & dosage , Pyridines/pharmacokinetics , Respiratory Mucosa/virology , Tetrazoles/administration & dosage , Tetrazoles/pharmacokinetics , Viral Fusion Protein Inhibitors/administration & dosage , Viral Fusion Protein Inhibitors/pharmacokineticsABSTRACT
Influenza therapeutics with new targets and mechanisms of action are urgently needed to combat potential pandemics, emerging viruses, and constantly mutating strains in circulation. We report here on the design and structural characterization of potent peptidic inhibitors of influenza hemagglutinin. The peptide design was based on complementarity-determining region loops of human broadly neutralizing antibodies against the hemagglutinin (FI6v3 and CR9114). The optimized peptides exhibit nanomolar affinity and neutralization against influenza A group 1 viruses, including the 2009 H1N1 pandemic and avian H5N1 strains. The peptide inhibitors bind to the highly conserved stem epitope and block the low pH-induced conformational rearrangements associated with membrane fusion. These peptidic compounds and their advantageous biological properties should accelerate the development of new small molecule- and peptide-based therapeutics against influenza virus.
