RESUMO
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.
Assuntos
Anticorpos Neutralizantes/química , Materiais Biomiméticos/farmacologia , Vírus da Influenza A Subtipo H1N1/efeitos dos fármacos , Influenza Humana/prevenção & controle , Piperazinas/farmacologia , Piridinas/farmacologia , Tetrazóis/farmacologia , Inibidores de Proteínas Virais de Fusão/farmacologia , Internalização do Vírus/efeitos dos fármacos , Administração Oral , Animais , Materiais Biomiméticos/administração & dosagem , Materiais Biomiméticos/farmacocinética , Brônquios/virologia , Células Cultivadas , Cães , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Glicoproteínas de Hemaglutininação de Vírus da Influenza/metabolismo , Humanos , Células Madin Darby de Rim Canino , Camundongos , Piperazinas/administração & dosagem , Piperazinas/farmacocinética , Piridinas/administração & dosagem , Piridinas/farmacocinética , Mucosa Respiratória/virologia , Tetrazóis/administração & dosagem , Tetrazóis/farmacocinética , Inibidores de Proteínas Virais de Fusão/administração & dosagem , Inibidores de Proteínas Virais de Fusão/farmacocinéticaRESUMO
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.