title: New small molecule entry inhibitors targeting hemagglutinin-mediated influenza a virus fusion.
abstract: Influenza viruses are a major public health threat worldwide, and options for antiviral therapy are limited by the emergence of drug-resistant virus strains. The influenza virus glycoprotein hemagglutinin (HA) plays critical roles in the early stage of virus infection, including receptor binding and membrane fusion, making it a potential target for the development of anti-influenza drugs. Using pseudotype virus-based high-throughput screens, we have identified several new small molecules capable of inhibiting influenza virus entry. We prioritized two novel inhibitors, MBX2329 and MBX2546, with aminoalkyl phenol ether and sulfonamide scaffolds, respectively, that specifically inhibit HA-mediated viral entry. The two compounds (i) are potent (50% inhibitory concentration [IC50] of 0.3 to 5.9 μM); (ii) are selective (50% cytotoxicity concentration [CC(50)] of >100 μM), with selectivity index (SI) values of >20 to 200 for different influenza virus strains; (iii) inhibit a wide spectrum of influenza A viruses, which includes the 2009 pandemic influenza virus A/H1N1/2009, highly pathogenic avian influenza (HPAI) virus A/H5N1, and oseltamivir-resistant A/H1N1 strains; (iv) exhibit large volumes of synergy with oseltamivir (36 and 331 μM(2) % at 95% confidence); and (v) have chemically tractable structures. Mechanism-of-action studies suggest that both MBX2329 and MBX2546 bind to HA in a nonoverlapping manner. Additional results from HA-mediated hemolysis of chicken red blood cells (cRBCs), competition assays with monoclonal antibody (MAb) C179, and mutational analysis suggest that the compounds bind in the stem region of the HA trimer and inhibit HA-mediated fusion. Therefore, MBX2329 and MBX2546 represent new starting points for chemical optimization and have the potential to provide valuable future therapeutic options and research tools to study the HA-mediated entry process.
authors.affiliation: Microbiotix Inc., Worcester, Massachusetts, USA.
authors.forename: Arnab
authors.initials: A
authors.lastname: Basu
authors.forename: Aleksandar
authors.initials: A
authors.lastname: Antanasijevic
authors.forename: Minxiu
authors.initials: M
authors.lastname: Wang
authors.forename: Bing
authors.initials: B
authors.lastname: Li
authors.forename: Debra M
authors.initials: DM
authors.lastname: Mills
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Ames
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Nash
authors.forename: John D
authors.initials: JD
authors.lastname: Williams
authors.forename: Norton P
authors.initials: NP
authors.lastname: Peet
authors.forename: Donald T
authors.initials: DT
authors.lastname: Moir
authors.forename: Mark N
authors.initials: MN
authors.lastname: Prichard
authors.forename: Kathy A
authors.initials: KA
authors.lastname: Keith
authors.forename: Dale L
authors.initials: DL
authors.lastname: Barnard
authors.forename: Michael
authors.initials: M
authors.lastname: Caffrey
authors.forename: Lijun
authors.initials: L
authors.lastname: Rong
authors.forename: Terry L
authors.initials: TL
authors.lastname: Bowlin
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000737:chemistry / Q000494:pharmacology*; D002460:Cell Line; D002645:Chickens; D006389:Hemagglutinins, Viral / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D053122:Influenza A Virus, H3N2 Subtype / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D053124:Influenza A Virus, H5N1 Subtype / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D009980:Influenza A virus / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D005585:Influenza in Birds / Q000821:virology*; D007251:Influenza, Human / Q000821:virology*; D011201:Poultry Diseases / Q000821:virology*; D054852:Small Molecule Libraries / Q000737:chemistry / Q000494:pharmacology*; D053586:Virus Internalization / Q000187:drug effects*
chemical_list: D000998:Antiviral Agents; D006389:Hemagglutinins, Viral; D054852:Small Molecule Libraries