title: Antiviral efficacy of the novel compound BIT225 against HIV-1 release from human macrophages.
abstract: Building on previous findings that amiloride analogues inhibit HIV-1 replication in monocyte-derived macrophages (MDM), Biotron Limited has generated a library of over 300 small-molecule compounds with significant improvements in anti-HIV-1 activity. Our lead compound, BIT225, blocks Vpu ion channel activity and also shows anti-HIV-1 activity, with a 50% effective concentration of 2.25+/-0.23 microM (mean+/-the standard error) and minimal in vitro toxicity (50% toxic concentration, 284 microM) in infected MDM, resulting in a selectivity index of 126. In this study, we define the antiretroviral efficacy of BIT225 activity in macrophages, which are important drug targets because cells of the monocyte lineage are key reservoirs of HIV-1, disseminating virus to the peripheral tissues as they differentiate into macrophages. In assays with acutely and chronically HIV-1Ba-L-infected MDM, BIT225 resulted in significant reductions in viral integration and virus release as measured by real-time PCR and a reverse transcriptase (RT) activity assay at various stages of monocyte-to-macrophage differentiation. Further, the TZM-bl assay showed that the de novo virus produced at low levels in the presence of BIT225 was less infectious than virus produced in the absence of the compound. No antiviral activity was observed in MDM chronically infected with HIV-2, which lacks Vpu, confirming our initial targeting of and screening against this viral protein. The activity of BIT225 is post-virus integration, with no direct effects on the HIV-1 enzymes RT and protease. The findings of this study suggest that BIT225 is a late-phase inhibitor of the viral life cycle, targeting Vpu, and is a drug capable of significantly inhibiting HIV-1 release from both acute and chronically infected macrophages.
authors.affiliation: Biotron Limited, St. Vincent's Centre for Applied Medical Research, Lowy-Packer Building, 405 Liverpool Street, Darlinghurst, NSW 2010, Australia.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Khoury
authors.forename: Gary
authors.initials: G
authors.lastname: Ewart
authors.forename: Carolyn
authors.initials: C
authors.lastname: Luscombe
authors.forename: Michelle
authors.initials: M
authors.lastname: Miller
authors.forename: John
authors.initials: J
authors.lastname: Wilkinson
mesh_terms: D019380:Anti-HIV Agents / Q000737:chemistry / Q000494:pharmacology*; D015153:Blotting, Western; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D024882:Drug Resistance, Viral / Q000187:drug effects; D015658:HIV Infections / Q000517:prevention & control / Q000821:virology; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics / Q000502:physiology / Q000648:ultrastructure; D015498:HIV-2 / Q000187:drug effects / Q000235:genetics; D054298:Human Immunodeficiency Virus Proteins / Q000037:antagonists & inhibitors; D006801:Humans; D008264:Macrophages / Q000187:drug effects / Q000821:virology*; D046529:Microscopy, Electron, Transmission; D015394:Molecular Structure; D016133:Polymerase Chain Reaction; D054334:Viral Regulatory and Accessory Proteins / Q000037:antagonists & inhibitors; D014771:Virion / Q000187:drug effects / Q000648:ultrastructure; D057074:Virus Release / Q000187:drug effects*; D014779:Virus Replication / Q000187:drug effects; D000086082:Viroporin Proteins
chemical_list: D019380:Anti-HIV Agents; D054298:Human Immunodeficiency Virus Proteins; D054334:Viral Regulatory and Accessory Proteins; C514859:vpu protein, Human immunodeficiency virus 1; D000086082:Viroporin Proteins