title: Identification of a small-molecule entry inhibitor for filoviruses.
abstract: Ebola virus (EBOV) causes severe hemorrhagic fever, for which therapeutic options are not available. Preventing the entry of EBOV into host cells is an attractive antiviral strategy, which has been validated for HIV by the FDA approval of the anti-HIV drug enfuvirtide. To identify inhibitors of EBOV entry, the EBOV envelope glycoprotein (EBOV-GP) gene was used to generate pseudotype viruses for screening of chemical libraries. A benzodiazepine derivative (compound 7) was identified from a high-throughput screen (HTS) of small-molecule compound libraries utilizing the pseudotype virus. Compound 7 was validated as an inhibitor of infectious EBOV and Marburg virus (MARV) in cell-based assays, with 50% inhibitory concentrations (IC(50)s) of 10 μM and 12 μM, respectively. Time-of-addition and binding studies suggested that compound 7 binds to EBOV-GP at an early stage during EBOV infection. Preliminary Schrödinger SiteMap calculations, using a published EBOV-GP crystal structure in its prefusion conformation, suggested a hydrophobic pocket at or near the GP1 and GP2 interface as a suitable site for compound 7 binding. This prediction was supported by mutational analysis implying that residues Asn69, Leu70, Leu184, Ile185, Leu186, Lys190, and Lys191 are critical for the binding of compound 7 and its analogs with EBOV-GP. We hypothesize that compound 7 binds to this hydrophobic pocket and as a consequence inhibits EBOV infection of cells, but the details of the mechanism remain to be determined. In summary, we have identified a novel series of benzodiazepine compounds that are suitable for optimization as potential inhibitors of filoviral infection.
authors.affiliation: Microbiotix, Inc., One Innovation Drive, Worcester, MA 01605, USA. abasu@microbiotix.com
authors.forename: Arnab
authors.initials: A
authors.lastname: Basu
authors.forename: Bing
authors.initials: B
authors.lastname: Li
authors.forename: Debra M
authors.initials: DM
authors.lastname: Mills
authors.forename: Rekha G
authors.initials: RG
authors.lastname: Panchal
authors.forename: Steven C
authors.initials: SC
authors.lastname: Cardinale
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Butler
authors.forename: Norton P
authors.initials: NP
authors.lastname: Peet
authors.forename: Helena
authors.initials: H
authors.lastname: Majgier-Baranowska
authors.forename: John D
authors.initials: JD
authors.lastname: Williams
authors.forename: Ishan
authors.initials: I
authors.lastname: Patel
authors.forename: Donald T
authors.initials: DT
authors.lastname: Moir
authors.forename: Sina
authors.initials: S
authors.lastname: Bavari
authors.forename: Ranjit
authors.initials: R
authors.lastname: Ray
authors.forename: Michael R
authors.initials: MR
authors.lastname: Farzan
authors.forename: Lijun
authors.initials: L
authors.lastname: Rong
authors.forename: Terry L
authors.initials: TL
authors.lastname: Bowlin
mesh_terms: D000998:Antiviral Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D001569:Benzodiazepines / Q000302:isolation & purification / Q000494:pharmacology; D004252:DNA Mutational Analysis; D004353:Drug Evaluation, Preclinical / Q000379:methods; D024882:Drug Resistance, Viral; D029043:Ebolavirus / Q000187:drug effects* / Q000502:physiology; D057166:High-Throughput Screening Assays / Q000379:methods; D006801:Humans; D020128:Inhibitory Concentration 50; D029024:Marburgvirus / Q000187:drug effects; D008958:Models, Molecular; D020125:Mutation, Missense; D011485:Protein Binding; D053586:Virus Internalization / Q000187:drug effects*
chemical_list: D000998:Antiviral Agents; D001569:Benzodiazepines