title: Small molecules VP-14637 and JNJ-2408068 inhibit respiratory syncytial virus fusion by similar mechanisms.
abstract: Here we present data on the mechanism of action of VP-14637 and JNJ-2408068 (formerly R-170591), two small-molecule inhibitors of respiratory syncytial virus (RSV). Both inhibitors exhibited potent antiviral activity with 50% effective concentrations (EC50s) of 1.4 and 2.1 nM, respectively. A similar inhibitory effect was observed in a RSV-mediated cell fusion assay (EC50=5.4 and 0.9 nM, respectively). Several drug-resistant RSV variants were selected in vitro in the presence of each compound. All selected viruses exhibited significant cross-resistance to both inhibitors and contained various single amino acid substitutions in two distinct regions of the viral F protein, the heptad repeat 2 (HR2; mutations D486N, E487D, and F488Y), and the intervening domain between HR1 and HR2 (mutation K399I and T400A). Studies using [3H]VP-14637 revealed a specific binding of the compound to RSV-infected cells that was efficiently inhibited by JNJ-2408068 (50% inhibitory concentration=2.9 nM) but not by the HR2-derived peptide T-118. Further analysis using a transient T7 vaccinia expression system indicated that RSV F protein is sufficient for this interaction. F proteins containing either the VP-14637 or JNJ-2408068 resistance mutations exhibited greatly reduced binding of [3H]VP-14637. Molecular modeling analysis suggests that both molecules may bind into a small hydrophobic cavity in the inner core of F protein, interacting simultaneously with both the HR1 and HR2 domains. Altogether, these data indicate that VP-14637 and JNJ-2408068 interfere with RSV fusion through a mechanism involving a similar interaction with the F protein.
authors.affiliation: Gilead, 333 Lakeside Dr., Foster City, CA 94404, USA.
authors.forename: Janet L
authors.initials: JL
authors.lastname: Douglas
authors.forename: Marites L
authors.initials: ML
authors.lastname: Panis
authors.forename: Edmund
authors.initials: E
authors.lastname: Ho
authors.forename: Kuei-Ying
authors.initials: KY
authors.lastname: Lin
authors.forename: Steve H
authors.initials: SH
authors.lastname: Krawczyk
authors.forename: Deborah M
authors.initials: DM
authors.lastname: Grant
authors.forename: Ruby
authors.initials: R
authors.lastname: Cai
authors.forename: Swami
authors.initials: S
authors.lastname: Swaminathan
authors.forename: Xiaowu
authors.initials: X
authors.lastname: Chen
authors.forename: Tomas
authors.initials: T
authors.lastname: Cihlar
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D001562:Benzimidazoles / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D002459:Cell Fusion; D002460:Cell Line; D002642:Chick Embryo; D006224:Cricetinae; D024882:Drug Resistance, Viral; D006801:Humans; D006835:Hydrazones; D008561:Membrane Fusion / Q000187:drug effects*; D008958:Models, Molecular; D010636:Phenols / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D018113:Respiratory Syncytial Virus, Human / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000472:pathogenicity; D013777:Tetrazoles / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D014760:Viral Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000998:Antiviral Agents; D001562:Benzimidazoles; D006835:Hydrazones; D010636:Phenols; D013777:Tetrazoles; D014760:Viral Fusion Proteins; C423511:VP-14637