title: A specific interaction of small molecule entry inhibitors with the envelope glycoprotein complex of the Junín hemorrhagic fever arenavirus.
abstract: Arenaviruses are responsible for acute hemorrhagic fevers worldwide and are recognized to pose significant threats to public health and biodefense. Small molecule compounds have recently been discovered that inhibit arenavirus entry and protect against lethal infection in animal models. These chemically distinct inhibitors act on the tripartite envelope glycoprotein (GPC) through its unusual stable signal peptide subunit to stabilize the complex against pH-induced activation of membrane fusion in the endosome. Here, we report the production and characterization of the intact transmembrane GPC complex of Junín arenavirus and its interaction with these inhibitors. The solubilized GPC is antigenically indistinguishable from the native protein and forms a homogeneous trimer in solution. When reconstituted into a lipid bilayer, the purified complex interacts specifically with its cell-surface receptor transferrin receptor-1. We show that small molecule entry inhibitors specific to New World or Old World arenaviruses bind to the membrane-associated GPC complex in accordance with their respective species selectivities and with dissociation constants comparable with concentrations that inhibit GPC-mediated membrane fusion. Furthermore, competitive binding studies reveal that these chemically distinct inhibitors share a common binding pocket on GPC. In conjunction with previous genetic studies, these findings identify the pH-sensing interface of GPC as a highly vulnerable target for antiviral intervention. This work expands our mechanistic understanding of arenavirus entry and provides a foundation to guide the development of small molecule compounds for the treatment of arenavirus hemorrhagic fevers.
authors.affiliation: Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana 59812, USA. celestine.thomas@umontana.edu
authors.forename: Celestine J
authors.initials: CJ
authors.lastname: Thomas
authors.forename: Hedi E
authors.initials: HE
authors.lastname: Casquilho-Gray
authors.forename: Joanne
authors.initials: J
authors.lastname: York
authors.forename: Dianne L
authors.initials: DL
authors.lastname: DeCamp
authors.forename: Dongcheng
authors.initials: D
authors.lastname: Dai
authors.forename: Erin B
authors.initials: EB
authors.lastname: Petrilli
authors.forename: Dale L
authors.initials: DL
authors.lastname: Boger
authors.forename: Richard A
authors.initials: RA
authors.lastname: Slayden
authors.forename: Sean M
authors.initials: SM
authors.lastname: Amberg
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Sprang
authors.forename: Jack H
authors.initials: JH
authors.lastname: Nunberg
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism*; D000998:Antiviral Agents / Q000737:chemistry / Q000494:pharmacology*; D001117:Arenaviridae Infections / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D002522:Chlorocebus aethiops; D006801:Humans; D018051:Junin virus / Q000235:genetics / Q000378:metabolism*; D011990:Receptors, Transferrin / Q000235:genetics / Q000378:metabolism*; D014709:Vero Cells; D014759:Viral Envelope Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D053586:Virus Internalization / Q000187:drug effects
chemical_list: D015703:Antigens, CD; D000998:Antiviral Agents; C068126:CD71 antigen; D011990:Receptors, Transferrin; D014759:Viral Envelope Proteins