title: A mutation in the Ebola virus envelope glycoprotein restricts viral entry in a host species- and cell-type-specific manner.
abstract: Zaire Ebola virus (EBOV) is a zoonotic pathogen that causes severe hemorrhagic fever in humans. A single viral glycoprotein (GP) mediates viral attachment and entry. Here, virus-like particle (VLP)-based entry assays demonstrate that a GP mutant, GP-F88A, which is defective for entry into a variety of human cell types, including antigen-presenting cells (APCs), such as macrophages and dendritic cells, can mediate viral entry into mouse CD11b(+) APCs. Like that of wild-type GP (GP-wt), GP-F88A-mediated entry occurs via a macropinocytosis-related pathway and requires endosomal cysteine proteases and an intact fusion peptide. Several additional hydrophobic residues lie in close proximity to GP-F88, including L111, I113, L122, and F225. GP mutants in which these residues are mutated to alanine displayed preferential and often impaired entry into several cell types, although not in a species-specific manner. Niemann-Pick C1 (NPC1) protein is an essential filovirus receptor that binds directly to GP. Overexpression of NPC1 was recently demonstrated to rescue GP-F88A-mediated entry. A quantitative enzyme-linked immunosorbent assay (ELISA) demonstrated that while the F88A mutation impairs GP binding to human NPC1 by 10-fold, it has little impact on GP binding to mouse NPC1. Interestingly, not all mouse macrophage cell lines permit GP-F88A entry. The IC-21 cell line was permissive, whereas RAW 264.7 cells were not. Quantitative reverse transcription (RT)-PCR assays demonstrate higher NPC1 levels in GP-F88A permissive IC-21 cells and mouse peritoneal macrophages than in RAW 264.7 cells. Cumulatively, these studies suggest an important role for NPC1 in the differential entry of GP-F88A into mouse versus human APCs.
authors.affiliation: Icahn School of Medicine at Mount Sinai, New York, NY, USA.
authors.forename: Osvaldo
authors.initials: O
authors.lastname: Martinez
authors.forename: Esther
authors.initials: E
authors.lastname: Ndungo
authors.forename: Lee
authors.initials: L
authors.lastname: Tantral
authors.forename: Emily Happy
authors.initials: EH
authors.lastname: Miller
authors.forename: Lawrence W
authors.initials: LW
authors.lastname: Leung
authors.forename: Kartik
authors.initials: K
authors.lastname: Chandran
authors.forename: Christopher F
authors.initials: CF
authors.lastname: Basler
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002460:Cell Line; D004252:DNA Mutational Analysis; D029043:Ebolavirus / Q000235:genetics / Q000502:physiology*; D004705:Endocytosis; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D000077296:Niemann-Pick C1 Protein; D011506:Proteins / Q000378:metabolism; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism*; D053586:Virus Internalization
chemical_list: D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D050505:Mutant Proteins; C106881:NPC1 protein, human; D000077296:Niemann-Pick C1 Protein; C106831:Npc1 protein, mouse; D011506:Proteins; D014759:Viral Envelope Proteins; C113189:envelope glycoprotein, Ebola virus