title: N-glycans on Nipah virus fusion protein protect against neutralization but reduce membrane fusion and viral entry.
abstract: Nipah virus (NiV) is a deadly emerging paramyxovirus. The NiV attachment (NiV-G) and fusion (NiV-F) envelope glycoproteins mediate both syncytium formation and viral entry. Specific N-glycans on paramyxovirus fusion proteins are generally required for proper conformational integrity and biological function. However, removal of individual N-glycans on NiV-F had little negative effect on processing or fusogenicity and has even resulted in slightly increased fusogenicity. Here, we report that in both syncytium formation and viral entry assays, removal of multiple N-glycans on NiV-F resulted in marked increases in fusogenicity (>5-fold) but also resulted in increased sensitivity to neutralization by NiV-F-specific antisera. The mechanism underlying the hyperfusogenicity of these NiV-F N-glycan mutants is likely due to more-robust six-helix bundle formation, as these mutants showed increased fusion kinetics and were more resistant to neutralization by a fusion-inhibitory reagent based on the C-terminal heptad repeat region of NiV-F. Finally, we demonstrate that the fusogenicities of the NiV-F N-glycan mutants were inversely correlated with the relative avidities of NiV-F's interactions with NiV-G, providing support for the attachment protein "displacement" model of paramyxovirus fusion. Our results indicate that N-glycans on NiV-F protect NiV from antibody neutralization, suggest that this "shielding" role comes together with limiting cell-cell fusion and viral entry efficiencies, and point to the mechanisms underlying the hyperfusogenicity of these N-glycan mutants. These features underscore the varied roles that N-glycans on NiV-F play in the pathobiology of NiV entry but also shed light on the general mechanisms of paramyxovirus fusion with host cells.
authors.affiliation: Department of MIMG, David Geffen Schoo; of Medicine at UCLA, Los Angeles, CA 90095, USA.
authors.forename: Hector C
authors.initials: HC
authors.lastname: Aguilar
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Matreyek
authors.forename: Claire Marie
authors.initials: CM
authors.lastname: Filone
authors.forename: Sara T
authors.initials: ST
authors.lastname: Hashimi
authors.forename: Ernest L
authors.initials: EL
authors.lastname: Levroney
authors.forename: Oscar A
authors.initials: OA
authors.lastname: Negrete
authors.forename: Andrea
authors.initials: A
authors.lastname: Bertolotti-Ciarlet
authors.forename: Daniel Y
authors.initials: DY
authors.lastname: Choi
authors.forename: Ian
authors.initials: I
authors.lastname: McHardy
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Fulcher
authors.forename: Stephen V
authors.initials: SV
authors.lastname: Su
authors.forename: Mike C
authors.initials: MC
authors.lastname: Wolf
authors.forename: Luciana
authors.initials: L
authors.lastname: Kohatsu
authors.forename: Linda G
authors.initials: LG
authors.lastname: Baum
authors.forename: Benhur
authors.initials: B
authors.lastname: Lee
mesh_terms: D000818:Animals; D002460:Cell Line; D004285:Dogs; D006031:Glycosylation; D006367:HeLa Cells; D045464:Henipavirus Infections / Q000517:prevention & control / Q000821:virology; D006801:Humans; D008561:Membrane Fusion / Q000235:genetics / Q000502:physiology*; D009500:Neutralization Tests; D045405:Nipah Virus / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D011134:Polysaccharides / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014760:Viral Fusion Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: C510755:F protein, Nipah virus; D011134:Polysaccharides; D014759:Viral Envelope Proteins; D014760:Viral Fusion Proteins; C116204:attachment protein G