title: Fusogenic activity of reconstituted newcastle disease virus envelopes: a role for the hemagglutinin-neuraminidase protein in the fusion process.
abstract: Enveloped viruses, such as newcastle disease virus (NDV), make their entry into the host cell by membrane fusion. In the case of NDV, the fusion step requires both transmembrane hemagglutinin-neuraminidase (HN) and fusion (F) viral envelope glycoproteins. The HN protein should show fusion promotion activity. To date, the nature of HN-F interactions is a controversial issue. In this work, we aim to clarify the role of the HN glycoprotein in the membrane fusion step. Four types of reconstituted detergent-free NDV envelopes were used, on differing in their envelope protein contents. Fusion of the different virosomes and erythrocyte ghosts was monitored using the octadecyl rhodamine B chloride assay. Only the reconstituted envelopes having the F protein, even in the absence of HN protein, displayed residual fusion activity. Treatment of such virosomes with denaturing agents affecting the F protein abolished fusion, indicating that the fusion detected was viral protein-dependent. Interestingly, the rate of fusion in the reconstituted systems was similar to that of intact viruses in the presence of the inhibitor of HN sialidase activity 2,3-dehydro-2-deoxy-N-acetylneuraminic acid. The results show that the residual fusion activity detected in the reconstituted systems was exclusively due to F protein activity, with no contribution from the fusion promotion activity of HN protein.
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Universidad de Salamanca, Plaza Doctores de la Reina s/n, Edificio Departamental, Lab109, 37007 Salamanca, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Cobaleda
authors.forename: I
authors.initials: I
authors.lastname: Muñoz-Barroso
authors.forename: A
authors.initials: A
authors.lastname: Sagrera
authors.forename: E
authors.initials: E
authors.lastname: Villar
mesh_terms: D000818:Animals; D004910:Erythrocyte Membrane / Q000378:metabolism; D015707:HN Protein / Q000737:chemistry / Q000502:physiology*; D007700:Kinetics; D008081:Liposomes; D008561:Membrane Fusion; D009522:Newcastle disease virus / Q000502:physiology*; D013552:Swine; D014760:Viral Fusion Proteins / Q000502:physiology*
chemical_list: D015707:HN Protein; D008081:Liposomes; D014760:Viral Fusion Proteins