title: Murine immune responses to virus-like particle-associated pre- and postfusion forms of the respiratory syncytial virus F protein.
abstract: Virus-like particles (VLPs) built on the Newcastle disease virus (NDV) core proteins, NP and M, and containing two chimeric proteins, F/F and H/G, composed of respiratory syncytial virus (RSV) fusion protein (F) and glycoprotein (G) ectodomains fused to the transmembrane and cytoplasmic domains of the NDV F and HN proteins, respectively, stimulate durable, protective RSV neutralizing antibodies in mice. Here, we report the properties of VLPs constructed to contain mutant RSV F protein ectodomains stabilized in prefusion (pre-F/F) or postfusion (post-F/F) configurations. The structures of the chimeric proteins assembled into VLPs were verified immunologically by their reactivities with a conformationally restricted anti-F protein monoclonal antibody. Following immunization of mice, without adjuvant, pre-F/F-containing VLPs induced significantly higher neutralizing antibody titers than the post-F/F-containing VLPs or the wild-type F/F-containing VLPs after a single immunization but not after prime and boost immunization. The specificities of anti-F IgG induced by the two mutant VLPs were assessed by enzyme-linked immunosorbent assay (ELISA) using soluble forms of the prefusion and postfusion forms of the F protein as targets. While both types of VLPs stimulated similar levels of IgG specific for the soluble postfusion F protein, titers of IgG specific for prefusion F induced by the pre-F/F-containing VLPs were higher than those induced by post-F/F-containing VLPs. Thus, VLPs containing a stabilized prefusion form of the RSV F protein represent a promising RSV vaccine candidate.
  
  
  OBJECTIVE
  The development of vaccines for respiratory syncytial virus has been hampered by a lack of understanding of the requirements for eliciting high titers of neutralizing antibodies. The results of this study suggest that particle-associated RSV F protein containing mutations that stabilize the structure in a prefusion conformation may stimulate higher titers of protective antibodies than particles containing F protein in a wild-type or postfusion conformation. These findings indicate that the prefusion F protein assembled into VLPs has the potential to produce a successful RSV vaccine candidate.
authors.affiliation: Department of Microbiology and Physiological Systems, Program in Immunology and Microbiology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
authors.forename: Lori
authors.initials: L
authors.lastname: McGinnes Cullen
authors.affiliation: Department of Microbiology and Physiological Systems, Program in Immunology and Microbiology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
authors.forename: Madelyn R
authors.initials: MR
authors.lastname: Schmidt
authors.affiliation: Department of Microbiology and Physiological Systems, Program in Immunology and Microbiology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Kenward
authors.affiliation: Department of Microbiology and Physiological Systems, Program in Immunology and Microbiology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
authors.forename: Robert T
authors.initials: RT
authors.lastname: Woodland
authors.affiliation: Department of Microbiology and Physiological Systems, Program in Immunology and Microbiology, University of Massachusetts Medical School, Worcester, Massachusetts, USA trudy.morrison@umassmed.edu.
authors.forename: Trudy G
authors.initials: TG
authors.lastname: Morrison
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005822:Genetic Vectors; D007074:Immunoglobulin G / Q000097:blood; D008807:Mice, Inbred BALB C; D009500:Neutralization Tests; D009522:Newcastle disease virus / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology; D022261:Respiratory Syncytial Virus Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D012136:Respiratory Syncytial Viruses / Q000235:genetics / Q000276:immunology*; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D058425:Vaccines, Virus-Like Particle / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D014760:Viral Fusion Proteins / Q000235:genetics / Q000276:immunology*
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; C526850:F protein, human respiratory syncytial virus; D007074:Immunoglobulin G; D011993:Recombinant Fusion Proteins; D022261:Respiratory Syncytial Virus Vaccines; D014614:Vaccines, Synthetic; D058425:Vaccines, Virus-Like Particle; D014760:Viral Fusion Proteins