title: Antigenic presentation of heterologous epitopes engineered into the outer surface-exposed helix 4 loop region of human papillomavirus L1 capsomeres.
abstract: BACKGROUND
  Human papillomavirus (HPV) L1 capsid proteins can self-assemble into pentamers (capsomeres) that are immunogenic and can elicit neutralizing antibodies. Structural modelling of L1 inter-pentameric interactions predicts that helix 4 (h4) of each of the five L1 monomers project laterally and outwards from the pentamer. We sought to utilize HPV L1 capsomeres as a vaccine platform by engineering heterologous epitopes within L1 derivatives deleted for h4 domain.
  
  
  RESULTS
  We used baculovirus - infected Trichoplusia ni cells and ultracentrifugation to synthesize and purify three 16L1 derivatives: one bearing a short deletion (amino acids 404-436) encompassing the h4 domain, and two others, each bearing a conserved neutralizing epitope of the human respiratory syncytial virus (RSV) fusion (F) protein (residues 255-278 and 423-436) that was substituted for the deleted L1 h4 domain residues. Each of the three capsomere derivatives was recognized by anti-L1 antibodies, while two bearing the RSV F-derived moieties were recognized by anti-RSV F antibodies. All three L1 derivatives formed ring-like structures that were similar in morphology and size to those described for native 16L1 capsomeres. When injected into mice, each of the capsomere derivatives was immunogenic with respect to L1 protein, and immunization with chimeric L1-RSV F pentamers resulted in RSV non-neutralizing antisera that recognized purified RSV F protein in immunoblots.
  
  
  CONCLUSIONS
  HPV L1 monomers bearing heterologous epitopes within the L1 h4 region can self-assemble into capsomeres that elicit antibody response against such non-HPV encoded epitopes. Thus, the L1 h4 region can function as a novel antigen display site within the L1 pentamer, which in turn may serve as a potential vaccine template.
authors.affiliation: Division of Infectious Diseases, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA. Yoshihiko_Murata@urmc.rochester.edu
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Murata
authors.forename: Paula M
authors.initials: PM
authors.lastname: Lightfoote
authors.forename: Robert C
authors.initials: RC
authors.lastname: Rose
authors.forename: Edward E
authors.initials: EE
authors.lastname: Walsh
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D036022:Capsid Proteins / Q000235:genetics* / Q000276:immunology; D000939:Epitopes / Q000235:genetics / Q000276:immunology*; D005260:Female; D051379:Mice; D008807:Mice, Inbred BALB C; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D009856:Oncogene Proteins, Viral / Q000235:genetics* / Q000276:immunology; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology; D018113:Respiratory Syncytial Virus, Human / Q000235:genetics / Q000276:immunology*; D022721:Vaccines, Virosome / Q000235:genetics / Q000276:immunology; D014760:Viral Fusion Proteins / Q000235:genetics / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D036022:Capsid Proteins; D000939:Epitopes; C526850:F protein, human respiratory syncytial virus; C114580:HPV L1 protein, Human papillomavirus; D009856:Oncogene Proteins, Viral; D011993:Recombinant Fusion Proteins; D022721:Vaccines, Virosome; D014760:Viral Fusion Proteins