title: Capsid display of a conserved human papillomavirus L2 peptide in the adenovirus 5 hexon protein: a candidate prophylactic hpv vaccine approach.
abstract: BACKGROUND
  Infection by any one of 15 high risk human papillomavirus (hrHPV) types causes most invasive cervical cancers. Their oncogenic genome is encapsidated by L1 (major) and L2 (minor) coat proteins. Current HPV prophylactic vaccines are composed of L1 virus-like particles (VLP) that elicit type restricted immunity. An N-terminal region of L2 protein identified by neutralizing monoclonal antibodies comprises a protective epitope conserved among HPV types, but it is weakly immunogenic compared to L1 VLP. The major antigenic capsid protein of adenovirus type 5 (Ad5) is hexon which contains 9 hypervariable regions (HVRs) that form the immunodominant neutralizing epitopes. Insertion of weakly antigenic foreign B cell epitopes into these HVRs has shown promise in eliciting robust neutralizing antibody responses. Thus here we sought to generate a broadly protective prophylactic HPV vaccine candidate by inserting a conserved protective L2 epitope into the Ad5 hexon protein for VLP-like display.
  
  
  METHODS
  Four recombinant adenoviruses were generated without significant compromise of viral replication by introduction of HPV16 amino acids L2 12-41 into Ad5 hexon, either by insertion into, or substitution of, either hexon HVR1 or HVR5.
  
  
  RESULTS
  Vaccination of mice three times with each of these L2-recombinant adenoviruses induced similarly robust adenovirus-specific serum antibody but weak titers against L2. These L2-specific responses were enhanced by vaccination in the presence of alum and monophoryl lipid A adjuvant. Sera obtained after the third immunization exhibited low neutralizing antibody titers against HPV16 and HPV73. L2-recombinant adenovirus vaccination without adjuvant provided partial protection of mice against HPV16 challenge to either the vagina or skin. In contrast, vaccination with each L2-recombinant adenovirus formulated in adjuvant provided robust protection against vaginal challenge with HPV16, but not against HPV56.
  
  
  CONCLUSIONS
  We conclude that introduction of HPV16 L2 12-41 epitope into Ad5 hexon HVR1 or HVR5 is a feasible method of generating a protective HPV vaccine, but further optimization is required to strengthen the L2-specific response and broaden protection to the more diverse hrHPV.
authors.affiliation: Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA. waihongwu@hotmail.com.
authors.forename: Wai-Hong
authors.initials: WH
authors.lastname: Wu
authors.affiliation: W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA. tanwee.alkutkar@gmail.com.
authors.forename: Tanwee
authors.initials: T
authors.lastname: Alkutkar
authors.affiliation: Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA. balukaranam@gmail.com.
authors.forename: Balasubramanyan
authors.initials: B
authors.lastname: Karanam
authors.affiliation: Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA. roden@jhmi.edu.|Department of Gynecology and Obstetrics, Johns Hopkins University School of Medicine, Baltimore, MD, USA. roden@jhmi.edu.|Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD, USA. roden@jhmi.edu.
authors.forename: Richard B S
authors.initials: RB
authors.lastname: Roden
authors.affiliation: W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA. gketner@jhsph.edu.
authors.forename: Gary
authors.initials: G
authors.lastname: Ketner
authors.affiliation: Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA. oaibeanu@aol.com.|W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA. oaibeanu@aol.com.|Division of Gynecologic Oncology, Sinai Hospital of Baltimore, Baltimore, MD, USA. oaibeanu@aol.com.
authors.forename: Okechukwu A
authors.initials: OA
authors.lastname: Ibeanu
mesh_terms: D000260:Adenoviruses, Human / Q000235:genetics*; D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D036022:Capsid Proteins / Q000235:genetics* / Q000276:immunology*; D061505:Cell Surface Display Techniques; D004337:Drug Carriers; D005260:Female; D008807:Mice, Inbred BALB C; D009856:Oncogene Proteins, Viral / Q000235:genetics / Q000276:immunology*; D053918:Papillomavirus Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D016896:Treatment Outcome; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology
chemical_list: D000276:Adjuvants, Immunologic; D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D036022:Capsid Proteins; D004337:Drug Carriers; C063316:L2 protein, Human papillomavirus type 16; D009856:Oncogene Proteins, Viral; D053918:Papillomavirus Vaccines; D014614:Vaccines, Synthetic; C018315:hexon capsid protein, Adenovirus