Preclinical refinements of a broadly protective VLP-based HPV vaccine targeting the minor capsid protein, L2. Issue 29 (26th June 2015)

• Record Type: Journal Article
• Authors: Tumban, Ebenezer; Muttil, Pavan; Escobar, Carolina Andrea A.; Peabody, Julianne; Wafula, Denis; Peabody, David S.; Chackerian, Bryce
• Is Part Of: Vaccine. Volume 33:Issue 29(2015)
• Page Start: 3346
• Page End: 3353
• Publication Date: 2015-06-26
• Subjects: MS2 and PP7 bacteriophages -- Virus-like particles -- HPV vaccine -- Adjuvants -- Formulation; Vaccines -- Periodicals; 615.372
• DOI: 10.1016/j.vaccine.2015.05.016
• Languages: English
• ISSNs: 0264-410X

Abstract

Highlights: Virus-like particles displaying an HPV16 L2 peptide (16L2-MS2 VLPs) are highly immunogenic over a range of doses. Immune responses to 16L2-MS2 VLPs last over 18 months. Spray-drying L2 VLPs enhances their stability. Spray dried L2 VLPs stored over 7 months at room temperature are highly immunogenic and protective against HPV infections. Abstract: An ideal prophylactic human papillomavirus (HPV) vaccine would provide broadly protective and long-lasting immune responses against all high-risk HPV types, would be effective after a single dose, and would be formulated in such a manner to allow for long-term storage without the necessity for refrigeration. We have developed candidate HPV vaccines consisting of bacteriophage virus-like particles (VLPs) that display a broadly neutralizing epitope derived from the HPV16 minor capsid protein, L2. Immunization with 16L2 VLPs elicited high titer and broadly cross-reactive and cross-neutralizing antibodies against diverse HPV types. In this study we introduce two refinements for our candidate vaccines, with an eye towards enhancing efficacy and clinical applicability in the developing world. First, we assessed the role of antigen dose and boosting on immunogenicity. Mice immunized with 16L2-MS2 VLPs at doses ranging from 2 to 25 μg with or without alum were highly immunogenic at all doses; alum appeared to have an adjuvant effect at the lowest dose. Although boosting enhanced antibody titers, even a single immunization could elicit strong and long-lasting antibody responses. We also developed a method to enhance vaccine stability. Using a spray dry apparatus and a combination of sugars & an amino acid as protein stabilizers, we generated dry powder vaccine formulations of our L2 VLPs. Spray drying of our L2 VLPs did not affect the integrity or immunogenicity of VLPs upon reconstitution. Spray dried VLPs were stable at room temperature and at 37 °C for over one month and the VLPs were highly immunogenic. Taken together, these enhancements are designed to facilitate implementation of a next-generation VLP-based HPV vaccine which addresses U.S. and global disparities in vaccine affordability and access in rural/remote populations.