Antibodies from women immunized with Gardasil cross-neutralize HPV 45 pseudovirions

Human papillomavirus (HPV) types 6, 11, 16 and 18 L1 virus-like particles (VLPs) have been used to generate the prophylactic quadrivalent vaccine, Gardasil. There is a high degree of L1 homology between HPV types and it is likely that there is a substantial degree of surface exposed viral epitope similarity. An investigation of vaccine-induced antibody binding and neutralization was undertaken focusing on A7 species members, HPV 18 and 45. Polyclonal sera from Gardasil recipients and from HPV 18 L1 VLP recipients were evaluated. Vaccine-induced antibodies were found to cross-neutralize HPV 45 pseudovirions (PsV) in vitro. Examination of a panel of monoclonal antibodies made against L1 VLPs revealed the presence of conformational, neutralizing epitopes on the surface of VLPs that may be shared between HPV 18 and HPV 45. These data demonstrate that Gardasil(r) immunization induces antibodies capable of neutralizing HPV 18 PsV and HPV 45 PsV in vitro.