Development of a Multiplexed HPV L1 Virus‐Like Particle Type‐Specific Immunoglobulin Subclass and Isotyping Assay

Abstract

GARDASIL™ has been proven in clinical trials as a highly effective vaccine for preventing HPV 6‐, 11‐, 16‐, or 18‐related pre‐cancerous lesions and genital warts. In this study, we compared the HPV‐type specific subclass and isotype humoral immune responses following vaccination to those induced by HPV infection. Sera collected from vaccinees at month 7 and month 60 post‐vaccination, naturally infected and negative subjects were tested to determine serum levels of HPV VLP‐specific IgG, IgG1, IgG3, IgG4 and IgA using a Luminex based, direct binding, subclass and isotyping assay method. The same serum samples were also evaluated for their levels of antibodies to type‐specific, neutralizing epitopes on the VLPs using a competitive immunoassay designed to measure type‐specific, neutralizing antibodies. Vaccination with GARDASIL™ induced high serum levels of VLP‐specific IgG, IgG1, IgG3, IgG4 and IgA antibodies, and such antibodies to VLP 6, 11, 16 and 18 were also detected at Mo 60 in a high proportion of subjects. These levels were comparable to or greater than antibody levels associated with subjects naturally infected with HPV. Importantly, serum anti‐L1, HPV IgA levels induced by vaccination may provide evidence of mucosal immunity that could protect the anogenital tract from HPV infection.