Correlating immunity with protection for HPV infection.

BACKGROUND: Cervical cancer is one of the most common types of cancer in women and is largely attributable to persistent infection with high-oncogenic risk human papillomavirus (HPV) types. Most HPV infections resolve spontaneously over 5 years, but, in a small fraction of women, persistent infection with high-risk HPV results in cervical intraepithelial neoplasia (CIN) grade 2/3 and eventually cervical cancer. PERSPECTIVES: Prophylactic vaccines based on HPV virus-like particles (VLPs) exploit the propensity of the immune system to protect against HPV infection and resulting diseases, including cancer. The quadrivalent (HPV types 6, 11, 16, 18) vaccine was 100% effective in preventing HPV 16- and 18-related CIN 2/3 in young, HPV-naïve women and possessed similar efficacy against anogenital warts and vaginal and vulvar neoplasias. HPV VLP vaccine-induced protection is mediated by anti-HPV antibodies specific for conformational "neutralizing" determinants on the HPV capsid.
CONCLUSIONS: The quadrivalent vaccine is highly immunogenic in human subjects; induces persistent, high-titer, neutralizing antibodies for at least 5 years; and induces immune memory responses. The quadrivalent HPV vaccine induces the greatest immune response in prepubertal children (9 to 12 years). Long-term follow-up studies are planned through the Nordic cancer registries to assess duration of HPV protection.