Human Papillomavirus (HPV) Vaccines: Limited Cross‐Protection against Additional HPV Types

Abstract

Approximately 15 different human papillomavirus (HPV) types from 5 species (A5, A6, A7, A9, and A11) may cause cervical cancer. They are grouped according to phylogenetic relatedness, which also correlates with carcinogenicity [1]. The majority of HPV types associated with human cancers are from species A7 (HPV-18, -39, -45, -59, and -68) and A9 (HPV-16, -31, -33, -35, -52, and -58). Given their similarity, phylogenetically related HPV types share capsid epitopes that can elicit a cross-reactive immune response, and, although serological cross-reactivity has been demonstrated in epidemiological studies of naturally infected women with and without cervical cancer [2, 3], vaccine-elicited neutralizing antibodies were expected to be largely type specific The recent development of and demonstration of efficacy for HPV-6, -11, -16, and -18 L1 virus-like particle vaccines against cervical and other lesions associated with vaccine types has generated enormous enthusiasm as a promising method for partial control of cervical and possibly other cancers. The possibility of cross-protection against other HPV types is an extremely important question, because it could increase the fraction of cervical cancers prevented A recent study showed that the bivalent vaccine against HPV-16 and -18 produced with ASO4 adjuvant (Cervarix) affords partial cross-protection against 6-month persistent infection with HPV-31, -45, and -52 [4], but no data on efficacy against lesions (cervical intraepithelia…