Naturally-occurring capsid protein variants of human papillomavirus genotype 31 represent a single L1 serotype

We investigated naturally-occurring variation within the major (L1) and minor (L2) capsid proteins of oncogenic human papillomavirus (HPV) genotype HPV31 to determine the impact on capsid antigenicity. L1L2 pseudoviruses (PsV) representing the three HPV31 variant lineages A, B and C exhibited comparable particle to infectivity ratios and morphology. Lineage-specific L1L2 PsV demonstrated subtle differences in susceptibility to neutralization by antibodies elicited following vaccination, pre-clinical L1 VLP immunization or by monoclonal antibodies; however, these differences were generally of a low magnitude. These data indicate diagnostic lineage-specific single nucleotide polymorphisms within the HPV31 capsid genes have a limited effect on L1 antibody mediated neutralization and that the three HPV31 variant lineages belong to a single L1 serotype. These data contribute to our understanding of HPV L1 variant antigenicity. IMPORTANCE: The virus coat (capsid) of the human papillomavirus contains major (L1) and minor (L2) capsid proteins. These proteins facilitate host cell attachment and viral infectivity and are the targets for antibodies which interfere with these events. In this study we investigated the impact of naturally-occurring variation within these proteins upon susceptibility to viral neutralization by antibodies induced by L1 VLP immunization. We demonstrate that HPV31 L1 and L2 variants exhibit similar susceptibility to antibody-mediated neutralization and that for the purposes of L1 VLP-based vaccines these variant lineages represent a single serotype