Surface conformational and linear epitopes on HPV-16 and HPV-18 L1 virus-like particles as defined by monoclonal antibodies

A panel of 24 monoclonal antibodies (MAbs) was generated against human papillomavirus (HPV) types 16 and 18 L1 virus-like particles (VLPs). The MAbs were screened for reactivity to a variety of VLPs prepared from HPV-6, -11, -16, -18, -31, -33, -35, and -45, cottontail rabbit papillomavirus, bovine papillomavirus type 1, and a set of 35 overlapping 20-amino-acid peptides spanning the entire HPV-16 L1 gene. Type-specific linear and conformational surface epitopes were detected as well as several cross-reactive linear epitopes that showed various levels of cross-reactivity between different genital HPV and animal papillomavirus L1s. Most of the linear epitopes were mapped using synthetic peptides, and the epitopes were identified as being either surface or buried within the VLP as defined by the pattern of reactivity in ELISA using intact and disrupted VLP antigen. These MAbs may be useful reagents to help define neutralizing epitopes of HPV-16 and -18 when infectivity assays become available, and to define the regions of L1 that are exposed on the surface or buried within the assembled capsid.