Mapping epitopes of human papillomavirus type16 L1 protein with a phage display epitope library

The objective of this study is to map epitopes on HPV16 L1 protein and provide information to the design of HPV16 prophylactic peptide vaccine. The epitopes on L1 protein were screened by polyclonal and two monoclonal antibodies (B8 and F4G3) against HPV16 L1 protein from a 6-mer fd phage display epitope library with the method of immuno-affinity screening (Bio- panning). After three rounds of Bio-panning, the positive phages were detected by L1 antibodies again with ELISA. The positive phages reacted strongly with L1 antibodies were then identified by DNA sequencing. Three mimotopes have been screened by polyclonal and two monoclonal antibodies. The mimotope (LSLFSC) reacted with monoclonal antibody B8 showed 50% homology with the sequence 270 ~ 275a.a (DSLFFY) of prototype HPV16 L1. Another mimotope (LTSSYS) reacted with polyclonal antibodies had 66% homology with the L1 sequence 516 ~ 521a. A(TTSSTS), also a mimotope (DRW-DRF) was found had the homologic RF with the known L1 sequence 441 ~ 446a. a. The mimotopes LSLFSC and DRWDRF were adjacent to the epitopes at 267 ~ 269a. a and 422 ~ 441 a. a reported by other researchers previously. Our results suggest that there might be a batch of epitopes on HPV16 L1 protein, and the predominant epitopes of HPV16 L1 protein are located in the above two domains. These results will be helpful for design of HPV16 prophylactic peptide vaccines and HPV polyvalent vaccines.