The h4 coil surface region of human papillomavirus type 58 L1 virus-like particle serves as a potential location for presenting the RG1 epitope peptide.

The licensed prophylactic human papillomavirus (HPV) vaccines, based on L1 virus-like particles (VLPs), effectively prevent infection and HPV-associated cancers caused by the vaccine types but offer limited protection against non-vaccine types. L2 N-terminal peptides, such as the RG1 epitope peptide, contain conserved cross-neutralizing epitopes, and their immunogenicity could be enhanced via display on the surface of L1VLPs. To our knowledge, there have been no reports on the construction and immunogenicity research of chimeric L1-L2 proteins based on HPV58 L1VLP, the third most prevalent high-risk type in Asia. Here, we inserted the RG1 epitope peptides at two sites of the highly expressed HPV58 L1 - the h4 coil region or the DE loop (with linkers) - to construct seven chimeras. These chimeras were expressed in insect cells, self-assembled into chimeric VLPs (cVLPs), and their immunogenicity was assessed in a mouse model. Notably, three cVLPs with h4 coil insertions elicited comparable levels of L1-specific antibody response in mice to the L1VLP control and induced cross-neutralizing antibody responses against fourteen pseudoviruses. Conversely, four cVLPs with DE loop insertions induced significantly lower L1-specific antibody titers compared with the L1VLP control ( < .001). This might be attributed to the disruption or obstruction of neutralizing epitope(s) targeted by HPV58-specific conformation-dependent monoclonal antibodies, caused by the sequence insertions. Our findings suggest that the h4 coil region of HPV58 L1VLP might be a potential location for RG1 epitope display, guiding the presentation of heterologous epitopes to develop chimeric HPV58 L1VLP-based vaccines.