Hepatitis B virus surface antigen as delivery vector can enhance Chlamydia trachomatis MOMP multi-epitope immune response in mice.

Chlamydia trachomatis is the leading cause of sexually transmitted infections worldwide. There is currently no commercially available vaccine against C. trachomatis. Major outer membrane protein (MOMP) of C. trachomatis is considered to be an ideal candidate for prophylactic vaccine. We designed a MOMP multi-epitope containing T- and B-cell epitope-rich peptides and developed hepatitis B surface antigen (HBsAg) as antigen delivery vehicle. In order to study the immunogenicity and efficacy of the candidate vaccine in a murine model of chlamydial genital infection, we engineered a recombinant plasmid expressing HBsAg and MOMP multi-epitope genes. Results of reverse transcription polymerase chain reaction and immunofluorescence assay revealed successful expression of the recombinant HBsAg/MOMP multi-epitope gene at both the transcription and translation levels. Intramuscular administration in mice was able to elicit not only antibodies against Chlamydia and HBsAg but also cytotoxic T lymphocyte activity against Chlamydia. In addition, mice inoculated with the rHBsAg were highly resistant to C. trachomatis genital infection. The rHBsAg DNA with MOMP multi-epitope appended at the C terminus of the HBsAg stimulated a stronger immune response and protective response than that appended at the N terminus. Together, our results suggested that use of a recombinant HBsAg encoding the MOMP multi-epitope could be a powerful approach to developing a safe and immunogenic C. trachomatis vaccine.