A recombinant multi-epitope protein MEP1 elicits efficient long-term immune responses against HIV-1 infection.

The effective protective HIV vaccine should elicit either protective antibodies or effective T cell response, or both. To improve the efficacy of HIV-1 vaccines, HLA polymorphism and HIV-1 diversity are 2 key factors to be considered for vaccine development. In this study, we expressed a recombinant multi-epitope protein MEP1 which has the same amino acid sequence as a DNA vaccine for Chinese population in our previous report. We found that MEP1 alone could elicit moderate levels of humoral and cellular immune responses, but these responses could not provide protection from challenge with a recombinant virus rTTV-lucgag, which expresses Gag of HIV-1 CRF_07BC. Nevertheless, when MEP1 was immunized with aluminum adjuvant, both humoral and cellular immune responses were significantly increased, and they were protective against virus infection; meanwhile, MEP1 with aluminum not only elicited early (10 d post immunization) but also a long-term (at least 44 weeks post immunization) immune responses in BALB/c mice. These results suggested that MEP1 has the potential to be developed as an effective vaccine candidate, and that suitable adjuvant is necessary for this protein to generate protective immune responses.