Comparative analysis of two HIV-1 multiepitope polypeptides for stimulation of immune responses in BALB/c mice.

A licensed vaccine against human immunodeficiency virus-1 (HIV-1) infection has not become available up to now. Hence, it is more rational to use immune-informatics tools for prediction of T cell epitopes (in silico study) and development of an effective epitope-driven vaccine against hypervariable pathogens. Multiepitope vaccines were considered as the next generation of an effective vaccine against HIV-1 infection. In the current study, we developed two different constructs encoding T cell epitopes derived from Nef, Vif, Vpu, Gp160 and P24 proteins in BALB/c mice. To overcome their poor immunogenicity, four different cell penetrating peptides (MPG and HR9 for DNA delivery, and CyLoP-1 and LDP-NLS for protein delivery), Montanide adjuvant, and heterologous prime-boost immunization strategy were utilized. The generation of cytokines, Granzyme B, and total IgG and its subclasses was determined using ELISA. Our data indicated that the levels of IFN-γ and Granzyme B in mice injected with Nef-Vif-Gp160-P24 multiepitope constructs were higher than those immunized with Nef-Vpu-Gp160-P24 multiepitope constructs. Moreover, the heterologous DNA priming/ multiepitope peptide boosting in both Nef-Vif-Gp160-P24 and Nef-Vpu-Gp160-P24 regimens induced significantly high antigen-specific IgG2a and IgG2b responses in comparison with other groups. There was no significant difference between MPG and HR9 as well as CyLoP-1 and LDP-NLS as a delivery system for enhancement of immune responses. Generally, the heterologous DNA prime/ multiepitope peptide boost modalities for both constructs could significantly enhance the levels of IgG2a, IgG2b, IFN-γ, and Granzyme B directed toward Th1 immune responses as compared to homologous prime/ boost with DNA or polypeptide constructs.