Gene and protein delivery using four cell penetrating peptides for HIV-1 vaccine development

Cell penetrating peptides (CPPs) can potently transport therapeutic molecules to target cells for treatment of a variety of diseases. Thus, their use is critical to improve therapeutic vaccines. Histidine-rich nona-arginine (HR9) and primary amphipathic peptide (MPG) showed the ability to transfer DNA into the cells. Moreover, the peptide derived from the C-terminal of the tumor suppressor protein p14ARF (M918) and arginine-rich peptide (penetratin) were utilized to deliver polypeptides and proteins into the living cells. In this study, the immunostimulatory properties of HIV-1 Nef DNA and protein constructs were evaluated using small heat shock protein 20 (sHsp20) and Freund's emulsion as an adjuvant, and four CPPs (HR9, MPG, M918, and penetratin) as a gene or protein carrier in BALB/c mice. Our data indicated that the HR9/DNA, MPG/DNA, M918/protein, and penetratin/protein complexes formed the stable nanoparticles that were effectively delivered in HEK-293T cell line at certain ratios. Moreover, a heterologous Hsp20-Nef DNA + MPG prime/rHsp20-Nef protein+M918 boost regimen significantly elicited higher levels of IgG2a, IgG2b, IFN-gamma, and Granzyme B directed toward Th1 responses in a long period (3 months) after the last immunization compared to other groups. Furthermore, the effective role of Hsp20 was detected as a natural adjuvant in enhancing immune responses against HIV-1 Nef antigen. These findings demonstrated that the simultaneous use of M918 and MPG CPPs as protein and gene carriers improves HIV-1 Nef-specific B- and T-cell immune responses as a promising approach for development of HIV-1 monovalent vaccine.