Three candidate epitope-vaccines in combination inducing high levels of multiantibodies against HIV-1

HIV-1 mutation results in immune evasion, which presents a serious challenge for conventional strategies for developing effective vaccines. So far, much experimental evidence indicates that HIV-1 particles in the blood of patients can be cleaned principally by neutralizing antibodies. Based on these facts, we prepared triple combination of epitope-vaccines with the objective of inducing antibodies with predefined multi-epitope-specificity against against HIV-1. According to the sequences of three neutralizing epitopes (RILAVERYLKD, ELDKWA and GPGPAFY, designated E1, E2, and E3, respectively) on HIV-1 envelope proteins, three epitope-peptides ((E1)2: C-(RILAVERYLKDG)
2
; (E2)4: C-(ELDKWAG)
4
; and (E3)2: C-(GPGPAFY)
2
) were synthesized and then conjugated with carrier protein keyhole limpet hemocyanin (KLH) or bovine serum albumin (BSA), and used for immunizing rabbi ts. After the vaccine course, the triple combination of epitope-vaccines induced high levels of predefined multi-epitope-specific antibodies. An immunoblotting-analysis derronstrated that the antibodies could recognize the native epitopes on both gp 41 protein and V3 loop peptide. Furthermore, we compared the immune responses of three doses of epitope-peptides in the candidate epitope-vaccine. Strong antibody responses to three epitopes were observed in a dose dependent manner, with increasing dose raising the immune response. This result indicated that immunotd erance did not occur using an epitope vaccine dose of 80 μg. Thus, our results demonstrate that epitope-vaccines in combination can synchronously induce high levels of antibodies with predefined multi-epitope-specificity against HIV-1, and may be used to develop effective vaccines against HIV as a new strategy.