Three candidate peptide-vaccines in combination to induce high levels of multiantibodies against HIV-1

N and C domains of human immunodeficiency virus type 1 (HIV 1) gp41 are demonstrated to play an important role in HIV entry and prevention. In addition, the V3 loop on gp120 was identified as the principal neutralizing determinant (PND). Based on the fact that a combination of several monoclonal antibodies to different neutralizing epitopes showed great protection against intravenous challenge and vaginal transmission of pathogenic HIV 1/Simian immunodeficiency virus (SIV) chimeric virus on macaques, three candidate peptide vaccines were prepared and used in combination to induce high levels of multiantibodies against HIV 1. The three peptides contained important functional regions on HIV 1 gp160. The N domain peptide (P1: aa550 579) and C domain peptide (P2: aa633 662) of gp41 and V3 peptide (P3: aa301 328) of gp120 were conjugated with bovine serum albumin (BSA) using the glutaraldehyde method. After the vaccination course, each of the three candidate peptide vaccines induced strong antibody response in rabbits. The three vaccines used in combination induced high levels of multiantibodies against the peptides of the N and C domains and the V3 loop, with the titer of antibodies up to 1∶64001∶25600 in rabbit sera in comparison with the titer of 1∶8001∶3200 induced by rgp41 or rgp160. Our results indicate that immunogenicities of the N and C domains and the V3 loop in these three candidate peptide vaccines were clearly stronger than those induced by rgp41 or rgp160, and these peptide vaccines used in combination synchronously induced high levels of multiantibodies against HIV 1, suggesting that used in combination they may provide a new vaccine strategy to induce strong multi antiviral activity. 