Induction of high levels of epitope-specific antibodies by epitope/peptide candidate vaccines against human immunodeficiency virus type- 1 (HIV-1)
To test the immunogenicity of GPGRAFY-epitope-based candidate vaccines, a peptide with four repetitive GPGRAFY epitopes, V3-P1 [C-(GPGRAFY)4], and a peptide (PND) of the principal neutralizing domain (V3 loop: amino acid 301- 328: C-TRPNNNTRKSIRIQRGPGRAFYTIGKI) on gp120 were synthesized and covalently coupled to a carrier protein BSA. Immunization of BALB/c mice and New Zealand White Rabbits with these conjugate vaccines engendered strong antibody responses against the PND (mouse serum titer by 1:12,800-25,600; rabbit serum titer by 1:6,400-12,800). Interestingly, the V3-P1-BSA conjugates and the PND-BSA conjugates could induce high levels of GPGRAFY-epitope-specific antibodies in the mice and rabbits (mouse serum titer by 1:25,600; rabbit serum titer by 1:12,800-25,600), while a recombinant gp160 subunit vaccine induced a low level of GPGRAFY-epitope-specific antibodies (serum titer by 1:400-1,600 in mice and rabbits). To confirm the above results, GPGRAFY- epitope-specific antibodies were isolated from rabbit sera induced by V3-P1- BSA, PND-BSA conjugates and rgp160 vaccine. In fact, 23-38 and 13-22 Âµg epitope-specific antibodies per milliliter serum were isolated from rabbit sera induced by V3-P1-BSA and PND-BSA conjugate, respectively, while 1.34 Âµg epitope-specific antibodies per milliliter serum were identified in rabbit serum induced by rgp160 vaccine. In the control group, only 0.069 Âµg proteins per milliliter serum were found in pooled pre-immune serum (normal serum). These results from mouse and rabbit experiments indicate that epitope and peptide vaccines both induce high levels of GPGRAFY-epitope-specific antibodies in comparison with rgp160 subunit vaccine, suggesting that epitope/peptide vaccines may be a new strategy to induce protective activity.
Microbiology and immunology
Yu, Tianwei; Bai, Yun; Dierich, Manfred P.; and Chen, Ying-Hua, "Induction of high levels of epitope-specific antibodies by epitope/peptide candidate vaccines against human immunodeficiency virus type- 1 (HIV-1)" (2000). PCOM Scholarly Papers. 1025.