Immunogenicity comparison of a multi-antigenic peptide bearing V3 sequences of the human immunodeficiency virus type 1 with TAB9 protein in mice

Abstract

The multiple antigenic peptide system (MAP) has been proposed as a novel and valuable approach for eliciting antibodies for peptides and developing synthetic vaccines. Multi-epitope polypeptides (MEP) have also been developed as an alternative to the recombinant approach for vaccines. The V3 loop from the HIV type 1 (HIV-1) external glycoprotein (gp120) contains the principal neutralization domain (PND). Antibodies against this region neutralize HIV-1 in vitro and in vivo. In this work, a novel presentation of di-epitope MAP was synthesized. A monomeric MAP carrying two identical JY1 V3 sequences as B-cell epitopes and the 830-843 region of tetanus toxoid as a T-helper cell epitope was synthesized. This basic structure was covalently linked to produce a four-JY1-branched homodimer (JY1-MAP4). Additionally, six different monomeric MAPs, bearing four copies of V3 from isolates LR150, JY1, RF, MN, BRVA and IIIB, were synthesized. These monomers were conveniently linked among themselves to produce homodimeric and heterodimeric MAPs of eight V3 branches (V3-MAP8). JY1-MAP8 elicited higher antibody titers in Balb/c mice than JY1-MAP4. The immunogenicity of two different, hexavalent V3-MAP8 mixtures and the MEP TAB9, which tandems the same six V3 sequences in a single molecule, were compared. The antibody response against the mixtures of the heterodimeric MAP showed a wider recognition pattern of the V3 region, while the homodimeric cocktail showed an intermediate pattern. Antibodies elicited by TAB9 recognized only the JY1, LR150 peptides. These results emphasize the influence of V3 epitope presentation upon the characteristics of the antibody response generated.

Enhanced immunogenicity and cross-reactivity of HIV-1 V3-peptide and multiple antigen peptides conjugated to distinct carrier proteins

“…We have previously shown that V3 cocktails with MAPs are a good strategy to present epitopes to the immune system [25]. In the context of this study we have demonstrated other possibilities.…”

“…The JY1-peptide and MAP were synthesized following procedures described elsewhere [25]. The B-cell epitope comprised the central 15 aa from V3 regions of gp120 of HIV-1 isolates: JY1, subtype D (RQSTPIGLGQALYTT).…”

“…Several recombinant multi-epitope HIV-1 peptide constructs have been described [24]. TAB9, which includes six V3 loop peptides (isolates LR150, JY1, RF, MN, IIIB and BRVA), was used in a phase I clinical study [25]. This recombinant protein was immunogenic and induced high levels of antibody neutralization, but the immune response was directed mainly at JY1 and LR150, and only weakly at MN, thereby indicating the need for considerable improvement [26].…”

Different Immune Response of Mice Immunized with Conjugates Containing Multiple Copies of Either Consensus or Mixotope Versions of the V3 Loop Peptide from Human Immunodeficiency Virus Type 1

“…Most of these strategies have relied on the use of combinations of several representa- tive peptide variants. We had earlier shown that V3 loopbased peptide cocktails, in the form of MAP dendrimers, were a good strategy of epitope presentation (9).…”

“…For instance, TAB9, which includes six V3 loop peptides (isolates LR150, JY1, RF, MN, IIIB, and BRVA), was used in a phase I clinical study (8). The recombinant protein was immunogenic and induced high levels of antibody neutralization, but the immune response was mainly directed at JY1 and LR150 and only weakly at MN, suggesting the need for considerable improvement (9). The problem with chimeric polypeptides of this type is that they adopt unpredictable 3D structures that favor the exposure of some epitopes, at the expense of others that in practice remain silent.…”