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

Abstract

The critical role that antibody responses to the V3 loop epitope play in human immunodeficiency virus type 1 (HIV-1) neutralization has caused this peptide to be used in many HIV-1 vaccine candidates. To enhance cross-reactivity toward several V3 sequences, a database of 50 peptides of the V3 region from HIV-1 subtype A was used to design both a consensus peptide and a combinatorial peptide (mixotope) library representative of these sequences. The two immunogens (consensus and mixotope) were incorporated into multiple antigen peptide (MAP) constructions, conjugated to a recombinant surface antigen from hepatitis B virus (HbsAg) carrier protein, and inoculated to mice in combination with a C4 (CD4-binding) peptide MAP construction, also conjugated to HBsAg. The respective responses and cross-reactivity to several V3 loop sequences of both types of immunogens were compared. Mice inoculated with the V3 consensus-MAP-HBsAg + C4-MAP-HBsAg mixture elicited higher antibody responses than those given the V3 mixotope-MAP-HBsAg + C4-MAP-HBsAg mixture. In addition, pooled serum from the first group of immunogens analyzed at dilution 1:100 had higher cross-reactivity against V3 peptides on cellulose membranes than those from mice given the combinatorial immunogen. Fine epitope mapping of both consensus and C4 peptide by the spot synthesis technique showed that sera of the first group strongly recognized both sequences in their entirety, whereas mice immunized with the mixotope library recognized only the N-terminal region of V3. These results seem to suggest that the V3 consensus peptide is superior to the combinatorial strategy in inducing potent and cross-reactive responses to HIV.

Designing Immunogens to Elicit Broadly Neutralizing Antibodies to the HIV-1 Envelope Glycoprotein

“…Due to the structural insights gained thus far, it appears that immunogen design strategies that target V3 need to take into account V3 structure and not simply focus on sequence. Design strategies include stabilization of V3 peptides on protein scaffolds or chimeras [34,79,109,162,313], conformationally constraining V3 via mutagenesis or chemically [13,14,28,118,122,277,278,336,337], conjugation of V3 peptides to foreign or carrier proteins [59,64,65,154], and identifying V3 variants or consensus sequences representative of potential V3 structures [93,94,138,206,325].…”

Enhancing Immunogenicity and Cross-Reactivity of HIV-1 Antigens by In Vivo Targeting to Dendritic Cells

“…To this end, several presentation strategies were examined, such as polymers [38], MAPs and peptides coupled to dextran microparticles [39]. Combined approaches, such as the coupling of MAPs to carrier proteins [40], were also tested [41].…”

Structures of Glycolipids Found in Trypanosomatids: Contribution to Parasite Functions

“…Impairment of B-cell responses [85,[91][92][93] sialylated, each parasite acquires about 1 10 7 sialic acid residues, resulting in a strong negative charge on the surface. This negatively charged coat is thought to provide protection against complement-independent lysis induced by human anti-galactosyl antibodies [67,68].…”