A Comparative Study of Different Presentation Strategies for an HIV Peptide Immunogen

Abstract

Different strategies have been used to increase the immunogenicity of an antigenic HIV peptide as a vaccine candidate. The selected B-cell epitope comprises 15 amino acids (317-331) of the V3 region of HIV-1, JY1 isolate (subtype D), in tandem with a T-helper epitope corresponding to the 830-844 region of tetanus toxoid. Several presentations, including oligomerization, multiple antigenic peptide dendrimers, and conjugation to dextran beads or to other macromolecular carriers, have been synthesized and evaluated. Murine sera from the different presentations of the V3 epitope have been compared with regard to antibody titers and cross-reactivity with heterologous HIV subtypes. The dendrimer version of the peptide conjugated to HBsAg protein was a better immunogen than the dendrimer alone and showed a higher immunogenicity than other multimeric presentations or than the peptide alone conjugated to dextran. The dendrimer version, either alone or conjugated to HBSAg, enhanced cross-reactivity toward heterologous V3 sequences relative to monomeric peptide. In addition, fine epitope mapping of the entire JY1 sequence by sera from the different immunization groups was performed by the spot synthesis technique. Results showed that the amino acids involved in molecular recognition were LXQXXY or LXQXLY, with particularly strong recognition of the C-terminal region LGQALY. However, cross-reactivity toward the heterologous sequences did not completely correlate with recognition of particular amino acids in the primary sequences. These results can find application in the development of HIV vaccine candidates.

Human Plasmacytoid Dendritic Cells Phagocytose, Process, and Present Exogenous Particulate Antigen

“…The TT peptide was synthesized manually according to standard protocols of solid-phase peptide synthesis, using the Fmoc/tert-butyl strategy (24). The N-terminus of the TT peptide was modified with FITC through linking via a Lys-Lys cathepsin-like cleavage site as described previously (25).…”

Human plasmacytoid dendritic cells efficiently cross-present exogenous Ags to CD8+ T cells despite lower Ag uptake than myeloid dendritic cell subsets

“…28 DCs were cultured for 0.5, 1, 4, and 18 hours in the presence of 5, 10, or 50M FITC-gp100 272-300 . Uptake of gp100 272-300 was determined by flow cytometry using FACS Calibur.…”

Carrier mediated protein and peptide stabilization

“…The pharmaceutical and biomedical potential of dendrimers includes gene and oligonucleotide delivery (Huddle et al, 1999;Yoo et al, 1999;Yoo & Juliano, 2000a;Zinselmeyer et al, 2002), vehicle for delivery of bioactive (Khopade et al, 2002;Bhadra et al, 2003;, development of vaccine (Cruz et al, 2004), and in the diagnostic field (Wiener et al, 1994). Prolonged residence time of the drug in the blood and protection of the bioactives from its environment with increased stability are other potential advantages of dendrimeric architecture.…”