A Simple Screening Method for Detecting Bindings between Oligopeptides and HLA‐DR Molecules on Filter Papers: Possible Application for Mapping of Putative Helper T‐Cell Epitopes on MSP1 of Plasmodium falciparum

Abstract

Binding capacities of synthetic peptides to HLA‐DR molecules were tested on filter papers to identify putative helper T‐cell epitopes on a malarial protein. The antigen tested was the merozoite surface glycoprotein 1 (MSP1) of Plasmodium falciparum, a vaccine candidate targeting the asexual erythrocytic stage. Bindings between synthetic oligopeptides and HLA‐DR molecules were tested. Such bindings were not non‐specific, and a known helper T‐cell epitope peptide showed positive binding to the restricting HLA‐DR molecule. By using this screening system, we observed the unequal distribution of HLA‐DR‐binding peptides in 10 out of 17 MSP1 blocks tested. Block #6 of MSP1 seemed to show the highest frequency in the positive binding; on the other hand, blocks #1 and #17, both of which were thought to be vaccine candidate regions, contained fewer HLA‐DR binding peptides. This was not inconsistent with the results that block #17 was less stimulatory to peripheral T cells than block #6. The peptides with positive binding to HLA‐DR showed actual epitope activities when we tested peptide‐driven proliferation of human bulk T‐cell lines, and association between the two parameters was statistically significant (P < 0.001). For more detailed information for vaccine development, peptides with both IgG‐ and HLA‐DR binding activities were mapped in block #17 of MSP1. Together with these results, we demonstrate that our simple screening system seems to provide essential information for vaccine development through uncovering locations of putative epitopes for human helper T cells.

Plasmodium vivaxPromiscuous T-Helper Epitopes Defined and Evaluated as Linear Peptide Chimera Immunogens

“…The frequency of responders among exposed individuals ranged from 18 to 48%, in contrast to 3 to 23% for nonexposed volunteers. Differences between groups were statistically significant for peptides 4,6,8,19,25, and 45 (P Ͻ 0.05). Most of the responders showed reactivity to more than one peptide; however, none of the volunteers responded to all of the peptides.…”

“…Eight peptides (no. 4,6,8,19,25,45,47, and 53) bound all four DR molecules. Six of these peptides (no.…”

“…Another recent study using peptide-binding assays on filter papers with soluble DRB1‫1010ء‬ and DRB1‫5040ء‬ biotinylated molecules identified several P. falciparum MSP-1 T-cell epitopes, with a high percentage (8.3 to 25.8%) of promiscuity noted (19). However, this study did not entail a complete survey of peptides representing the entire protein and did not utilize competition peptide-binding assays.…”

Survival of memory T cells specific for Japanese cypress pollen allergen is maintained by cross‐stimulation of putative pectate lyases from other plants

“…We prepared synthetic oligopeptides to determine an epitope recognized by a Cha o 1‐specific T‐cell clone. On the basis of screening data of bindings between oligopeptides and purified HLA‐class II molecules on filter papers, as described by Fu et al (21), we synthesized 16‐mer peptides from candidate regions of Cha o 1 by the F‐moc method. Since Cha o 1 is supposed to be a pectate lyase, its identified epitope sequence was applied to a homology search in a protein database, FASTA (Version 3.0t84).…”