Identification of T epitopes within a potential Plasmodium falciparum vaccine antigen. A study of human lymphocyte responses to repeat and nonrepeat regions of Pf155/RESA.
PBMC from Melanesians who had high antibody reactivities to fusion proteins encompassing the 3' and the 5' repeat regions of the ring infected E surface antigen (Pf155/RESA), were tested for their ability to respond to synthetic and recombinant peptides representing regions of Pf155/RESA. The aim was to identify T cell epitopes within the Ag. Most of the synthetic peptides from the nonrepeat regions of Pf155/RESA were selected for study on the basis of their tendency to form amphipathic alpha-helices. Peptides representing immunodominant B cell epitopes were also tested. Three-quarters of the Melanesian donors responded to the recombinant peptides (Ag 1505 and Ag 632-100) and to the 8 x 4 mer, a synthetic peptide representative of the 3' repeat region. Whereas all the remaining eight peptides tested elicited a response in at least one donor, three peptides (M40, M42, and BTA3) representing sequences in the nonrepeat regions showed greatest promise as potentially useful T epitopes. Responses in control donors were also observed to most of the peptides but the percentage of responders was lower. T cell bulk lines specific to Ag 1505 and Ag 632-100 were established. All donors were HLA tissue typed, but no obvious correlations between responsiveness and HLA type were observed. Our results suggest that there are T cell epitopes within and outside the repeat regions of Pf155/RESA.
Rzepczyk
C M
CM
Queensland Institute of Medical Research, Brisbane, Australia.
Ramasamy
R
R
Ho
P C
PC
Mutch
D A
DA
Anderson
K L
KL
Duggleby
R G
RG
Doran
T J
TJ
Murray
B J
BJ
Irving
D O
DO
Woodrow
G C
GC
Parkinson
D
D
Brabin
B J
BJ
Alpers
M P
MP
D000328:Adult; D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan / Q000032:analysis* / Q000276:immunology; D000954:Antigens, Surface / Q000276:immunology*; D000939:Epitopes / Q000032:analysis* / Q000276:immunology; D006680:HLA Antigens / Q000235:genetics; D006650:Histocompatibility Testing; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects; D008542:Melanesia; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000276:immunology*; D015800:Protozoan Proteins; D012091:Repetitive Sequences, Nucleic Acid; D013601:T-Lymphocytes / Q000276:immunology*; D014612:Vaccines / Q000032:analysis*; D014614:Vaccines, Synthetic / Q000032:analysis* / Q000276:immunology
D000953:Antigens, Protozoan; D000954:Antigens, Surface; D000939:Epitopes; D006680:HLA Antigens; D015800:Protozoan Proteins; D014612:Vaccines; D014614:Vaccines, Synthetic; C050256:ring-infected erythrocyte surface antigen (RESA), Plasmodium falciparum