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Infect Immun, August 1998, p. 3579-3590, Vol. 66, No. 8
Department of Molecular Microbiology and
Immunology,
Received 17 December 1997/Returned for modification 6 March
1998/Accepted 6 May 1998
We have characterized HLA-DR-restricted T-cell epitopes on the
27-kDa protein (Pfg27), a sexual stage-specific antigen, of the
human malaria parasite Plasmodium falciparum in subjects
with a history of malaria. Pfg27, expressed early in the sexual stages, is recognized by monoclonal antibodies capable of reducing the infectivity of gametocytes in mosquitoes. By using 16 Pfg27-specific CD4+-T-cell clones derived from three donors, seven
different T-cell epitopes were identified. Among them, P11 (amino acids
191 to 210 of the Pfg27 sequence, IDVVDSYIIKPIPALPVTPD) was found to contain a previously described binding motif for multiple HLA-DR allotypes. Indeed, P11 was found to be promiscuous in that it could be
recognized by T cells in the context of at least five different HLA-DR
molecules. The cytokine profile of the clones was mixed. Seven of nine
T-cell clones exhibited a Th0-like cytokine profile, producing high
levels of gamma interferon (IFN-
0019-9567/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Mapping of Specific and Promiscuous HLA-DR-Restricted T-Cell
Epitopes on the Plasmodium falciparum 27-Kilodalton
Sexual Stage-Specific Antigen

) and interleukin-4 (IL-4) upon
stimulation with specific peptides and mitogens. The other two clones
had a Th1-like cytokine profile with high expression of IFN-
and no
IL-4. Identification of a promiscuous epitope in Pfg27 could play a
significant role in the design of a subunit vaccine for suppressing
malaria transmission.
*
Corresponding author. Mailing address: Department of
Molecular Microbiology and Immunology, The Johns Hopkins University
School of Hygiene and Public Health, 615 N. Wolfe St., Baltimore MD
21205. Phone: (410) 955-7177. Fax: (410) 955-0105. E-mail:
nkumar{at}jhsph.edu.
Present address: Medicina Inst. de Immunologia, University of
Venezuela, Caracas, Venezuela.
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