A novel Plasmodium falciparum sporozoite and liver stage antigen (SALSA) defines major B, T helper, and CTL epitopes
Bottius, E.; BenMohamed, L.; Brahimi, K.; Gras, H.; Lepers, J.P.; Raharimalala, L.; Aikawa, M.; Meis, J.; Slierendregt, B.; Tartar, A.; Thomas, A.; Druilhe, P.
Journal of Immunology 156(8): 2874-2884
1996
ISSN/ISBN: 0022-1767 PMID: 8609407 Document Number: 456567
A novel Plasmodium falciparum gene encoding a 70 000 MW protein, expressed in both sporozoite and liver stages (SALSA), with a vaccine potential that stems from its antigenic features is identified and partially characterized. Antigenicity and immunogenicity studies were conducted in individuals exposed to malaria, in immunized mice, and in chimpanzees, using a recombinant protein and 2 synthetic peptides. Results show that the SALSA nonrepetitive sequence defines (1) major B cell epitopes, as shown by a high prevalence of antibodies to each peptide in 3 African areas differing in their level of endemicity; (2) Th epitopes, as demonstrated by lymphoproliferation and IFN- gamma secretion in cells from the individuals from one of the low transmission areas, as well as helper effect upon antibody secretion in mice; and (3) epitopes for cytolytic lymphocytes, demonstrated in immunized and sporozoite-challenged chimpanzees, and associated with MHC class I leukocyte antigens. The latter are of particular importance, because this is the only part of the malaria life cycle in which the parasite is located in a cell expressing class I antigens and because CD8+ lymphocytes were found to be responsible for protection in experimental models.