A longitudinal study of antibodies to the Plasmodium falciparum antigen Pf155/RESA and immunity to malaria infection in adult Liberians.
118 adult Liberians from 2 villages were studied prospectively for one year with monthly blood examinations for malaria parasites. The crude parasite rate was 41.5% and the crude gametocyte rate was 6.1%. The inoculation rate varied between 0.075 in the dry season and almost 0.4 in the rainy season, which is in accordance with other data from holoendemic areas. 47.5% (56) had a titre to the Pf155/RESA antigen less than or equal to 1/50 ('low responders') and 52.5% (62) had a titre of greater than or equal to 1/250 ('high responders'). The response was not age-dependent in this adult population, which may suggest that genetic factors are determining whether the individual become a high or low responder. Antibodies against the Pf155/RESA antigen were measured in 2 surveys 8 months apart, and the mean antibody response to Pf155/RESA and its EENV sequence was constant without seasonal variation. Pf155/RESA high responders had lower parasite densities during all 3 seasons surveyed, and Pf155/RESA high responders, with high antibody reactivity against the (EENV)6 sequence from the 3' repeat region of Pf155/RESA, had significantly lower parasite densities in the rainy season of 1987. The data suggest that high titres of antibodies to the Pf155/RESA antigen, and especially to its EENV sequence, might play a role in protective immunity in adults.
Petersen
E
E
Malaria Research Unit, Liberian Institute for Biomedical Research, Charlesville, Margibi County.
Høgh
B
B
Marbiah
N T
NT
Perlmann
H
H
Willcox
M
M
Dolopaie
E
E
Hanson
A P
AP
Björkman
A
A
Perlmann
P
P
D000328:Adult; D000818:Animals; D000913:Antibodies, Protozoan / Q000032:analysis*; D000954:Antigens, Surface / Q000276:immunology*; D005260:Female; D006801:Humans; D007109:Immunity; D007988:Liberia; D008288:Malaria / Q000097:blood / Q000276:immunology* / Q000469:parasitology; D008297:Male; D010963:Plasmodium falciparum / Q000276:immunology*; D011446:Prospective Studies; D015800:Protozoan Proteins / Q000276:immunology*; D012621:Seasons
D000913:Antibodies, Protozoan; D000954:Antigens, Surface; D015800:Protozoan Proteins; C050256:ring-infected erythrocyte surface antigen (RESA), Plasmodium falciparum