title: Longitudinal study of natural immune responses to the Plasmodium falciparum apical membrane antigen (AMA-1) in a holoendemic region of malaria in western Kenya: Asembo Bay Cohort Project VIII.
abstract: We investigated the development and maintenance of proliferative and antibody responses to apical membrane antigen-1 (AMA-1) epitopes in a holoendemic area of western Kenya. Young children (< 10 years), older children (10-17 years), and adults (> or = 18 years) were followed longitudinally for antibody and T-cell responses at 3 time points with an interval of 3-4 months. The proliferative responses against the AMA-1 T epitopes (PL171, PL172, PL173, PL186, PL191, and PL192) were not stable during follow-up; however, response to mycobacterial antigen PPD was highly stable. The responder frequencies were similar in all 3 time points except for epitope PL192. The younger and older children responded more frequently to T-cell epitopes, but the differences were not significant. A positive proliferative response to PL191 was associated with a significantly lower risk of parasitemia at subsequent follow-up (relative risk, 0.5; P = 0.03). The presence of antibody response to B epitopes PL169, PL170, PL173, PL187, and PL192 in one time point was associated with a subsequent response (P = 0.0001-0.008) suggesting a stable response. Younger (P = 0.046) and older children (P = 0.017) more frequently responded to epitope PL169 than did adults, and adults responded more frequently to PL187 than did younger children (P = 0.009). Responses to AMA-1 T-cell epitopes were short lived, and antibody responses were relatively stable.
authors.affiliation: Division of Parasitic Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Public Health Service, U.S. Department of Health and Human Services, Atlanta, Georgia, USA. VXU0@CDC.GOV
authors.forename: V
authors.initials: V
authors.lastname: Udhayakumar
authors.forename: S
authors.initials: S
authors.lastname: Kariuki
authors.forename: M
authors.initials: M
authors.lastname: Kolczack
authors.forename: M
authors.initials: M
authors.lastname: Girma
authors.forename: J M
authors.initials: JM
authors.lastname: Roberts
authors.forename: A J
authors.initials: AJ
authors.lastname: Oloo
authors.forename: B L
authors.initials: BL
authors.lastname: Nahlen
authors.forename: A A
authors.initials: AA
authors.lastname: Lal
mesh_terms: D000293:Adolescent; D000328:Adult; D000595:Amino Acid Sequence; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D000953:Antigens, Protozoan / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology; D002648:Child; D015331:Cohort Studies; D000939:Epitopes / Q000276:immunology; D006801:Humans; D007630:Kenya; D008213:Lymphocyte Activation; D016778:Malaria, Falciparum / Q000276:immunology*; D008565:Membrane Proteins / Q000276:immunology*; D008969:Molecular Sequence Data; D018512:Parasitemia / Q000276:immunology; D010446:Peptide Fragments / Q000235:genetics / Q000276:immunology; D010963:Plasmodium falciparum / Q000276:immunology*; D015800:Protozoan Proteins / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D000939:Epitopes; D008565:Membrane Proteins; D010446:Peptide Fragments; D015800:Protozoan Proteins; C090077:apical membrane antigen I, Plasmodium