title: Effects of age, hemoglobin type and parasite strain on IgG recognition of Plasmodium falciparum-infected erythrocytes in Malian children.
abstract: BACKGROUND
  Naturally-acquired antibody responses to antigens on the surface of Plasmodium falciparum-infected red blood cells (iRBCs) have been implicated in antimalarial immunity. To profile the development of this immunity, we have been studying a cohort of Malian children living in an area with intense seasonal malaria transmission.
  
  
  RESULTS
  We collected plasma from a sub-cohort of 176 Malian children aged 3-11 years, before (May) and after (December) the 2009 transmission season. To measure the effect of hemoglobin (Hb) type on antibody responses, we enrolled age-matched HbAA, HbAS and HbAC children. To quantify antibody recognition of iRBCs, we designed a high-throughput flow cytometry assay to rapidly test numerous plasma samples against multiple parasite strains. We evaluated antibody reactivity of each plasma sample to 3 laboratory-adapted parasite lines (FCR3, D10, PC26) and 4 short-term-cultured parasite isolates (2 Malian and 2 Cambodian). 97% of children recognized ≥1 parasite strain and the proportion of IgG responders increased significantly during the transmission season for most parasite strains. Both strain-specific and strain-transcending IgG responses were detected, and varied by age, Hb type and parasite strain. In addition, the breadth of IgG responses to parasite strains increased with age in HbAA, but not in HbAS or HbAC, children.
  
  
  CONCLUSIONS
  Our assay detects both strain-specific and strain-transcending IgG responses to iRBCs. The magnitude and breadth of these responses varied not only by age, but also by Hb type and parasite strain used. These findings indicate that studies of acquired humoral immunity should account for Hb type and test large numbers of diverse parasite strains.
authors.affiliation: Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America.
authors.forename: Amir E
authors.initials: AE
authors.lastname: Zeituni
authors.forename: Kazutoyo
authors.initials: K
authors.lastname: Miura
authors.forename: Mahamadou
authors.initials: M
authors.lastname: Diakite
authors.forename: Saibou
authors.initials: S
authors.lastname: Doumbia
authors.forename: Samuel E
authors.initials: SE
authors.lastname: Moretz
authors.forename: Ababacar
authors.initials: A
authors.lastname: Diouf
authors.forename: Gregory
authors.initials: G
authors.lastname: Tullo
authors.forename: Tatiana M
authors.initials: TM
authors.lastname: Lopera-Mesa
authors.forename: Cameron D
authors.initials: CD
authors.lastname: Bess
authors.forename: Neida K
authors.initials: NK
authors.lastname: Mita-Mendoza
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Anderson
authors.forename: Rick M
authors.initials: RM
authors.lastname: Fairhurst
authors.forename: Carole A
authors.initials: CA
authors.lastname: Long
mesh_terms: D000367:Age Factors; D000913:Antibodies, Protozoan / Q000276:immunology*; D000953:Antigens, Protozoan / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004912:Erythrocytes / Q000378:metabolism / Q000469:parasitology*; D006454:Hemoglobins / Q000145:classification* / Q000235:genetics; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D015994:Incidence; D016778:Malaria, Falciparum / Q000453:epidemiology / Q000235:genetics / Q000276:immunology* / Q000469:parasitology*; D008302:Mali / Q000453:epidemiology; D010963:Plasmodium falciparum / Q000276:immunology*; D012621:Seasons
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D006454:Hemoglobins; D007074:Immunoglobulin G