title: Antibodies to Plasmodium falciparum antigens vary by age and antigen in children in a malaria-holoendemic area of Kenya.
abstract: BACKGROUND
  Antibodies are important in protection against infection and disease caused by Plasmodium falciparum, but the frequencies of antibodies to multiple P. falciparum antigens in children are not well-characterized.
  
  
  METHODS
  IgG and IgM antibodies to the vaccine candidate antigens circumsporozoite protein, thrombospondin-related adhesive protein, liver stage antigen-1, apical membrane antigen-1, erythrocyte-binding antigen-175 and merozoite surface protein-1 were measured by enzyme-linked immunosorbent assay in 110 children 0-50 months of age in a malaria holoendemic area of Kenya.
  
  
  RESULTS
  A similar pattern was seen for IgG antibodies to circumsporozoite protein, thrombospondin-related adhesive protein, apical membrane antigen-1 and erythrocyte-binding antigen-175: high frequencies (70-90%) in children 0-4 months of age; a decrease in children 5-20 months of age (35-71%); and progressive increases in children 21-36 and 37-50 months of age (53-80% and 60-100%, respectively). In contrast, IgG antibodies to liver stage antigen-1 were infrequent in children 0-4 months of age (5%) and increased with age to 64%, and IgG antibody frequencies to merozoite surface protein-1 were similar across age groups (26-52%). IgG antibodies to all antigens were predominantly of the IgG1 and IgG3 subclasses. Frequencies of IgM antibodies to all antigens were low in children 0-4 months of age (0-15%) and increased with age (24-56% in the oldest children).
  
  
  CONCLUSIONS
  In children in a malaria-holoendemic area, IgM antibody to all P. falciparum antigens is infrequent in the first 4 months of life but increases with age and increased exposure. The pattern of age-related IgG response frequencies to P. falciparum antigens varies significantly by antigen.
authors.affiliation: Kenya Medical Research Institute, Kisian, Kenya.
authors.forename: Kiprotich
authors.initials: K
authors.lastname: Chelimo
authors.forename: Ayub V
authors.initials: AV
authors.lastname: Ofulla
authors.forename: David L
authors.initials: DL
authors.lastname: Narum
authors.forename: James W
authors.initials: JW
authors.lastname: Kazura
authors.forename: David E
authors.initials: DE
authors.lastname: Lanar
authors.forename: Chandy C
authors.initials: CC
authors.lastname: John
mesh_terms: D000367:Age Factors; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D000953:Antigens, Protozoan / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D019353:Endemic Diseases; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007223:Infant; D007231:Infant, Newborn; D007630:Kenya / Q000453:epidemiology; D016778:Malaria, Falciparum / Q000453:epidemiology / Q000276:immunology; D010963:Plasmodium falciparum / Q000276:immunology*
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D007074:Immunoglobulin G