title: Predominant influence of environmental determinants on the persistence and avidity maturation of antibody responses to vaccines in infants.
abstract: BACKGROUND
  Immune responses are complex traits influenced by genetic and environmental factors. We previously reported that genetic factors control early antibody responses to vaccines in Gambian infants. For the present study, we evaluated the determinants of the memory phase of immunoglobulin G (IgG) responses.
  
  
  METHODS
  Antibody responses to tetanus toxoid (TT), measles vaccines, and environmental antigens (total IgG levels) were measured in 210 Gambian twin pairs recruited at birth. Intrapair correlations for monozygous and dizygous pairs were compared to estimate the environmental and genetic components of variations in response.
  
  
  RESULTS
  In contrast to antibody responses measured in infants at age 5 months, 1 month after immunization, no significant contribution of genetic factors to anti-TT antibody and total IgG levels was detected at age 12 months. Genetic factors controlled measles antibody responses in 12-month-old infants, which indicates that the increasing influence of environmental determinants on anti-TT responses was not related to the older age of the children but, rather, to the time elapsed since immunization. Environmental factors also predominantly controlled affinity maturation and the production of high-avidity antibodies to TT.
  
  
  CONCLUSIONS
  Genetic determinants control the early phase of the vaccine antibody response in Gambian infants, whereas environmental determinants predominantly influence antibody persistence and avidity maturation.
authors.affiliation: Institute for Medical Immunology, Universite Libre de Bruxelles, Gosselies, Belgium.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Marchant
authors.forename: Maria
authors.initials: M
authors.lastname: Pihlgren
authors.forename: Tessa
authors.initials: T
authors.lastname: Goetghebuer
authors.forename: Helen A
authors.initials: HA
authors.lastname: Weiss
authors.forename: Martin O C
authors.initials: MO
authors.lastname: Ota
authors.forename: Susana E
authors.initials: SE
authors.lastname: Schlegel-Hauter
authors.forename: Hilton
authors.initials: H
authors.lastname: Whittle
authors.forename: Paul-Henri
authors.initials: PH
authors.lastname: Lambert
authors.forename: Melanie J
authors.initials: MJ
authors.lastname: Newport
authors.forename: Claire-Anne
authors.initials: CA
authors.lastname: Siegrist
mesh_terms: D000375:Aging; D000907:Antibodies, Bacterial / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D000915:Antibody Affinity; D000917:Antibody Formation / Q000235:genetics; D004777:Environment; D004797:Enzyme-Linked Immunosorbent Assay; D005714:Gambia; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D007223:Infant; D008458:Measles Vaccine / Q000008:administration & dosage / Q000276:immunology; D013745:Tetanus Toxoid / Q000008:administration & dosage / Q000276:immunology; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic; D014612:Vaccines / Q000008:administration & dosage / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D000914:Antibodies, Viral; D007074:Immunoglobulin G; D008458:Measles Vaccine; D013745:Tetanus Toxoid; D014612:Vaccines