title: Demonstration of immunologic memory using serogroup C meningococcal glycoconjugate vaccine.
abstract: BACKGROUND
  Studies of glycoconjugate vaccines have traditionally used an immune challenge with a plain polysaccharide vaccine to demonstrate immunologic memory. Plain polysaccharide vaccines are poorly immunogenic in children and can induce subsequent immunologic hyporesponsiveness. We therefore assessed the use of glycoconjugate vaccines as an alternative method of demonstrating immunologic memory.
  
  
  METHODS
  Children immunized with hepatitis B vaccine or serogroup C meningococcal glycoconjugate vaccine (MenCC) at age 2, 3, 4 months received a plain polysaccharide meningococcal serogroup A/C vaccine (MenACP) or MenCC at age 12 months. A post hoc analysis of serum bactericidal activity responses to MenCC assessed whether this differed in MenCC primed and MenCC naive infants.
  
  
  RESULTS
  MenCC primed children displayed higher geometric mean serum bactericidal titers than MenCC naive children following MenACP (1518 compared with 30; P = 0.003). A similar difference was seen after a dose of MenCC to toddlers (MenCC primed: 8663, MenCC naive: 710; P < 0.001). The latter comparison became a borderline significance after adjusting for higher pretoddler immunization serum bactericidal geometric mean titers in the MenCC primed group (P = 0.068).
  
  
  CONCLUSIONS
  Administration of glycoconjugate vaccines provides an important alternative method of demonstrating immunologic memory, avoiding the use of plain polysaccharide vaccines that are potentially deleterious in children. This has implications for the design of all future clinical trials of glycoconjugate vaccines.
authors.affiliation: Department of Paediatrics, University of Oxford, Oxford, UK. matthew.snape@paediatrics.ox.ac.uk
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Snape
authors.forename: Jenny M
authors.initials: JM
authors.lastname: Maclennan
authors.forename: Stephen
authors.initials: S
authors.lastname: Lockhart
authors.forename: Mike
authors.initials: M
authors.lastname: English
authors.forename: Ly-Mee
authors.initials: LM
authors.lastname: Yu
authors.forename: Richard E
authors.initials: RE
authors.lastname: Moxon
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Pollard
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood; D001770:Blood Bactericidal Activity; D004311:Double-Blind Method; D005260:Female; D017325:Hepatitis B Vaccines / Q000276:immunology; D006801:Humans; D007117:Immunization, Secondary; D007074:Immunoglobulin G / Q000097:blood; D007156:Immunologic Memory / Q000276:immunology*; D007223:Infant; D008297:Male; D022401:Meningococcal Vaccines / Q000008:administration & dosage / Q000276:immunology*; D013997:Time Factors
chemical_list: D000907:Antibodies, Bacterial; D017325:Hepatitis B Vaccines; D007074:Immunoglobulin G; D022401:Meningococcal Vaccines; C410218:serogroup C meningococcal conjugate vaccine