title: Effect of carrier protein priming on antibody responses to Haemophilus influenzae type b conjugate vaccines in infants.
abstract: OBJECTIVE
  To assess the effect of priming with diphtheria and tetanus toxoid vaccine (DT) at 1 month of age on the anticapsular polyribosylribitol phosphate (PRP) antibody responses of infants vaccinated with Haemophilus influenzae type b polysaccharide-tetanus toxoid conjugate (PRP-T) or PRP oligosaccharide-cross-reactive mutant diphtheria toxin conjugate (HbOC).
  
  
  METHODS
  Randomized controlled trial with serum samples assayed blindly.
  
  
  METHODS
  Healthy infants enrolled in private pediatric practices; 94 (91%) of 103 infants had prevaccination and postvaccination serum samples available for analysis.
  
  
  METHODS
  Two groups received DT vaccination at 1 month of age and subsequent injections of PRP-T or HbOC conjugate vaccines at 2, 4, and 6 months of age. The control groups were not vaccinated with DT but received PRP-T or HbOC at the same ages as the carrier-primed groups. Infants in all groups were given a booster injection of unconjugated PRP at 12 months of age to assess induction of immunologic memory.
  
  
  METHODS
  Concentrations of serum antibody to PRP.
  
  
  RESULTS
  The DT-primed infants given PRP-T had twofold to threefold higher geometric mean anti-PRP antibody responses after one (P < or = .01), two (P < or = .01), or three (P = .06) doses of conjugate vaccine than the infants of the unprimed group. The primed infants also had threefold higher memory antibody responses to the booster PRP injection given at 12 months of age (concentration of 24.4 vs 8.4 micrograms/mL in infants not primed with DT; P < .01). The DT-primed infants given HbOC had twofold to threefold higher antibody responses after one (P = .07) or two (P < .01) doses of conjugate vaccine than the unprimed HbOC group, but there were no significant differences after the third dose of conjugate vaccine or after the PRP booster injection.
  
  
  CONCLUSIONS
  Vaccination with DT at 1 month of age increases the magnitude of the anti-PRP antibody responses to conjugate vaccination. With HbOC, the effect of carrier priming was present for up to 6 months of age, whereas in infants vaccinated with PRP-T, enhanced immunity was present for at least 12 months.
authors.affiliation: Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St Louis, MO.
authors.forename: D M
authors.initials: DM
authors.lastname: Granoff
authors.forename: S J
authors.initials: SJ
authors.lastname: Holmes
authors.forename: R B
authors.initials: RB
authors.lastname: Belshe
authors.forename: M T
authors.initials: MT
authors.lastname: Osterholm
authors.forename: J E
authors.initials: JE
authors.lastname: McHugh
authors.forename: E L
authors.initials: EL
authors.lastname: Anderson
mesh_terms: D000907:Antibodies, Bacterial / Q000096:biosynthesis*; D000942:Antigens, Bacterial / Q000276:immunology; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology; D001426:Bacterial Proteins / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology*; D004168:Diphtheria Toxoid / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology*; D022422:Diphtheria-Tetanus Vaccine; D004338:Drug Combinations; D018073:Haemophilus Vaccines / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology*; D006193:Haemophilus influenzae / Q000276:immunology*; D006801:Humans; D007115:Immunization Schedule; D007117:Immunization, Secondary; D007156:Immunologic Memory / Q000276:immunology*; D007223:Infant; D011135:Polysaccharides, Bacterial / Q000276:immunology; D013745:Tetanus Toxoid / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology*; D018074:Vaccines, Conjugate / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D004168:Diphtheria Toxoid; D022422:Diphtheria-Tetanus Vaccine; D004338:Drug Combinations; D018073:Haemophilus Vaccines; C055753:Haemophilus influenza type b polysaccharide vaccine-tetanus toxin conjugate; D011135:Polysaccharides, Bacterial; D013745:Tetanus Toxoid; D018074:Vaccines, Conjugate; C061963:HibTITER protein, Haemophilus influenzae