title: Functional antibodies elicited by two heptavalent pneumococcal conjugate vaccines in the Finnish Otitis Media Vaccine Trial.
abstract: In the Finnish Otitis Media Vaccine Trial, the now-licensed pneumococcal conjugate vaccine containing polysaccharides conjugated to protein CRM(197) (PncCRM) and the experimental pneumococcal polysaccharide-meningococcal outer membrane protein complex conjugate vaccine (PncOMPC), showed similar efficacy profiles against acute otitis media despite different antibody concentrations in sera. We now report the opsonophagocytic activities (OPA) in these sera. OPA, antibody concentration, and avidity for serotypes 6B, 19F, and 23F were determined in sera of infants who received either pneumococcal conjugate (PCV) or control vaccine at 2, 4, and 6 months of age and either the homologous or pneumococcal polysaccharide vaccine at 12 months of age. OPA varied by vaccine and serotype. The majority of PCV recipients had positive OPA after the fourth dose, while OPA was undetectable in the control group. Coinciding with the efficacy data, the concentration of antibodies required for 50% killing was low for 6B and high for 19F for both PCVs. Contradictory to the efficacy data, PncOMPC induced lower functional capacity to 23F than PncCRM. OPA correlated with antibody concentration, while avidity and functional capacity of antibodies showed no correlation. The OPA data provide valuable additional information for serotype-specific differences in protection and when evaluating serotype-specific immunogenicity and should thus be considered when defining serological correlates of protection.
authors.affiliation: Dept. of Vaccines, National Public Health Institute, Mannerheimintie 166, 00300 Helsinki, Finland. nina.ekstrom@ktl.fi
authors.forename: Nina
authors.initials: N
authors.lastname: Ekström
authors.forename: Merja
authors.initials: M
authors.lastname: Väkeväinen
authors.forename: Jouko
authors.initials: J
authors.lastname: Verho
authors.forename: Terhi
authors.initials: T
authors.lastname: Kilpi
authors.forename: Helena
authors.initials: H
authors.lastname: Käyhty
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood / Q000276:immunology*; D000915:Antibody Affinity; D002675:Child, Preschool; D005387:Finland; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007223:Infant; D022401:Meningococcal Vaccines / Q000276:immunology*; D050296:Microbial Viability; D009895:Opsonin Proteins / Q000276:immunology; D010033:Otitis Media / Q000517:prevention & control*; D010587:Phagocytosis; D011008:Pneumococcal Infections / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000276:immunology*; D013223:Statistics as Topic; D013296:Streptococcus pneumoniae / Q000276:immunology* / Q000502:physiology
chemical_list: D000907:Antibodies, Bacterial; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022401:Meningococcal Vaccines; D009895:Opsonin Proteins; D022242:Pneumococcal Vaccines