[Show abstract][Hide abstract] ABSTRACT: Antibody-mediated killing of Streptococcus pneumoniae (pneumococcus) by phagocytes is an important mechanism of protection of the human host against pneumococcal infections. Measurement of opsonophagocytic antibodies by use of a standardized opsonophagocytic assay (OPA) is important for the evaluation of candidate vaccines and required for the licensure of new pneumococcal conjugate vaccine formulations. We assessed agreement among six laboratories that used their own optimized OPAs on a panel of 16 human reference sera for 13 pneumococcal serotypes. Consensus titers, estimated using an analysis-of-variance (ANOVA) mixed-effects model, provided a common reference for assessing agreement among these laboratories. Agreement was evaluated in terms of assay accuracy, reproducibility, repeatability, precision, and bias. We also reviewed four acceptance criterion intervals for assessing the comparability of protocols when assaying the same reference sera. The precision, accuracy, and concordance results among laboratories and the consensus titers revealed acceptable agreement. The results of this study indicate that the bioassays evaluated in this study are robust, and the resultant OPA values are reproducible for the determination of functional antibody titers specific to 13 pneumococcal serotypes when performed by laboratories using highly standardized but not identical assays. The statistical methodologies employed in this study may serve as a template for evaluating future multilaboratory studies.
[Show abstract][Hide abstract] ABSTRACT: Finnish and Israeli infants received an 11-valent mixed carrier pneumococcal conjugate vaccine (11PCV) with or without aluminum adjuvant at the age of 2, 4, 6, and 12 months. We measured opsonophagocytic activity (OPA) of antibodies to pneumococcal strains of serotypes 4, 6B, 14, 19F, and 23F. At 7 months, OPA was clearly detected for all the serotypes. At 13 months, OPAs increased further and the proportion of individuals with a positive OPA ranged between 81 and 100%. The adjuvant improved functional activity of antibodies to serotype 6B pneumococci. In conclusion, immunization of infants with the 11PCV induced functionally active antibodies.
[Show abstract][Hide abstract] ABSTRACT: We have investigated the association between the concentration of anti-polysaccharide pneumococcal capsule-specific (anti-PS) immunoglobulin G and the killing activity, in serum, in invasive pneumococcal disease (IPD) events and response to 23-valent polysaccharide vaccine in human immunodeficiency virus (HIV)-infected Ugandans. Case patients with IPD had lower concentrations of anti-PS IgG before and after vaccination and before the IPD event (P<.01 for 5 [i.e., 4, 9V, 14, 18C, and 19F] of 6 serotypes assessed). After vaccination, case patients were less likely than were control subjects to develop detectable serum killing activity against the 2 serotypes tested--for 19F, this activity was detected in 16% of case patients versus 37% of control subjects (P=.08); for 23F, it was detected in 11% of case patients versus 40% of control subjects (P=.02). Thus, absolute concentration of anti-PS IgG and an attenuated response to polysaccharide are associated with risk of IPD in HIV-infected adults.
The Journal of Infectious Diseases 09/2004; 190(4):707-12. · 5.85 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Finnish and Israeli infants received an 11-valent mixed-carrier pneumococcal conjugate vaccine with or without aluminum adjuvant at 2, 4, 6, and 12 months of age. The relative avidity of serotype 1-, 5-, 6B-, 14-, 19F-, and 23F-specific IgG antibodies in serum obtained at 7, 12, and 13 months of age was measured by EIA, using thiocyanate as a chaotropic agent. For all serotypes, except 14, avidity increased between the ages of 7 and 12 months. After boosting at 12 months, avidity further increased for all serotypes. The adjuvant improved antibody avidity against serotype 5. The IgG antibodies produced were mainly IgG1 subclass, although some infants also produced IgG2 after boosting. In conclusion, the immunization of infants with this 11-valent pneumococcal conjugate vaccine increased avidity of IgG, suggesting successful immunologic priming.
The Journal of Infectious Diseases 12/2001; 184(9):1211-5. · 5.85 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Pneumococcal surface protein A (PspA), pneumococcal surface adhesin A (PsaA), and pneumolysin (Ply) are common to virtually all Streptococcus pneumoniae isolates. They are immunogenic and protective against pneumococcal challenge in animals and are the major candidates for a protein-based pneumococcal vaccine for humans. However, little is known of the natural development of antibodies to these proteins in humans. The objective of this study was to evaluate the natural development of antibodies to PspA, PsaA, and Ply in relation to pneumococcal infection and carriage in young children. Serum antibodies to these proteins were measured by EIA in children at ages 6, 12, 18, and 24 months and in their mothers. All age groups were capable of producing antibodies to the 3 proteins. The antibody concentrations increased with age and were strongly associated with pneumococcal exposure, whether by carriage or infection (acute otitis media).
The Journal of Infectious Diseases 11/2000; 182(4):1146-52. · 5.85 Impact Factor