Influence of age, social patterns and nasopharyngeal carriage on antibodies to three conserved pneumococcal surface proteins (PhtD, PcpA and PrtA) in healthy young children.
The acquisition of specific antibodies is paramount to protect children against pneumococcal diseases, and a better understanding of how age, ethnicity and/or Streptococcus pneumoniae (Spn) nasopharyngeal carriage influence the acquisition of antibodies to pneumococcal surface proteins (PSP) is important for the development of novel serodiagnostic and immunisation strategies. IgG antibody titres against three conserved PSP (PhtD, PcpA and PrtA) in the sera of 451 healthy children aged 1 to 24 months from Israel [Jewish (50.1 %) and Bedouin (49.9 %)] were measured by enzyme-linked immunosorbent assay (ELISA), while nasopharyngeal swabs from these children were assessed for the presence of Spn. Globally, anti-PhtD and anti-PrtA geometric mean concentrations (GMC; EU/ml) were high at <2.5 months of age [PhtD: 35.3, 95 % confidence interval (CI) 30.6-40.6; PrtA: 71.2, 95 % CI 60-84.5], was lower at 5-7 months of age (PhtD: 10, 95 % CI 8-12.4; PrtA: 17.9, 95 % CI 14.4-22.1) and only increased after 11 months of age. In contrast, an increase in anti-PcpA was observed at 5-7 months of age. Anti-PcpA and anti-PrtA, but not anti-PhtD, were significantly higher in Bedouin children (PcpA: 361.6 vs. 226.3, p = 0.02; PrtA: 67.2 vs. 29.5, p < 0.001) in whom Spn nasopharyngeal carriage was identified earlier (60 % vs. 38 % of carriers <6 months of age, p = 0.002). Spn carriage was associated with significantly higher anti-PSP concentrations in carriers than in non-carriers (p < 0.001 for each PSP). Thus, age, ethnicity and, essentially, nasopharyngeal carriage exert distinct cumulative influences on infant responses to PSP. These specific characteristics are worthwhile to include in the evaluation of pneumococcal seroresponses and the development of new PSP-based vaccines.
Department of Child and Adolescent Medicine, University Hospitals of Geneva, Geneva 1211, Switzerland.
A
A
Hagerman
K M
KM
Posfay-Barbe
S
S
Grillet
M M
MM
Ochs
R H
RH
Brookes
D
D
Greenberg
N
N
Givon-Lavi
R
R
Dagan
C-A
CA
Siegrist
D000367:Age Factors; D000907:Antibodies, Bacterial / Q000097:blood*; D000942:Antigens, Bacterial / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology*; D002352:Carrier Proteins / Q000276:immunology*; D002353:Carrier State / Q000453:epidemiology*; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay; D005006:Ethnicity; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007223:Infant; D047908:Intracellular Signaling Peptides and Proteins; D007557:Israel / Q000453:epidemiology; D008297:Male; D008565:Membrane Proteins / Q000276:immunology*; D009305:Nasopharynx / Q000382:microbiology; D011008:Pneumococcal Infections / Q000453:epidemiology*; D060756:Social Networking; D013296:Streptococcus pneumoniae / Q000276:immunology*
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D002352:Carrier Proteins; D007074:Immunoglobulin G; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C113653:PcpA protein, Streptococcus