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J Infect Dis. 2005 Aug 1;192(3):387-93. Epub 2005 Jun 23.

Antibody responses to nasopharyngeal carriage of Streptococcus pneumoniae in adults: a longitudinal household study.

Author information

1
Immunobiology Unit, Institute of Child Health, University College London, UK. d.goldblatt@ich.ucl.ac.uk

Abstract

BACKGROUND:

Natural immunity to Streptococcus pneumoniae is thought to be induced by exposure to S. pneumoniae or cross-reactive antigens. No longitudinal studies of carriage of and immune responses to S. pneumoniae have been conducted using sophisticated immunological laboratory techniques.

METHODS:

We enrolled 121 families with young children into this study. Nasopharyngeal (NP) swabs were collected monthly for 10 months from all family members and were cultured in a standard fashion. Cultured S. pneumoniae isolates were serotyped. At the beginning (month 0) and end (month 10) of the study, venous blood was collected from family members >18 years old. Serotype-specific antipolysaccharide immunoglobulin G (IgG) and functional antibody and antibodies to pneumolysin, pneumococcal surface protein A (PspA), and pneumococcal surface antigen A (PsaA) were measured in paired serum samples.

RESULTS:

Levels of anticapsular IgG increased significantly after carriage of serotypes 9V, 14, 18C, 19F, and 23F by an individual or family member. For serotype 14, a higher level of anticapsular IgG at the beginning of the study was associated with reduced odds of carriage (P = .006). There was a small (approximately 20%) but significant increase in titers of antibodies to PsaA and pneumolysin but no change in titers of antibody to PspA.

CONCLUSIONS:

Adults respond to NP carriage by mounting anticapsular and weak antiprotein antibody responses, and naturally induced anticapsular IgG can prevent carriage.

PMID:
15995951
DOI:
10.1086/431524
[Indexed for MEDLINE]

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