NATURAL ANTIBODIES AGAINST SEVERAL PNEUMOCOCCAL VIRULENCE PROTEINS IN CHILDREN IN THE PRE-PNEUMOCOCCAL VACCINE-ERA: THE GENERATION R STUDY.
ESPID Education. Lebon A. 06/07/11; 7707
Dr. Ankie Lebon
Dr. Ankie Lebon

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Abstract
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ABSTRACT

Background
The currently available pneumococcal vaccines do not protect against all serotypes of Streptococcus pneumoniae. A shift towards non-vaccine serotypes causing colonization and invasive disease has occurred and studies on protein-based vaccines are undertaken. We assessed the association between specific antibodies against pneumococcal virulence proteins and colonization and respiratory tract infections (RTI). Additionally, we assessed to what extend colonization induces a humoral immune response.

Material and Methods
Nasopharyngeal swabs were cultured for pneumococcus at 1.5, 6, 14 and 24 months of age. Serum samples were obtained at birth, 6, 14 and 24 months (n=57 children providing 177 serum samples). Data were collected prior to the pneumococcal vaccine-era. IgG, IgA and IgM levels against seventeen pneumococcal protein vaccine candidates were measured using a bead based flow cytometry technique (xMAP®, Luminex Corporation). Information regarding RTI was questionnaire-derived.

Results
IgG levels to all proteins were high in cord blood, decreased in the first 6 months and increased again thereafter, contrary to the course of IgA and IgM levels. Specific antibodies were induced upon colonization. Increased levels of IgG against BVH-3, NanA and SP1003 at 6 months, NanA, PpmA, PsaA, SlrA, SP0189 and SP1003 at 14 months and SlrA at 24 months were associated with a decreased number of RTI in the 3rd year of life but not with colonization. Maternal anti-pneumococcal antibodies did not protect against pneumococcal colonization and infection.

Conclusions
Certain antibodies against pneumococcal virulence proteins, some of which are induced by colonization, are associated with a decreased number of RTIs in children. This should be taken into account for future pneumococcal vaccine studies.
ABSTRACT

Background
The currently available pneumococcal vaccines do not protect against all serotypes of Streptococcus pneumoniae. A shift towards non-vaccine serotypes causing colonization and invasive disease has occurred and studies on protein-based vaccines are undertaken. We assessed the association between specific antibodies against pneumococcal virulence proteins and colonization and respiratory tract infections (RTI). Additionally, we assessed to what extend colonization induces a humoral immune response.

Material and Methods
Nasopharyngeal swabs were cultured for pneumococcus at 1.5, 6, 14 and 24 months of age. Serum samples were obtained at birth, 6, 14 and 24 months (n=57 children providing 177 serum samples). Data were collected prior to the pneumococcal vaccine-era. IgG, IgA and IgM levels against seventeen pneumococcal protein vaccine candidates were measured using a bead based flow cytometry technique (xMAP®, Luminex Corporation). Information regarding RTI was questionnaire-derived.

Results
IgG levels to all proteins were high in cord blood, decreased in the first 6 months and increased again thereafter, contrary to the course of IgA and IgM levels. Specific antibodies were induced upon colonization. Increased levels of IgG against BVH-3, NanA and SP1003 at 6 months, NanA, PpmA, PsaA, SlrA, SP0189 and SP1003 at 14 months and SlrA at 24 months were associated with a decreased number of RTI in the 3rd year of life but not with colonization. Maternal anti-pneumococcal antibodies did not protect against pneumococcal colonization and infection.

Conclusions
Certain antibodies against pneumococcal virulence proteins, some of which are induced by colonization, are associated with a decreased number of RTIs in children. This should be taken into account for future pneumococcal vaccine studies.
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