Outpacing the pneumococcus: Antibody dynamics in the first few days following pneumococcal capsular antigen stimulation.

Children in developing countries are frequently exposed to the pneumococcus, but few develop invasive pneumococcal disease (IPD). We test the hypothesis that natural variation exists in the rapidity of IgG responses following exposure to pneumococcal polysaccharides, and that these differences are sufficiently great to affect susceptibility to and outcome of IPD. We recruited children aged 24-36 months, who had recovered from IPD, and age-matched healthy controls and vaccinated them with 1 dose of the 23-valent PPV to mimic natural exposure.

Association between antibodies against group B Streptococcus surface proteins and recto-vaginal colonisation during pregnancy.

Group B Streptococcus (GBS) recto-vaginal colonisation in pregnant women is the major risk factor for early-onset invasive GBS disease in their newborns. We aimed to determine the association between serum antibody levels against 11 GBS surface proteins and recto-vaginal acquisition of GBS colonisation during pregnancy. Sera collected from pregnant women at 20-25 weeks and ≥37 weeks of gestation age were measured for IgG titres against GBS surface proteins using  a multiplex immunoassay.

Reduced Transplacental Transfer of Group B Streptococcus Surface Protein Antibodies in HIV-infected Mother-Newborn Dyads.

We evaluated the effect of maternal HIV infection on transplacental antibody transfer specific to 8 group B Streptococcus (GBS) surface proteins among 81 HIV-uninfected and 83 HIV-infected mother-newborn pairs using a multiplex immunoassay. Significantly lower antibody titers were detected in HIV-infected mothers and HIV-exposed uninfected newborns compared to HIV-uninfected mother-newborn dyads. Maternal HIV infection was also associated with reduced transplacental transfer of antibodies for Sip (25.

Natural acquired group B Streptococcus capsular polysaccharide and surface protein antibodies in HIV-infected and HIV-uninfected children.

Group B Streptococcus (GBS) is a major cause of invasive disease in young infants and also in older immunocompromised individuals, including HIV-infected persons. We compared naturally acquired antibody titres to GBS polysaccharide and surface protein antigens in HIV-uninfected and HIV-infected children aged 4-7 years. A multiplex Luminex immunoassay was used to measure IgG concentrations against GBS capsular polysaccharides (CPS) for serotypes Ia, Ib, III and V; and also extracellular localizing proteins which included cell-wall anchored proteins: Fibrinogen binding surface Antigen (FbsA), GBS Immunogenic Bacterial Adhesin (BibA), Surface immunogenic protein (Sip), gbs0393, gbs1356, gbs1539, gbs0392; and lipoproteins gbs0233, gbs2106 and Foldase PsrA.

Phenotypic, genomic, and transcriptional characterization of Streptococcus pneumoniae interacting with human pharyngeal cells.

Background: Streptococcus pneumoniae is a leading cause of childhood morbidity and mortality worldwide, despite the availability of effective pneumococcal vaccines. Understanding the molecular interactions between the bacterium and the host will contribute to the control and prevention of pneumococcal disease.

Results: We used a combination of adherence assays, mutagenesis and functional genomics to identify novel factors involved in adherence.

Transcriptional adaptation of pneumococci and human pharyngeal cells in the presence of a virus infection.

Background: Viral upper respiratory tract infections are associated with increased colonization by Streptococcus pneumoniae but the mechanisms underlying this relationship are unclear. The objective of this study is to describe a comprehensive picture of the cellular interaction between the adhering bacteria and host cells in the presence or absence of a viral co-infection.

Results: Gene expression profiles of Detroit-562 pharyngeal cells, which were either mock-infected or infected with human respiratory syncytial virus (RSV) or human parainfluenza virus 3 (HPIV3), were analyzed using human microarrays.