Esther L. German, United Kingdom

Liverpool School of Tropical Medicine Clinical Sciences

Author Of 3 Presentations

 Conference Calendar

ASSESSING PNEUMOCOCCAL COLONIZATION NICHES (NOSE VS OROPHARYNX) IN YOUNG AND OLDER ADULTS DURING EXPERIMENTAL HUMAN PNEUMOCOCCAL CARRIAGE (ID 550)

Session Name
Basic Sciences - Conventional and Molecular Microbiology
Presenter
Authors

Abstract

Background

Pneumococcal nasopharyngeal colonization is increasingly used as a surrogate marker for disease risk, thus accurate detection is crucial. However, it is not known if host age affects the colonization niche and, consequently, pneumococcal (Spn) detection in adults. Using the Experimental Human Pneumococcal Challenge (EHPC) model, we investigated if detection of pneumococcal carriage in the nose and oropharynx changes with increasing age.

Methods

Healthy adults (n=112) were intranasally inoculated with Spn6B and monitored for a month. Volunteers were split into young 18-55yrs (n=57) and older adults >55yrs (n=55). Colonization was determined by lytA and 6AB-specific multiplex qPCR assay in both raw and culture-enriched nasal wash (NW) and oropharyngeal swab (OPS). Colonization status was compared at 2, 7 and 14 days post-inoculation in both niches.

Results

We observed that the Spn6B colonization rate decreases with ageing in both NW (young 70.2%, older 50.9%) and OPS (young 64.9%, older 34.5%). Pneumococcal presence is higher in NW than OPS in both groups (young 70.2%-64.9% and older 50.9%-34.5%).

Conclusions

Pneumococcal presence in the nasopharynx is age-dependent. The nose, as assessed by NW sampling, seems to be the best niche for detection of pneumococcal colonization in adults, regardless of their age.

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THE MUCOSAL AND SYSTEMIC ANTIBODY REPERTOIRE FOLLOWING EXPERIMENTAL PNEUMOCOCCAL CHALLENGE IN HEALTHY ADULTS (ID 993)

Session Name
Basic Sciences - Immunology, Pathogenesis, and Host-pathogen Interactions
Presenter
Authors

Abstract

Background

In the experimental human pneumococcal challenge (EHPC) model, healthy adults are intranasally inoculated with a pneumococcal challenge strain. A panproteome Streptococcus pneumoniae array, containing over 2,600 pneumococcal proteins, was used to screen systemic and mucosal antibodies from EHPC volunteers.

Methods

IgG and IgA responses were profiled in a cohort of 150 volunteers challenged with serotype 6B pneumococci, half of whom were susceptible to experimental colonization and the other half remained protected. Serum and nasal wash samples collected pre- and post-EHPC were probed on the S. pneumoniae panproteome microarray with simultaneous detection of IgA and IgG binding.

Results

Hundreds of pneumococcal proteins were reactive with serum and nasal wash IgG and IgA. IgA- and IgG-reactive proteins showed high levels of overlap. However, over 200 proteins were reactive only with IgG. Antibodies against numerous proteins significantly increased following challenge. Unsupervised clustering showed subject-specific stability of antibody profiles in serum, but independently grouped profiles in nasal wash samples collected before and after challenge. No specific profile differences were observed in pre-EHPC samples between susceptible and protected groups, but the response to EHPC showed unique antigen reactivity patterns.

Conclusions

A single encounter with pneumococci can elicit broad changes in mucosal and systemic antibody responses to pneumococcal proteins.

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CHARACTERIZING THE IMMUNE RESPONSE TO EXPERIMENTAL PNEUMOCOCCAL CARRIAGE IN OLDER ADULTS (ID 682)

Session Name
Basic Sciences - Immunology, Pathogenesis, and Host-pathogen Interactions
Presenter
Authors