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Human Nasal Challenge with Streptococcus pneumoniae Is Immunising in the Absence of Carriage

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Wright, Adam, Ferreira, Daniela ORCID: https://orcid.org/0000-0001-7730-9477, Gritzfeld, Jenna, Wright, Angela, Armitage, Kathryn, Jambo, Kondwani C., Bate, Emily, El Batrawy, Sherouk, Collins, Andrea M. and Gordon, Stephen ORCID: https://orcid.org/0000-0001-6576-1116 (2012) 'Human Nasal Challenge with Streptococcus pneumoniae Is Immunising in the Absence of Carriage'. PLoS Pathogens, Vol 8, Issue 4, e1002622.

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Abstract

Infectious challenge of the human nasal mucosa elicits immune responses that determine the fate of the host-bacterial interaction; leading either to clearance, colonisation and/or disease. Persistent antigenic exposure from pneumococcal colonisation can induce both humoral and cellular defences that are protective against carriage and disease. We challenged healthy adults intra-nasally with live 23F or 6B Streptococcus pneumoniae in two sequential cohorts and collected nasal wash, bronchoalveolar lavage (BAL) and blood before and 6 weeks after challenge. We hypothesised that both cohorts would successfully become colonised but this did not occur except for one volunteer. The effect of bacterial challenge without colonisation in healthy adults has not been previously assessed. We measured the antigen-specific humoral and cellular immune responses in challenged but not colonised volunteers by ELISA and Flow Cytometry. Antigen-specific responses were seen in each compartment both before and after bacterial challenge for both cohorts. Antigen-specific IgG and IgA levels were significantly elevated in nasal wash 6 weeks after challenge compared to baseline. Immunoglobulin responses to pneumococci were directed towards various protein targets but not capsular polysaccharide. 23F but not 6B challenge elevated IgG anti-PspA in BAL. Serum immunoglobulins did not increase in response to challenge. In neither challenge cohort was there any alteration in the frequencies of TNF, IL-17 or IFNγ producing CD4 T cells before or after challenge in BAL or blood. We show that simple, low dose mucosal exposure with pneumococci may immunise mucosal surfaces by augmenting anti-protein immunoglobulin responses; but not capsular or cellular responses. We hypothesise that mucosal exposure alone may not replicate the systemic immunising effect of experimental or natural carriage in humans.

Item Type: Article
Subjects: WA Public Health > Preventive Medicine > WA 115 Immunization
WC Communicable Diseases > Infection. Bacterial Infections > Bacterial Infections > WC 200 Bacterial infections (General or not elsewhere classified)
WC Communicable Diseases > Infection. Bacterial Infections > Bacterial Infections > WC 210 Streptococcal infections (General or not elsewhere classified)
WC Communicable Diseases > Infection. Bacterial Infections > Bacterial Infections > WC 217 Pneumococcal infections
Faculty: Department: Groups (2002 - 2012) > Clinical Group
Digital Object Identifer (DOI): https://doi.org/10.1371/journal.ppat.1002622
Depositing User: Users 379 not found.
Date Deposited: 25 Sep 2012 12:41
Last Modified: 06 Feb 2018 13:05
URI: http://archive.lstmed.ac.uk/id/eprint/3014

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