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Contributed Talk 3: The role of metabolic and immunological competition in structuring pneumococcal populations and the effects of vaccination

Presented by: 
ER Watkins University of Oxford
Date: 
Tuesday 28th October 2014 - 12:00 to 12:15
Venue: 
INI Seminar Room 1
Abstract: 
Streptococcus pneumoniae (the pneumococcus) is a major cause of bacterial pneumonia, septicemia and meningitis worldwide. Traditional serotyping methods have demonstrated that pneumococcal populations are highly diverse, with over 90 capsular serotypes. More recently, whole genome sequencing has revealed extensive diversity among the metabolic genes, and that metabolic alleles tend to segregate in non-overlapping associations with the antigenic serotype. Here, we use a multilocus model in which strains are composed of metabolic, antigenic and virulence components to explain these patterns of structuring through ecological and immunological competition in the host.

Currently, pneumococcal protein conjugate vaccines target only a small subset of its >90 known capsular serotypes. We use our model to show that a strain-targeted vaccination strategy could alter the genomic profile of non-vaccine strains, potentially leading to an increase in their transmissibility and virulence. The results are consistent with data on the changes in the population structure of the pneumococcus following vaccination, including support at the whole genome level in a collection of 600 pneumococcal genomes.

Similar non-overlapping associations among metabolic and antigenic alleles have been observed in a number of other bacterial pathogens, suggesting that metabolic and immunological competition may play important roles in the maintenance of pathogen population structure more generally. Our vaccination findings also have implications for strain-targeted vaccination in a range of bacterial and viral systems.

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Presentation Material: 
University of Cambridge Research Councils UK
    Clay Mathematics Institute London Mathematical Society NM Rothschild and Sons