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Generation of genic diversity among Streptococcus pneumoniae strains via horizontal gene transfer during a chronic polyclonal pediatric infection
Journal article   Open access

Generation of genic diversity among Streptococcus pneumoniae strains via horizontal gene transfer during a chronic polyclonal pediatric infection

N Luisa Hiller, Azad Ahmed, Evan Powell, Darren P Martin, Rory Eutsey, Josh Earl, Benjamin Janto, Robert J Boissy, Justin Hogg, Karen Barbadora, …
PLoS pathogens, v 6(9), pp e1001108-e1001108
16 Sep 2010
PMID: 20862314
url
https://doi.org/10.1371/journal.ppat.1001108View
Published, Version of Record (VoR) Open

Abstract

Genome, Bacterial Streptococcus pneumoniae - classification Humans Infant Phylogeny Respiratory Tract Infections - genetics Genetic Variation Respiratory Tract Infections - microbiology Gene Transfer, Horizontal - physiology Recombination, Genetic Pneumococcal Infections - genetics Alleles Streptococcus pneumoniae - genetics Polymorphism, Single Nucleotide - genetics Pneumococcal Infections - microbiology Gene Expression Regulation, Bacterial Chronic Disease Mucous Membrane - microbiology
Although there is tremendous interest in understanding the evolutionary roles of horizontal gene transfer (HGT) processes that occur during chronic polyclonal infections, to date there have been few studies that directly address this topic. We have characterized multiple HGT events that most likely occurred during polyclonal infection among nasopharyngeal strains of Streptococcus pneumoniae recovered from a child suffering from chronic upper respiratory and middle-ear infections. Whole genome sequencing and comparative genomics were performed on six isolates collected during symptomatic episodes over a period of seven months. From these comparisons we determined that five of the isolates were genetically highly similar and likely represented a dominant lineage. We analyzed all genic and allelic differences among all six isolates and found that all differences tended to occur within contiguous genomic blocks, suggestive of strain evolution by homologous recombination. From these analyses we identified three strains (two of which were recovered on two different occasions) that appear to have been derived sequentially, one from the next, each by multiple recombination events. We also identified a fourth strain that contains many of the genomic segments that differentiate the three highly related strains from one another, and have hypothesized that this fourth strain may have served as a donor multiple times in the evolution of the dominant strain line. The variations among the parent, daughter, and grand-daughter recombinant strains collectively cover greater than seven percent of the genome and are grouped into 23 chromosomal clusters. While capturing in vivo HGT, these data support the distributed genome hypothesis and suggest that a single competence event in pneumococci can result in the replacement of DNA at multiple non-adjacent loci.

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Collaboration types
Domestic collaboration
International collaboration
Web of Science research areas
Microbiology
Parasitology
Virology
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