Population Genetics of <em>Streptococcus dysgalactiae</em> Subspecies <em>equisimilis</em> Reveals Widely Dispersed Clones and Extensive Recombination David J. McMillan Debra E. Bessen Marcos Pinho Candace Ford Gerod S. Hall José Melo-Cristino Mário Ramirez 10.1371/journal.pone.0011741 https://plos.figshare.com/articles/dataset/Population_Genetics_of_Streptococcus_dysgalactiae_Subspecies_equisimilis_Reveals_Widely_Dispersed_Clones_and_Extensive_Recombination/142503 <div><h3>Background</h3><p><em>Streptococcus dysgalactiae</em> subspecies <em>equisimilis</em> (SDSE) is an emerging global pathogen that can colonize and infect humans. Although most SDSE isolates possess the Lancefield group G carbohydrate, a significant minority have the group C carbohydrate. Isolates are further sub-typed on the basis of differences within the <em>emm</em> gene. To gain a better understanding of their molecular epidemiology and evolutionary relationships, multilocus sequence typing (MLST) analysis was performed on SDSE isolates collected from Australia, Europe and North America.</p><h3>Methodology/Principal Findings</h3><p>The 178 SDSE isolates, representing 37 <em>emm</em> types, segregate into 80 distinct sequence types (STs) that form 17 clonal complexes (CCs). Eight STs recovered from all three continents account for >50% of the isolates. Thus, a small number of STs are highly prevalent and have a wide geographic distribution. Both ST and CC strongly correlate with group carbohydrate. In contrast, eleven STs were associated with >1 <em>emm</em> type, suggestive of recombinational replacements involving the <em>emm</em> gene; furthermore, 35% of the <em>emm</em> types are associated with genetically distant STs. Data also reveal a history of extensive inter- and intra-species recombination involving the housekeeping genes used for MLST. Sequence analysis of single locus variants identified through goeBURST indicates that genetic change mediated by recombination occurred ∼4.4 times more frequently than by point mutation.</p><h3>Conclusions/Significance</h3><p>A few genetic lineages with an intercontinental distribution dominate among SDSE causing infections in humans. The distinction between group C and G isolates reflects recent evolution, and no long-term genetic isolation between them was found. Lateral gene transfer and recombination involving housekeeping genes and the <em>emm</em> gene are important mechanisms driving genetic variability in the SDSE population.</p></div> 2010-07-23 00:41:43 genetics subspecies reveals dispersed clones recombination