These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Directional gene movement from human-pathogenic to commensal-like streptococci.
    Author: Kalia A, Enright MC, Spratt BG, Bessen DE.
    Journal: Infect Immun; 2001 Aug; 69(8):4858-69. PubMed ID: 11447161.
    Abstract:
    Group A streptococci (GAS) are highly pathogenic for humans, and their closest genetic relatives, group C and G streptococci (GCS and GGS, respectively), are generally regarded as commensals, although they can be found in association with human disease. As part of an effort to better understand the evolution of virulence, the phylogenetic relationships between GAS, GCS, and GGS were examined. The nucleotide sequence was determined for an internal portion of seven housekeeping (neutral) loci among >200 isolates of GAS and 34 isolates of GCS or GGS obtained from human subjects. Genotypic analysis failed to show support for the separation of GCS and GGS into two distinct populations. Unlike GAS, there was poor concordance between emm type and genetic relatedness among GCS and GGS. All housekeeping genes within GAS displayed relatively low levels of sequence diversity. In contrast, individual GCS and GGS strains had mosaic genomes, containing alleles at some loci that were similar or identical to GAS alleles, whereas the alleles at other loci were about 10 to 30% diverged. The data provide evidence for a history of recent interspecies transfer of neutral genes that exhibits a strong net directionality from GAS donors to GCS and GGS recipients. A model for the evolution of GAS and of GCS and GGS is described.
    [Abstract] [Full Text] [Related] [New Search]