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: Similar superantigen gene profiles and superantigen activity in norwegian isolates of invasive and non-invasive group a streptococci.
    Author: Michaelsen TE, Andreasson IK, Langerud BK, Caugant DA.
    Journal: Scand J Immunol; 2011 Nov; 74(5):423-9. PubMed ID: 21707691.
    Abstract:
    Group A streptococcus (GAS) harbours several virulence factors, including M protein (coded by the emm gene) and superantigens (SAgs). SAgs are extracellular toxins that directly activate the immune system by cross-binding to the HLA class II molecule and T cell receptor (TCR), thereby causing activation of up to 30% of the T cells and subsequent massive secretion of cytokines. Forty-eight GAS strains isolated from patients at Norwegian hospitals between 1988 and 2004 were included in this study. Of these, 24 were invasive streptococcal toxic shock syndrome (STSS) or necrotizing fasciitis (NF) isolates and 24 were non-invasive pharyngitis isolates, matched for having the same T-type and year of isolation as the invasive isolates. The isolates were characterized by emm sequence typing, multilocus sequence typing (MLST) and SAg gene profiles. A correlation between T-type, emm type, sequence type and SAg gene profile was revealed. No difference between invasive and non-invasive isolates regarding serotype or genotype was demonstrated. Selected invasive and non-invasive isolates with identical SAg gene profiles were analysed for SAg activity in bacterial growth culture media with and without human cell culture media added. A human T cell proliferation assay was used as measurement for SAg activity and simultaneously we also measured the cytokine content in normal human peripheral blood leucocyte cell culture media. The results revealed that invasive and non-invasive isolates did not differ significantly in SAg activity as it is present in semipurified bacterial culture medium.
    [Abstract] [Full Text] [Related] [New Search]