Related Experiment Videos
Two novel superantigens found in both group A and group C Streptococcus
Thomas Proft1, Phillip D Webb, Vanessa Handley
1Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
Infection and Immunity
|February 22, 2003
Summary
Novel streptococcal superantigen genes speL and speM were found in some Streptococcus pyogenes strains, not Streptococcus equi. These toxins are highly mitogenic and target specific T cells, suggesting potential roles in disease.
Area of Science:
- Microbiology
- Immunology
- Genetics
Background:
- Streptococcal superantigens are potent immune activators.
- The genetic diversity and distribution of superantigens influence pathogenicity.
Purpose of the Study:
- To identify and characterize novel streptococcal superantigen genes.
- To investigate the distribution and function of speL and speM genes in Streptococcus species.
Main Methods:
- Genome database analysis to identify novel superantigen genes.
- Genotyping of Streptococcus equi and Streptococcus pyogenes isolates.
- Recombinant protein expression and functional assays (mitogenicity, MHC binding).
Main Results:
- Two novel superantigen genes, speL(Se) and speM(Se), were identified in Streptococcus equi genome database.
- Orthologous speL and speM genes were found in a small percentage of Streptococcus pyogenes isolates (15% and 5%), but not in S. equi.
- Recombinant SPE-L and SPE-M were highly mitogenic for human lymphocytes and bound MHC class II molecules.
- speL gene showed a strong association with Streptococcus pyogenes M89, a serotype linked to acute rheumatic fever.
Conclusions:
- The speL and speM genes are likely located on mobile genetic elements, facilitating inter-isolate and inter-group transfer.
- SPE-L and SPE-M are potent T cell activators, primarily targeting Vbeta1.1 expressing T cells.
- The presence of speL in M89 strains suggests a potential role in acute rheumatic fever pathogenesis.