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Characterization of the canine type C enterotoxin produced by Staphylococcus intermedius pyoderma isolates
V M Edwards1, J R Deringer, S D Callantine
1Department of Microbiology, Molecular Biology, and Biochemistry, University of Idaho, Moscow 83844, USA.
Infection and Immunity
|June 1, 1997
Summary
Canine staphylococcal enterotoxin C (SECcanine) from Staphylococcus intermedius shares high sequence identity with other SECs but differs in T-cell interactions. This study characterizes SECcanine, revealing conserved superantigen properties and potential roles in canine pyoderma.
Area of Science:
- Microbiology
- Immunology
- Toxicology
Background:
- Type C staphylococcal enterotoxins (SECs) are conserved proteins with antigenic cross-reactivity.
- Toxins from Staphylococcus species other than Staphylococcus aureus remain largely uncharacterized.
- Staphylococcus intermedius is implicated in producing SECs and other staphylococcal enterotoxins (SEs).
Purpose of the Study:
- To characterize the molecular, biological, and immunological properties of canine SEC (SECcanine) from pathogenic S. intermedius isolates.
- To investigate the sequence identity and T-cell receptor interaction profile of SECcanine.
- To assess the role of SECcanine in staphylococcal pathogenesis, particularly in canine pyoderma.
Main Methods:
- Molecular characterization of SECcanine, including amino acid sequence and isoelectric point (pI).
- Biological assays to assess emetic response in monkeys and T-cell proliferation in a Vbeta-dependent manner.
- Sequence analysis to compare SECcanine with known SEC variants and identify key residues influencing T-cell interactions.
Main Results:
- SECcanine, a mature protein of 239 amino acids with a pI of 7.0, was identified.
- Purified SECcanine induced emesis in monkeys and T-cell proliferation, consistent with known SE properties.
- SECcanine exhibited >95% sequence identity to other SEC variants, most closely related to SEC2 and SEC3, but induced a Vbeta profile typical of SEC1.
- A conserved cysteine residue at position 26 in SECcanine was identified as potentially responsible for subtype-dependent T-cell receptor interactions.
Conclusions:
- Superantigen toxins produced by various Staphylococcus species are highly conserved in biological and structural aspects.
- SECcanine's properties suggest a conserved role for staphylococcal superantigens in pathogenesis.
- The frequent association of SECcanine with canine pyoderma highlights its importance in staphylococcal survival and disease.