Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Biology and Microbiology

First Advisor

David J. Hurley


The enterotoxins produced by Staphylococcus aureus (SEs), are a group of toxins which mediate persistent infection in hosts of various species. The SEs have been classified as superantigens in humans and mice. A superantigen is a molecule that induces massive proliferation of T cells by interaction with the Vβ portion of the T cell receptor and MHC class II molecules. This response induces both CD4 and CD8 cell phenotypes to be present in the blast cell population. In the typical response of cells to superantigens IL-2 is produced and IL-2 receptors expression increases. The expression of MHC class I and II surface proteins are upregulated. The staphylococcal enterotoxins, SEA, SEB, and TSST, were examined for superantigenic activity with bovine and porcine peripheral blood lymphocytes (PBLs). SEA, SEB, and TSST were found to be mitogenic for both bovine and porcine PBLs. This mitogenesis induced by the SEs could by inhibited by specific anti-toxin antibodies in bovine and porcine PBLs and by MHC class I and class II monoclonal antibodies in bovine PBLs, suggesting an interaction with MHC and T cell receptor consistent with superantigen stimulation. The cells activated by the SEs in bovine PBLs also produced IL-2 and had increased upregulated IL-2 receptors on the cell surface. The dividing cells also contained both CD4 and CD8 bearing cells. Essentially 100 percent of the dividing cells were positive for the T cell marker CD3. MHC class I and II receptors were upregulated during SE activation. Our data supports the conclusion that the SEA, SEB, and TSST act as superantigen with bovine and porcine PBLs. Further, we examined cultures of bacteria isolated from clinical veterinary cases for mitogenic activity. This suggested mitogenic activity was identified from 80% of clinical isolates and this activity could represent novel superantigens.

Library of Congress Subject Headings

Cattle -- Immunology
Swine -- Immunology
Staphylococcus aureus




South Dakota State University



Rights Statement

In Copyright