Superantigenic activity of toxic shock syndrome toxin-1 is resistant to heating and digestive enzymes

Aims: To elucidate the stability of superantigenic activity and pathogenesis of toxic shock syndrome toxin 1 (TSST‐1) and staphylococcal enterotoxin A (SEA) against heating and digestive enzymes. Methods and Results: Purified TSST‐1 and SEA were treated with heating, pepsin and trypsin that are related to food cooking, stomach and intestine conditions. The integrity, superantigenic activity and toxicity of treated TSST‐1 and SEA were analysed by Western blotting, spleen cell culture, cytokine assay and toxic shock models. Both TSST‐1 and SEA showed strong resistance to heating, pepsin and trypsin digestion. Furthermore, the treated TSST‐1 showed significant higher induction of interferon‐γ and toxic shock compared with that of SEA. Pepsin‐ or trypsin‐digested TSST‐1 fragments still showed significant superantigenic and lethal shock toxicities. Conclusions: The superantigenic activity of TSST‐1 was stable to heating and digestive enzymes. Pepsin‐ and trypsin‐digested TSST‐1 fragments still showed superantigenic and lethal shock activities, indicating that digested TSST‐1 could cross epithelial cells and induce systemic toxicity. Significance and Impact of the Study: This study found, for the first time, that pepsin‐ or trypsin‐digested smaller TSST‐1 retained significant superantigenic and lethal shock activities. The different resistance of TSST‐1 and SEA participates in the different pathogenic activities during food poisoning and toxic shock syndrome.