Fig. 2

Characteristics and activities of SAg toxins. A Three-dimensional structures of SEA, SEB and SEC as representative of SAg toxins. B Diagram of superantigen (left) and normal antigen (right) bind to MHC class II of APC and T-cell receptor, CD28 molecules. C Superantigenic activities of SAg toxins, that induce massive cytokine production and subsequently cause inflammation and toxic shock in humans and animals. This figure was prepared and modified from Hu et al. (2014, 2018). SE, staphylococcal enterotoxins; APC, antigen-presenting cells; MHC, major histocompatibility comlex; TCR, T-cell antigen receptor