Superantigens are -

Superantigens are a class of antigens that cause non-specific activation of T-cells resulting in polyclonal T cell activation and massive cytokine release. Superantigens bind first to the MHC Class II and then coordinate to the variable alpha or beta chain of T-cell Receptors . Eg: S. Aureus (enterotoxins), Group A streptococci (pyrogenic exotoxin), HIV(Nef), Rabies virus (nucleocapsid protein) etc.... Ref: Ananthanarayan & Panikers textbook of microbiology 9th edition pg:90