Toxoid

From Freepedia

A toxoid is a bacterial toxin whose toxicity as been weakened or supressed while other properties, typically immunogenicity, are maintained. Toxoids are used in vaccines as they induce an immune response to the original toxin or increase the response to another antigen. For example, the tetanus toxoid is derived from the tetanospasmin produced by Clostridium tetani and causing tetanus.