has role protective antigen role protective antigen Corynebacterium diphtheriae protein Tox Oliver He Allen Xiang Protegen ID: 750; NCBI Protein GI: 38199106; NCBITaxon: 1717 In 1923, it was discovered that treatment with formalin eliminated the toxicity of diphtheria toxin (DT) without destroying its immunogenicity. Formalinreated DT, now called diphtheria toxoid, rapidly became the preferred vaccine against diphtheria, and diphtheria toxoid (usually in combined vaccines, such as diphtheriaetanus toxoidsertussis vaccine [DTP] or diphtheriaetanus toxoidscellular pertussis vaccine [DTaP] for children and tetanusiphtheria toxoids vaccine for adults [Td]) is still used throughout the world for active immunization against diphtheria [PubMed: 10657208]. protein