Diphtheria CRM197

Diphtheria CRM197: is a non-toxic mutant of diphtheria toxin, currently used as a carrier protein for polysaccharides and haptens to make them immunogenic. There is some dispute about the toxicity of CRM197, with evidence that it is toxic to yeast cells and some mammalian cell lines. There is also evidence suggesting that, compared with tetanus toxoid, there is less carrier-induced suppression of the immune response, especially when there are many individual polysaccharides linked to the same carrier protein.