Diphtheria toxin CRM197 mutant (CRM197) (CRM197)

Diphtheria toxin CRM197 mutant (CRM197) is a genetically detoxified variant of the diphtheria toxin produced by Corynebacterium diphtheriae, characterized by a single amino acid substitution of glutamic acid for glycine at position 52 (PMID: 21939744). This specific mutation abolishes the protein's ADP-ribosyltransferase activity, rendering it non-toxic, while preserving its ability to bind to the heparin-binding EGF-like growth factor (HB-EGF) receptor and its overall structural integrity. CRM197 is extensively utilized as a carrier protein in conjugate vaccines, where it is chemically linked to bacterial polysaccharides to convert them from T-cell independent to T-cell dependent antigens (PMID: 24007525). This conversion is critical for inducing high-affinity antibodies and immunological memory, particularly in infants and young children. Beyond its role in vaccinology, CRM197 is explored as a therapeutic agent for cancers that overexpress HB-EGF and as a delivery vehicle for transporting drugs across the blood-brain barrier (PMID: 15661748). Its safety and efficacy have been demonstrated through its inclusion in several widely used pediatric vaccines, including those for pneumococcal and meningococcal diseases.

Other names

CRM197Cross-reacting material 197Diphtheria toxin G52E mutantCRM-197

CRM197 functions as a carrier protein by providing T-cell epitopes that facilitate the recruitment of T-helper cells, which in turn stimulate B-cells to produce high-affinity antibodies and establish immunological memory against conjugated polysaccharides (PMID: 24007525). Additionally, it acts as an HB-EGF inhibitor by competitively binding to the receptor, potentially inhibiting tumor cell proliferation (PMID: 15661748).