Diphtheria toxin CRM197 protein (CRM197)

Diphtheria toxin CRM197 protein is a genetically detoxified mutant of the native diphtheria toxin produced by Corynebacterium diphtheriae. It contains a single amino acid substitution (Gly52Glu) that eliminates the ADP-ribosyltransferase activity responsible for the toxin's lethality while preserving its structural integrity and ability to bind the Heparin-binding EGF-like growth factor (HB-EGF) receptor. CRM197 is widely utilized in the pharmaceutical industry as a carrier protein for conjugate vaccines, where it enhances the immunogenicity of bacterial polysaccharides by providing essential T-cell epitopes. Beyond its role in vaccinology, CRM197 is investigated as a targeted delivery vehicle for anti-cancer therapies due to its high affinity for HB-EGF, which is frequently upregulated in various solid tumors. Its dual utility as an immunological adjuvant and a receptor-specific ligand makes it a critical component in modern preventive and therapeutic medicine.

Other names

Cross-reacting material 197Mutant diphtheria toxin CRM197Diphtheria toxin G52E mutantCRM197 carrier protein

CRM197 acts as a carrier protein that converts T-cell independent polysaccharide antigens into T-cell dependent antigens, inducing high-affinity antibodies and immunological memory. It also functions as a specific ligand for the Heparin-binding EGF-like growth factor (HB-EGF) receptor, which is often overexpressed in cancer cells, allowing for targeted delivery of therapeutic agents.