CRM₁₉₇ is a genetically detoxified diphtheria toxin with glutamic acid substituted for glycine at position 52.  Fina Biosolutions (FinaBio) offers protein-A purified antibodies for the detection of CRM₁₉₇ and diphtheria toxin in ELISA and Western blot applications.  Rabbit polyclonal and mouse monoclonal antibodies are available, in both unlabeled and biotinylated forms.  EcoCRM^®, FinaBio’s E. coli expressed CRM₁₉₇, was used as the immunogen for the antibody production, however, the antibodies should recognize Corynebacterium diphtheria toxin and toxoid.