Human Anti-Diphtheria Toxoid IgG ELISA Kit

Diphtheria is an infectious and potentially fatal disease caused by Corynebacterium diphtheriae. It is generally accepted that the potent diphtheria toxin secreted by C. diphtheriae is the main virulence factor and that the symptoms of the disease are related to the action of the toxin. Diphtheria toxin (DT) is a single-chain 62kDa protein consisting of 535 amino acid residues produced by Corynebacterium diphtheriae. containing a lysogenic beta phage. DT mediates its cytolethal effects by inhibiting protein synthesis in susceptible cells. The DT molecule is Y-shaped and contains two functionally distinct regions: A and B. The A fragment located at the N-terminus contains a catalytic domain that prevents protein synthesis in the cell. The B fragment located at the C-terminus consists of a transmembrane domain that helps transfer the catalytic domain from the endosome to the cytoplasm and a receptor domain that helps bind the heparin-binding epidermal growth factor receptor on the surface of susceptible cells.

Figure 1. Schematic representation of diphtheria toxin
(Source: Shafiee F, et al. 2019)

In the last century, some researchers found that diphtheria toxin lost its toxicity while maintaining immunogenicity after heat and formalin treatment. In this way, the treated diphtheria toxin was called diphtheria toxoid and was used in diphtheria vaccine preparation. Conventional vaccines are produced in several steps: cultivation of Corynebacterium diphtheriae and clarification of the toxin-containing medium, followed by concentration and inactivation of the toxin, purification of the toxoids by means of diafiltration and adsorption on aluminum salts. The quality of diphtheria toxoid depends mainly on the detoxification process, in which reaction conditions such as formaldehyde concentration, reaction time and temperature, and matrix composition are very important.

Traditionally used in combination with tetanus and pertussis antigens, the diphtheria–tetanus–pertussis (DTP) vaccine was one of the first vaccines used in humans to protect against three serious and potentially fatal diseases that affect children and adults. Diphtheria vaccines are now also frequently used in combination with other antigens, such as Hib component, hepatitis B and inactivated polio vaccines. As the epidemiology of the diphtheria pathogen has changed, researchers have identified the emergence of infections caused by non-producing strains of diphtheria that cannot be prevented by current vaccines containing only diphtheria toxoids, and there is a need to continue to develop prophylactic vaccines against non-producing strains of diphtheria.

Human Anti-DT IgG ELISA