All are true regarding diphtheria toxin EXCEPT :
Ans. is 'd' i.e Toxin is necessary for local wound production " Corynebacterium Diptheria does not need to be toxigenic to establish localized infection, In the nasopharynx or skin, but non toxigenic strains do not yield the localized or systemic effect" - JawetzWhat I get from the above lines is that Non toxigenic strains of C diphtheriae can cause local wound production or infection but they will not be able to produce clinical effects.C.Diphtheriae produces a heat labile exotoxinThe production of this toxin depends largely on the concentration of Iron. Toxin production is optimal at 0.14mg/ml and is suppressed at 0.5 mg/mlThe toxigenicity of the Diptheria Bacillus depends on the presence in it of corynephages (tox+ i.e. toxigenic).Non toxigenic strains may be rendered toxigenic by infecting them with Beta phage or some other tox* phage.This is known as lysogenic conversion or phage conversion.Toxin inhibits the protein synthesis by inhibiting the polypeptide chain elongation.
Toxin blocks elongation of protein
Beta lysogenic strain produces toxin
Iron is critical for toxin production
Toxin is necessary for local wound production
Corynebacterium