All are true regarding diphtheria toxin except ?
Option 4 Corynebacteriam diphtheriae does not need to be toxigenic to establish localized infection. Option 1, 2, 3 Mechanism of Action of diphtheria toxin Has 2 fragments: Fragment A (active unit) Fragment A is internalized into the host cells and then causes- ADP ribosylation of elongation factor 2(EF2) - inhibition of EF2- irreversible inhibition of translation step of protein synthesis- cell death. Fragment B (binding unit) Binds to the host cell receptors (such as epidermal growth factor) Helps in entry of fragment A. Toxin Production is dependent on: Phage coded: DT is coded by b corynophage carrying tox gene. Iron concentration: Toxin production depends on optimum iron concentration (0.1 mg/liter). DT repressor gene (DtxR) is an iron dependent negative regulator of DT production and iron uptake in C.diphtheriae.
Toxin blocks elongation of protein
Beta lysogenic strain produces toxin
Iron is critical for toxin production
Toxin is necessary for local wound production
Systemic Bacteriology Pa 1 (Gram Positive Cocci, Gram Negative Cocci)