Exotoxin

• Exotoxins


  Proteins, secreted by certain gram-positive or gram-negative Bacteria; generally heat-labile
• Exotoxins


  • Specific; usually bind to specific cell receptors or structures; either cytotoxin, enterotoxin, or neurotoxin with defined, specific action on cells or tissues
  • Often highly toxic in picogram to microgram quantities, sometimes fatal
  • Highly immunogenic; stimulate the production of neutralizing antibody (antitoxin)
  • Heat or chemical treatment may destroy toxicity, but treated toxin (toxoid) remains immunogenic
  • Nonpyrogenic, do not produce fever in the host
• Exotoxins are often encoded on extrachromosomal elements or lysogenic bacteriophages