Differences between Exotoxins and Endotoxins

differences between Exotoxins and Endotoxins

Property	Exotoxins	Endotoxins
Biomolecule/Chemistry	Proteins	Lipopolysaccharide-Lipoprotein complex
Location of genes	Plasmid or bacteriophage	Bacterial chromosome
Source	Excreted by certain gram positive or gram negative bacteria	Cell wall of Gram Negative bacteria, released only after lysis of cells
Heat Stability	Destroyed rapidly at 60oC (except staphylococcal enterotoxin)	Stable at 100oC for one hour
Mode of Action (Symptoms)	Specific. Either cytotoxin, enterotoxin or neurotoxin with defined action on cells or tissues	General. fever, diarrhea, vomiting
Toxicity	Highly toxic, often fatal (fatal dose on the order of 1 µg)	Weakly toxic, rarely fatal (fatal dose on the order of hundreds of micrograms)
Immunogenicity	Highly immunogenic, stimulate the production of neutralizing antibody (antitoxins)	Relatively poor immunogenicity
Toxoid potential/Vaccines	Treatment of toxin with formaldehyde will destroy toxicity, but treated toxins remain immunogenic. Toxids used as vaccines	No toxoid formed and no vaccine available
Typical disease	Tetanus, diphtheria, botulism	Meningococcemia, sepsis by gram negative rods