Exotoxins Vs Endotoxins- Definition And 29 Major Differences

Differences Between Exotoxins Vs Endotoxins

Toxins are small chemicals, peptides, or proteins created by living cells that, when they come into contact with or are ingested by tissues, can result in morphological changes or structural damage. Enzymes and toxins both contribute significantly to the pathogenicity of pathogenic bacteria. Toxins can promote invasiveness, harm cells, impair biological functions, or provoke an immune reaction and cell damage.

Exotoxins Vs Endotoxins
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Toxins are of two types: Exotoxins Vs Endotoxins

S.N. Character Exotoxins Endotoxins
1.       Definition Proteins are produced inside pathogenic bacteria as a part of their growth and metabolism. Lipid portions of lipopolysaccharides (LPSs) are part of the outer membrane of bacteria.
2.       Produced by Mostly Gram-positive bacteria and some Gram-negative bacteria. Gram-negative bacteria.
3.       Chemical Nature Protein (polypeptide) complexes Lipopolysaccharide-protein complexes
4.       Molecular weight  10KDa.  50-1000KDa.
5.       Components Usually composed of two subunits, A and B. Composed of three basic components:
The A subunit is seen to have catalytic activity, whereas the B subunit is required for binding with an appropriate cell receptor. 1.  O-antigen
2.  Core oligosaccharide
3.  Lipid A
6.       Enzymes present Hyaluronidase, Collagenase, certain protease, Nuclease, Neuraminidase, Certain protease, Phospholipase A Catalase, Fibrolysin, IgA / IgG proteases
7.       Chromosomal Location Located on extrachromosomal genes (e.g., plasmids). Located on chromosomal genes.
8.       Secreted by Secreted by organisms; living cell An integral part of the cell wall; lysed cell
9.       Secretion Secreted out of the cell. Generally not released outside the cell until the death of a cell.
10.    Cell Lysis Not required Required
11.    Stability to heat Heat labile (60-80°C) Heat stable (250°C)
12.    Filtration Filterable Not Filterable
13.    Boiling Denatured on boiling Not denatured on boiling.
14.    Enzyme Activity Mostly has enzymatic activity. Enzymatic activity absent or limited.
15.    Specificity Exotoxins are enzymes; this makes them highly specific in their mechanism and for their host cells. Endotoxins are comparatively not very specific in nature.
16.    Specific receptors Usually binds to specific receptors. Specific receptors not found.
17.    Specificity to a bacterial strain Specific to certain bacterial strains. Not specific to any bacterial strain.
18.    Immunogenicity Highly immunogenic. Weakly immunogenic.
19.    Fever Induction No Fever by induction of interleukin 1 (IL-1) production.
20.    Toxicity Highly toxic, fatal in µg quantities. Moderately toxic, fatal in mg quantities.
21.    Mode of action Various modes (Mostly by enzyme-like mechanisms). Includes TNF and Interlukin-1
22.    Potency High: A single toxin molecule can act on a large number of host cells. Low: A large amount of toxin is needed to cause disease.
23.    Effects Either cytotoxin, enterotoxin, or neurotoxin with defined action on cells or tissues. General symptoms such as fever, diarrhea, vomiting, etc.
24.    Neutralization by Antibodies It can be neutralized. It cannot be neutralized.
25.    Detection Detected by many tests (neutralization, precipitation, etc.) Detected by Limulus lysate assay.
26.    Conversion to Toxoids Possible (On treatment with formalin). eg. For the prevention of diphtheria, botulism, and tetanus. Not possible
27.    Availability of vaccines Effective vaccines are available. No effective vaccines are available.
28.    Diseases caused Tetanus, diphtheria, botulism, etc. Meningococcemia, sepsis by gram-negative rods, etc.
29.    Examples Toxins produced by Staphylococcus aureus, Bacillus cereus, Streptococcus pyogenes, Bacillus anthracis Toxins produced by E.coli, Salmonella Typhi, Shigella, and Vibrio cholera


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