Exotoxin Vs Endotoxin | 25 Differences, Types and Examples

Bacteria release substances that are harmful to the host. These are exotoxins and endotoxins.

Exotoxins are toxic substances that are secreted by bacteria outside of their cell. While the endotoxins are toxins located within the cell membrane.

Exotoxin Vs Endotoxin

Exotoxin Vs Endotoxin

Sl.NO Characteristics Exotoxins Endotoxins
1SourceProduced from the live gram-
positive and gram-negative
They are formed only in gram-negative bacteria. Further, they are secreted during the growth and death of bacteria.
2LocationMostly secreted outside the
living cell
Present in the outer plasma membrane
3ChemistryHas Protein, with two components (A and B).Made of lipopolysaccharide complex on the outer membrane
10 KDa. 50-1000 kDa.
5IsolationFilterablePartially filterable.
6Genetic linkFrequently carried by extra-chromosomal genes such as plasmids.They are synthesized directly by
chromosomal genes.
7TypesBased on their structural and
physiological properties, these are
classified as.
1) AB Exotoxin
2) Specific host site Exotoxin
3) Membrane Disrupting-Exotoxin
a) Channel-forming
b) Phospholipase
4) Superantigen
8Bacterial ExamplesBacillus cereus, Staphylococcus aureus, Streptococcus pyogenes.E.coli, Salmonella typhi, Shigella, Vibrio cholera.
Botulism, Diphtheria, tetanusGram-negative infections, Meningococcemia.
10SymptomsNo Feverish symptomsHigh-temperature fever due to the release of interleukin-1.
11ToxicityHighly toxic and even fatal in microgram
Moderate toxicity.
12Toxoid ProductionToxins get converted to antigenic, nontoxic
Not converted to toxoids
13DenaturationAre easily denatured by boiling. (Sterilization)Do not get denatured.
No enzymatic activity. High enzymatic activity
15AntigenicityExotoxins have high antigenicity.Endotoxins have poor antigenicity.
16SpecificitySpecific to a particular Strain. Nonspecific.
17Host Receptors for entryExotoxins usually enter host cells through specific
No specific receptors for the entry of endotoxins.
18 Antigenicity Exotoxins have high antigenicity. That is they can evoke a strong immune response in the host. Endotoxins have poor antigenicity.
19Immune SpecificitySpecific to a particular StrainNonspecific.
20Immune Neutralization Because of a strong immune response, they can be neutralized by
They are not neutralized by antibodies.
21 Vaccines Effective vaccines are available against exotoxins. No effective vaccines are available against endotoxins.
22Role in DiseaseExotoxins affect a human host in
three main ways:
1) Ingestion of exotoxin
2) Colonization of mucosal surface
3) Colonization of a wound or abscess.
Endotoxins mediate toxicity in the host through interleukins and Tumor Necrosis factors.
23Effect on HostHighly variable between different
Similar to all endotoxins.
24Enzyme ActivityNo enzymatic activity. High enzymatic activity.
25EnzymesCollagenase, hyaluronidase, nuclease, protease, neuraminidase,
phospholipase A.
Catalase, IgA/IgG proteases, fibrinolysin.

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