Differences

Difference between exotoxins and endotoxins – exotoxins vs endotoxins

Exotoxin is a toxins produced by bacteria. Exotoxins can cause damage to the host by damaging cells or disrupting normal cell metabolism....

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MN Editors
This article writter by MN Editors on January 20, 2022

Microbiology Notes is an educational niche blog related to microbiology (bacteriology, virology, parasitology, mycology, immunology, molecular biology, biochemistry, etc.) and different branches of biology.

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Difference between exotoxins and endotoxins - exotoxins vs endotoxins
Difference between exotoxins and endotoxins - exotoxins vs endotoxins

What is Exotoxin?

Exotoxin is a toxins produced by bacteria. Exotoxins can cause damage to the host by damaging cells or disrupting normal cell metabolism. They are extremely powerful and could cause significant harm on the human host. Exotoxins can be released, or, as with endotoxins, they can be released when cells. Gram negative pathogens can release outer membrane vesicles with lipopolysaccharide endotoxin, as well as some viral proteins within the bounding membrane as well as other toxins in the intra-vesicular content and thus add an unimagined dimension to the widely-known membrane vesicle transport, which is extremely active in the interface between host and pathogen.

They can act locally or cause systemic effects. Exotoxins that are well-known include botulinum toxin , produced by Clostridium botulinum, Corynebacterium diphtheriae toxinthat is produced in diphtheria-related symptoms that can be life-threatening; tetanospasmin , produced by Clostridium Tetani. The toxic properties of the majority of exotoxins are able to be neutralized through heat or chemical treatment to create an toxoid. They retain their antigenic properties and are able to make antitoxins and when it comes to Tetanus and diphtheria they are used to create vaccines.

Exotoxins are prone to antibodies created from the immune system however some are so harmful that they could cause death for the person who is exposed to them prior to the time that your immune system gets the chance to build defences to defend against them. In these cases the antitoxin, which is an anti-serum that contains antibodies, may be administered to help provide an immune system that is passive.

What is Endotoxin? 

Pyrogens can cause fever. Endotoxin is a kind of pyrogen that is a part of the cell wall exterior of Gram-negative bacteria, such as E. coli (see image). Endotoxin is a type of lipopolysaccharide, LPS. LPS is composed from the lipid A part comprising fatty acids and disaccharide polysaccharides, phosphates along with the O-antigen (see the image). The lipid A component of LPS is responsible for the molecule’s endotoxin activities. While lipid A isn’t able to directly harm any tissues however, our immune system cells both animals and humans alike consider it to be an indication of that there is a presence of bacteria. Therefore, they trigger the body’s immune system to fight off unwanted invaders. The reaction is entirely natural, i.e. there is no previous exposure to the endotoxin has to be had. Additionally, it could help keep our beneficial intestinal bacteria within as well as keeping out the spread of pathogenic bacteria coming from outside.

Because of the serious effects of infection, injectable health products like a vaccine or intravenous solutions must be sterilized and free from live organisms, however, the manufacturing process to kill bacteria could cause the release from LPS and endotoxin in the solution. As with sepsis or a bacterial infection in the event that enough endotoxin enters into our bloodstream or spinal fluid, we may suffer from shock, fever, or organ damage. In extreme cases, it can even result in death.

So, implantables and injectables products that come into contact with blood stream or spinal fluid are checked for sterilization (the presence of no live organisms) as well as for endotoxin. Endotoxin testing helps ensure that the quality of the product is safe and secure.

Difference between exotoxins and endotoxins – exotoxins vs endotoxins

CharacterExotoxinsEndotoxins
DefinitionThe pathogenic bacteria produce proteins as part of their metabolism and growth.Lipid parts from lipopolysaccharides (LPSs) which form the part of the outer membranes of bacteria.
Produced byThe majority of Gram positive bacteria are additionally Gram negative bacteria.Gram negative bacteria.
Chemical NatureProtein (polypeptide) complexesLipopolysaccharide-protein complexes
Molecular weight10KDa.50-1000KDa.
ComponentsUsually , it is composed by two units A and B..
It is believed as having catalytic properties and the B subunit appears to be necessary to bind with a suitable cell receptor.
Comprised of three components:1. O-antigen2. Core Oligosaccharide3. Lipid A
Enzymes presentHyaluronidase, Collagenase, certain protease, Nuclease, Neuraminidase, Certain protease, Phospholipase ACatalase, Fibrolysin, IgA Catalase, Fibrolysin, IgA IgG proteases
Chromosomal LocationThey are located on extrachromosomal gene (e.g. plasmids).It is located on chromosomal genes.
Secreted byOrganisms secrete this information ; living cellsPart of the cell wall that is integral Cell wall; cell lysed
SecretionThe cell is sucked out of its secret.Generally, cells are not released from the cell until the cell dies.
Cell LysisNot necessaryRequired
Stability to heatHeat labile (60-80degC)Stable heat (250degC)
FiltrationFilterableNot Filterable
BoilingDenatured by boilingNot denatured upon boiling.
Enzyme ActivityMost of the time, it is involved in enzymatic activities.The activity of enzymes is either absent or minimal.
SpecificityExotoxins are enzymes. This makes them extremely specific in their function as well as for the cells they host.Endotoxins are not remarkably particular in nature.
Specific receptorsTypically, they bind to receptors.The receptors are not specific enough to be identified.
Specificity to the bacterial strainParticular to a specific strain of bacterial.There is no specificity to any bacteria type.
ImmunogenicityHighly immune-enhancing.Immunely weak.
Fever InductionNoThe cause of fever is the induction by interleukin 1 (IL-1) production.
ToxicityHighly toxicand fatal in small amounts.Moderately toxic, fatal when in mg amounts.
Method of actionMany different ways (Mostly through similar enzymes).Includes TNF and Interlukin-1
PotencyThe High One molecule is able to affect an array of host cells.Low A significant amount of toxin is required for the development of the disease.
EffectsIt could be cytotoxin, enterotoxin or neurotoxin that has a specific action on tissues or cells.General symptoms like vomiting, diarrhea, fever and so on.
Neutralization by AntibodiesIt is possible to neutralize.It is not neutralized.
DetectionIt is detected by a variety of tests (neutralization or precipitation, for example.)The detection was made by Limulus Lysate Assay.
Conversion to ToxoidsPossible (On treatment with formalin). eg. to prevent botulism, diphtheria, and Tetanus.It’s not possible.
Available vaccinesEffective vaccines available.No effective vaccines available.
Infections that are caused byTetanus, diphtheria, botulism etc.Sepsis, meningococcalemia by gram negative rods, etc.
ExamplesToxins created through Staphylococcus aureusBacillus cereusStreptococcus pyogenesBacillus anthracisToxins created through E.coliSalmonella Typhi, ShigellaVibrio Cholera
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