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

Character	Exotoxins	Endotoxins
Definition	The 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 by	The majority of Gram positive bacteria are additionally Gram negative bacteria.	Gram negative bacteria.
Chemical Nature	Protein (polypeptide) complexes	Lipopolysaccharide-protein complexes
Molecular weight	10KDa.	50-1000KDa.
Components	Usually , 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 present	Hyaluronidase, Collagenase, certain protease, Nuclease, Neuraminidase, Certain protease, Phospholipase A	Catalase, Fibrolysin, IgA Catalase, Fibrolysin, IgA IgG proteases
Chromosomal Location	They are located on extrachromosomal gene (e.g. plasmids).	It is located on chromosomal genes.
Secreted by	Organisms secrete this information ; living cells	Part of the cell wall that is integral Cell wall; cell lysed
Secretion	The cell is sucked out of its secret.	Generally, cells are not released from the cell until the cell dies.
Cell Lysis	Not necessary	Required
Stability to heat	Heat labile (60-80degC)	Stable heat (250degC)
Filtration	Filterable	Not Filterable
Boiling	Denatured by boiling	Not denatured upon boiling.
Enzyme Activity	Most of the time, it is involved in enzymatic activities.	The activity of enzymes is either absent or minimal.
Specificity	Exotoxins 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 receptors	Typically, they bind to receptors.	The receptors are not specific enough to be identified.
Specificity to the bacterial strain	Particular to a specific strain of bacterial.	There is no specificity to any bacteria type.
Immunogenicity	Highly immune-enhancing.	Immunely weak.
Fever Induction	No	The cause of fever is the induction by interleukin 1 (IL-1) production.
Toxicity	Highly toxicand fatal in small amounts.	Moderately toxic, fatal when in mg amounts.
Method of action	Many different ways (Mostly through similar enzymes).	Includes TNF and Interlukin-1
Potency	The 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.
Effects	It 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 Antibodies	It is possible to neutralize.	It is not neutralized.
Detection	It is detected by a variety of tests (neutralization or precipitation, for example.)	The detection was made by Limulus Lysate Assay.
Conversion to Toxoids	Possible (On treatment with formalin). eg. to prevent botulism, diphtheria, and Tetanus.	It’s not possible.
Available vaccines	Effective vaccines available.	No effective vaccines available.
Infections that are caused by	Tetanus, diphtheria, botulism etc.	Sepsis, meningococcalemia by gram negative rods, etc.
Examples	Toxins created through Staphylococcus aureus, Bacillus cereus, Streptococcus pyogenes, Bacillus anthracis	Toxins created through E.coli, Salmonella Typhi, Shigella, Vibrio Cholera