Bacterial Toxins
Poisonous substance produced by certain species of bacteria are called bacterial toxins.
There are two types of toxins;
1. Exotoxins
2. Endotoxins
Exotoxins
1. Heat - labile proteins secreted outside cell wall by certain species of gram +ve and garm -ve bacteria.
(Inactivated at high temperature)
2. It is antigenically strong, so it used for making toxoids.
3. Toxoids are non poisonous, non toxic substance produced by treatment of exotoxins with formaldehyde.
As result, their toxic proteins are destroyed but antigenic properties remains high to stimulate antibodies.
For example;
Tetanus toxoid
Diphtheria toxoid
Endotoxins
Endotoxins are heat stable lipopolysaccharides (LPS), which form integral part of cell wall of gram -ve bacteria.
Their toxicity depends on lipid component (lipid A).
These are not recreated outside bacterial cell wall.
These are only obtained by cell lysis.
(After death of gram -ve bacteria).
Toxoid can't made from endotoxins.
Their toxicity cannot be completely neutralize by antibodies and weakly antigenic.
1. Pyrigenicity; increase body temperature
2. Endotoxic shock; large dose of endotoxins cause endotoxic shock.
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