A toxic or poisonous substance produced by the biological processes of biological organisms.
A toxin that has had its toxic properties removed, but retains its ability to generate an immune response.
A poisonous product formed by an organism, such as a pathogenic bacterium, a plant or an animal, usually having a high molecular weight, often a protein or a polysaccharide, but occasionally a low-molecular weight agent such as tetrodotoxin.
An altered form of a toxin, possessing little or no toxic power.
a poisonous substance produced during the metabolism and growth of certain microorganisms and some higher plant and animal species
a bacterial toxin that has been weakened until it is no longer toxic but is strong enough to induce the formation of antibodies and immunity to the specific disease caused by the toxin;
a poison of plant or animal origin, especially one produced by or derived from microorganisms and acting as an antigen in the body.
A toxoid is an inactivated toxin (usually an exotoxin) whose toxicity has been suppressed either by chemical (formalin) or heat treatment, while other properties, typically immunogenicity, are maintained. Toxins are secreted by bacteria, whereas toxoids are altered form of toxins; toxoids are not secreted by bacteria.
A toxin is a harmful substance produced within living cells or organisms; synthetic toxicants created by artificial processes are thus excluded. The term was first used by organic chemist Ludwig Brieger (1849–1919), derived from the word toxic.Toxins can be small molecules, peptides, or proteins that are capable of causing disease on contact with or absorption by body tissues interacting with biological macromolecules such as enzymes or cellular receptors.