- A substance that has been treated to destroy its toxic properties but retains the capacity to stimulate production of antitoxins, used in immunization.
- A toxin which has lost its toxophoric group, but has retained the haptophoric group, so t. at it can still unite with the corresponding antitoxin. Such bodies result from the toxins by heat and age. They can be utilized in immunization, as though the toxophoric group were present.
- An altered form of a toxin, possessing little or no toxic power.
- A <xref>toxin</xref> that has had its <xref>toxic</xref> properties removed, but retains its ability to generate an <xref>immune response</xref>
- 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