|MadSci Network: Microbiology|
A cytotoxin assay uses a cell tissue culture (for example Chinese hamster ovary cells) to detect (and sometimes quantify) a soluble biological toxin. As an example, the toxin or filtrate from a stool sample is applied to the cell culture. If a toxic substance (that the cells are sensitive to) is present in the sample, the cells will exhibit cytopathic effect (CPE) (cell pathology). Although these type of tests can detect toxic substances, they cannot identify the toxic substance A cytoxicity neutralization assay, is a biological assay in which the sample containing the unknown toxin is treated with a specific antibody. If the specific toxin is present in the sample it will be neutralized and will not demonstrate CPE. So if you run a standard CTA and get CPE then run a CTNA you can be sure that the specific toxin is present in the sample.
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