Binding Assays for the Quantitative Detection of P. brevis Polyether Neurotoxins in Biological Samples and Antibodies as Therapeutic Aids for Polyether Marine Intoxication
Annual rept. 1 Dec 1986-30 Nov 1987
MIAMI UNIV CORAL GABLES FL
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The polyether lipid-soluble toxins isolated from the marine dinoflagellate Ptychodiscus brevis formerly Gymnodinium breve bind to a unique site, Site V, associated with voltage-dependent sodium channels in rat brain synaptosomes. Using tritiated PbTx-3 as a specific probe for binding a Site V, a K sub d of 2.9 nM and a Bmax of 6.8 pmolesmg synaptosomal protein has been determined. Binding equilibria and displacement by unlabeled PbTx-3 occur in a comparable concentration range to that of saxitoxin site I. Labeled toxin can be displaced in a competitive manner by any of the other 5 naturally-occuring toxins the quantitative displacement ability of each appears to reflect individual potency in fish bioassay. Preliminary K sub i calculations have been made for four of the toxins. A comparison of ED50 in radioimmunoassay and ED50 in synaptosome binding for detection of toxins which possess the structural backbone of PbTx-3, the immunizing hapten. Thus, the two assays have quantitative applicability the former with respect to potency and the latter with respect to structure. Preliminary experiments involving conversion of the radioimmunoassay to urease enzyme linked form have been successful. Keywords Antibodies Brevetoxin.