Etude de pré-validation du test de cytodétection des toxines diarrhéiques (acide okadaïque) dans les coquillages contaminés

A cytodetection test of diarrhoeic phycotoxins was developped by both IFREMER and Nantes University. Its principle is based on cell morphological changes of KB strain, induced by inhibition of protein-phosphatases involved in cytoskeleton building. This test has been shown sensitive, fast and specific for protein phosphatase inhibitors like diarrhoeic toxins (specialy okadaic acid in France). It shows a high repeatability and reproducibility with pure toxin for the cell strain is highly stable (minimal active concentration or MAC = 125 ng OA.ml-1) In order to evaluate the efficiency oftransfering.the method to coastallaboratories, the assay was subjected to a prevalidation study. The sampling, consisting of five species of shellfish, was carried out during two years in the context of the REPHY monitoring network and was therefore monitored by the mouse test. Samples extracts were divided between four laboratories which have performed on them the KB cytotoxicity test, independently and blindly . Extracts were also analysed by HPLC. The results show 50% homogeneity between the operators, an the species considered. This weak value is probably due to the difficulty to appreciate the cell morphological differencies, corresponding to the MAC. When considering how to manage a ban shellfish farming areas , the comparison between KB test and mouse-test shows that KB test is more severe but does not show faise negative. That is in agreement with the european recommandations. Nevertheless, extracts of sorne species ( Glycymeris and Cerastoderma), proved to be non toxic on mi ce but were active on KB cells, consequently, sorne interferences would exist in certain cases. Globally, the procedure fits with the constraints of a routine teste but it cannot be considered as a semi quantitative-test because of its weak reproducibility. It is preferable to use it as a screening test for the most traded shellfish, like mussel.