AMPLIFIED IMMUNOASSAY ELISA-ELCA FOR MEASURING CLOSTRIDIUM-BOTULINUM TYPE-E NEUROTOXIN IN FISH FILLETS

The measurement of Clostridium botulinum type E toxin in fish was acco mplished using an amplified immunoassay (enzyme-linked immunosorbent a ssay-enzyme-linked coagulation assay [ELISA-ELCA]) based on the coagul ation cascade. Fresh catfish fillets inoculated with a mixture of spor es from five strains of C. botulinum type E were packaged in high barr ier film with air, vacuum and modified atmosphere and stored at 4, 8 o r 16 degrees C for up to 75 days. Toxin production was monitored durin g storage by both mouse bioassay (trypsin and non-trypsin treated) and ELISA-ELCA on the non-trypsinized samples. All 26 inoculated products that were positive by the mouse bioassay were also positive by ELISA- ELCA. Of 35 uninoculated samples which were not toxic in mouse bioassa y, none were positive by ELISA-ELCA; of 73 inoculated samples which we re not toxic by mouse bioassay, 14 had toxin measurable by the ELISA-E LCA. The position of these immunoassay-positives in the sampling seque nce indicated that the toxin was identified by the immunoassay before it was found in the mouse bioassay. These results suggest that the ELI SA-ELCA technique is a usable alternative to the mouse bioassay for mo nitoring C. botulinum type E toxin production in fish challenge studie s.