RAPID ENZYME-LINKED IMMUNOSORBENT TESTS FOR DETECTING ANTIBODIES TO EDWARDSIELLA-ICTALURI IN CHANNEL CATFISH, ICTALURUS-PUNCTATUS, USING EXOANTIGEN

A rapid enzyme-linked immunosorbent assay (ELISA) was developed to evaluate sera from channel catfish with and without Edwardsiella ictaluri infection. Anti-E. ictaluri antibodies were detected in the sera from 94 of 100 infected catfish. Specific antibodies were not detected in the sera from 100 non-infected fish. The ELISA was based on the Falcon Assay Screening Test (FAST) and was performed in 30 min. An E. ictaluri exoantigen was used in the FAST-ELISA. The immunodominance of the exoantigen was shown by reactivity with monoclonal antibody (MAb) against the predominant epitope of E. ictaluri. The FAST-ELISA was found to be ideal for serodiagnosis and seroepidemiological purposes of detecting and monitoring E. ictaluri antibody responses.