ENZYME-LINKED IMMUNOSORBENT-ASSAY (ELISA) FOR RAINBOW-TROUT (ONCORHYNCHUS-MYKISS) VITELLOGENIN

1. A specific and simple enzyme-linked immunoassay for rainbow trout ( Onchorynchus mykiss) vitellogenin (Vtg) is described. This assay is pe rformed using a rabbit antiserum for Vtg purified from trout plasma. 2 . This assay is based upon the competition between soluble Vtg and Vtg adsorbed on microtiter plates, for the rabbit anti-Vtg antibody bindi ng sites. 3. The adsorbed Vtg-antibody complexes are revealed through the peroxidase-antiperoxidase antibody, which is colored by o-phenylen diamin. This assay can be performed in a day and a night. 4. Under our conditions, 90-20% of binding gave a sensibility range of 33-1473 ng/ ml. With almost a 50% binding yeld (335 ng/ml) the intra-assay coeffic ient of variation(CV) was 5.2% (n=26) and the inter-assay CV was 12.5% (n=5). 5. There was low immunological cross-reactivity with sera from other salmonids and with ovary extracts. Extracts of liver from oestr ogenized male rainbow trout yielded displacements parallel to the vite llogenin standard and to mature female serum or oestrogenized male ser um. 6. This enzyme immunoassay is simple and easy to use. Its great sp ecificity allows its use only for the rainbow trout species.