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 performed 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 binding sites. 3. The adsorbed Vtg-antibody complexes are revealed through the peroxidase-antiperoxidase antibody, which is colored by o-phenylendiamin. 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 yield (335 ng/ml) the intra-assay coefficient 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 oestrogenized male rainbow trout yielded displacements parallel to the vitellogenin standard and to mature female serum or oestrogenized male serum. 6. This enzyme immunoassay is simple and easy to use. Its great specificity allows its use only for the rainbow trout species.