A competitive enzyme immunoassay for follicle-stimulating hormone in ovine plasma using biotin-streptavidin amplification

Abstract

To determine follicle-stimulating hormone (FSH) concentration in ovine plasma, a second-antibody enzyme immunoassay using biotin-streptavidin amplication (BS-EIA) was developed and was validated by comparison with a routine radioimmunoassay (RIA). Ovine FSH was labelled with D-biotinyl-b.epsi;-aminocaproic acid-N-hydroxysuccinimide ester (biotin-7-NHS). The minimum and maximum detection limits were 0·40 ng mL^-1 and 25·0 ng mL^-1 respectively in the BS-EIA. Plasma samples from three superovulated ewes were measured for FSH by both BS-EIA and RIA. Correlation between values obtained by BS-EIA and RIA was 0· 86 (n = 106), and the linear regression had a slope of 0·88 and an intercept of -0·07 (R² = 0·74). The baseline of BS-EIA was slightly lower than that of RIA (0·69 ng mL^-1v. 1·10 ng mL^-1). The intra-assay and inter-assay coefcients of variation in BS-EIA were 13·8% and 16·7% (n = 106) respectively. The recovery rates were 104· 8 2·7% (mean±s.e.m., n = 14). Changes in plasma FSH concentration from superovulated ewes evaluated by BS-EIA corresponded well with the results of routine RIA.