Abstract :
The current study describes the optimization and validation of an enzyme-linked
immunosorbent assay (ELISA) for the quantification of growth hormone (GH) in blood
plasma of goats, Capra hircus. A microtiter plate based competitive assay was developed
using a capture ELISA for anti-ovine GH and biotinylated ovine GH. Ovine GH standards
were prepared in charcoal–dextran stripped goat plasma. The assay was optimized in terms
of sensitivity, specificity and precision. The sensitivity of the assay was 50 pg GH/100 l,
which corresponds to 0.5 ng/ml plasma. A dose–response inhibition curve resulting from
serially diluted goat plasma was parallel to the standard curve using ovine GH and thus it
confirmed the similar specificity of ovine GH standard and endogenous GH in goat plasma
for ovine GH antibody. The precision of the assay, i.e., the intra- and inter-assay coefficients
of variations (for repeatability and reproducibility, respectively) for the pooled plasma samples
containing two GH concentrations (32 and 2 ng/ml) were 6.72%, 11.2%, 7.1% and 12.8%,
respectively. To physiologically validate the assay, goats were treated with human growth
hormone-releasing factor (hGRF) and there was an immediate rise in plasma GH levels in
hGRF-treated goats. This ELISA is economic, safe, quick (requires only 48 h), convenient and
the first competitive enzyme immunoassay described for caprine GH.
