Monoclonal antibody capture fluorometric enzyme linked immunosorbent assay for detection of porcine growth hormone in plasma

A specific and sensitive fluorometric enzyme-linked immunosorbent assay (ELISA) was developed to measure growth hormone in swine plasma. Homogeneous pig growth hormone (pGH) was purified from pituitary gland, and used to raise monoclonal (mAb) and polyclonal antibodies. The mAb showing the highest reactivity was used as solid-phase antibody to capture pGH, while the rabbit biotin-labelled antibodies against pGH, followed by β-galactosidase-avidin-conjugate, were used for detection of mAb-bound pGH. The calibration graph was linear over the range 0.05-25ngml-1. Plasma did not interfere with the ability to measure pGH and the assay proved suitable for measuring pGH in plasma without any prior treatment of samples. Cross-reactivity and recovery tests confirmed the specificity of the method. The intra- and inter-assay coefficients of variation ranged between 7.2% and 9.7% and 12.1% and 18.7%, respectively. The analytical specificity of the method was validated by provocative tests for GH using the GH-releasing hexapeptide GHRP-6 in prepubertal gilts. The ELISA developed is sensitive, reproducible and suitable for measuring GH in pig plasma, and offers an alternative to radioimmunoassay.