Active Immunization against Adrenocorticotropic Hormone in Growing-Finishing Barrows: An Initial Trial and Evaluation

Abstract

MATERIALS AND METHODS Antigen preparationPorcine adrenocorticotropic hormone (ACTH) extracted from the pituitary (Sigma Chemical Co., Saint Louis, MO, USA) was conjugated to keyhole limpet hemocyanin (KLH) or human histone carrier using either 3-maleimidobenzoic acid N-hydroxysuccinimide (MBS) or glutaraldehyde, under a 2 × 2 × 2 factorial arrangement of treatments; main effects included hapten (ACTH vs none), carrier and crosslinker. The hapten-carrier conjugation using MBS was performed following the procedure of Liu et al. (1979). Briefly, 70 mg KLH or histone dissolved in 4.4 ml of 50 mM phosphate-buffered saline (PBS), pH 7.4, was mixed with 875 µl of 6.0 mg MBS/ml N, N-dimethyl formamide solution for 30 min on a rocker at room temperature. After removing free MBS on a P-6 disposable gel filtration column (Bio-Rad, Hercules, CA, USA), fractions corresponding to activated carrier were pooled and mixed with 13.2 ml PBS containing 70 mg dissolved ACTH or none for 3 h on a stirring plate. The hapten-carrier