Potentiation of the growth-promoting activity of porcine growth hormone (pGH) with an antibody generated in rabbits to the peptide sequence pGH110-118.

An effort was made to identify the antigenic epitope(s) of porcine GH (pGH) capable of inducing antibodies which would enhance the growth-promoting activity of the hormone. Several peptide sequences of the pGH molecule were synthesized and the antibodies to these peptides were generated in rabbits. The majority of these antibodies were found to be immunoreactive with both intact pGH and their respective peptide antigens. The biological activity of the antibodies was tested in growth-retarded hypophysectomized rats. Daily injections with pGH alone significantly increased their growth rate and treatment with a combination of pGH and antibody specific to the peptide sequence 110-118 further heightened the somatogenic effect. Administration of this antibody alone did not enhance the growth rate of hypophysectomized rats, neither did antibodies raised to intact pGH or the other peptide sequences. The present findings suggest that antibody with a particular pGH epitope specificity is able to increase the somatogenic activity of pGH and that the peptide corresponding to pGH amino acids 110-118 may prove useful in the development of growth promoting vaccines.