EFFECT OF PEPTIDE TO CARRIER RATIO ON THE IMMUNE AND OVARIAN RESPONSETO INHIBIN IMMUNIZATION IN CATTLE

We report on the effects of the peptide to carrier ratio on the immune and biological response io inhibin immunization in cattle. A peptide sequence from the alpha(C)-subunit of bovine inhibin was synthesized a nd conjugated to human serum albumin (HSA) at ratios of 4.3 moles (L) and 13.1 moles (M) of peptide per mole of HSA. Hereford-cross heifers (n = 6 per group) were injected with 3 mg of one of the peptide conjug ates at primary, followed by a booster injection (1.5 mg) 11 weeks lat er. Control heifers (n = 6) were injected with HSA only. Blood samples were taken at regular intervals to measure antibody titre. Ovulation rate was measured by ultrasonography. Antibodies were generated in bot h peptide immunized groups. Control heifers and group L heifers had 1 ovulation at all ovulatory cycles monitored. Ovulation rate was increa sed (P < 0.05) in group M immunized heifers, with four of six heifers having twin ovulations in the first cycle following boost. These data support those of previous studies which indicated that immunization ag ainst the alpha(C)-subunit of bovine inhibin significantly disrupted t he mechanism(s) controlling ovulation rate in cattle. It also indicate s that both the immune and associated biological response, is dependen t on the nature of the conjugate used for immunization, specifically t he ratio of peptide to carrier. (C) 1997 Elsevier Science B.V.