| Abstrakt: |
Previous studies evaluating porcine zona pellucida antigens for immunocontraceptive purposes have in some cases revealed altered ovarian function in association with antibody response. This study was undertaken in an attempt to identify zona immunogens that do not cause adverse endocrine effects. To this end, we investigated the effects of highly purified preparations of native and deglycosylated pig zona pellucida antigens on ovarian function and immune response in the rabbit. Thirty female rabbits were immunized, 5 per group, with 100 micrograms each of either 1) SIZP, solubilized isolated zonae pellucidae; 2) ZP3, a purified porcine zona preparation containing the two principle glycoproteins, ZP3 α and ZP3 β, endo-β-galactosidase-digested ZP3 glycoproteins (~ 30% deglycosylated) termed 3) ZP3 α/EBGD and 4) ZP3 β/EBGD; and chemically deglycosylated ZP3 α and ZP3 β (≥ to 92% deglycosylated), termed 5) ZP3 α/DG and 6) ZP3 β/DG. Rabbits injected with saline (n = 2) or Freund's adjuvant alone (n = 3) served as controls. Serum LH, FSH, estradiol, and progesterone were measured at 5-day intervals during seven 20-day cycles of hCG-induced pseudopregnancy over 42 wk. Anti-ZP3 titers, determined by RIA, developed in all treatment groups and correlated directly with carbohydrate content. Animals immunized with SIZP, ZP3, and ZP3 β/EBGD showed a significant elevation of LH and FSH and a significant decline of peak progesterone levels by the fourth pseudopregnancy cycle. In contrast, animals immunized with ZP3 α/EBGD, ZP3 α/DG, and ZP3 β/DG showed no significant elevations of gonadotropins and continued to display cyclic progesterone secretion in response to hCG. These data implicate zona carbohydrate in the pathogenesis of ovarian dysfunction associated with zona antigen immunization, and encourages the use of specific deglycosylated zona molecules in the continued efforts to develop a zona-based contraceptive vaccine. |
