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 alpha and ZP3 beta,
endo-beta-galactosidase-digested ZP3
glycoproteins (approximately 30% deglycosylated) termed 3) ZP3 alpha/EBGD and 4) ZP3 beta/EBGD; and chemically deglycosylated ZP3 alpha and ZP3 beta (greater than or equal to 92% deglycosylated), termed 5) ZP3 alpha/DG and 6) ZP3 beta/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 beta/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 alpha/EBGD, ZP3 alpha/DG, and ZP3 beta/DG showed no significant elevations of
gonadotropins and continued to display cyclic
progesterone secretion in response to hCG.(ABSTRACT TRUNCATED AT 250 WORDS)