Fertility Control in the Bitch by Active Immunization with Porcine Zonae Pellucidae: Use of Different Adjuvants and Patterns of Estradiol and Progesterone Levels In Estrous Cycles1,2

Abstract

To determine the changes in patterns of 17 beta-estradiol and progesterone levels underlying abnormal cycles in bitches immunized with solubilized crude porcine zonae pellucidae (cPZP), to attempt to circumvent these problems by immunizing with a purified zona fraction (pPZP), and to test the effectiveness of different adjuvants, bitches were immunized with cPZP or pPZP 2-6 times with no adjuvant, Freund's adjuvant, alum adjuvant, or the adjuvant CP-20,961. The bitch immunized without adjuvant had a low titer with a normal cycle and fertility. Immunization with cPZP and adjuvant produced moderate to high titers of antizona antibodies and infertility. Bitches with high titers experienced abnormal estrous cycles. Estradiol rose during proestrus, but instead of falling sharply in early estrus as in controls, it remained elevated. Progesterone did not rise. The moderate-titered bitches had normal cycles and steroid patterns. Bitches immunized with pPZP had moderate titers. Cycles were normal after 3 injections, but after 6 injections one bitch had an abnormal cycle. One pPZP-immunized bitch remained fertile but the others were infertile. Alum was the mildest adjuvant, causing no injection site lesions, but the highest titers occurred with Freund's and CP-20,961 adjuvants. All three adjuvants induced titers sufficient to inhibit fertility. Infertility in bitches immunized with PZP may be due to prevention of zona penetration, because their antisera inhibited zona penetration of oocytes by spermatozoa in vitro. However, alterations in ovarian function preventing ovulation and luteinization could be involved in high-titered bitches.

Long-term effects of porcine zonae pellucidae immunocontraception on ovarian function in feral horses (Equus caballus)

“…The date of parturition indicates an unusually late conception (~2 5 August) for Assateague mares and suggests that her antibody titres had fallen to a concentration which allowed conception. Urinary endocrine data for oestrone conjugates and non-specific progesterone metabolites were consistent with data on plasma hormones for mares in late pregnancy (Ginther, 1979 These alterations in ovarian function are consistent with data from PZP-treated rabbits (Skinner et al, 1983(Skinner et al, , 1984, dogs (Mahi-Brown et al, 1985) and baboons (Dunbar et al, 1989).…”

Fecal 20-oxo-pregnane concentrations in free-ranging African elephants (Loxodonta africana) treated with porcine zona pellucida vaccine

“…Therefore, further investigation of cycling patterns in both free-ranging untreated and treated populations of African elephant is necessary to evaluate the effect of pZP on the reproductive cycle. Our data demonstrate ongoing luteal activity in all elephants treated with pZP vaccine at TPNR, challenging current speculations that pZP treatment may alter ovarian function by destroying oocytes or follicular cells as has been proposed in dogs [54]. Furthermore, our results demonstrate that in the two years following pZP treatment at TPNR, estrous cycles are present amongst nearly half of treated individuals, indicating ovarian functionality.…”

Antifertility effects of porcine zona pellucida-3 immunization using permissible adjuvants in female bonnet monkeys (Macaca radiata): reversibility, effect on follicular development and hormonal profiles

“…The antifertility effect of active immu¬ nization with PZP antigens has been demonstrated in several animal models (Skinner et al, 1984;Mahi-Brown et al, 1985;Sacco et al, 1989). However, some of these studies have shown a transient (Sacco et al, 1983) or an irreversible (Skinner et al, 1984) …”