Development of Injectable and Oral Contraceptive Technologies and Their Assessment for Wildlife Population and Disease Management
Porcine Zona Pellucida Immunocontraception in
The National Wildlife Research Center and various cooperators have conducted
immunocontraceptive research with porcine
zona pellucida (PZP) for several years. Species tested in this research
include the white-tailed deer (Odocoileus virginianus) and
the coyote (Canis latrans).
The zona pellucida is a membrane that coats the egg. Sperm must bind
to and penetrate the zona pellucida to fertilize the egg. Immunizing
an animal with zona pellucida from pigs causes the production of antibodies
that bind to the host's zona pellucida and prevent fertilization of
the egg. Females successfully immunized with PZP will cycle and ovulate
normally but will not conceive.
The PZP vaccine is a highly effective contraceptive, but unfortunately
it causes multiple estrous cycles in female deer. These multiple cycles
and the recurrent sexual activity (and deer movements) associated with
them may increase deer-vehicle collisions and other deer-human conflicts.
The PZP vaccine does not seem to cause multiple estrous cycles in other
species on which it has been tested, and it may prove to be a highly
useful infertility agent for other wildlife.