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PZP Vaccine Knowledge Center

What Is the Porcine Zona Pellucida (PZP) Vaccine and How Does It Work?

A non-cellular membrane known as the zona pellucida (ZP) surrounds all mammalian eggs. The ZP consists of several glycoproteins (proteins with carbohydrates attached), one of which, ZP3, is the sperm receptor (the molecule which permits attachment of the sperm to the egg during the process of fertilization).

The PZP (Porcine Zona Pellucida) vaccine is derived from the ZP protein from porcine ova. PZP is produced by a complex process whereby the ZP is removed from the ovum, the glycoproteins are extracted, isolated, and converted into a vaccine. The PZP is emulsified with an adjuvant to which stimulates the animals’ immune system.

When this vaccine is injected into the muscle of the target female animal, it stimulates her immune system to produce antibodies against the vaccine. These antibodies also attach to the zona pellucida (sperm receptor) of the female’s own eggs distorting their shape, thereby blocking fertilization. In this adaptive system the immunological memory allows for the booster inoculations to have a more vigorous reaction thereby activating an immune response that blocks fertilization again

The PZP vaccine is usually given in a series of 2 vaccinations, 2-6 weeks apart, and then a booster every 8-12 months, depending on the species.

If you are interested in starting a non-captive wildlife project, please contact The Science and Conservation Center. There may be agencies in your state or country that must be contacted prior to starting a fertility control project.
Important! An import permit must be obtained prior to shipping PZP internationally.

Characteristics of the Ideal Wildlife Contraceptive

Minimum 90% efficacy
Able to deliver remotely (no animal handling)
Reversible contraceptive effects
Safe for use in pregnant animals
Absence of significant health side effects, Short- or long term
No passage of the contraceptive agent through food chain
Minimal effects upon individual and social behaviors
Low cost

PZP Vaccine

90% or greater efficacy
Able to deliver remotely with small darts
Regain fertility after discontinued use
Safe to give to pregnant and lactating animals
No debilitating health side effects even after long term use
Vaccine cannot pass through the food chain
Almost no effects on social behaviors
Low cost
Has been in use for 35 years
Effective across many species (additional benefit)

PZP Vaccine Delivery Protocol

To achieve effective PZP contraception, the initial treatment should be consistent with the seasonal pattern of reproduction for the individual species.

For species with a well-defined and short (2-3 months or less) breeding season , a minimum of two inoculations should be given during the first year of treatment. The first inoculation (primer) can be given any time of the year but the second inoculation must be given 1-2 months prior to breeding activity but no sooner than 2 weeks following the primer dose.

Until data are obtained that suggest otherwise, single annual booster inoculations may be given during subsequent years in some species. In year-round breeders, evidence indicates that booster inoculations should be given every seven to eight months (see Frank et al. 2005).

The standard dose of PZP antigen for animals is 100 µg of protein in phosphate buffered saline or sterile water. This dose may be adjusted downward for some species and will be determined prior to administration.

PZP Vaccine Training and Certification

PZP (or ZonaStat-H) is federally approved (EPA reg. no. 86833-1), thus individuals are required to undergo training through the Science & Conservation Center and obtain a pesticide applicators license through their state agency which represents the EPA (in Montana it is the Montana Department of Agriculture), prior to receiving or applying the PZP vaccine to wild equids. 

Equine contraceptive certification is offered at various times throughout the year. Training takes place over 3 days at the Science & Conservation Center during which attendees receive both educational and hands-on training. 

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Did you know?

African Elephants

Location: Africa

Population: 415,000

African elephants possess remarkable communication abilities. They employ various vocalizations like trumpets, roars, and rumbles to convey different messages within their herd. Alongside vocal cues, they also utilize body language, such as ear movements and trunk gestures, to express themselves. Among these, the low-frequency rumbles stand out, capable of traveling over long distances, playing a pivotal role in facilitating long-distance communication among these intelligent and sociable creatures.