This article is a reprint from the Science and Conservation Center
In 1998, a new approach to wildlife contraception was launched. Immunocontraception is based on the same principles as disease prevention through vaccination. We vaccinate ourselves and other animals against diseases by injecting dead or attenuated (weakened) disease bacteria or viruses, or molecules which are harmless but similar to the toxins that these disease organisms produce. Our immune systems produce antibodies that attack the material we injected and any similar organisms or their toxins in our systems. An immunocontraceptive vaccine works in the same manner, only it causes the production of antibodies against some essential event or structure in the reproductive process.
There are a variety of immunocontraceptive vaccines under development, including vaccines against brain reproductive hormones such as gonadotropin-releasing hormone (GnRH); pituitary hormones such as luteinizing hormone (LH), follicle-stimulating hormone (FSH); vaccines against steroid reproductive hormones such as estrogen and progesterone; and vaccines against the sperm or the egg, which in turn prevent fertilization.
The advantage of vaccines are that they can be delivered in very small doses, and because they are primarily protein, they are readily destroyed in digestion and cannot pass through the food chain (see Orser 1965). The primary disadvantage is that there is sometimes significant species differences with regard to efficacy, and even differences between individual within the same species. The vaccine which has so far had the largest application to wildlife is the porcine zona pellucida, or PZP vaccine.