The relationship between domesticated animals and humans is a close one, and has existed for at least ten thousand years. It is important to understand the immune defenses of many animals, in addition to the immune defenses of humans and mice. Animals have evolved many different ways of responding to bacteria and viruses. Many diseases threatening humans are zoonotic, which means that they are shared between humans and animals. Designing better vaccines for animals and selective breeding for better immune responses adresses the dual goals of protecting animal health and economic productivity directly and indirectly protecting human health by decreasing the reservoirs of bacteria and viruses carried by animals. The goal of our project is is characterize the genetic diversity of a family of immune receptors in domesticated animals and use this information for selective breeding and the design of better vaccines.