They are an excellent weapon in disease prevention. Vaccines stimulate an animal's natural defense system, called the immune system, which protects the body from an invading illness. Vaccines are important because they help prevent infectious diseases which can spread rapidly through livestock herds and some illnesses work so quickly that medicine can not help. Genes and Vaccines Diseases are caused by micro-organisms such as bacteria or viruses. Inside the DNA are genes which act like libraries of hereditary information.
Every gene is responsible for producing a particular type of protein.
Each protein has a particular role to play. These proteins are involved in stimulating protection from disease and are called antigens. Different diseases can be recognized by the unique shape and structure of their antigens. The antigen's job is to alert the animal's immune system that a disease has invaded its body. When the immune system recognizes the antigens it prepares for battle against the disease.