In DNA vaccination, instead of giving a vaccine which is made from a disease-causing organism, a piece of genetic material (DNA) is used to immunize the patient. This DNA is in a form that will cause it to produce vaccine proteins within the host cells; in essence, the patient’s own cells become vaccine producing factories. The genetic instructions are given to the host. Because of the way DNA vaccines operate they are generally considered to be safer than conventional vaccines and can potentially make more effective vaccines against viral infections, parasites and cancers. However, despite many years of research, DNA vaccines tend not to work well in large mammals and there are currently no commercially available DNA vaccines for use in humans.