Edward Jenner$(1796)$, an English physician prepared the first vaccine when he injected the fluid from the sore of milkmaid suffering from cowpox into the body of a healthy boy which when exposed later to smallpox, exhibited resistance to the disease. Louis Pasteur $(1879)$ found that ageing cultures of cholera bacteria were too weak to cause disease, when injected into chickens. But chickens injected with these cultures became immune of fowl-cholera. By using this method, Pasteur developed a vaccine against rabies in $1885 .$