Antigens are commonly referred to as substances that are capable of triggering an immune response in a host by activating the lymphocytes or initiating antibody production against infections. Depending upon the fact that they either enter the human body or originate within the body, viral antigens are classified as foreign or self-antigens respectively. Among these, self-antigens comprise mutated or overexpressed proteins. However, foreign antigens are likely to include bacteria, parasites, viruses, chemicals and sometimes toxins & proteins found in food products.