Antibodies are produced B lymphocytes in human bodies as the primary immune system. The antibody is a protein molecule which destroy bacteria or virus called as antigen. When a person is affected by bacterial or viral infection antibodies are produced. Once an antibody is created it still remain for future infections for the lifetime of an individual. Various antibodies are produced in response to various infections. For example antibodies produced for chicken pox and influenza is different.
The antigen is the harmful substance like bacteria, virus, fungi or toxin which cause the production of antibody by the immune system. Antigen invades into a body from infections of various diseases. It also created by the body due to toxic substances.
Antibiotics are used to destroy or inhibit the growth of bacteria and microorganisms and are used to prevent infectious diseases in general. Most of them used for medical purposes are manufactured synthetically whereas some are produced by fungi and bacteria. It has no effects on viral diseases. Penicillin is most common antibiotics against various bacterial infections for which Alexander fleming was awarded Nobel price in 1945.