Human Health and Disease — BIOLOGY STD 12 Science — Question

→The principle of immunisation or vaccination is based on the property of 'memory' of the immune system.
→In vaccination, a preparation of antigenic proteins of pathogen or inactivated/weakened pathogen (vaccine) are introduced into the body.
→The antibodies produced in the body against these antigens would neutralise the pathogenic agents during actual infection.
→The vaccines also generate memory- B and T-cells that recognise the pathogen quickly on subsequent exposure and overwhelm the invaders with a massive production of antibodies.
→If a person is infected with some deadly microbes to which quick immune response is required as in tetanus, we need to directly inject the preformed antibodies, or antitoxin (a preparation containing antibodies to the toxin).
→Even in case of snakebites, the injection which is given to the patients, contains preformed antibodies against the snake venom. This type of immunisation is called passive immunization.
→Recombinant DNA technology has allowed the production of antigenic polypeptides of pathoges in bacteria or yeast.
→Vaccines produced using this approach allow large scale production and hence greater availability for immunisation, e.g., hepatitis B vaccine produced from yeast.