question_answer 74)

  What is the basic principle of vaccination? How do vaccines prevent microbial infections? Name the organism from which hepatitis-B vaccineis produced.

Answer:

                  The principle of vaccination is based on the property of 'memory' of immune system .In vaccination, a preparation of antigenic proteins or inactivated/live but weakened pathogens is introduced into the body. The antigens generate primary immune response by producing antibodies along with memory B-cells and T-cells. When the vaccinated person is attacked by the same pathogens, the existing memory B-cells and T-cells recognize the antigen and overwhelm the invaders with massive production of lymphocytes and antibodies, Hepatitis-B vaccine is produced from yeast.