Question

Which of the following properties of acquired immunity is the basis of vaccination?

Answer 1

The adaptive or acquired immune system of the body shows the following features -

• Specificity - It is specific for each type of pathogen. It can differentiate between various types of foreign molecules and antigens and produce specific antibodies against them.
• Diversity - Acquired immunity can develop against a wide variety of different pathogens, their toxins and diverse categories of molecules. It has the ability to produce millions of different types of antibodies depending on the antigens it encounters.
• Discrimination - It can differentiate between self (host’s) and non-self (foreign) cells and molecules.
• Memory - The first encounter between a specific foreign agent and the immune system generates an immune response to eliminate the foreign agent. The immune system often retains the memory of this encounter and manifests a faster and heightened response in case of a second encounter with the same foerign body.

Basis of vaccination:-

• The principle of immunisation or vaccination is based on the property of the immune system to retain memory.
• In the preparation of vaccines, killed, inactivated/weakened pathogens or antigenic proteins of pathogens are introduced in 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 recognize the pathogen quickly on subsequent exposure and attack the invaders with a massive production of antibodies.