Question

Immunity acquired after an infection is

Answer 1

Infection is the entry and multiplication of pathogens within the body.

Active immunity

• Active immunity is the type of immunity developed in the body due to production of antibodies in the host’s body after exposure to an antigen.
• Antigens present on the cell surface of infectious pathogens interact with B-lymphocytes and trigger them to divide and differentiate into plasma cells and memory B cells.
• The plasma cells produce antibodies that bind with the antigens and eliminate them.
• The memory B cells are the lymphocytes which are capable of memorising their first encounter with the antigen and can launch a very fast second response in case of subsequent encounters with the same antigen in future.
• Upon exposure to the same antigen in future, the memory cells immediately differentiate into plasma cells which produce antibodies and eliminate the antigens much faster. Thus, active immunity is acquired after an organism suffers from an infection.