VMC 221: Veterinary Immunology and Serology (1+1)

INTRODUCTION- BIOLOGICALS AND IMMUNOLOGICALS

• Edward Jenner in 1796 observed that dairymaids contracted with cowpox seemed to be protected against small pox.
• He injected fluid from blister of cowpox into 8 years old boy and observed protection against small pox. This technique of introducing immunity became known as vaccination (Vacca in Latin means cow).
• Small pox was controlled and eventually the disease was eliminated.
• Vaccination is a procedure of introducing a safe antigen (vaccine) into a host to induce immunity against infection. In general vaccine is a suspension of living or inactivated organisms used as antigen to provide immunity against infection. Several developments have come to produce safe and effective vaccines and also in delivering the vaccine.
• Immune Response is the reaction of the body to foreign substances resulting in the formation of antibodies and lymphokines. When an antigen or infection enters in a body, it invokes a series of reaction leading to either succumb to infection or provide immunity. The immunity can be acquired by active or passive ways by introducing a safe and potent antigen (vaccine) into a body.
• Active immunity is produced when the host reacts to an antigen and produce antibody. The immunity develops slowly and persists for a long time. Active immunity may be acquired by two different ways
  • Natural: When produced due to natural infection by infectious organisms 
  • Artificial: This is produced by the host’s body in response to inoculation of an antigen.
• Passive immunity: The antibody is prepared elsewhere and subsequently introduced into host’s body. The immunity is rapidly established but persists for short duration. Passive immunity is also acquired by two different ways: a) Natural: Maternal antibody from mother to foetus (Transplacental transfer) or colostrum antibody through milk from mother to neonates.b) Artificial: By injection of immune serum or by transfer of lymphocyte or immune cells.