It is a fraction obtained from the plasma of normal individuals and rich in antibodies against viral antigen. The antibody present in gamma globulins is directed against superficial envelope of susceptible virus and block its penetration into the host cell (phase 1 inhibitor).
Therapeutic uses: Intramuscular injection given during the early infection stage can partially alleviate the progression of measles, poliomyelitis, rabies and hepatitis. Protection lasts for 2-3 weeks and injection can be repeated every 2-3 weeks. It confers a passive immunity to the virus.