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

DOUBLE DIFFUSION IN TWO DIMENSION
(OUCHTERLONY TEST)

• In this test two or more wells are cut into the agar.
• Antibody is added to one well and antigen to the other wells.
• Lines of precipitation form where antigen and antibody which are both diffusing into the agar meet in optimal proportions.
• This test can be used to find out relationship between antigens.
• The possible outcomes of the test are
  • The two precipitin lines join - line of identity - the two antigen are identical
  • The two lines cross each other - line of non identity - the two antigens are completely different
  • The lines merge with a spur formation - a partial identity exists indicating that the antigens share an epitope but one of the antigens possess an epitope not present in the other .
• Coggins test is a gel diffusion test used to diagnose equine infectious anemia (EIA) in horses.