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

THE PRECIPITIN RING TEST

• The antigen is carefully layered over the antiserum, without mixing so that an interphase is formed. Diffusion of each reagent occurs into the other.
• If the system is homologous, precipitation will occur at the point in the tube where the proper ratio of antigen to antibody is reached.
• Example: Ascoli’s test for anthrax diagnosis.