Purpose: To quantitate serum antibody to a specific avian pathogen


  1. Viral antigen is precoated onto a microtiter plate.

  2. Serum is added to the coated wells. If antibody is present, it will bind specifically to the viral antigen. Unbound material is removed by a washing procedure.

  3. An anti-chicken antibody conjugated with horseradish peroxidase enzyme is next added to the viral antigen-antibody complex. This reagent binds to any chicken antibody that remains in the plate.

  4. Finally, O-phenylenediamine.2HCL (OPD) and hydrogen peroxide substrate is added to the wells of the plate. When antibody is present, the enzymatic reaction which occurs results in a color change which can be read visually or by a spectrophotometer.

  5. Color development and intensity can be directly related to the amount of antibody in the original serum sample. Commercial kits are available for many of the poultry diseases (e.g. NC, Br, AE, AI, MG, IBD, REO, and RE). Some laboratories have automated systems and computers which analyze results and generate a graphic and numerical report.



Purpose: To quantitate antibody to specific viral avian pathogens.

1.  The test has two parts:

  1. Neutralization - The virus and the serum are mixed in a test tube and incubated for a specified time period. If antibody to the specific virus being tested is present, it will neutralize the virus.

  2. Assay - The unneutralized virus is assayed in a cell culture system or in embryonating chicken eggs. The amount of unneutralized virus depends on the amount of antibody present in the test serum.

2.  This is a well established diagnostic and research tool but compared to the HI and ELISA tests is much more expensive and time consuming.


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