4.3 Testing for the presence of virus (haemagglutination test)
All strains of ND virus and some other avian viruses and bacteria have compounds
(haemagglutinins) on their envelopes that will attach to special sites (called
receptors) on the surface of red blood cells, causing them to clump together
(Thayer and Beard 1998). This process is called haemagglutination and is
depicted in Figure 9. The clumps of red blood cells settle in specific patterns
on glass slides or agglutination plates, or in the wells of plastic microtitre plates.
In our experience, this test is best performed using plastic 96-well V-bottomed
microtitre plates