[Kinetics of NDV-specific antibodies in hens: I. Methods and reproducibility of HAH tests]

1. It is recommended to use for the hemagglutination inhibition test (HI test) 0,85% saline solution (pH 6,8), for dilution of sera (log2 dilution), NDV (4 HA units) and for suspension of chicken red blood cells (1%). 2. No evidence was obtained that the use of various buffers for the HI test influenced the titer. 3. Various strains of NDV (G 35, Herts, Italia, Montana, R 1111) have similar HI titers. However for standardization purposes it is recommended to use known and characterized strains of NDV such as Montana or Italia. 4. Similar results were obtained using the macro method according to Salk and the micro method according to Takatsy. 5. The use of the recommended procedure results in high reproducibility of the HI titers obtained.