Comparison of the enzyme‐linked immunosorbent assay (elisa), haemagglutination inhibition test and agar gel precipitation test for detection of antibodies to avian infectious bronchitis virus

Summary The immune response after vaccination with infectious bronchitis virus (IBV) under field conditions was measured by the ELISA, haemagglu‐tination‐inhibition (HI) and agar‐gel precipitin (AGP), tests. Vaccinations were performed in three flocks and one experimental group via the drinking water with the vaccine strains H 120 and H 52. In each flock 40 random serum samples were taken every 2 weeks and tested individually. In the experimental group blood samples were collected every week from each of the 10 chickens. The primary vaccination with H 120 resulted in a rapid increase of antibody titre as detected by ELISA followed by a slow decrease over the next few weeks. By the HI and AGP tests no antibody responses could be seen after this primary vaccination. Revaccination with the H 52 strain provoked a further increase in ELISA titres. In the experimental group, and in flock W, a similar increase occurred by the HI test and precipitating antibodies appeared. The formation of HI antibodies in flock ...