Effect of Antigen Source on the Sensitivity of Avian Influenza Virus Haemagglutination Inhibition Test

The effect of variation in the source of Avian Influenza Virus (AIV) antigen on the sensitivity of Haemagglutination Inhibition (HI) test was examined. For this purpose, HI antigen of AIV subtypes H5 and H7 were either prepared or procured from different sources and used to determine the antibody levels against AIV subtypes H5 and H7 in chickens, using HI test. The HI test was standardized using 30 serum samples collected from a flock experimentally vaccinated against AIV subtypes H5N9 and H7N1 under controlled conditions. The test serum samples were collected from the field among chickens vaccinated against AIV subtypes H5N9 and H7N1 vaccines and subjected to HI test using a variety of HI antigens belonging to H5 and H7 subtypes. The results reflected that the type of AIV strain used in the HI antigens affected the levels of antibody titre determination from the same samples. The effect of this variation on reliability of data regarding sero-surveillance and vaccine efficacy testing for avian influenza among poultry is discussed.