In the present study, attempts were made to prepare fluorescein-conjugated polyclonal antibodies to be used for accurate routine diagnosis of NDV. Ten male boskat rabbits, ten male guinea pigs and two male goats were subcutaneously hyperimmunized with NDV (Lasota strain). The mean HI antibody titers raised against NDV in rabbits, guinea pigs and goats were 8, 7 and 8.5log2, respectively. The globulin contents of the prepared antisera were precipitated by ammonium sulphate and then conjugated with FITC. In order to evaluate the accuracy of the prepared conjugates in diagnostic purposes, direct FAT was applied for identification of NDV in impression smears prepared from various tissues of experimentally infected chickens using tenfold serial dilutions of the prepared conjugated antisera. Rabbits, guinea pig and goat conjugates showed clear positive reactions up to the dilution of 1/100000, 1/10000 and 1/1000000, respectively. The overall findings indicated that accurate and precise diagnosis of ND can be achieved by direct FAT using fluorescein-conjugated anti-NDV polyclonal antibodies.
Key words: Newcastle disease virus, Hyperimmune sera, Fluorescien-isothiocyanate.