An improved ELISA method, using a streptavidin-biotin complex, for detecting Marek's disease virus antigens in feather-tips of infected chickens.

To improve sensitivity in the detection of Marek's disease virus (MDV) antigens in extracts of feather tips from infected chickens, we added a preformed streptavidin-biotin complex to the standard enzyme-linked immunosorbent assay (ELISA). Rabbit anti-chicken IgG-alkaline phosphatase that is used in the standard ELISA as the conjugate was replaced by a biotinylated rabbit anti-chicken IgG plus the streptavidin-biotin peroxidase complex (ABC) system. The ABC-ELISA system was correlated to the standard ELISA. There was increased sensitivity in the detection of MDV antigens present at low concentrations, while at the higher concentrations detection was similar to that in the standard ELISA. Both ELISA systems had the same increased sensitivity when compared with that of the agar gel precipitation (AGP) test.