Field Application of Enzyme-Linked Immunosorbent Assay for Screening of Equine Infectious Anemia

Abstract

Field application of an indirect enzyme-linked immunosorbent assay for screening for an equine infectious anemia (EIA) antibody to p25 antigen by means of a robot system was performed. This system has been utilizing for quarantining racehorses in the facilities of the Japan Racing Association since 1994 because finding are obtained rapidly. The results can be obtained within 2.5 hr. with this system. Every one of 500 normal racehorses was negative with this system, but they included 31 sera showing a non-specific precipitin line on agar gel immunodiffusion test (AGID). On the other hand, only 2.9% of 775 non-specific sera on AGID were positive with this system. Conversion of optical density was observed by retrospective investigation of the sera from ELISA positive horses. The substances that cause false positives with this system and AGID were identified as bovine serum albumin and transferrin by immunofixation electrophoresis and AGID. The optical density of the false positives was reduced by adding bovine serum albumin or transferrin to the diluent of the samples. In view of these results, it has been suggested that the system is highly reliable for screening in EIA field surveys.