馬伝染性貧血ウイルス抗体検出用ELISAの開発

Abstract

An enzyme-linked immunosorbent assay (ELISA) using purified equine infectious anemia (EIA) virus antigen was developed for the detection of antibodies to EIA virus. The purified antigen was analyzed by SDSpolyacrylamid gel electrophoresis, and 26 kilodalton polypeptide (26 K) was predominantly detected. In order to define the minimal absorbance reading (MAR) for a positive reaction, sera collected from 5 horses experimentally infected with EIA virus were examined by western blotting (WB) for the appearance of specific EIA antibody. Positive reaction against the 26 K was first observed at 18 days post-infection in 2 horses. Since these two sera showed an absorbance reading of approximately 0.5 by the ELISA, the MAR was established as 0.5. A serum which had been adjusted to give an absorbance reading of approximately 0.5 was applied as a reference, and test-samples showing an absorbance reading greater than that of the reference serum were judged to be positive. The detection of antibodies by the ELISA was compared with that by the agar gel immunodiffusion (AGID) test. The rate of coincidence between the tests was 90% in sera from horses with experimentally induced EIA and 99.6% in sera from horses in the field. Sera not in agreement were confirmed by WB, and the ELISA was evaluated to be more sensitive than the AGID test. Only 0.4% of the sera tested gave false-positive results by the ELISA. The present results indicate that the ELISA is a useful test for detecting antibodies to EIA virus.