Comparison of commercial enzyme-linked immunosorbent assays and agar gel immunodiffusion tests for the serodiagnosis of equine infectious anemia.

The purpose of this study was to estimate the performance characteristics (accuracy, detection limit, and precision) of commercially available enzyme-linked immunosorbent assay (ELISA) and agar gel immunodiffusion (AGID) kits in comparison with a reference AGID kit for the detection of equine infectious anemia (EIA) antibodies in horses for regulatory use in Canada. A total of 285 positive and 315 negative samples by the reference AGID were tested blindly on 2 other AGID and 4 ELISA kits. Commercially available AGID kits for the serodiagnosis of EIA were found equivalent. The 3 ELISAs directed against antibodies to the p26 core protein also performed relatively well in comparison with the reference AGID, with excellent relative accuracy and acceptable precision. The single ELISA directed against antibodies to the gp45 trans-membrane viral protein yielded a lower relative sensitivity. The performance characteristics of the ELISAs directed against antibodies to p26 are, therefore, adequate to support the implementation of ELISA for regulatory purposes in Canada.