Detection of equine infectious anemia virus in horse leukocyte cultures derived from horses in various stages of equine infectious anemia viral infection.

The enzyme-linked immunosorbent assay (ELISA) antigen-positive and agar-gel immunodiffusion test (AGID)-negative horses do not have infective equine infectious anemia (EIA) virus. The ELISA testing of horse leukocyte culture (HLC) supernatants did detect EIA virus in a HLC that was infected with the Wyoming strain of EIA virus and in HLC derived from horses in febrile, acute, or subacute stages of EIA infection. In supernatants of HLC derived from chronic and inapparent carrier horses, EIA virus was not detected with ELISA. Direct fluorescent antibody tests detected EIA virus in HLC infected with 10(6)TCID50 of the Wyoming strain of EIA virus and in 50% of the HLC from febrile acute or subacute horses. The direct fluorescent antibody testing of HLC derived from chronic and inapparent carrier horses did not detect cell-associated EIA virus. The pony inoculation test proved to be the most reliable and accurate method for detecting infective EIA virus in horses in various stages of EIA infection and accurately correlated with the AGID test.