SEROLOGIC DETECTION OF BLUETONGUE VIRUS-INFECTION OF BLACK-TAILED DEER - COMPARISON OF SERUM NEUTRALIZATION, AGAR-GEL IMMUNODIFFUSION, AND COMPETITIVE ELISA ASSAYS

Three adult black-tailed deer (Odocoileus hemionus columbianus) and fo ur fawns were inoculated with bluetongue virus (BTV) serotype 10 or 17 , or epizootic hemorrhagic disease virus (EHDV) serotype 1. Animals we re bled at irregular intervals thereafter and the presence of virus-sp ecific antibodies in serum determined by agar gel immunodiffusion (AGI D), serum neutralization (SN) and competitive enzyme-linked immunosorb ent assay (CELISA) tests. Serum antibodies to BTV were detected in all three tests for 692 days after inoculation (DAI) of adult deer, but b oth the SN and AGID tests gave either erroneous or misleading results. Serum from one deer was negative by the AGID test at 409 DAI with BTV -10 but was positive at 248 and 692 DAI; also one adult and one fawn h ad antibodies by the SN test to serotypes of BTV with which they were not inoculated. The AGID test for EHDV had false positive results with some sera from animal inoculated only with BTV, and it consistently h ad false negative results with serum samples collected from an EHDV-in oculated deer at 140 DAI and thereafter. The C-ELISA was the most usef ul test for the detection of antibodies to BTV because it rapidly gave quantitative and accurate results.