Experimental infection of calves with epizootic hemorrhagic disease virus

Objective-To determine whether experimental inoculation With a field strain of epizootic hemorrhagic disease virus serotype-2 (EHDV-2) suspected of ca using clinical disease in naturally infected cattle would cause clinical di sease in calves. Animals-8 calves. Procedure-A strain of EHDV-2 isolated from a white-tailed deer that died of hemorrhagic disease was passaged twice in deer and used to inoculate 6 cal ves SC and ID; the other 2 calves were used as controls. Physical examinati ons, CBC, lymphocyte blastogenesis assays, and coagulation assays were perf ormed; rectal temperature, interferon production, and serum neutralizing an tibody responses were measured; and virus isolation was attempted every oth er day for 21 days after inoculation and then every fourth day for another 30 days. Calves were euthanatized on postinoculation day 51, and necropsy w as performed. Results-Calves inoculated with EHDV-2 became infected, as evidenced by deve lopment of viremia and seroconversion. However, the virus did not cause det ectable clinical disease, clinicopathologic abnormalities, or gross lesions . Viremia was prolonged despite development of a serum neutralizing antibod y response. A white-tailed deer inoculated with the same EHDV-2 strain deve loped clinical signs of epizootic hemorrhagic disease, demonstrating that t he inoculum was virulent. Conclusion-Carves experimentally infected with EHDV-2 developed viremia and seroconverted but did not develop detectable clinical disease.