IN-VITRO REPLICATION OF EPIZOOTIC HEMORRHAGIC-DISEASE AND BLUETONGUE VIRUSES IN WHITE-TAILED DEER PERIPHERAL-BLOOD MONONUCLEAR-CELLS AND VIRUS-CELL ASSOCIATION DURING IN-VIVO INFECTIONS

In vitro and in vivo infections were conducted to determine if the epi zootic hemorrhagic disease (EHD) and bluetongue (BT) viruses would rep licate in peripheral blood mononuclear (PBM) cells of white-tailed dee r (Odocoileus virginianus). All of the North American EHD and BT virus es (EHD virus serotypes 1 and 2, and BT virus serotypes 2, 10, 11, 13, and 17) replicated in vitro in cultures of white-tailed deer PBM cell s. However, this replication appeared to be monocyte-dependent and was not enhanced by lymphocyte blastogenesis induced by the addition of c oncanavalin A. In white-tailed deer infected with either EHD virus ser otype 2 or BT virus serotype 10, virus could be isolated consistently from PBM cells only from post-infection day 4 through 8, although they remained viremic through post-infection day 21. In highest viral tite rs were associated with the erythrocyte fraction, and in no cases did viral titers detected in the platelet, PBM cell or polymorphonuclear c ell fractions approach titers observed in whole blood. In the in vitro infections of white-tailed deer erythrocytes, the EHD and BT viruses were associated with pits in the erythrocyte membrane. This associatio n may be important in the long-term viremia observed in deer.