EFFECT OF T-LYMPHOCYTE DEPLETION ON THE PATHOGENESIS OF MARBLE SPLEEN DISEASE VIRUS-INFECTION IN RING-NECKED PHEASANTS

The purpose of this study was to determine the effect of cyclosporine (CSP)mediated T-lymphocyte depletion on the pathogenesis of marble spleen disease virus (MSDV) infection in ring-necked pheasants. Seventy-two G-week-old pheasants were divided into three groups; one group of 18 birds was inoculated with MSDV, a second group of 18 birds was treated with CSP, and a third group of 36 birds was both treated with CSP and inoculated with MSDV. Two birds each from both of the smaller groups and four birds from the largest study group were necropsied periodically over a 14-day period. T-lymphoblastogenesis assays documented significant T-cell depression in the CSP-treated groups. Routine histology and immunohistochemical staining for MSDV antigen demonstrated that the CSP-treated MSDV-inoculated birds had higher lesion incidence, had wider tissue distribution of virus, and retained virus in tissues longer than did the MSDV-inoculated-only birds. These results indicate that T-lymphocytes play a role in the host response to infection with MSDV.