Histopathologic and immunohistochemical findings in two white-tailed deer fawns persistently infected with Bovine viral diarrhea virus.

Bovine viral diarrhea virus (BVDV) is an important pathogen of domestic cattle. Serologic, experimental, and individual case studies explored the presence and pathogenesis of the virus in wild ungulates; however, there remain large gaps in knowledge regarding BVDV infection in nonbovine species. Live twins were born from a white-tailed deer (Odocoileus virginianus) doe infected with noncytopathic BVDV during its first trimester of pregnancy. The twins died at 1 day of age from trauma unrelated to the infection, and tissues were collected for histologic and immunohistochemical examination. The most significant histologic abnormality was diffuse depletion of B-lymphocytes in both fawns. The BVDV antigen was distributed widely throughout many tissues and cell types, most notably epithelium and vascular endothelium, consistent with that reported in cattle. In contrast to cattle, lymphocytes exhibited only very rare positive staining.