OVINE LENTIVIRUS EXPRESSION AND DISEASE - VIRUS-REPLICATION, BUT NOT ENTRY, IS RESTRICTED TO MACROPHAGES OF SPECIFIC TISSUES

To better define the relationship between lentivirus infection and lym phoproliferative or inflammatory disease, we studied postmortem specim ens of 38 sheep naturally infected with ovine lentivirus (OvLV) and wi th different clinical manifestations of OvLV-associated disease. Immun ohistochemistry, in situ hybridization, and virus isolation were used to localize viral protein, viral RNA, and infectious virus to specific cells and tissues. Viral protein or infectious virus was found in cel ls morphologically and histochemically compatible with macrophages (Mo s), but only in lung, bone marrow, mammary gland, lymphnode, spleen, s ynovium, brain, and spinal cord, frequently in association with lympho cyte infiltrates. In contrast, viral RNA was found in a variety of cel l types, including epithelium, Mos, and Mo-like cells, and in a wider range of tissues, with or without OvLV-associated lesions. In summary, these findings suggest that in vivo: 1), OvLV can enter a variety of cell types, 2), productive infection is restricted to cells of Mo line age, and 3), cells expressing viral proteins are limited to specific t issues, those associated with OvLV-induced diseases.