Pathogenesis of caprine arthritis encephalitis virus. Cellular localization of viral transcripts in tissues of infected goats.

Pathologic specimens of 18 goats with classical lesions of caprine arthritis-encephalitis (CAE) virus infection were examined morphologically and by in situ hybridization using molecularly cloned CAEV deoxyribonucleic acid (DNA) to determine which tissues and cells of naturally infected goats supported virus replication. Large numbers of cells with viral transcripts were detected in inflamed brain, spinal cord, lung, joints, and mammary gland. These cells were morphologically compatible with macrophages. Fewer cells with viral transcripts were seen in noninflamed tissues. Viral RNA was identified in macrophagelike cells in lung, liver, spleen, and lymph nodes, in cells lining the vessels of brain and synovium, and in epithelial cells of intestinal crypts, renal tubules, and thyroid follicles. These data suggest that the cell tropism of lentiviruses may extend beyond the narrow boundaries of lymphocytes and macrophages.