Detection of SIV in rhesus monkey thymus stroma cell cultures

To clarify the pathogenesis of SIV-induced thymus atrophy, the presence of SIV within thymus stromal cell cultures (epithelial cells, IDC, macrophages or fibroblasts) was investigated. The material studied consisted of 15 thymus specimens of rhesus macaques infected with SIVmac251 (2-4 months postinoculation). No viral antigen was detected, either in the cultures, by immunohistochemistry, or in cell culture supernatants, by ELISA (p17 antigen), and no viral RNA was detected by in situ hybridization. Only after coculture with the C8166 cell line, was virus detected in 2 out of 15 stroma cultures. The fact that the virus could only be detected after several passages of coculture with the C8166 cell line indicates that the virus exists in the thymus stroma cells in the form of proviral DNA. The infection of thymus stromal cells may contribute to the destruction of the thymus microenvironment and to the SIV-induced thymus atrophy.