BIPHASIC IN-VITRO REGULATION OF RETROVIRAL REPLICATION BY CD8(-PRIMATES() CELLS FROM NONHUMAN)

CD8(+) T cells from naturally infected disease-resistant sooty mangabe ys (Cercocebus atys) secrete a soluble factor which inhibits the in vi tro replication of the simian immunodeficiency virus (SIV). To gain fu rther insight on the mechanism(s) involved, CD8(+) effector T cells an d target cells from sooty mangabeys were immortalized and cloned. The target cells were then stably transfected with an SIV-LTR-CAT construc t or with the parental CAT plasmid as a control. A quantitative RT-PCR method, providing the necessary sensitivity, was developed to monitor the influence of the cloned CD8(+) T cells on the CATmRNA contained i n the target cells. It could be demonstrated that a soluble factor was secreted by the cloned CD8(+) T cells from sooty mangabeys, which app eared to regulate CATmRNA activity in a dose-dependent and reversible manner. Kinetic experiments showed that the CATmRNA transcriptional ac tivity was initially augmented at 30 min postcoculture and was followe d by a marked decrease in transcriptional activity after a few hours. This immediate early response could be mitigated utilizing H7, Calmodu lin, or PDTC (a pyrrolidone derivative of dithiocarbamate), suggesting that the pathway was protein kinase-dependent and that the NF-KB site may be involved. The inhibitory effect could also be overcome using a protein synthesis inhibitor, suggesting that protein synthesis was ne eded to negatively regulate CATmRNA activity and hence SIV promoter ac tivity.