Figure 1. A) Model to account for the differences in gene expression in latently infected cell lines compared with their uninfected parental cell lines. During the production of an HIV latently infected cell line, HIV is added to cells, which are then maintained in culture for a long period of time. During this maintenance in culture, there is selection for cells that can maintain HIV in latency (latency-favoring cellular environment [LFCE] cells), because the large majority of cells that do not maintain HIV in latency die (replication-favoring cellular environment [RFCE] cells). The remaining, living cells are then subjected to limiting dilution cloning to produce HIV latently infected cell lines. These cell lines are further characterized to show that they contain an HIV provirus that can be induced into active viral replication, and the cells’ gene expression profiles are determined and compared with the gene expression profiles of the uninfected parental cells. Such studies have revealed significant differences in the expression profiles of the latently infected cells compared with the uninfected parental cells. Studies to determine whether different HIV latently infected cell lines, produced using the same host cell and cloned virus, have similar or different patterns of cellular gene expression, are in progress. B) Cellular genes differentially expressed in an HIV latently infected cell line and the effect on HIV latency of targeting products of the differentially expressed genes. The figure shows results for two agents, clastolactacystin-β-lactone, a proteasome inhibitor, and resveratrol, an upstream activator of transcription factor Egr1. In the top left of each panel is a color map of the expression profile of the gene(s) in the latently infected cells compared with the uninfected parental cell line before (No) and after (in hours) activation into lytic replication. (Green indicates relative expression lower than the uninfected control; red indicates relative expression higher than the uninfected control.) The proteasome genes were overexpressed, and Egr1 was underexpressed in the latently infected cells compared with their uninfected parental cells before induction. The bar graphs show the fold change in HIV p24 antigen, a marker for viral replication, following treatment with the indicated agent. Tumor necrosis factor-α (TNF-α) serves as a positive control agent. All experiments except the “no AZT” data were produced from cells that were also treated with AZT to ensure that HIV p24 antigen production resulted only from reactivated latent infection and not subsequent rounds of viral replication. Clastolactacystin-β-lactone and resveratrol activated HIV replication in the latently infected cells. These agents, therefore, represent two new classes of agents that can activate HIV replication in at least some latently infected cell lines.