Chlorhexidine is a Potent Inhibitor of HIV-1 Gene Expression. (A) Cells were treated for 4-5 h with TG003, TG009 or chlorhexidine, then doxycycline was added to induce expression of the endogenous HIV-1 provirus. Twenty-four hours later, cell media were harvested, and HIV-1 Gag (p24) protein levels determined by ELISA. Shown are the average of >9 independent assays, asterisks denoting results determined to significantly different from control (DMSO +Dox.) at a p value < 0.01. (B) As described in A, but cells were treated with varying doses of chlorhexidine to identify the minimum dose required to suppress HIV-1 gene expression. (C) To assess the effect of chlorhexidine on cell viability, cells were incubated with indicated dose of chlorhexidine (0.5 - 10 μM) for 24 h then an XTT assay performed. Level of XTT conversion, which measures the number and metabolic activity of the cells, was compared to DMSO-treated cells.