Design and assay of inhibitors of HIV-1 Vpr cell killing and growth arrest activity using microbial assay systems

Viral protein R (Vpr), one of the accessory gene products encoded by the human immunodeficiency virus type 1 (HIV-1) genome, has a number of functions, including causing a growth arrest of HIV-1-infected cells and possibly the death of uninfected bystander cells. In microbial assay systems, the C-terminal portion of Vpr can cause cell death when added externally, and when expressed in yeast it causes growth arrest. In this study we have sought to obtain inhibitors of the Vpr functions that affect the microbial systems. Our first approach employed peptide display, which identified a number of sequences, including a heptapeptide sequence, GETRAPL, involved in binding to the C-terminus of Vpr. To determine whether GETRAPL could block the extracellular cytocidal activity of Vpr, the heptapeptide was synthesized and found to have some blocking activity in microbial assays. A second approach led to the finding that melittin inhibitors had activity against Vpr extracellular activities. In a third approach, compounds were tested against the Vpr-induced growth arrest. A number of compounds were found to abrogate the growth arrest, and some also inhibited Vpr's extracellular activity.