Differential effects of a hydrophobic tripeptide on human immunodeficiency virus type 1 (HIV-1)-induced syncytium formation and viral infectivity.

The synthetic hydrophobic peptide, Z-D-Phe-L-Phe-Gly, was shown previously to inhibit the infectivity of paramyxoviruses and the fusion of Sendai virus with liposomes. We examined the ability of this peptide to inhibit HIV-1 infectivity in A3.01, Sup-T1, and H9 cells and syncytium formation between these cells and chronically infected H9 cells. Although the peptide inhibited syncytium formation in a dose-dependent manner, its effect on virus infectivity was very limited. Our results suggest that the mechanisms of interaction of the HIV-1 envelope glycoprotein gp120/gp41 with the target cell membrane leading to membrane fusion may be different in cell-cell and virus-cell fusion.