Human immunodeficiency virus type-1 (HIV-1) replication is unaffected by human secretory leukocyte protease inhibitor

Human secretory leukocyte protease inhibitor (SLPI); a serine protease inhibitor found concentrated in secretory fluids, has been postulated to participate in the body's natural defense against infection by the human immunodeficiency virus type-1 (HIV-1) by affecting trypsin-like enzymes on the surface of target cells. SLPI was evaluated for potential antiviral activity against laboratory, clinical and monocytotropic strains of HIV-1 in human T-cell lines, peripheral blood lymphocytes and monocyte/macrophage cultures. SLPI was tested in a single cycle of infection assay and under conditions in which SLPI was preincubated both with target cells and with virus and then maintained during the virus-to-cell adsorption phase and throughout the entire culture period. However, SLPI did not exert anti-HIV activity under any experimental conditions; and mechanistic studies showed SLPI to have no inhibitory activity on HIV-1 binding, reverse transcriptase or protease. Thus, SLPI exhibited no suggestive anti-HIV-1 activity.