CYSTEINE PROTEASES OF TRICHOMONAS-VAGINALIS DEGRADE SECRETORY LEUKOCYTE PROTEASE INHIBITOR

Sexually transmitted diseases, including trichomoniasis, are risk fact ors for acquisition of human immunodeficiency virus (HIV) infection. E nhancement mechanisms are unknown. Secretory leukocyte protease inhibi tor (SLPI) from saliva appears to prevent transmission of HIV through inhibition of virus entry into monocytic cells in vitro. This study wa s undertaken to determine if secreted cysteine proteases of Trichomona s vaginalis degrade SLPI and render it nonfunctional. It was determine d if SLPI levels were decreased in vaginal fluids from pregnant women infected with T. vaginalis, Isolated proteases were incubated with rec ombinant human SLPI, and the degradation was followed by Western analy sis with SLPI antiserum. SLPI levels were measured by ELISA in vaginal fluids from women infected with T. vaginalis and uninfected controls. Cysteine proteases cleaved SLPI and rendered it nonfunctional. Median levels of SLPI from infected patients were 26% of those of controls ( P <.005). The degradation of SLPI in association with trichomonal infe ction may increase the risk of HIV acquisition.