HIV-1 infectivity and host range modification by cathepsin D present in human vaginal secretions

Objective: To investigate HIV-1 infectivity in the natural environment of v aginal secretions. Design: Vaginal wash samples collected from 14 healthy women were incubated in vitro with various HIV-1 strains for 10 min at 37 degrees C and then as sayed for infectivity on primary lymphocyte cultures, or on CEM cells, or o n CD4- ME180 cells derived from vaginal epithelium. Methods: HIV-1 infectivity was measured by early virus growth in the variou s host cells tested using a quantitative p24 assay and by the Karber proced ure. Results: Preincubation of HIV-1(IIIB) with vaginal wash samples or 2 mu g/m l cathepsin D increased the ability of the virus to grow in lymphocyte cult ures. The vaginal wash effect was abolished by 5 mu g/ml pepstatin A, an in hibitor of aspartyl proteases. Presence of precursor and mature forms of ca thepsin D in vaginal wash was demonstrated after passage through a pepstati n A-agarose column. Median tissue culture infective doses of HIV-1(IIIB) an d HIV-1(JRFL) strains were increased 14.4-fold and 18-fold, respectively, a fter preincubation in vaginal wash sample, and were increased by pretreatme nt with 2 mu g/ml cathepsin D. When CD4 receptors of CEMss cells were block ed by OKT4a monoclonal antibody, the cells lost susceptibility to HIV-1(III B), but supported the growth of virus pretreated with vaginal wash sample o r cathepsin D. These treated viruses were able to initiate infection of CD4 - ME180 epithelial cells, which were not receptive to untreated virus. ME18 0 cells were shown to possess the messenger of CXC-chemokine receptor-4. Conclusions: Vaginal secretions may help HIV-1 transmission to women by inc reasing infectivity for CD4+ cells and allowing entrance into some CD4- epi thelial cells. (C) 1999 Lippincott Williams & Wilkins.