Protection of cynomolgus macaque against cervicovaginal transmission of SIVmac251 by the spermicide benzalkonium chloride

We evaluated the potential effectiveness of a spermicide cationic surfactan t, benzalkonium chloride (BZK), to prevent the transmission of simian immun odeficiency virus (SIV) after intravaginal inoculation in 12 cynomolgus mac aques. The inoculation procedure involved deposition of 6.7 ivag-AID(50) of cell-free SIVmac251 into the receiving: vagina, four times over a 2-week p eriod, at the end of the luteal phase of the menstrual cycle. Six randomly selected females received vaginally foam containing BZK (7.37%, wt/wt) befo re each inoculation (BZK group), whereas the remaining were not pretreated (control group). In controls, 5 animals presented persistent SIV infection and 1 had a transient viremia. The number of uninfected animals was higher in the BZK group (6 of 6) than in controls (0 of 6). These findings demonst rate that BZK placed in the vaginal receptacle prior to SIV inoculation pro vides a significant protection in vivo. The wide spectrum of antimicrobial activities of BZK (including HIV) in addition to its efficiency to block th e transmucosal passage of SIV in the macaque model qualifies this drug as a n attractive topical microbicide to prevent sexually transmitted infections in humans.