Effect of a cellulose acetate phthalate topical cream on vaginal transmission of simian immunodeficiency virus in rhesus monkeys

Human immunodeficiency virus type 1 (HIV-1) infection continues to spread i n developing countries, mostly through heterosexual transmission. The devel opment of a safe and cost-effective topical microbicide, effective against a range of STDs including HIV-1, would greatly impact the ongoing epidemic. When formulated in a vehicle, a micronized form of cellulose acetate phtha late (CAP), which is an inactive pharmaceutical excipient, has been shown t o inactivate HIV-1, herpes simplex virus types 1 and 2, cytomegalovirus, Ne isseria gonorrhoeae, Trichomonas vaginalis, Haemophilus ducreyi, and Chlamy dia trachomatis in vitro. Formulated CAP was also shown to be effective aga inst herpes simplex virus type 2 in vivo. Here we show that a formulation o f CAP protected four of six rhesus monkeys from vaginal infection with simi an immunodeficiency virus. Thus, CAP may be a candidate for use as a topica l microbicide for preventing HIV-1 infection in humans.