Topical microbicides for the prevention of genital herpes infection

Genital herpes is one of the most prevalent sexually transmitted infections worldwide and is the most common cause of genital ulcers. Despite increased public awareness and the initiation of efforts to prevent transmission, the prevalence of herpes simplex virus (HSV) type 2 continues to increase. What makes HSV so difficult to control is that most sexual and perinatal transmission occurs during unrecognized or asymptomatic shedding. The impact of genital herpes as a public health threat is amplified because of its epidemiological synergy with HIV/AIDS. Thus, there is an urgent need for novel prophylactic methods, such as topical microbicides designed for genital application, to prevent both HSV and HIV transmission. Several candidate microbicides are being advanced to clinical trials based on in vitro activity and animal studies. These include compounds that inactivate virus directly, those that enhance innate immunity, and drugs that block viral binding and entry. A more vigorous evaluation of the safety of these and other candidate topical microbicides in development should include assessment of the impact of repeated application on innate host defences in the genital tract.