A topical microbicide that silences two genes can safely protect against genital herpes infection for as long as one week, according to a joint study by researchers at the Albert Einstein College of Medicine of Yeshiva University and Harvard Medical School.
The study, carried out in mice and published today in Cell Host & Microbe , represents a major step toward developing a vaginal microbicide that offers women convenient, long-lasting protection against herpes infection. Such a microbicide might also help in controlling the AIDS epidemic, since the blisters caused by genital herpes make people more susceptible to HIV infection. The study's principal investigators were Deborah Palliser, Ph.D., assistant professor of microbiology & immunology at Einstein and Judy Lieberman, M.D., Ph.D., professor of pediatrics, Harvard Medical School.
An estimated one in five American adults is infected with herpes simplex virus 2 (HSV-2), which causes the sexually transmitted disease known as genital herpes. Most people don't realize they're infected, since symptoms are often mild and can be mistaken for other conditions. When symptoms do occur, they usually appear as blisters on or around the genitals or rectum. When the blisters break, they leave tender sores that usually take two to four weeks to heal. HSV-2 infection is incurable and persists in the body indefinitely, although the number of outbreaks tends to decrease over time.
The most effective way to prevent the transmission of HSV-2 is to avoid sexual contact during an active outbreak and to use condoms for sexual contact between outbreaks. When an outbreak occurs, promptly taking the suppressive antiviral drug valacyclovir can help minimize symptoms and reduce the risk of transmitting the virus.
The microbicide in this study is based on RNA interference (RNAi), a mechanism cells use to protect their genetic machinery from viruses and other threats. RNAi employs short, double-stranded RNAs called small interfering RNAs, or siRNAs. In 2001, scientists discovered that synthetic siRNAs can induce RNA interference in mammalian cells-a finding that has triggered interest in harnessing this strategy for biomedical research and drug development.