A potential barrier to sexually transmitted diseases for women has been developed by scientists working on a revolutionary medical breakthrough called RNA interference. The researchers have produced an anti-viral cream women could apply before sex and which may continue to provide protection against viruses such as HIV and herpes for days.
Tests on mice have shown that in principle the cream is effective and does not appear to produce any side effects. Clinical trials on humans could be made within two years.
A study in the journal Nature, by Judy Lieberman, of Harvard Medical School in Boston, has shown that mice protected by the cream suffer no ill-effects and were significantly more protected against herpes than a control group of animals that had not been given the anti-viral cream.
Professor Lieberman said tests show 80 per cent of the control group of mice died when exposed to twice the lethal dose of herpes virus, yet only about 20 per cent of the mice given the cream died.
The cream, called a microbicide, contains small molecules of RNA that have been designed to interfere with or "silence" key genes of the herpes virus. A fatty substance called lipids help to transport the RNA molecules into the cells of the animal's reproductive tracts.
"When we mixed the RNA with the lipid it got taken up by all the cells of the tissues," Professor Lieberman said. "And it lasted for at least nine days. That means it could provide a stable anti-viral environment that would last for weeks in people."
The ultimate aim of the scientific research is to produce RNA molecules targeted against key genes of HIV.