New Cream May Prevent Herpes

We all know that it is very important to protect ourselves against the many STDs that are out there today. Soon enough, it may be as simple as applying a cream to help protect against getting herpes, one of the most common of the STDs in the United States. A new study shows that small anti-herpes RNA molecules applied to the vagina has protected mice against new herpes simplex virus type 2 (HSV-2) infections for approximately one week.

Genital herpes is a sexually transmitted disease (STD) which is caused by the herpes simplex viruses type 1(HSV-1) or type 2 (HSV-2) infection. When signs do occur, they usually appear as one or more blisters on or around the rectum or genitals. The blisters eventually break which leave tender ulcers (sores) that may take two to four weeks to heal the first time the breakout occurs. Typically, another outbreak can appear weeks or even months after the first time, but it almost always is less severe that the first time and shorter in healing time. Although this type of infection can stay in the body indefinitely, the number of outbreaks tend to decrease as the years pass. This is why many people, even though they don’t have an outbreak, can pass the virus onto their partners. Even without visible signs of an outbreak, the virus is still very contagious. 

This preventive treatment the researchers are testing to help prevent the virus, uses small interfering RNA or siRNA molecules. These molecules are tiny bits of genetic material that are designed to switch off specific genes. The treatment for herpes uses two siRNAs. One keeps vaginal cells from producing a molecule that the herpes virus used to help it infect cells and the other siRNA targets a viral gene that is required for herpes reproduction.

A researcher from Harvard, Judy Lieberman Ph. D, said in a news release, “One of the attractive features of the compound we developed is that it creates in the tissue a state that’s resistant to infection, even if applied up to a week before sexual exposure. This aspect has a real practicality to it. If we can reproduce these results in people, this could have a powerful impact on preventing transmission.”

The main cause of genital herpes is HSV-2. It is considered a sexually transmitted infection, although the mother-to-infant transmission of the infection occurs during the process of birth.

Researchers have believed for a long time that HIV and herpes could be prevented by vaginal application of an antiviral agent. However, to be of any real use to women, such “vaginal microbicides,” even if they are effective, must be long lasting, safe, and non-messy.

Lieberman’s team created an earlier version of the topical siRNA but found that the formulation that they used actually encouraged the herpes infection. Their most recent, two-pronged siRNA treatment avoids this problem, at lease with the mice. However, the same target that the researchers used in the vaginal cells of the mice, a molecule called nectin-1, is also found on the vaginal cells of humans. Blocking the nectic-1 does not seem to harm the mice. It may not be harmful to human either, as the molecule seems to be needed during development but not during the adult life of a human.

This suggests that the drug might not be very safe during pregnancy, but if it does work in adults that are sexually active, it would still be a huge benefit to the health of humans. It is estimated that 536 million people throughout the world are infected with HSV-2, and the HSV-2 infection makes it a lot easier for a person to get infected with HIV.

Lieberman and his colleagues suggest that their siRNA might also be able to work against HIV virus as well.