They are unpleasant and look stupid: herpes blisters. So far, only the symptoms can be treated, but not the cause. A new gene therapy could change that.

First the lip tingles and itches, then it swells and finally small blisters form: Most people are familiar with the symptoms of cold sores. The trigger is an infection with the so-called herpes simplex viruses. Basically, a distinction is made between two forms:

In Germany, around 85 percent of adults are infected with the herpes simplex virus type 1. It is therefore far more common than the herpes simplex virus type 2, which occurs in 10 to 30 percent of all Germans.

Although herpes is generally harmless, it is still annoying. Because so far only the symptoms can be suppressed, not eliminated. A US research team from the Fred Hutch Cancer Center in Seattle has now presented a new approach.

For their study, they first infected mice with the herpes simplex virus type 1 (HSV-1). They then carried out experimental gene therapy.

“Special gene molecules are injected into the blood to detect where the herpes virus is located in the body,” the scientists explain in a press release. “The mixture contains laboratory-modified viruses called vectors, commonly used in gene therapies, as well as enzymes that act like molecular scissors. Once the vector reaches the nerve centers where the herpes virus resides, the molecular scissors cut the herpes virus genes to damage them or remove the virus altogether.”

The highlight: “These cuts damage the virus so much that it cannot repair itself. Then the body’s repair systems recognize the damaged DNA as foreign and eliminate it.”

Gene therapy eliminated the infected mice

It took about a month for the treated mice to show these declines, and the decline of the virus appeared to become more complete over time, the researchers write. Their conclusion: “Our new study shows that we can reduce both the amount of virus in the body and the virus release.”

The team had already presented a similar approach in 2020, but has now made it simpler and safer. “Our simplified gene therapy approach is effective in eliminating the herpes virus and has fewer side effects on the liver and nerves,” explains Keith Jerome, a professor in the Division of Vaccines and Infectious Diseases at Fred Hutch. “This suggests the therapy will be safer and easier for humans to produce because it contains fewer components.”

The scientists write that they are encouraged by the positive effects of gene therapy in animal models and now want to translate these findings into treatments for humans – in addition to HSV-1 also for HSV-2. However, one must coordinate with the federal authorities “to ensure the safety and effectiveness of gene therapy,” they emphasize.