Experimental gene therapy is 90% effective against genital and oral herpes

Researchers at the Fred Hutchinson Cancer Center have made significant strides in developing an experimental gene therapy for herpes simplex virus (HSV), showing promising results in pre-clinical studies.

The therapy, designed to target both genital and oral herpes, has demonstrated the potential to remove 90% or more of the infection and reduce the release of the virus, suggesting a decrease in transmission rates.

“Herpes is very sneaky. It hides out among nerve cells and then reawakens and causes painful skin blisters,” explained Keith Jerome, MD, PhD, a professor in the Vaccine and Infectious Disease Division at Fred Hutch. “Our aim is to cure people of this infection, so that they don’t have to live with the worry of outbreaks or of transmitting it to another person.”

The findings, published in Nature Communications, mark a crucial step forward in the pursuit of a gene therapy cure for herpes. The therapy involves injecting gene-editing molecules into the bloodstream, where they seek out the virus within the body. This mixture includes laboratory-modified viruses, known as vectors, and enzymes that function as molecular scissors. These components work together to locate and target the herpes virus residing in nerve clusters, cutting its DNA to either damage or eliminate the virus entirely.

“We are using a meganuclease enzyme that cuts in two different places in the herpes virus’s DNA,” said Martine Aubert, PhD, the study’s first author and principal staff scientist at Fred Hutch. “These cuts damage the virus so much that it can’t repair itself. Then the body’s own repair systems recognize the damaged DNA as foreign and get rid of it.”

Using mouse models, the researchers observed that the experimental therapy eliminated 90% of HSV-1 after facial infection (oral herpes) and 97% of HSV-1 after genital infection.

Related Stories:

These reductions were evident within a month of treatment, with the virus load continuing to decrease over time. Additionally, the therapy significantly reduced both the frequency and amount of viral shedding.

“If you talk to people living with herpes, many are worried about whether their infection will transmit to others,” Jerome noted. “Our new study shows that we can reduce both the amount of virus within the body and how much virus is shed.”

One of the significant advancements in this study is the simplification of the gene-editing treatment, making it safer and easier to produce. In a previous 2020 study, the team used three vectors and two different meganucleases. The current study uses just one vector and one meganuclease capable of making two cuts in the viral DNA.

“Our streamlined gene-editing approach is effective at eliminating the herpes virus and has fewer side effects on the liver and nerves,” Jerome added. “This suggests that the therapy will be safer for people and easier to produce since it has fewer components.”

While the researchers are encouraged by the results in animal models, they emphasize the need for careful preparation before clinical trials. They are also working on adapting the gene-editing technology to target HSV-2 infections, which cause genital herpes.

“We’re collaborating with numerous partners as we approach clinical trials so we align with federal regulators to ensure the safety and effectiveness of the gene therapy,” Jerome said. “We deeply appreciate the support of herpes advocates as they share our vision for curing this infection.”

Herpes simplex virus (HSV) is a widespread infection that persists for life once contracted. Current therapies only suppress symptoms, which include painful blisters, but cannot eliminate the virus. According to the World Health Organization, an estimated 3.7 billion people under the age of 50 (67%) have HSV-1, and about 491 million people aged 15-49 (13%) worldwide have HSV-2.

Herpes can lead to other health complications. HSV-2 increases the risk of acquiring HIV, and HSV-1 has been linked to dementia in some studies.

This research was funded by the National Institutes of Health, the Caladan Foundation, and over 2,000 donors. The meganucleases used in the study are derivatives of commercially available enzymes.

The promising results of this study bring hope to millions of individuals living with herpes. As researchers move forward, their goal is to develop a safe, effective gene therapy that can be made widely available, potentially transforming the lives of those affected by this persistent and often painful virus.

Note: Materials provided above by the The Brighter Side of News. Content may be edited for style and length.

Like these kind of feel good stories? Get the Brighter Side of News' newsletter.