An experimental gene therapy for genital and oral herpes removed 90% or more of the infection and suppressed viral shedding in pre-clinical studies, a new report shows.

Researchers at Fred Hutch Cancer Center who developed and tested the therapy published their findings in Nature Communications.

The experimental gene therapy involves injecting into the blood a mixture of gene editing molecules that includes a laboratory-modified vector plus enzymes that work like molecular scissors to snip away at the herpes virus’s genes to damage them or remove the virus entirely.

“We are using a meganuclease enzyme that cuts in two different places in the herpes virus’s DNA,” says first author Martine Aubert, PhD, 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.”

In mouse models of the infection, the experimental therapy eliminated 90% of herpes simplex virus 1 (HSV-1) after facial infection, also known as oral herpes, and 97% of herpes HSV-1 after genital infection. It took about a month for the treated mice to show these reductions, and the reduction of virus seemed to get more complete over time.

The team is also working on adapting the gene editing technology to target HSV-2 infections and eyeing human trials in the future.

The work was funded by the National Institutes of Health, the Caladan Foundation and more than 2,000 donors.