The study, published April 23 in The Journal of Infectious Diseases, found that the two herpes simplex viruses — known as HSV-1 and HSV-2 — mix their genetic material together, or “recombine,” more often than thought. (HSV-1 classically causes oral infections and HSV-2 causes genital infections.)

The researchers “found, basically, that there was considerably more recombination than had previously been appreciated,” between the two viruses, said study co-author Dr. Alex Greninger, an assistant professor of laboratory medicine at the University of Washington (UW) School of Medicine…

As a result, the genital herpes virus (HSV-2) continues to evolve, which could have negative implications for public health, the researchers said. For example, HSV-2 might evolve in a way that makes it resistant to current antiviral drugs.The ability of HSV-2 to mix with HSV-1 could also be a barrier to the development of a vaccine against herpes, which doesn’t yet exist, Greninger added.