The Evolutionary Origins of Herpes: Virus Infected Humans Before They Were Human

Scientists have uncovered the evolutionary origins of human herpes: chimpanzees. It turns out that the human herpes simplex virus (HSV) -1 and -2 infected hominids before their evolutionary split from chimps about 6 million years ago and jumped from chimpanzees to our ancient ancestors about 1.6 million years ago.

About two-thirds of the human population is infected with at least one herpes simplex virus. This virus is commonly presented as cold sores on the mouth or lips or blisters on the genitals. In fact, humans are the only primates that have two herpes simplex viruses.

In order to learn more about the herpes virus, the researchers compared the HSV-1 and HSV-2 gene sequences to the family tree of simplex viruses from eight monkey and ape host species. They used advanced models of molecular evolution to estimate ancient viral divergence times. This allowed them to determine when HSV-1 and HSV-2 were introduced into humans.

"The results help us to better understand how these viruses evolved and found their way into humans," said Joel Wertheim, one of the researchers, in a news release. "Animal disease reservoirs are extremely important for global public health. Understanding where our viruses come from will help guide us in preventing future viruses from making the jump into humans."

In the end, the researchers found that HSV-2 was far more genetically similar to the herpes virus found in chimpanzees. This seemed to indicate that humans must have acquired it from an ancestor of modern chimps about 1.6 million years ago, prior to the rise of modern humans about 200,000 years ago. In contrast, HSV-1 has been present in humans for far longer.

"Comparing virus gene sequences gives us insight into viral pathogens that have been infecting us since before we were humans," said Wertheim in a news release.

The findings are published in the journal Molecular Biology and Evolution.