Herpes labialis, a virus possibly 5000 years old

The modern strain of the cold sore virus, which causes cold sores, dates back about 5,000 years, according to the authors of a new study.

“We were able to determine that all the variations of modern strains date back to a certain period at the end of the Neolithic, at the beginning of the Bronze Age,” explained Christiana Scheib, co-lead author of this study published on Wednesday. in the journal Science Advances.

The current herpes would therefore only be 5,000 years old, an age lower than imagined: “It is a bit surprising because it was assumed that herpes co-evolved with humans for a long time,” this expert in ancient DNA told AFP. and population genetics, linked to the University of Cambridge.

In humans, about 3.7 billion are infected for life with the HSV-1 virus that causes cold sores, according to the World Health Organization.

However, the history of this virus and how it spread remain poorly understood, particularly as ancient examples are hard to find.

Ms. Scheib’s team examined the DNA of hundreds of people’s teeth from ancient archaeological finds. Only four of them carried the herpes virus. It was by sequencing its genome that researchers determined when its contemporary incarnation appeared.

Humans have probably been living with herpes for much longer. One can imagine that an earlier strain was probably circulating among humans when they first left Africa millions of years ago.

But it took until relatively recent times for it to take its current form.

A potential suspect, the kiss

How to explain this change?

The researchers’ first theory: About 5,000 years ago, humanity was in a period of great migration from Eurasia to Europe, and this movement could have affected the virus.

Another hypothesis: the development of facial herpes in the Neolithic detected in ancient DNA could have coincided with a new cultural practice, the romantic and sexual kiss. “Textual evidence begins to appear in the Bronze Age about romantic kissing,” which may have changed how the virus spread, according to Christina Scheib.

The earliest known mention of kissing is in a Bronze Age South Asian manuscript, suggesting that the practice may have passed to Europe later.

The facial herpes virus is usually passed from parent to child, but kissing may have provided a new way for it to spread from host to host, the study co-author explained.

Kissing “is not a universal human trait,” he said, noting the difficulty of determining when the practice began or whether it is definitively linked to the spread of HSV-1.

The other co-lead author of the study, Charlotte Houldcroft, also from Cambridge, also pointed out that a virus like herpes evolves on a much longer timescale than a virus like COVID-19.

“Facial herpes hides in its host for life and is transmitted only by oral contact, so mutations occur slowly over centuries and millennia,” he said.

“Previously, genetic data on herpes only went back to 1925,” he said, calling for more “in-depth research” to understand the evolution of viruses.

“Only genetic samples dating back hundreds or even thousands of years will help us understand how DNA viruses like herpes or monkeypox, as well as our own immune systems, adapt to each other,” according to this researcher.

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