The herpes virus, which usually causes sores on the lips and is lifelong, currently infects an estimated 3.7 billion people worldwide. An international team of scientists led by the University of Cambridge say the rise of cold sores may have coincided with the arrival of a new cultural practice imported from the East: romantic and sexual kissing .
The history of herpes is millions of years old. The forms that the virus has infect various species ranging from bats to corals. However, despite being very common in humans, scientists say ancient examples of HSV-1 (the herpes simplex virus behind cold sores) were surprisingly hard to find.
“The world has watched COVID-19 mutate at a rapid rate for weeks and months. A virus like herpes evolves on a much longer timescale,” said co-author Dr. Charlotte Houldcroft, from the Department of Genetics at Cambridge. “Facial herpes hides in its host for life and is only transmitted by oral contact, so mutations occur slowly over centuries and millennia. We need to do in-depth research over time to understand how herpes evolve.” DNA viruses like this one,” he said. “Previously, genetic data for herpes only went back to 1925.”
The researchers managed to locate herpes in the remains of four individuals over a period of a thousand years, and extracted the viral DNA from the roots of the teeth. Herpes is often associated with oral infections , and two of the old corpses had gum disease. The third smoked tobacco. The oldest sample comes from an adult man found in the Ural Mountains in Russia and dates from the late Iron Age , about 1,500 years ago.
Two other samples are a woman and a man from Cambridge (UK). The woman was found in an Anglo-Saxon cemetery dating from the 6th-7th centuries of our era and located a few kilometers south of the city. The man, meanwhile, is a young adult from the late 14th century who suffered from terrible abscessed teeth and was buried on the grounds of the Cambridge charity hospital, which would later become St. John’s College.
Finally, the last sample is from a young adult male, avid clay pipe smoker, found in Holland. He most likely died in a French attack in 1672.
“We looked at ancient DNA samples from around 3,000 archaeological finds and only got four matches to herpes,” says study co-author Dr. Meriam Guellil, from the Institute of Genomics at the University of Tartu.
“By comparing ancient DNA with herpes samples from the 20th century, we were able to analyze the differences and estimate a mutation rate and thus a timeline for the evolution of the virus,” said Dr. Lucy van Dorp, co-senior author, from the UCL Institute of Genetics.
Dr. Christiana Scheib, co-author of the study, is a researcher at St. John’s College, University of Cambridge and director of the ancient DNA laboratory at the University of Tartu: ” All primate species have a form of herpes , so we assume it has been with us since our own species left Africa.” “However, something happened about 5,000 years ago that allowed one strain of herpes to overtake all others, possibly an increase in transmissions, which could have been related to kissing.”
Scientists point out that the earliest known record of kissing is found in a Bronze Age manuscript from South Asia. This custom would have traveled from Eurasia to Europe during the migrations. The Roman emperor Tiberius himself tried to ban kissing in official acts in his day as a way to prevent the spread of diseases, such as herpes. However, for most of human prehistory the herpes simplex virus would have been transmitted from mother to newborn.
According to the WHO, currently two-thirds of the world’s population under the age of 50 are carriers of the herpes simplex virus. Generally this is not a problem beyond the uncomfortable sores that form on the lips. However, the virus can become deadly if combined with conditions such as sepsis or COVID-19 itself.
Referencia: Guellil, M. et. al. 2022. Ancient herpes simplex 1 genomes reveal recent viral structure in Eurasia. Science Advances. DOI: 10.1126/sciadv.abo4435
