May 17, 2024
Neanderthals carried the same viruses as us 50,000 years ago and this raises questions

Neanderthals carried the same viruses as us 50,000 years ago and this raises questions

AnginaAnginagastroenteritis, herpesherpes… and if NeanderthalNeanderthal had suffered from the same illnesses as us? In any case, this is what a team of researchers from the University of São Paulo in Brazil say.

While it is certain that prehistoric humans were affected by many illnesses, we did not know, until now, whether the viruses involved were the same as those we know today. However, a new study could provide answers to this question.

Three types of viruses found in the bones of a Neanderthal

Because by analyzing theDNADNA taken from the bones of a Neanderthal individual who died 50,000 years ago, a team of scientists succeeded in identifying the signature of three viruses which are still circulating today: a adenovirusadenovirususually responsible for respiratory diseases, conjunctivitisconjunctivitis or gastroenteritisgastroenteritisa herpes virus generally responsible for skin conditions, and a papillomavirus, which is sexually transmitted.

If it was considered that the DNA signature of these viruses resulted from a contaminationcontamination a posteriori, the results of the analyzes suggest that they did indeed affect the Neanderthal individual whose remains were found in the Chagyrskaya cave in Russia. Their sequence geneticgenetic is in fact slightly different from that of these three families of viruses which are currently circulating. These would therefore be the oldest viruses affecting humans discovered to date.

What if Neanderthals had been wiped out by an epidemic?

These results, which are presented in an article which has not yet been evaluated by other scientists and which should therefore be taken with caution, could help to understand the extinction of Neanderthals. Among the hypotheses proposed, there is in fact that of the epidemic which would have ravaged this speciesspecies human about 40,000 years ago in Europe.

The oldest known human virus has just been discovered in samples dated 31,000 years ago. But this adenovirus, which still infects most young children today, would have been transmitted to us by our Neanderthal ancestors.

Article from Céline DeluzarcheCéline Deluzarche published on July 18, 2021

Respiratory viruses ruin our winterswinters for at least 31,000 years. But their origin could even go back much, much further, even before the appearance ofHomo sapiensHomo sapienssuggests a new study by Danish and British researchers pre-published on the bioRxiv site.

SophieSophie Holtsmark Nielsen and his colleagues analyzed two teeth from human remains found at the archaeological site of Yana, in far northern Siberia, and dated to 31,600 years ago. Previous DNA analyzes were able to determine that they belonged to children aged 10 to 12 years old. By carrying out more advanced analyses, the team discovered the DNA trace of four Herpesviruses in the teeth, including herpes simplexsimplexresponsible in particular for the buttons feverfever. But the teeth also contained DNA from human adenovirus C (HAdV-C), well known to cause mild respiratory illnesses in children.

Oldest human virus: a record pushed back by 25,000 years

This virus is the oldest in humans to date », assures Sofie Holtsmark Nielsen. The record until now belonged to a virusHepatitis BHepatitis B 7,000 years old (Read below). “ This therefore pushes back direct evidence of human viral infections by 25,000 years. », underlines the researcher. But the team didn’t stop there. She carried out a reconstruction phylogeneticphylogenetic of the virus, by comparing ancient viral DNA to that of modern strains. Their common ancestorcommon ancestor could thus be determined and dated. “ These viruses evolve with their respective host species, sometimes over millions of years “, explains Sofie Holtsmark Nielsen. According to its conclusions, the oldest ancestor of adenovirus C would have appeared 701,850 years ago (with a range between 487,000 and 963,000 years), i.e. well before Homo sapiens (300,000 years ago). Respiratory infections would therefore have already affected our Neanderthal cousins ​​who populated Europe 400,000 years ago.

Did you know ?

Human adenovirus C (HAdV-C) is a highly contagious virus responsible for mild respiratory infections in children, particularly those under two years of age. This virus is particularly widely used as a viral vector for vaccines or gene therapies (in an attenuated form).

Viruses as old as life itself

Our results suggest that the current genetic diversity of HAdV-C predates modern human origins and likely originated from our ancestors hominidshominidswrite the authors in their study. It is unclear, however, whether this diversity is the result of divergent viral lineages migrating out of Africa with their human hosts, or of interspecies transmissions from archaic humans outside Africa. “. It is also impossible to know whether these old viruses were more or less pathogenspathogens than today.

Thanks to advances in DNA analysis, researchers are now able to reconstruct virus genomes from very incomplete genome fragments. Recent studies have demonstrated that the measles virus emerged more than 2,500 years ago, and that the bacteriumbacterium responsible for the plagueplague would date back 5,700 years. But viruses are arguably as old as life itself. Viruses were already infecting insectsinsects 300 million years ago, a 2001 study published in the journal PNAS showed.

Article by Céline Deluzarche published on 05/17/2018

Two teams of researchers sequenced the genome of an ancient hepatitis B virus from human teeth and bones. This virus, which is believed to have circulated around 7,000 years ago, is significantly different from the one we currently know in humans.

Two recent studies succeeded in identifying and sequencing the genome of ancient hepatitis B viruses. The first, posted online on May 10, 2018 on the bioRxiv site (where the researchers share still unpublished versions of their work), comes from a team led by Ben Krause-Kyora and Johannes Krause. These two German researchers analyzed three teeth from skeletons dated from 1,000 to 5,000 BC. The second, whose main author is the zoologistzoologist Eske Willerslev (University of Copenhagen), was published in Nature last May 9. She looked at samples aged between 800 and 4,500 years old.

To reconstruct the genomes of viruses, Eske Willerslev and his colleagues took a little “searched the trash”, jokes the researcher. They in fact analyzed the sequences which had been eliminated because they did not belong to the human genome. It is from these pieces that we can reconstruct the genomes of viruses, “a bit like a puzzle”summarizes Eske Willerslev, cited by The Atlantic. In fact, it is not a genome but multiple different forms of the hepatitis B virus (16 for the first study, 12 in the second) that the researchers discovered.

Even more surprising, none of these forms corresponds to a strain currently known in humans. Five of them, however, seem similar to strains observed in Africa in chimpanzeechimpanzee and the gorilla. According to Krause-Kyora’s calculations, the hepatitis B virus has circulated in western and central Europe since at least 7,000 BC. Until now, the oldest virus ever studied came from a mummified child from the 15the century in the Naples region.

Predicting the evolution of current viruses

This discovery is very important because it tells us about the possible evolution of current viruses. Until now, we have only sequenced recent strains. “It’s like trying to understand evolution by only studying living animals”illustrates Terry Jones, interviewed by theEvening Standardresearcher at the University of Cambridge and co-author of the study published in Nature. However, some of the mutations discovered are likely to come back, observes Eske Willerslev, the main author. By studying these old forms, for example by injecting them into mice, we could observe their effects and their virulence. The study of ancient viruses also helps us understand the migrations of prehistoric humans.

Hepatitis B is currently one of the most widespread viruses in humans. There are more than 250 million chronic carriers, according toWHOWHO, and the disease is responsible for nearly 900,000 deaths each year. Hepatitis B infects liverliver but the virus circulates in the blood and is therefore found in bones and teeth. Furthermore, if researchers were specifically interested in this virus, it is because its genetic materialgenetic material is composed of DNA and notRNARNA (like those of Ebola, measlesmeasles or the flu for example), which therefore makes it possible to sequencingsequencing with traditional methods.

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