The very viruses that tried to hijack their bodies are scattered among the genes passed down.
It's possible to tell a thing or two about disease by looking for signs of invaders in our own bodies. A new study has shown that buried virus remnants can be found in healthy tissues as well.
Human retroviruses make up about 8% of a person's genome. Retroviruses have the ability to insert a template of their genome into the DNA of a cell.
Many HERVs have gone extinct but bits of their genomes can still have an impact on our biology. For both positive and negative things.
It is possible for a viral insert to be copied throughout a new body for tens of millions of years.
The most recent ones integrated into the human genome belong to a subgroup of HERVs. The subgroup was acquired by our primate ancestors about 35 million years ago.
Proviruses that were acquired in the distant past now play a role in the birth of a baby. Others may be able to block cellularreceptors.
Some of the effects of HERVs are not helpful. The human body can be activated by proviruses that are intact. The HML-2 proviruses are found in many types of cancer. Scientists have proposed using HML-2 expression as a marker for disease.
A new study shows that healthy human tissue has HML-2 expression.
HML-2 expression in a non-diseased human body has not been well characterized.
Data on HML-2 expression can be found in various disease contexts, along with evidence of expression in some non-diseased tissues, but examination of all tissues in a host hasn't been done.
54 types of non-diseased tissue were analyzed. They found HML-2 transcripts in all of the tissue types they analyzed.
Nineteen and seventeen proviruses were expressed.
There was a high number of proviral remnants in the thyroid as well as in the pituitary glands.
Over time, many of the proviruses identified by researchers had been damaged. Some were still intact.
The results of this discovery have important clinical implications.
HML-2 transcripts should be measured against a background expression in healthy tissue if they are to be used as a disease marker. It could look like all tissue is sick.
John Coffin says that they have found that nearly all normal human tissues express at least one of about three dozen proviruses.
This finding will give us a basis for further studies to understand the role of these elements in human biology and disease.
The HML-2 group of HERVs is made up of numerous, closely related proviruses, but each one is unique and may have acquired different changes in the human genome.
It will take a lot of research to understand the functional consequences of each.
The results of the current study seem to show that older proviruses are expressed more in the human genome. It's possible younger proviruses have their expression suppressed because they are more threatening.
Some biological advantages may have been selected over time because older proviruses have had more time to evolve. That is just an idea.
The role of HERVs in human biology is a mystery at the moment.
There was a study published.
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