How fragments of ancient viruses in the human genome affect the body

Our DNA contains the genes of not only ourdirect ancestors. As we discussed earlier, every modern human contains Neanderthal genes. But, as it turned out, that's not all. Our DNA also contains traces of viruses that once attacked the body of ancient people. The search for these very traces helps scientists understand what diseases people suffered from thousands of years ago. But, most importantly, ancient viruses, quite possibly in our bodies, quite possibly play a role in modern diseases such as cancer. And in recent years, scientists are finding more and more evidence of this.

Human DNA contains the genome of thousands of different ancient retroviruses

What role do ancient viruses play in the genome?

A few decades ago, it was believed thatendogenous viral elements, that is, traces of ancient viruses, of which there are thousands in the human body, are dormant in the human body, and do not manifest themselves in any way. They were classified as so-called “junk DNA”, that is, a part of the genome that does not perform any function, but simply exists.

However, in the last few years itassumption began to be questioned. The fact is that science has made great strides forward in terms of studying genes. New, more sensitive methods make it possible to more accurately determine the influence of genes on certain processes in the body, as well as determine when they are active and when they are really in a dormant state.

Traces of retroviruses in the genome went to man from ancient ancestors

Ancient viruses and cancers

In a recent study, a group of scientistsfocused on the activation of one of the ancient viruses in healthy tissues of people with cancer. They were especially interested in tissues around tumors. Recall that healthy cells that are located around malignant ones play an important role in the development of oncology. In fact, cancer makes them work for itself, as we talked about earlier.

In their study, the researchers used samplestissues taken after death from almost 950 people. They included 54 types of healthy tissues found throughout the body, including in such key organs as the brain, heart, kidneys, liver, etc. The authors of the work analyzed which of the genes were “turned on”. Scientists were able to identify them by specific strands of RNA.

Scientists investigate traces of ancient viruses around cancerous tumors

The authors tried to find evidencethe existence of active "human endogenous retroviruses" (HERV) present in the genome. One such virus is HML-2. It appeared in the human genome several hundred thousand years ago. Moreover, it was found only in the human genome. Other primates, the closest relatives of humans, do not have it.

In all 54 healthy tissue samples, scientistsfound active HML-2. Moreover, the virus was most active in the pituitary and thyroid glands, as well as in healthy tissues around tumors. Scientists report this in the publication PLOS Biology.

How ancient viruses affect cancer

The main question remains open - what is HERVdoes in healthy cells, and how does it affect a cancerous tumor? According to scientists, when HERV is activated, viral fragments do not produce full-fledged viruses that can infect cells. Most likely, as a result of their activation, cells begin to build certain RNA molecules, which subsequently induce cells to build certain proteins.

No evidence that HERV is in any wayway affects the course of the disease and, moreover, provokes the appearance of cancer, scientists do not. However, according to the researchers, HERV can be used as a potential cancer biomarker. That is, by the presence of HERV in certain tissues, theoretically, it is possible to diagnose the disease.

In the near future, scientists want to find out how HERVbehave in malignant cells. Moreover, the team plans to pay attention not only to HML-2, but also to other endogenous retroviruses. It is possible that the new study will provide more answers to the questions. However, even the current study is a clear confirmation that the genome of ancient viruses in our body is not at all in a dormant state, as previously thought.

Needless to say, this is not the first time thatit turns out that "junk DNA" is not actually "junk" but performs a specific function in the body. Earlier we talked about the fact that "junk DNA" can affect a person's drug addiction. It follows that further study of HERV may help to better understand the nature of some diseases and find new, more effective methods of treatment and diagnosis.