There are some distant relations we would generally be glad to be ignorant of. Jack the Ripper, Charles Manson, Genghis Khan… But what about a virus?

Turns out, humans wouldn’t be here if we didn’t have a grandpa-virus somewhere a long time ago who infected us and changed our DNA forever.

To be more specific, we are related to retroviruses. Our genome is made up of at least 5% retroviral DNA. Despite what you are probably thinking, ignorance wouldn’t have been bliss when it comes to these distant relations.

 

Researchers have long known of our part viral genetic identity. One of the biggest findings was that we, as mammals, most likely owe our very existence to our retroviral infection and splicing millions of years ago.

Dr Hano Maree, Senior Researcher, Geneticist and Biotechnology expert at ARC Infruitec-Nietvoorbij, explains that the viruses that infected us were special and highly beneficial in the long run.

“These were retroviruses, like HIV, that integrated into our original genome, our proto-human, millions of years ago, and it changed us.

“It was a driver for evolution. One of the great evolutionary advantages it gave us as mammals was it helped us to form placentas.

“Mammals, as a kingdom, diverged from the reptiles and the other egg-laying animals in that we formed a placenta that can be linked to a viral protein that integrated into our genome.

“We have it now. It doesn’t jump out again and make virus particles.

“They are endogenous now.”

Now, a new study has revealed that the benefits of our viral heritage extend to far more complex and tangibly human traits than ever thought before.

Johan Jakobsson, and other researchers from Lund University in Sweden, found that retroviruses play a central role in the basic functions of the human brain. These viruses seem to regulate which genes are to be expressed in the complex dynamics of brain formation and development.

These findings show that retroviruses have played a much larger and more active role in the development of our cellular machinery over the course of evolution.

“We have been able to observe that these viruses are activated specifically in the brain cells and have an important regulatory role. We believe that the role of retroviruses can contribute to explaining why brain cells in particular are so dynamic and multifaceted in their function. It may also be that the viruses’ more or less complex functions in various species can help us to understand why we are so different,” says Jakobsson, head of the research team for molecular neurogenetics at Lund University.

The research has opened up vast new possibilities in understanding and fighting brain-related diseases and ailments, because large parts of the genome we used to consider redundant has now proven to be central to our knowledge of the brain.

The study can be found here