Reconstructed virus from human genome.

A team of French scientists has announced the construction of a five million-year-old virus from a part of the human genome. This ancient virus can help us understand how the genetic excess creates cancer.

HIV - A type of Retrovirus (Illustrative image: nature)

Viruses belong to the Retrovirus group, they can insert copies of their genetic material into DNA after infecting human eggs or sperm millions of years ago, and paste into the original genome a large number of copies of aunty material. of them. The remnants of these copies in transient DNA are called Human Endogenous Retrovirus_HERVs.

Currently, copies of HEVRs make up 8% of our genetic code. However, these copies underwent quite a bit of mutation and degeneration, so scientists could not find them even though they could still transform themselves into new viruses that could infect.

Recently, Thierry Heidmann at Villejuif and Gustav Roussy Institute, and colleagues have just brought one of the Retrovirus types on the genome back to life. They named it Phoenix (phoenix), a mythical bird born from its own ashes.

"That's great. It's a kind of" Jurassic park "experiment to revive a virus once upon a time," said John Coffin, a retrovirus expert at Tufts University, Boston, Massachusetts.

Revival

Heidmann's group focused on a particular group of Retroviruses infected on human cells nearly 5 million years ago, leaving nearly 30 copies of themselves in the modern human genome. Copies of virus remnants carry a number of different points in the sequence due to the mutations they accumulate through the evolution of genomics. By comparing them, the team works on all copies of a virus organization.

John Coffin a Tufts University retrovirus expert (Photo: retrovirus.info)

The team then used the DNA sequence of the two HERVs obtained, directed mutation (???) to create a version of the original Phoenix. Then infect human cells to verify.

Results: Ancient viruses can replicate themselves and produce new viral particles, and these virus particles can infect healthy cells, copy and insert into the host cell's genom.

The study suggests that cells infected with a large number of copies of Retrovirus are circulated by a cycle: retroviruses produce new viral particles, particles excrete one cell and infect eggs and sperm. then repeat the cycle. This may have happened completely several hundred thousand years ago.

Dangerous infection:

The team also noted that some HERVs in our genome are still able to infect by connecting portions of the three HERVs together (splicing can occur spontaneously in the cell) to form a complete correction. Heidmann argues that the human genome is probably always a safe place - since HERVs have not been discovered to be naturally infectious.

Ancient viruses can help us understand when and how Retrovirus makes cancer, Coffin said. The researchers found that the cells of the tumors certainly contained retrovirus proteins or the entire virus, as if a HERV had just reactivated. Equipped with the active virus, they could be tested. when the actual infection quickly turns into an epidemic.

Heidmann points out that this type of ancient retrovirus is about 1,000 times worse than the famous HIV retrovirus strain. The team has also used genetic engineering to reconstruct an ancient viral strain that can only replicate itself once and cannot grow beyond control. " It may return to be a dangerous pathogen. , but may not be sure , "Coffin.

Huynh Nhu Ngoc Hien