Some viruses are able to introduce into the host cell genome copies of part of their genome. They double with the host cell and, when they find the right time, cause an infection. But when they fold, sometimes they suffer mutations and, as they accumulate, they lose the capacity to cause infection. However, fragments of DNA do not disappear. In fact, French scientists have succeeded in resurrecting a virus that had introduced fragments of DNA to the human genome 5 million years ago.
The DNA fragments of this virus have remained in the human genome to date, although they are now unable to duplicate themselves and cause infections. Researchers have departed from these remnants of DNA to rebuild and reactivate the virus. Once resurrected, it is able to bend and become infected with new cells.
The study of this virus allows to determine whether these gene traces affect cancer. Researchers believe that some of the virus DNA that was integrated in the same way into human DNA can still be active, some of them affecting cancer. In fact, in certain tumors, whole virus and virus proteins have been found.