Tufts Medicine

Retroviruses, such as HIV, and humans evolved together. Photo: Voth Lab/University of Chicago

Scientists at the medical schools at Tufts and the University of Michigan have found 19 new pieces of nonhuman DNA lurking between human genes, apparently from viruses that infected our ancestors hundreds of thousands of years ago.

One stretch of DNA, found in about 50 of the 2,500 people studied, contains an intact genetic recipe for an entire virus. That one might “allow us to study a viral epidemic that took place long ago,” said Tufts virologist John Coffin, the senior author on the study that was published in the Proceedings of the National Academy of Sciences. The new research, he said, “provides important information necessary for understanding how retroviruses and humans have evolved together.”

Other studies have tried to link DNA sequences derived from a virus to cancer and other diseases, but their occurrence is rare. “This is a thrilling discovery,” said co–first author Julia Wildschutte, who began the work as a Ph.D. student in Coffin’s lab. “It will open up many doors to research.”