Ancient retroviruses spurred evolution of gene regulatory networks in humans and other primates

When ancient retroviruses slipped bits of their DNA into the primate genome millions of years ago, they successfully preserved their own genetic legacy. Today an estimated 8 percent of the human genetic code consists of endogenous retroviruses (ERVs)–the DNA remnants from these so-called “selfish parasites.”

Surprisingly, the infected hosts and their primate descendants also appear to have benefited from this genetic invasion, new evidence suggests. The ancient retroviruses–distant relatives of the human immunodeficiency virus (HIV)–helped a gene called p53 become an important “master gene regulator” in primates, according to a study published this week in the online early edition of Proceedings of the National Academy of Sciences.

Ancient retrovirus sheds light on HIV pandemic

Human resistance to a retrovirus that infected chimpanzees and other nonhuman primates 4 million years ago ironically may be at least partially responsible for the susceptibility of humans to HIV infection today.

“This ancient virus is a battle that humans have already won. Humans are not susceptible to it and have probably been resistant throughout millennia,” said senior author Michael Emerman, Ph.D., a member of the Human Biology and Basic Sciences divisions at the Hutchinson Center. “However, we found that during primate evolution, this innate immunity to one virus may have made us more vulnerable to HIV.”