“Genetic Theft” – Bats Loot Gene From Ebola Ancestors, Why?
Study suggests that a gene encoding a viral protein has been carefully preserved in Myotis bats for millions of years
Some 18 million years ago, an ancestor of mouse-eared bats “stole” genetic material from an ancient virus related to Ebola.
The swiped genetic sequence — a gene called VP35 — has remained largely intact in the bats despite the passage of time, with few changes since it was co-opted, a new study finds. The research also sheds light on the gene’s possible function in bats, suggesting that it may play a role in regulating the immune system’s response to threats.
“We’re using a multidisciplinary approach to understand the evolution, structure and function of a viral gene co-opted by a mammal,” says Derek J. Taylor, PhD, an evolutionary biologist at the University at Buffalo. “From an evolutionary standpoint, it’s rare that you can actually see a viral gene sequence like this that has remained intact in a mammalian host. Most of these things are eroded over time — they get chopped up and shuffled around.
“But VP35 is highly conserved. It’s similar in all the bats we looked at, and the bat versions remain very close to what you see in modern Ebola and Marburg viruses. This conservation suggests that the gene has been preserved for an important purpose.”
In Ebola and Marburg viruses today, the VP35 gene carries instructions for building a protein that blocks the immune response of infected animals, enabling disease to take hold. When scientists used artificial synthesis to create bat VP35 proteins in the lab, these proteins also acted as immune suppressors, but they were less potent than viral VP35s.
The study answers some important questions, but many mysteries remain. For example: Is the VP35 gene active in mouse-eared bats? Do mouse-eared bats produce any VP35 proteins? If the bats do make VP35 proteins, why is this beneficial?
“Our study explores VP35 function, but further research is needed to determine the specific evolutionary benefit,” Taylor says. “Why has this gene been conserved for so long? We don’t quite know the answer, and it’s possible that VP35 has some other function in bats that we haven’t yet discovered.”
The study was published in the journal Cell Reports on July 24, with Megan R. Edwards, PhD, of Georgia State University as first author. The project was led by Christopher F. Basler, PhD, of Georgia State; Daisy W. Leung, PhD, of the Washington University School of Medicine; and Taylor, a professor of biological sciences in the UB College of Arts and Sciences.