A new study conducted by scientists at the Albert Einstein College of Medicine found that bats have been waging a war against the Ebola virus for approximately 25 million years. The study claims that the molecular battle could shed light on which bat species are at risk for harboring the virus and how they transmit it to humans.
"We knew from our previous research that Ebola virus infects host cells by attaching its surface glycoprotein to a host cell receptor called NPC1," said Kartik Chandran, co-author of the study, in a press release. "Here, we show how bats have evolved to resist Ebola infection and how, in turn, the virus could have evolved to overcome that resistance."
Ebola outbreaks among humans are believed to begin when a person comes in contact with an animal carrying the virus, and the new findings point to bats as possible viral reservoirs. In addition, the findings also shed light on how the Ebola virus interacts with its hosts.
The study examined exposed cells from four types of African bats, two of which have been linked to various filoviruses, including Ebola. The scientists discovered that cells from the African straw-colored fruit bat were the only ones resistant to Ebola virus infection, making it an unlikely host.
"We mapped this resistance to a single amino acid change in the NPC1 gene of this bat," said Chandran. "This tiny change prevents Ebola from binding to the NPC1 receptor."
The researchers then found that a single modification of an amino acid in Ebola's surface glycoprotein could destroy this resistance and make the African straw-colored fruit bat susceptible to infection, pointing to the possibility that filovirus' may evolve to infect hosts with receptor types that allow for easier infection.
Using genetic analysis, the team examined the NPC1 gene in 13 bat species and found that the specific location of the NPC1 receptor where Ebola attaches has evolved rapidly in bats in comparison to humans and other primates. What caused this rapid evolution? The researchers believe a prolonged co-evolutionary "arms race" between bats and filoviruses was the cause, with each trying to genetically trump the other.
"We discovered that a gene segment derived from a filovirus found its way into some bat genomes at least 25 million years ago," said Chandran, which is almost twice as long as previously believed that bats had been exposed to the filovirus.
"Identifying potential animal reservoir hosts for Ebola virus will provide a crucial guide for public health prevention and response programs going forward," said John Dye, co-author of the study.
The findings were published in the Dec. 23 issue of eLife.
