While questions remain about the origin of COVID-19, many scientists now believe the virus spread to humans from bats. Two Texas Tech University researchers are now taking a closer look at whether bats also could offer a solution to the pandemic.
Bats are well known as carriers of several viruses, some are related to viruses that can make humans very sick; this latest coronavirus, SARS-CoV-2, shares a common ancestor with a bat coronavirus. However, the bats don't appear to suffer any ill effects."
David Ray, Associate Professor, Department of Biological Sciences, Texas Tech University
"We hope to find specific patterns in the bats that appear to explain how they manage to tolerate viruses. For example, one of the ways they appear to do that is to dampen their immune response."
"Our immune system seems to go a little out of control when it encounters this virus, causing what's known as a cytokine storm that can sometimes do more damage than the virus itself. We want to find out how the immune system responds differently in bats and, potentially, inform clinicians on how we might be able to replicate that in humans."
Thanks to a grant through the National Science Foundation's (NSF) Rapid Response Research (RAPID) funding mechanism, Diana Moreno Santillán, a postdoctoral researcher in biological sciences, will be working with Ray over the next year to investigate how immune system genes and immune responses differ between bats and humans as well as how the specific proteins associated with SARS-CoV-2 in bats differ from the human versions of the same proteins.
"Our approach will be to examine bat genome assemblies from 10 species to identify patterns of gene duplication, gain and loss and relate those patterns to differences in how bats respond to viral infection," Ray said.
"As evolutionary biologists, our specialty is in comparing organisms to one another to see how the differences may have come about."
"For example, if some bats on the evolutionary tree do show a susceptibility to this or other viruses, while others in a different part of the tree don't, we can investigate exactly what changes have made the difference. Without understanding the evolutionary relationships, that is not possible."
"This research," Moreno Santillán added, "will give us a greater perspective to understand the impact of how these host-pathogen interactions between bats and viruses have molded unique adaptations in bats that have allowed them to 'get used to' these viruses."
There's a lot of work to be done in a short time frame. Because of the pressing threat of the coronavirus, the NSF is funding dozens of research projects on COVID-19 to mobilize the scientific community to better understand and develop measures to respond to it.
"The grant is called RAPID for a reason," Ray explained. "This is a special mechanism through the NSF that prioritizes approaches that need immediate attention. Thus, the funding is only for one year."
Luckily, Texas Tech is well positioned for such research as the home of the Natural Science Research Laboratory (NSRL), a repository of hundreds of thousands of preserved animal tissue specimens within the Museum of Texas Tech University that researchers can use for projects just like this one.
The NSRL added the 150,000th specimen in its mammal collection, a black and white spotted bat, earlier this year.
Ray and Moreno Santillán will complete this work in collaboration with Liliana Dávalos of Stony Brook University and Angelique Corthals of the City University of New York. Dávalos, a field leader in bat evolution, will guide some of the gene structure and gene expression analyses.
Corthals is interested in how genes not directly involved in the immune response - such as those associated with energetics and metabolism - could influence immune system performance under stress.
For Moreno Santillán, an important message to convey through this research is that people should neither be afraid of bats nor blame them for COVID-19, because virus transmission is extremely complicated.
"Although bats are reservoirs of viruses, that does not mean transmission to humans is common or a high risk," Moreno Santillán said.
"Just as bats are adapted to viruses, viruses also are adapted to their natural hosts, so the probability that a bat-borne virus successfully adapts to a human in a short period of time is low."
"A lot of random mutations and recombination events are needed before a bat-borne virus can infect humans. In fact, an intermediary host and constant interaction is regularly needed for this to happen."
"Having said that, we need to spread the message that bats are not to blame, nor are they a health risk. Quite the contrary, bats provide us incalculable benefits, such as plague control, seed dispersion and pollination. At the end, if there is something bats should be blamed for, it's tequila."