How Bats Beat Coronaviruses Could Hold the Key to Tackling COVID-19 Pandemic
Exploring the DNA of bats to understand some of their "extraordinary" characteristics, like how they avoid viral infections, could help us beat the COVID-19 pandemic, according to the authors of a study.
SARS-CoV-2, the germ which causes COVID-19, is a member of the large coronavirus family of viruses. SARS-CoV-2 is closely related to a bat virus, and may have jumped to humans via an intermediary host. SARS and MERS diseases, as well as some forms of the common cold, are also caused by coronaviruses.
In a study published in the journal Nature, a team of scientists assembled the most complete bat genomes ever by taking a close look at the DNA of six bats. Those were the greater horseshoe bat, the Egyptian fruit bat, the pale spear-nosed bat, the greater mouse-eared bat, the Kuhl's pipistrelle, and the velvety free-tailed bat.
As well as being tolerant of viruses, according to co-author Sonja Vernes of the Max Planck Institute for Psycholinguistics, bats are the only mammals that can fly, have "extreme longevity," stay healthy in their old age, avoid cancer, can see in the dark using vocalizations, and communicate with one another similarly to how humans learn to speak.
By comparing the bat genomes with those of other mammals, the scientists pinpointed special features these animals have, including anti-viral genes, and others related to immunity and inflammation.
Bats have "superpowered" immune systems Vernes, founding co-director of the Bat1K consortium which aims to sequence the genomes of all the approximately 1,300 living bat species, told Newsweek. Having access to information on the genomes of these "extraordinary" creatures is "instrumental" understanding how animals react to and cope with coronaviruses, she said.
The team found what are known as "fossilized viruses," or evidence the animals had survived viral infections in the past, in the bats' genes.
"These changes may contribute to bats' exceptional immunity and points to their tolerance of coronaviruses," Vernes said.
Asked how the research could help with tackling COVID-19 outbreaks and future pandemics, Vernes said: "Understanding why bats do not have strong inflammatory responses to coronavirus infections at a genomic and mechanistic level could help us devise methods to prevent or counteract severe reactions in humans.
"In the long term, such genomes will also help us understand the transmission of coronaviruses within and between species, which is extremely important for managing and preventing future pandemics."
Vernes said that one way to tackle coronaviruses is to understand and counter why they trigger severe responses in our bodies. COVID-19 is thought to be serious in some patients, for instance, because SARS-CoV-2 appears to make their immune system overreact.
Co-author professor Emma Teeling, head of zoology at University College Dublin and co-founding director of Bat1K, told Newsweek bats initially have a strong antiviral response to a pathogen, but this is coupled with an "equally aggressive" anti-inflammatory response. This in turn prevents the immune system from harmfully overreacting.
"They are able to mount the perfect immune response," said Teeling, adding this is reflected in their genomes.
"For us to better-survive and tolerate viral infections we need to study bats' response to see when to switch on the anti-viral response and when to then throttle it to enable us to have a better outcome," she said.
"These genes, their regulation and their modification hold the key. And now we have the genome targets and their sequence that we need to focus on to translate these genomic findings to help and enhance human treatments."
The study also revealed that bats are most closely related to the Ferreuungulata group of animals that includes dogs, cats, seals, whales, pangolins and hoofed animals called ungulates. In addition, genes related to hearing may help them with echolocation which the animals use to hunt and navigate in darkness.
No other animals, apart from humans and mice, have had their genes examined in such depth, according to the team. The researchers have been sequencing, assembling and analyzing the six genomes since 2017. In contrast to this team's work, the gene annotations of mice and humans "have received many years of curation and refinement from thousands of researchers over tens of years," said Vernes.
"I think what was surprising was just how much we could get from these genomes," said Vernes. "We knew they would be a key resource for evolutionary and genomic studies, but what we found was a treasure trove that will contribute to studies across a range of fields for years to come."
