Most scientists today believe the COVID-19 pandemic began at a Chinese wet market, with the coronavirus in question likely originating from a bat. It wouldn’t be surprising, given that many viruses have been linked to bats, including the Ebola, Marburg, Nipah and Hendra viruses, as well as coronaviruses like SARS-1 and MERS. But the bats don’t get sick. In fact, the reason so many bat species are full of all kinds of viruses is because their strong immune systems can keep pathogens at bay.
Yet until recently, scientists didn’t fully understand why bats are so good at harboring pathogens that don’t seem to harm them. A recent study in the journal Nature solves part of that mystery by breaking down exactly how bats can live specifically with coronaviruses and not show symptoms.
“These defense mechanisms are linked to their immune system – on one hand the immune system of the bats makes it harder for the viruses to replicate upon infection,” study co-author Dr. Sonja C. Vernes, University of St. Andrews School of Biology, told Salon. “On the other hand the bats suffer less from inflammation usually caused by an animal's own immune system that can cause so much harm following infection.”
The study authors learned this by sequencing high-quality coronavirus genomes from 10 new bat species, drawing from resources made available through an international research consortium known as the Bat1K project. Through their detailed analysis, the scientists discovered that bats exhibit more adaptations in their immune genes, and at a more frequent pace, than other mammals.
In addition to explaining how bats’ immune systems keep up with coronaviruses, and possibly all viruses, the research also sheds light on bats’ evolutionary history. The genetic breakdown indicates that the species fortunate enough to be Chiroptera possess special immune systems because of a common ancestor which had an unexpectedly high number of immune genes with these beneficial signatures.
“Some of these changes seem to have occurred early in evolution suggesting that the evolution of their superpowered immune system could be closely linked to the evolution of their ability to fly,” Vernes said.
By learning more about how bats protect themselves from viruses and other pathogens, humans can develop better medicines for our own bodies.
“The changes found in bat genomes give us exciting anti-viral targets to explore,” Vernes said. “This could lead to medical breakthroughs that help us protect ourselves from future viral pandemics. These findings also help us understand the interaction between viruses and other animals like bats – an important step in preventing future pandemics.”
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