Bats could be key to fighting the next pandemic

• 

In a recent report, researchers now believe bats could be vital in helping us survive future pandemics and believe we have a lot to learn from them. As a result, global genomics research to uncover how bats evade the worst effects of some of the world's most dangerous viruses, including the one responsible for Covid-19, has been established.

"Bats have the potential to teach us a lot about how to fight disease," said University College Dublin researcher Emma Teeling, who was instrumental in establishing the Bat1K project.

Teeling believes that bats are noteworthy for a variety of reasons. They are the only mammals that can fly and live extraordinarily long lives for creatures their size, and many of them hunt using sound waves. They also occur in an astonishing range of shapes and sizes, from the bumblebee bat, which is the size of an insect, to Australian fruit bats with two-meter wingspans.

Some bats catch fish, others eat insects, and three of them, the common vampire bat, the hairy-legged vampire bat, and the white-winged vampire bat, consume blood. "Other species have evolved the longest mammalian tongues, allowing them to stick them down into huge long flowers to get their nectar," Teeling explained.

Why are scientists so invested in bats? 

The reason for scientists' current fascination with bats stems from the discovery that they can host a startling number of potentially lethal viruses, including the coronaviruses that caused the SARS and MERS pandemics, as well as the Marburg, Nipah, and Hendra viruses, without apparent ill effects. "There is a kind of peace treaty between bats and the pathogens they host," virologist Joshua Hayward of Melbourne's Burnet Institute recently stated in Nature.

Bats are also thought to be the original source of the Sars-CoV-2 virus which causes Covid-19. “Horseshoe bats from Asia are considered to be the original reservoir of the virus that evolved to become Sars-CoV-2, which changed most likely in an intermediate species of mammal,” said Teeling.

Read next: New study identifies cause of post-COVID-19 syndrome

“That animal became infected by a bat, probably in a market, changing the viral progenitor of Sars-CoV-2 into an agent that could spread through humans. The end result was the Covid-19 pandemic.”

As a result, Teeling believes that Sars-CoV-2 was most likely not generated in a lab, given the amount of new data indicating that it most likely occurred accidentally during the mixing of animals in the market.

Bats; unaffected virus reservoirs 

However, these discoveries raise an important point. How do bats operate as reservoirs for so many diseases that are deadly to other species, including people, while being unaffected? Scientists are currently working to solve this puzzle. "The answer has got to do with their ability to fly," Teeling explained.

Flight is extremely demanding, necessitating large quantities of energy for any creature wishing to take to the skies. The release of this high energy within the body of a mammal should result in the destruction of some of its cells. DNA fragments are predicted to break off and float around its body.

These fragments of genetic information are recognized by immune cells in non-flying mammals and are frequently interpreted as indicators of an invasion by a disease-causing organism. A counterattack is launched, which can result in severe inflammation. In many cases, like Covid-19, inflammation is the primary cause of serious reactions that might lead to death.

Read next: Can Llama's save us from COVID-19?

“But bats lack that intense response,” said Teeling. “Over the course of their evolution – which began around 80 million years ago – they have modulated their immune systems so that their responses have dampened down. Inflammation does not occur nearly so often or severely. As a result, they can carry all these viruses without suffering dangerous reactions.”

In other words, because bats evolved to fly, they had to create immune systems that are significantly less prone to induce harmful inflammation. In this way, they can deal with infections without experiencing the strong reactions that plague other types of animals. It is unclear how they achieve this, but it is now being closely scrutinized.

What is the  Bat1K project?

Teeling founded the Bat1K project with Professor Sonja Vernes of St Andrews University, with the participation of other institutions such as the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden and the Sanger Institute near Cambridge.

Its ambitious but simple goal is to build high-quality genomes for all bat species. In this way, the full DNA instructions - which come in billions of pieces - that are carried by the 1,450 or more bat species that have developed over our globe should be unraveled.

Only a few bat genomes have been sequenced to date, but scientists are confident that these analyses will soon reveal the precise mechanisms by which bats avoid succumbing to the viruses they host, with the ultimate goal of using this knowledge to develop medicines that mimic that behavior in humans.“Bats are not responsible for bringing disease to humans,” added Teeling.

“We have encroached on their lives, not the other way round. More importantly, we need to be prepared for the next pandemic, and if bats can point out ways to modify our immune responses speedily, that will demonstrate just how important they are to our world.”

Read next: China Studies Blood Bank Samples for COVID-19 Origins Probe