Bat News: Pandemic Potential

Researchers have analyzed the virome of individual bats and established a number of disease mechanisms that could play a role in a potential future pandemic (1).

“We found the bats sampled carried a lot of viruses; they are important reservoirs,” says University of Sydney Professor of Virology and paper co-author, Edward C. Holmes, “These viruses often jump between hosts: this is the process of cross-species virus transmission that underpins disease emergence.”

The study focused on the Yunnan province in China, an area that allows for unique virological research thanks to its large pool of wild bat species and recorded viruses with zoonotic potential. Rather than taking a wider view of bat species as a whole, the team instead looked at individual animals, “Most studies of animal viromes use pooled samples representing multiple individuals (say 10–20). This is cheaper, but you miss what happens in individual animals,” says Holmes.

“The main benefit is that we can accurately determine exactly what viruses infect individual animals and in what proportions, and how frequently these viruses can jump between individual animals,” he added.

The team also used an “unbiased omics” approach, which saw them sequence all of the genetic material found in each individual animal without looking for a particular virus, as opposed to PCR methods. This allowed the researchers to get a comprehensive view of how abundant a virus was in individual bats. “In theory, this can be done for any species. The issue is that this approach just costs a lot more money,” Holmes explained.

Through this methodology, the team also discovered a case of recombinant coronavirus in an individual bat that was a mixture of a SARS-CoV-1-like and SARS-CoV-2-like virus from bats – meaning that the viruses are naturally exchanging genes within the bat population.

Strikingly, the unique recombinant coronavirus showed the genetic traits required to spread to humans. “This novel recombinant bat virus had a receptor binding domain that was very closely related to that found in SARS-CoV-2 – as close as any bat virus described to date,” Holmes explained, “[It was] able to bind to the key receptor used by coronaviruses to infect human cells (called ACE2). So, bat viruses exist in nature with the genetic traits necessary to cause disease outbreaks in humans.”

The implications of the study highlight the potential for bats and other wildlife to play host to a virus or viruses capable of fueling future pandemic outbreaks. Holmes says that our knowledge of the entire virological landscape is still limited, and that future disease protection must have adequate surveillance in areas where animals and humans come into contact. “This sort of refined surveillance is the most important tool we have to prevent the next pandemic.”