SASKATOON, Saskatchewan — As scientists race to discover a vaccine for the coronavirus, one team thinks they’ve uncovered how the virus has been able to survive in bats without killing them. Their study may also reveal how coronavirus jumped from animals to humans, sparking the global pandemic.
Canadian researchers at the University of Saskatchewan (USask) say they have found out why bats can carry coronaviruses for months without getting sick. Their findings, published in Scientific Reports, reveals that bats have a “super immunity” to coronavirus strains.
Many of those strains, like Middle East Respiratory Syndrome (MERS), Severe Acute Respiratory Syndrome (SARS), and the COVID19-causing SARS-CoV-2, are believed to have originated in bats.
“The bats don’t get rid of the virus and yet don’t get sick,” microbiologist Vikram Misra said in a statement. “We wanted to understand why the MERS virus doesn’t shut down the bat immune responses as it does in humans.”
According to the Canadian researchers, a bat’s immune system and the viruses keep adapting to each other after the animal has been infected. Misra says the coronavirus starts working together with the bat, keeping it healthy even if it’s been infected for several months.
“Instead of killing bat cells as the virus does with human cells, the MERS coronavirus enters a long-term relationship with the host, maintained by the bat’s unique ‘super’ immune system,” Misra explained. “SARS-CoV-2 is thought to operate in the same way.”
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The study says this unique balance between bat immunity and the coronavirus is likely disrupted by stress; tipping the balance and making the illness contagious. The USask team believes the loss of natural habitats and exposure to wet markets may trigger the virus to multiply and spread to others.
“We see that the MERS coronavirus can very quickly adapt itself to a particular niche, and although we do not completely understand what is going on, this demonstrates how coronaviruses are able to jump from species to species so effortlessly,” Darryl Falzarano of USask’s Vaccine and Infectious Disease Organization said.
Misra adds that what makes the bat immune system special is it does not produce inflammation-causing proteins after being infected by MERS. The bat’s natural antiviral response continues to work, unlike in humans where a coronavirus infection shuts it down. The scientists are now looking at how the virus adapts and multiplies in humans.
“This information may be critical for predicting the next bat virus that will cause a pandemic,” Misra said.
To date, the SARS-CoV-2 virus has infected more than three million people worldwide and killed about seven percent of those with COVID-19.