Similar to how a smoke detector sounds off an alarm, certain genes sense when a virus enters the body and set off an alarm triggering an immune response in most mammals.
According to a recent study published in Frontiers in Immunology, pangolins – mammals which resemble an anteater with scales and often regarded as the ‘missing link’ between bats and humans, lack two of those virus-sensing genes.
However, the finding is significant because while pangolins are considered to be one among other carriers of coronavirus; they emerge capable to resist the virus through some other unknown mechanism. Understanding their evolutionary advantage may point to possible treatment options for coronavirus in humans.
“Our work shows that pangolins have survived through millions of years of evolution without a type of antiviral defence that is used by all other mammals,” says study co-author Leopold Eckhart from the Medical University of Vienna in Austria.
“Further studies of pangolins will uncover how they manage to survive viral infections, and this might help to devise new treatment strategies for people with viral infections,” Eckhart asserted.
While the study identified genetic differences between pangolins and other mammals, the scientists said they did not investigate the impact of those differences on the antiviral response.
Eckhart added that another gene, RIG-I, that acts as a sensor against viruses in the body, should also be studied further as it could defend against coronaviruses.
Researchers focused on pangolins because the exotic animal may have transmitted the virus to humans last year, creating the interspecies jump required for the COVID-19 pandemic to take hold (bats have also been identified as possible agents of infection).
In order to obtain their results, they analyzed the genome sequence of pangolins and compared it to other mammals including humans, cats, dogs and cattle.
In humans, coronavirus can cause an inflammatory immune response called Cytokine Storm, which then worsens outcomes. Pharmaceutical suppression of gene signalling, the authors suggest, could be a possible treatment option for severe cases of COVID-19.
Eckhart cautions though that such a remedy could open the door to secondary infections, ‘the main challenge is to reduce the response to the pathogen while maintaining sufficient control of the viruses. An over-activated immune system can be moderated by reducing the intensity or by changing the timing of the defence reaction’.
Scientists have not yet understood how exactly pangolins survive coronavirus, only that their lack of these two signalling genes might have something else to do with it.
The study offers a starting point to better understand the fundamental characteristics of coronavirus, the body’s response and the best options for treatment.