The anteater-like mammals, pangolins, possess an evolutionary advantage against coronavirus, according to researchers, who say that understanding the animal's immune system may help develop new treatment options for COVID-19.
According to scientists from the Medical University of Vienna in Austria, certain genes sense when a virus enters the body, and trigger an immune response in most mammals.
However, they noted in the study, published in the journal Frontiers in Immunology, that pangolins, which may have carried the novel coronavirus from bats to humans, lack two of those virus-sensing genes. The researchers believe that the finding is significant since pangolins can be carriers of coronavirus while they also seem to tolerate it via an unknown mechanism. Understanding this evolutionary advantage may point to possible treatment options for coronavirus in humans, the researchers added.
In the study, the scientists analysed the genome sequence of pangolins and compared it to other mammals including humans, cats, dogs, and cattle. "Our work shows that pangolins have survived through millions of years of evolution without a type of antiviral defense that is used by all other mammals," says study co-author Leopold Eckhart from the Medical University of Vienna.
"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 said.
In humans, he said, coronavirus can cause an inflammatory immune response called a cytokine storm, which worsens outcomes.
While pharmaceutical suppression of gene signaling could be a possible treatment option for severe cases of COVID-19, Eckhart cautioned 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 virus," he said, adding that an overactivated immune system can be moderated.
According to Eckhart, this can be done by reducing the intensity or by changing the timing of the human body's defense reaction.
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 said another gene, RIG-I, which also acts as a sensor against viruses, should be studied further as it could defend against coronaviruses.
The scientists believe that the study offers a starting point to better understand the characteristics of the novel coronavirus, the body's response, and the best options for treatment.
