SARS-CoV-2, the novel coronavirus that causes COVID-19, caught the world off-guard when it crossed into humans late last year. It even surprised many of the experts most likely to understand it best.
To Siddappa Byrareddy, a virologist at the University of Nebraska and expert on viral epidemiology, the most surprising aspect of this pandemic is the virus’s pathogenicity, or the ease with which it can cause disease.
“We’re still trying to understand its spread. We don’t know why this virus is more pathogenic than other viruses.”
Some evidence suggests that SARS-CoV-2 enters lung cells by latching onto so-called ACE2 receptors coating their surfaces.
That it can apparently do this with great ease might explain some of the virus’s pathogenicity. It also provides a clue, as to why the infection appears more deadly for men. At least one recent report suggests that men may have more ACE2 receptors than women.
These results, however, remain preliminary and rely on small sample groups.
“Really, we don’t have a definite answer,” says Byrareddy. “We need to do more experiments quickly.”
Another surprise came from the virus’s origin.
Although originally thought to have moved into humans from bats, a less-known animal called the pangolin is slowly emerging as a more likely culprit.
Federico Giorgi, professor of genetics at the University of Bologna and an expert on the genetics of COVID-19, points out that many, if not most coronavirus studies had focused on bats. Following past outbreaks of SARS and MERS, researchers thought of bats as the most likely reservoir of a future coronavirus outbreak.
Until now, there had been almost no studies on viruses found within pangolins.
“This,” says Giorgi, “gives us an idea of the complex ecosystem at work in the world of viruses. [Pangolins] were under-studied as reservoirs of wild viruses. That is going to change now.”
Professor Giorgi hopes that more will be done to study metagenomics, the study of genetic material found in environmental samples.
“Metagenomics,” he says, “will be the key to be ready for future pandemics”