Just three months ago we were all enjoying that lazy week between Christmas and New Year’s. Everyone’s life is very different now, and it’s safe to say that no one expected 2020 to follow this route. They say the only constant in life is change, and what a change it’s been. In times like these, one of the most pressing questions we all find ourselves asking is why. Why now?
Ultimately, that’s a question no one can answer; it’s impossible to say why this virus emerged when it did. Scientists may be able to shed some light on how, though. A new study has concluded that pangolins, or scaly anteater-like mammals, may have been the viral missing link that facilitated SARS-CoV-2’s transition from bats to humans.
It’s been agreed upon by experts for a good while now that this new coronavirus strain appears to have originated in bats. Bats aren’t capable of spreading the virus directly to humans, however, meaning an intermediary host must have been involved. Back in January, research was published theorizing that snakes were that missing link. That theory has failed to hold up, mostly because coronaviruses are only known to infect birds and mammals, and snakes are neither.
This new research, performed primarily by scientists affiliated with the University of Michigan, essentially puts to bed the notion that snakes were involved in the development of this global pandemic.
Additionally, it disproves another recent piece of research on SARS-CoV-2 that concluded the virus shared “uncanny similarities” to a protein associated with HIV-1, the virus that causes AIDS. That HIV study received a great deal of pushback from the scientific community and was never even officially released.
Still, with all of these varying theories on the virus’ origin floating around, professor Yang Zhang of Michigan’s Department of Computational Medicine and Bioinformatics & Department of Biological Chemistry and his team set out to analyze SARS-CoV-2’s genome more closely and carefully in pursuit of some answers.
We’re learning more and more about the virus on an almost daily basis. So, this time around researchers had access to larger and newer sets of data as well as more accurate bioinformatics methods (software for interpreting DNA).
While that initial HIV study had concluded that SARS-CoV-2 and HIV-1 share four unique spike protein regions, this study’s authors disproved that idea by identifying those four genetic sequence segments within several other viruses, including bat coronavirus.
Next, after finding a fundamental error in the analysis that pointed to snakes as the viral missing link, the research team compared DNA and protein sequences from pangolins to SARS-CoV-2’s genome. They ended up discovering protein sequences in sick pangolins’ lungs that were a 91% match to SARS-CoV-2’s proteins. Furthermore, the pangolin coronavirus’ spike protein receptor-binding domain featured only five amino acid differences to the human strain of SARS-CoV-2. For reference, SARS-CoV-2 and bat coronavirus are distinguished by 19 differences.
There’s a whole lot of scientific lingo in those findings, but they can all be boiled down pretty simply: the coronavirus found in pangolins is very similar to the strain of SARS-CoV-2 that is currently infecting people all over the world.
In conclusion, the study’s authors say their evidence strongly suggests that pangolins spread the virus to humans after somehow contracting it from bats. Of course, there are no definitive answers right now and there was possibly more than one intermediate host.
Nonetheless, these findings represent a significant step forward in understanding how the virus made the jump to humans.
The full study can be found here, published in the Journal of Proteome Research.