Virus World

Following the emergence of SARS-CoV-2 in China in late 2019 a number of variants have emerged, with two of these – Alpha and Delta – subsequently growing to global prevalence. One characteristic of these variants are changes within the Spike protein, in particular the receptor binding domain (RBD). From a public health perspective these changes have important implications for increased transmissibility and immune escape; however, their presence could also modify the intrinsic host-range of the virus. Using viral pseudotyping we examined whether the variants of concern (VOCs) Alpha, Beta, Gamma and Delta have differing host ACE2 receptor usage patterns, focusing on a range of relevant mammalian ACE2 proteins. All four VOCs were able to overcome a previous restriction for mouse ACE2, with demonstrable differences also seen for individual VOCs with rat, ferret or civet ACE2 receptors, changes which we subsequently attribute to N501Y and E484K substitutions within the Spike RBD.

Preprint Available in bioRxiv (Nov. 24, 2021):

https://doi.org/10.1101/2021.11.23.469663

And what that tells us about the pandemic. Like any virus, SARS-CoV-2 has been mutating constantly since the beginning of the pandemic. Until November 2020, though, that didn’t seem to matter. That’s when scientists in the United Kingdom noticed an alarming change: The virus had mutated in a way that made it more transmissible. Within a month, similar reports were emerging from places around the world. Suddenly, it seemed the virus was changing at an alarming rate. SARS-CoV-2 hasn’t actually been mutating faster, though. Instead, by letting it spread around the world, we’ve just given it more and more opportunities to mutate as it replicates. The result is that after countless random mutations, there are signs that the virus is beginning to adapt to our natural defenses. And because it’s completely normal for a virus to change over time, we shouldn’t expect it to stop. The only real way to stop those changes is to stop giving the virus so many opportunities.

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https://youtu.be/Ha6yUxze1vk