Sunday SciKu | Pruning

Researchers at the University of Pittsburgh have been exploring the ways SARS-CoV-2 mutates at the spike protein to evade antibodies. Coronaviruses have an error-checking system that keeps them more stable from mutation than other RNA viruses, but it turns out the proofreader doesn’t notice deletions. So there are certain segments in the spike protein sequence that can be removed without eliminating binding and replication, and we can see these same deletions again and again as we look through the genomic databases, with the virus slowly evolving to avoid our immune response. This is one of the selective pressures that makes a virus less deadly over time, as it sacrifices some of its binding affinity for immune evasion.

Last summer, our plum tree was overburdened with fruit, to the point where I had to prop up limbs to keep them from breaking, so a few weeks ago I was out there figuring out where to prune it, like some big spike protein sticking out of the earth. The combination became this week’s SciKu.

 

proofreading
the plum tree
for lines to cut

 

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