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1/ This is one of the most interesting pre-prints I have seen this past month. I consider this study in two parts. https://www.biorxiv.org/content/10.1101/2020.11.03.367391v1
2/ In the first part, Nussenzweig and colleagues show compelling data that memory B cells specific for RBD (the target of neutralizing antibodies against SARS2) undergo affinity maturation over time.
3/ They demonstrate this by cloning mAbs from the memory B cells, sequencing the B cells to show SHM, and characterizing the improved binding capacity of the mAbs.
4/ The increased SARS2 memory B cells at 6 months is also consistent with our findings, in a completely independent cohort and reagents, which is also nice to see. 
5/ In the second part of their study they show provocative data that replicating SARS2 can persist in the intestinal epithelium for 90 days. Nucleocapsid protein found in 5 individuals. Coronavirus virions seen in 1 subject by electron microscopy.
6/ The authors conclude this antigen may drive the affinity maturation. Still, a more conventional explanation is also allowed:
7/ These viral data are limited in number, so much caution is warranted. Still, it is very intriguing. The observation that SARS2 could be present in the gut for > 90 days is perplexing from a viral clearance perspective.
