There's an odd trend in recent SARS-CoV-2 evolution around the FCS, & it might have some connection to the spike NTD.
FCS-weakening mutations have been unprecedentedly common in JN.1. But though they seem to grow overall, there are odd swings.
There's a correlation with NTD mutations... 1/
Specifically, S:S31- (which adds an N30 glycan), doesn't tolerate these mutations nearly as well as BA.2.86* descendants that lack the deletion—including variants w/ S:T22N, which adds an N22 glycan.
KP.3.1.1 & XEC were ~identical elsewhere in spike, so they make for a near-perfect comparison. 2/
But there doesn't see to be anything special about T22N: JN.1* variants lacking both T22N and S31- favored FCS-weakening mutations as well. So it seems to be S:31- specifically that disfavors these FCS weakeners. 3/
And now recently we seem to have another intriguing trend: two S:31- variants have picked up the presumably FCS-enhancing S:K679R—LP.8.1.1 and MC.10.2.1.
The only real difference between LP.8.1 and LP.8.1.1 is S:K679R, and LP.8.1.1 has been outgrowing LP.8.1 for months now. 4/
Comments
A likely story, Eddie!
The baby infected by the new CoV has no reported contact with pets or wildlife.
Suspicious! (/s)
Here's the sequence:
https://www.ncbi.nlm.nih.gov/nuccore/MW405347.1
It's one of the few changes in the Spike AA sequence.
Good paper discussing the virus:
https://www.sciencedirect.com/science/article/pii/S2352771421000720
FCS-weakening mutations have been unprecedentedly common in JN.1. But though they seem to grow overall, there are odd swings.
There's a correlation with NTD mutations... 1/
KP.3.1.1 & XEC were ~identical elsewhere in spike, so they make for a near-perfect comparison. 2/
The only real difference between LP.8.1 and LP.8.1.1 is S:K679R, and LP.8.1.1 has been outgrowing LP.8.1 for months now. 4/