I am getting lots of questions if my pre-print about some #SARSCoV2 sequences that were removed from Sequence Read Archive tell us anything about lab accident versus natural zoonosis.
I posted summary of pre-print below, but did not directly address this point explicitly (1/n)
The answer is NO. The people using it to strongly support either argument are those that have become so emotionally invested in their opinion that they have lost the ability to analyze anything objectively outside of the framework of that argument. (2/n)
What the pre-print does imply is as follows:
First, there may be additional relevant data in obscure locations that aren't the places where we are accustomed to looking (e.g., on the Google Cloud, in table 1 of a paper on diagnostics, etc):
Second, in my opinion, anybody doing phylogenetics on early #SARSCoV2 sequences from China should spend as much time on metadata as algorithms. Sequences in databases may be non-representative. Sequences collected in Guangdong might be from infections from Wuhan. Etc. (4/n)
Third, preprint provides modestly more evidence for progenitor being in clade A (not market clade), & substantially more evidence it might have T at site 29095. However, current inferences are likely based on incomplete data. @sergeilkp says it best:
We used pseudovirus deep mutational scanning to characterize all mutations to a recent H3N2 HA. This approach uses virions that can only undergo one round of cell entry & so are not pathogens capable of causing disease.
As can be seen below, constraint due to mutational impacts on cell entry are widely distributed across HA including receptor-binding pocket and fusion peptide. But mutational constraint due to HA stability is concentrated at trimer and HA1-HA2 interface.
In new study, we find dramatic differences in specificities of serum neutralizing antibodies in infants w single infection by a recent SARS-CoV-2 strain versus adults/children imprinted by an early viral strain.
As background, immune response to a virus is “imprinted” by first exposure, since later exposures to new viral strains often activate pre-existing B-cells.
For SARS-CoV-2, most people globally imprinted by an early viral strain from either vaccination or infection in 2020-2021.
However, small but growing fraction of population has instead been imprinted by more recent viral strain.
Specifically, we compared adults/children imprinted by original vaccine then infected w XBB* strain in 2023 vs infants only infected w XBB* in 2023.
I’ve updated SARSCoV2 antibody-escape calculator w new deep mutational scanning data of @yunlong_cao @jianfcpku
My interpretation: antigenic evolution currently constrained by pleiotropic effects of mutations on RBD-ACE2 affinity, RBD up-down position & antibody neutralization
@Nucleocapsoid @HNimanFC @mrmickme2 @0bFuSc8 @PeacockFlu @CVRHutchinson @SCOTTeHENSLEY To add to thread linked above, human British Columbia H5 case has a HA sequence (GISAID EPI_ISL_19548836) that is ambiguous at *both* site Q226 and site E190 (H3 numbering)
Both these sites play an important role in sialic acid binding specificity
@Nucleocapsoid @HNimanFC @mrmickme2 @0bFuSc8 @PeacockFlu @CVRHutchinson @SCOTTeHENSLEY If you are searching literature, these sites are E190 and Q226 in H3 numbering, E186 and Q222 in mature H5 numbering, and E202 and Q238 in sequential H5 numbering (see: )dms-vep.org/Flu_H5_America…