In our last article, we mentioned the selection pressure analysis of SARS-CoV-2 spike glycoproteins. Now, we have analyzed spike glycoprotein sequences of SARS-CoV. No single purifying selection site was found in SARS-CoV spike glycoproteins as was revealed from our last analysis of SARS-CoV-2 spike glycoproteins.
The analysis was performed using Hyphy  on the Datamonkey server . BUSTED , MEME , and FUBAR  methods were used. MEME  and FUBAR  found 6 and 2 sites respectively under positive selection. The threshold was set to 0.05 (p-value) for MEME and 0.9 (posterior probability) for FUBAR. Additionally, unlike SARS-CoV-2, BUSTED  found evidence of selection on the tested branches of the phylogeny of SARS-CoV spike glycoproteins. It implies that there is at least one site on one branch that has experienced gene-wide episodic positive selection.
Interestingly, negative selection has not been found in both SARS-CoV and SARS-CoV-2 spike glycoproteins. Besides, only a small number of sites have been found to be experienced positive selection. These sites of SARS-CoV spike proteins under selection are being analyzed further.
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