We are posting information about why Pfizer may want to block investigations and knowledge. Here we post two excerpts, one specifically linking to Pfizer’s pill that targets 3CLpro. Note that bovine coronavirus (BCoV) links to yak coronavirus:
’Early studies of coronaviruses and arteriviruses estimated the mutation rate to be 10(-3 ) to 10(-4) substitutions per site per year, the range that is typical for other RNA viruses, with (much) smaller genomes, whose replicase fidelity is known to be low. Most recently, these nubers were confirmed for SARS-CoV, HCoV-OC43, PHEV and HCoV-NL63. Using this rate and a (relaxed) molecular clock model, Vijgen et al estimated the time of the most recent common ancestors of BCoV and HCoV-OC43 and of PHEV, BCoV, and HCoV-OC43 to be in the late 19th century and not earlier than in the middle of the 16th century, respectively. Under a strict molecular clock model, the time of the most recent common ancestors pf HCoV-229E and HCoV-NL63 was estimated to be in the 11th century.
However, in contrast to the numbers cited above, it was also reported that SARS-CoV may have evolved at a lower mutation rate, approximating 0.1 replacement per genome per replication, and an unusually high genome stability was claimed for an isolate of HCoV-OC-43....corresponding to a mutation rate of 5.7 x 10(-6) substitutions per site per year.
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It is common that the number of synonymous substitutions per synonymous site (dS) exceeds the number of nonsynonymous ones (dN), and an especially high and poorly understood dS/dN ratio was reported for the S protein of PHEV.
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In the most conserved parts of the genome, nonsynonymous substitutions start to accumulate significantly only between the major nidovirus groups separated by relatively large evolutionary distances. In these viruses, replacements have sometimes been accepted at places of extraordinary conservation,e.g., in the active site of 3CLpro, which are not known to have been mutated in their DNA homologs. Although little is known about the absolute time scale of nidovirus evolution, it could have taken millions of years to generate the diversity observed in the most conserved enzymes.’
(Gorbalenya AE, Genomics and Evolution of the Nidovirales, in Nidoviruses, ASM Press, 2008)
This is in conjunction with the published probability that HCoV-OC43 jumped to Homo sapiens via bovine coronavirus (BCoV). Thus, the yak sequences we have posted also link a likely species crossover from yak to pig or vice versa.