@glipsnort - I read somewhere that covid-19 has RNA repair mechanisms. Do you know if this is correct? If so, it should mutate more slowly.
Hi Marty. Yes, coronaviruses have a proofreading capacity that other RNA viruses lack. This lets them get by with a relatively large genome. The numbers I’ve seen are that SARS-CoV-2’s substitution rate (per base pair per time) is about half that of influenza A, which has a fairly high rate. The substitution rate is the rate at which mutations accumulate in a lineage; it depends on both the mutation rate and the degree of selective constraint on the genome.
To some extent it doesn’t matter. The substitution rate for this virus amounts to about 0.5 mutations per transmission, and many orders of magnitude more mutations than that occur within each host. Given that probably tens of millions of people have been infected, and that the SARS-CoV-2 genome is 30,000 base pairs long, all of the simple mutations have occurred many, many times during the pandemic. So if any provided a substantial selective advantage, they would have long since become common.
2 Likes