What's the relationship between the following?
- Mutation rates (expressed as "mutations per year" for a virus like e.g. COVID-19 (SARS-CoV-2). E.g. this article mentions "The rate looks to be about 24 mutations per year"
- Actual virion replication error rates in a single host cell, measured as e.g. error rates per released virion from the infected cell, i.e. (# of mutated released virions) per infected cell.
I would assume that mutations happen at a single virion-cell level because there are differences in e.g. nucleotides in RNA between:
- the virion infecting a cell (e.g. ACE2 for SARS-CoV-2)
- the released virions from that same single cell
If so, wouldn't one argue that:
- replication errors (at the nucleotide and thus released virion level) can easily happen, potentially billions of times during the infection of a single host organism
- there is no "single successful" mutation or RNA variant within a host, rather, we have a distribution of RNAs, many of which could be simultaneously transmitted to another host organism?
I quote from e.g. this paper:
On a per-site level, DNA viruses typically have mutation rates on the order of 10E-8 to 10E-6 substitutions per nucleotide site per cell infection (s/n/c). RNA viruses, however, have higher mutation rates that range between 10E−6 and 10E−4 s/n/c
Again, wouldn't that mean that a single host could 1) easily generate many mutations of the same virus and 2) pass most of those uniquely generated mutations to another host? If so, how come we can simply say "24 mutations (over time) per year"?