4 ms·

What I was taught in Virology 575 at UW-Madison: new viruses face intense selective pressure, and this tends to make them less pathogenic over time as they make

What I was taught in Virology 575 at UW-Madison: new viruses face intense selective pressure, and this tends to make them less pathogenic over time as they make their way through the new host population.

davidandgoliath 5y ago
That seems to make sense.
sjg007 5y ago
You should ask for your money back because you were miseducated.
- maxharris 5y ago
  Two questions: why so rude, and what do you base that on?
nikolay 5y ago
Except that you forgot the key element - this is in the long run and not so applicable to RNA viruses! A lot of people will die until covid becomes the new seasonal flu!
- maxharris 5y ago
  > and not so applicable to RNA viruses Are you sure about that? RdRps have quite the error rate, which means faster evolution. (And yes, I'm aware that the error rate in these vary based on the RdRp's sequence, but in either case, these are both higher than DNA transcription.) I do agree with the rest of your comment. Go get vaxxed, people!
- postalrat 5y ago
  Many will die long after people forget about 2020 and 2021. Not much we can do to stop that.
- sjg007 5y ago
  A lot of people will continue to die until we get a robust vaccine.
alecst 5y ago
Yea and you'll hear the guys on TWiV saying it too. But it's not quite that simple. It works out that way in the short term if the virus kills you right away, but there is not quite as much evolutionary pressure if the virus spreads during its presymptomatic period, as is the case with SARS-CoV-2. And there's the fact that Omicron mutated a whole lot without spreading (it doesn't share a lineage with Delta) which makes me think that this naive form of evolutionary pressure cannot be responsible for its reduced lethality.
- sjg007 5y ago
  Sars-Cov2 will happily live in animals without killing them but will still kill humans.
- nyokodo 5y ago
  > not quite as much evolutionary pressure if the virus spreads during its presymptomatic period That isn’t the only form of evolutionary pressure. The more your host population builds up immunity to the viral bag of tricks the more evolutionary trade offs there must be to remain infectious and over time they tend to harm the virulence. For example, Omicron seems to be very good at replicating in the upper respiratory but not so good in the lungs. Destructive mutations can still occur but they become much less probable over time. > Omicron mutated a whole lot without spreading One theory is that it did mutate through spread but in mice not humans. [1] 1: https://www.biorxiv.org/content/10.1101/2021.12.14.472632v1.full.pdf https://www.biorxiv.org/content/10.1101/2021.12.14.472632v1....

davidandgoliath 5y ago

That seems to make sense.

sjg007 5y ago

You should ask for your money back because you were miseducated.

maxharris 5y ago
Two questions: why so rude, and what do you base that on?

nikolay 5y ago

Except that you forgot the key element - this is in the long run and not so applicable to RNA viruses! A lot of people will die until covid becomes the new seasonal flu!

maxharris 5y ago
> and not so applicable to RNA viruses Are you sure about that? RdRps have quite the error rate, which means faster evolution. (And yes, I'm aware that the error rate in these vary based on the RdRp's sequence, but in either case, these are both higher than DNA transcription.) I do agree with the rest of your comment. Go get vaxxed, people!
postalrat 5y ago
Many will die long after people forget about 2020 and 2021. Not much we can do to stop that.
sjg007 5y ago
A lot of people will continue to die until we get a robust vaccine.

alecst 5y ago

Yea and you'll hear the guys on TWiV saying it too. But it's not quite that simple. It works out that way in the short term if the virus kills you right away, but there is not quite as much evolutionary pressure if the virus spreads during its presymptomatic period, as is the case with SARS-CoV-2. And there's the fact that Omicron mutated a whole lot without spreading (it doesn't share a lineage with Delta) which makes me think that this naive form of evolutionary pressure cannot be responsible for its reduced lethality.

sjg007 5y ago
Sars-Cov2 will happily live in animals without killing them but will still kill humans.
nyokodo 5y ago
> not quite as much evolutionary pressure if the virus spreads during its presymptomatic period That isn’t the only form of evolutionary pressure. The more your host population builds up immunity to the viral bag of tricks the more evolutionary trade offs there must be to remain infectious and over time they tend to harm the virulence. For example, Omicron seems to be very good at replicating in the upper respiratory but not so good in the lungs. Destructive mutations can still occur but they become much less probable over time. > Omicron mutated a whole lot without spreading One theory is that it did mutate through spread but in mice not humans. [1] 1: https://www.biorxiv.org/content/10.1101/2021.12.14.472632v1.full.pdf https://www.biorxiv.org/content/10.1101/2021.12.14.472632v1....