Heppenheimer
Well-Known Member
Viruses rely on replication errors to mutate. The more chances the virus has to replicate, the more it has to mutate. Viruses, compared to bacteria, have a very limited genome, so it needs as many chances as possible to develop a useful mutation that gives it some kind of competitive advantage. The vast majority of mutations, though, make the resulting virus much less infectious, and hence, never get a chance to replicate. Drive those numbers into the ground with vaccination, and vaccine and anti-viral (for those viruses that we have antiviral treatment) resistance becomes less likely. This is largely the reason we were able to control HIV. With so few viral replications, the chances for the virus to develop resistance to the broad array of medications we use to fight the disease dropped significantly.This mantra keeps being repeated but I would like to pose the question of if it is really true or not. Isn't a virus less likely to mutate and evade defenses if it is spreading easily?
Bacteria don't become antibiotic resistant (the ones that weren't to start with) until antibiotics are overused. I always thought that was an example of Darwinism. If the bacteria isn't being killed off by antibiotics, it has no need to evolve to resist them.
Is it the same with a virus with respect to vaccines? Delta is thriving. Doesn't a random mutation have just as much chance to make it less contagious as more and therefore, why would it "want" to mutate?
I'm genuinely asking the question so if there is a real expert in these things, please answer.
Bacteria, though, have much larger genomes and therefore many more potential mechanisms to develop antibiotic resistance. Sustained, selective evolutionary pressure is more important for them to develop resistance than raw numbers of replications. Unlike viruses, who mostly only need to evade the various tools of the immune system to replicate, individual bacteria cells also directly compete against each other to sustain themselves. So, the random mutation that produces antibiotic resistance will not only allow that bacteria and it's progeny to evade the effects of the antibiotic, but will then be able to out-compete those lines who haven't developed the resistance.