Why does drug resistance easily evolve but vaccine resistance does not?
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Why does drug resistance easily evolve but vaccine resistance does not?
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Re: Why does drug resistance easily evolve but vaccine resistance does not?
#2My understanding is that we're unable to created effective vaccines against RNA viruses as RNA replication doesn't have the built-in "checksum" mechanism that DNA has. When DNA replicates, because the two strands of the helix are essentially mirror images of each other, it is easier to create an exact copy without mutations. RNA, not having this property, allows for more mutations during replication. This increased mutation rate is what causes the viruses to change so quickly and what makes the vaccines we create quickly useless against the changed virus.
Re: Why does drug resistance easily evolve but vaccine resistance does not?
#3"Here we argue that vaccines are less vulnerable to pathogen evolution than are antimicrobial drugs because of differences in the way drugs and vaccines work. We contend that two key features of vaccines have large, synergistic effects on the rate at which resistance arises and then spreads"
"(a) Timing of action - For most infectious diseases, hours to days elapse between exposure to a pathogen and symptomatic infection in a host ... Pathogen replication during this incubation period creates opportunities for mutations to arise"
"(b) Multiplicity of therapeutic targets within and between hosts - The benefit of combination therapy is based on the premise that resistance can only be acquired by the simultaneous acquisition of resistance to each component drug. The probability of simultaneous acquisition becomes vanishingly small as the number of drugs increases. A vaccine, however, often exposes the host immune system to multiple pathogen proteins (antigens), and multiple potential binding sites (epitopes) on each antigen. Epitopes are recognized and bound by components of the immune system analogously to how biochemical molecules would interact with a drug or its downstream products. This means that immunity is in effect acting like combination therapy, but with substantially more component effectors (and hence targets) than any drug cocktail."
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"One set of differences between vaccines and drugs stem from the fact that vaccine effects are mediated through host immune responses while drugs effects are mediated through chemical pathways"
They discount this as being a major factor but the only evidence they provide is that "resistance is seen against drugs such as solfonamides that also act indirectly."
It could also be considered that the immune system is adaptive and its capacities evolve during a person's lifetime and that the collective immune system within a population group evolves depending on the spread (or lack there of) of disease within the population group.
With vaccines we are triggering the evolution of individual and group immune systems in ways that we don't fully understand and so unlike with drugs where once resistance is formed we have to develop a new drug, individual and group immune systems continue to evolve even if the vaccines don't change. The same vaccine administered now may be triggering different responses than it did 100 years ago.
Re: Why does drug resistance easily evolve but vaccine resistance does not?
#4My understanding is that we're unable to created effective vaccines against RNA viruses as RNA replication doesn't have the built-in "checksum" mechanism that DNA has. When DNA replicates, because the two strands of the helix are essentially mirror images of each other, it is easier to create an exact copy without mutations. RNA, not having this property, allows for more mutations during replication. This increased m…
Flu, polio, and measles are rna viruses which are regularly vaccinated against.
Re: Why does drug resistance easily evolve but vaccine resistance does not?
#5The decreasing effectiveness of the flu vaccine suggests to me that the flu metagenome is evolving resistance to our vaccine generation strategy.
Re: Why does drug resistance easily evolve but vaccine resistance does not?
#6The decreasing effectiveness of the flu vaccine suggests to me that the flu metagenome is evolving resistance to our vaccine generation strategy.
It's not, each year we have to guess which strains will be prevalent, and sometimes they get it wrong.
Re: Why does drug resistance easily evolve but vaccine resistance does not?
#7The decreasing effectiveness of the flu vaccine suggests to me that the flu metagenome is evolving resistance to our vaccine generation strategy.
I don't really see any obvious trend in this graph over the last 13 years:
https://www.cdc.gov/flu/professionals/vaccination/effectiven...
Re: Why does drug resistance easily evolve but vaccine resistance does not?
#8"Here we argue that vaccines are less vulnerable to pathogen evolution than are antimicrobial drugs because of differences in the way drugs and vaccines work. We contend that two key features of vaccines have large, synergistic effects on the rate at which resistance arises and then spreads" "(a) Timing of action - For most infectious diseases, hours to days elapse between exposure to a pathogen and symptomatic infec…
Herd immunity affects timing and variation in the community affects multiplicity. You aren’t wrong but I believe you are restating the conclusions in another way.
Re: Why does drug resistance easily evolve but vaccine resistance does not?
#9My understanding is that we're unable to created effective vaccines against RNA viruses as RNA replication doesn't have the built-in "checksum" mechanism that DNA has. When DNA replicates, because the two strands of the helix are essentially mirror images of each other, it is easier to create an exact copy without mutations. RNA, not having this property, allows for more mutations during replication. This increased m…
Flu, polio, and measles are rna viruses which are regularly vaccinated against.
Wow, you're right, I guess that kind of kills my theory. I knew that flu was which explained why there's a new vaccine every year and it's often not effective against the current strain. But I had thought that polio and measles were DNA viruses.
Re: Why does drug resistance easily evolve but vaccine resistance does not?
#10Not a biologist here, but hoping maybe one can correct me on this: isn't it an important factor that in the immune system the signaling cells themselves have evolved to respond to variants of a given pathogen's protein marker, whereas drugs are always presenting the same chemical challenge?