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My background is life sciences and I'm leaning towards an answer already but would just like to hear some input. We have been seeing bacteria evolving to become resistant to ever increasing numbers of the antibiotics we have. I read this morning that there are "super bug" strains becoming resistant to Colistin, the antibody of last resort when all else has failed.
It seems to me we might be cultivating an equally troubling trait among influenza viruses with the flu shots we are using. I'm not talking about resistance though, in this case. Instead I'm talking about influenza becoming ever more variable in its replication. Flu viruses have always been "sloppy" replicators which is why we constantly need new vaccines. However, aren't these vaccines selecting for populations of influenza virus that show faster and more repeated replication errors? Aren't we creating the basis for a pandemic of a wildly replicating super virus, shifting its genome so quickly and thoroughly that vaccines have no chance to be made quickly enough? Am I missing something?
"populations of influenza virus that show faster and more repeated replication errors"
Not a specialty of mine, just an observation:
Describe an inheritable mechanism that would cause this to happen. I can't think of one.
Replication errors due to outside influences seems a much more plausible occurrence. From what little I've read, variants are typically generated in biological cesspits where various species (such as pigs, ducks, and humans) all live tightly packed and in squalor. The primary "motivation" for a virus living happily within a pig to change would seem to be only that the pig has been able to mount defenses. Even then the variation wouldn't need to be huge, just enough to circumvent the defenses.
Thanks. Looks like this is something well recognized. Using your quoted title as a search it appears that there is a balance that is important for the virus, being able to adapt quickly through replication errors but still maintaining genome integrity. Interesting, so maybe that necessary balance will keep it from getting out of hand.
Viral genetic diversity, which is ultimately determined by mutation rates, has therefore a profound effect on the design of antiviral strategies.
Viral mutation rates are not merely caused by polymerase errors, but also by the ability of a virus to correct DNA mismatches by proofreading and/or post-replicative repair. Furthermore, other sources of mutation include host enzymes, spontaneous nucleic acid damage, and even special genetic elements located within some viral genomes whose specific function is to produce new mutations. Mutation rates are modulated by additional factors, including proteins involved in replication other than the polymerase, the mode of replication, and the template sequence and structure. In this review, we discuss how these different factors control viral mutation rates.
I've never heard it stated anywhere throughout my entire science education that virus's are "sloppy" replicators.
The human immunodeficiency virus (HIV, shown here budding from a white blood cell) is one of the fastest evolving entities known. It reproduces sloppily, accumulating lots of mutations when it copies its genetic material. It also reproduces at a lightning-fast rate — a single virus can spawn billions of copies in just one day. To fight HIV, we must understand its evolution within the human body and then ultimately find a way to control its evolution.
The human immunodeficiency virus (HIV, shown here budding from a white blood cell) is one of the fastest evolving entities known. It reproduces sloppily, accumulating lots of mutations when it copies its genetic material. It also reproduces at a lightning-fast rate — a single virus can spawn billions of copies in just one day. To fight HIV, we must understand its evolution within the human body and then ultimately find a way to control its evolution.
That is not a very scientific way of explaining things. I posted a very good publsied paper above on why viruses mutate. It's not because they are "sloppy" replicators.
While I love the Berkeley site for Understand Evolution...it's written for simplicity and for non-scientists.
They use the term Macro-evolution which is not used in modern college Evolution Biology courses. It's an outdated term not used in the Biological sciences today...I have a BS in Biology with a Chemistry minor in addition to a grad degree in molecular diagnostics and have NEVER heard the term Macro-evolution or "sloppy" replicators.
I would like to also point out that every species including humans experiences replication errors. However cells have mechanisms (DNA polymerases) that proofread to prevent and/or repair these errors....however they sometimes miss errors and the result is a genetic mutation.
Viral polymeraces exist but they are much more crude functioning than cellular DNA polymerases. Unlike cellular host polymerases that require a strict regulation of transcription and replication, viral polymerases generally lack proofreading abilities and thus explore large areas of mutational space that could facilitate viral evolution. This is the reason they are continuously and rapidly evolving.
The whole reason I put sloppy in quotes was to indicated that it was a non-technical, generic term for something with a lot of variability. One of my stints was 4 years at the NCI in the Mammary Gland Carcinogenesis Program. We worked a lot on MMTV and it was not uncommon for people to use that term when discussing some RNA viruses. Admittedly, this was back in the 70s and 80s so that bit of jargon or slang has perhaps fallen out of use.
Regarding macro-evolution, that phrase arose, IMO, because of the irrefutable evidence of the evolution of bacteria and other rapidly reproducing organisms. In order to continue to deny the existence of evolution at work on the "macro" scale (humans specifically) those opposed to evolution can continue to deny evolution exists by restricting its sphere of influence to the "micro" world. A life scientist makes no such distinction, evolution is evolution, regardless of the size of the organism.
That is not a very scientific way of explaining things. I posted a very good publsied paper above on why viruses mutate. It's not because they are "sloppy" replicators.
It doesn't claim virus are sloppy replicators, rather it claims HIV is a sloppy replicator, which is one of the reasons they've been unable to develop an HIV vaccine. There are probably a handful of virus that are rather sloppy in their reproduction.
Quote:
Originally Posted by Matadora
They use the term Macro-evolution which is not used in modern college Evolution Biology courses. It's an outdated term not used in the Biological sciences today...I have a BS in Biology with a Chemistry minor in addition to a grad degree in molecular diagnostics and have NEVER heard the term Macro-evolution or "sloppy" replicators.
When I returned to university to get additional degrees earlier this century, the term macro-evolution was used in connection with morphological changes, while micro-evolution was used for more subtle changes, for example, changes in pigmentation of skin, feathers or hair of any organism.
...When I returned to university to get additional degrees earlier this century, the term macro-evolution was used in connection with morphological changes, while micro-evolution was used for more subtle changes, for example, changes in pigmentation of skin, feathers or hair of any organism.
Interesting. I had not heard this usage but as I mentioned, I'm a retired geezer and haven't been keeping up.
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