Comments on: The quasispecies concept

By: reverse phone lookup

reverse phone lookup — Thu, 17 Nov 2011 21:23:00 +0000

Looks like you’ve done your research very well.

By: Smyrna

Smyrna — Sun, 16 Oct 2011 23:22:00 +0000

Thank you for your fascinating and beneficial short classes,

Does mutation occur randomly or there are some hot-spot regions? I mean, are there any conserved regions or divergent regions in RNA virus genomes? Thanks again…

By: Shuvolinamukherjee

Shuvolinamukherjee — Thu, 21 Apr 2011 14:10:00 +0000

yes i agree completely we can never make viruses fall under taxonomical specieses as they are constantly changing…”quasispecies” is an apt terminology

By: Influenza variations | Mystery Rays from Outer Space

Influenza variations | Mystery Rays from Outer Space — Tue, 27 Apr 2010 10:16:11 +0000

[...] an average sequence even though the vast majority of the genomes are different from that average. (Here and here are Vincent Racaniello’s explanations at The Virology Blog.) Two sequences is just [...]

By: profvrr

profvrr — Thu, 28 May 2009 22:42:58 +0000

Yes, such variation would indeed explain viruses like rhinovirus that
exist as many serotypes. But much more variation occurs than is
evident by serotype. For example, there are about 100 serotypes of
rhinovirus, but the virus continues to undergo variation that does not
seem to produce new serotypes.

By: profvrr

profvrr — Thu, 28 May 2009 15:42:58 +0000

By: Teeny

Teeny — Mon, 25 May 2009 21:02:02 +0000

Would this be the reason for some viruses having so many serotypes? (classic one I have in mind is rhinovirus)

By: profvrr

profvrr — Wed, 13 May 2009 15:50:31 +0000

Any biological population is a mix of sequences and therefore a quasispecies. RNA viruses get all the attention because they cannot correct errors and their sheer numbers makes their quasispecies more extensive than any other.

By: Matt Dubuque

Matt Dubuque — Wed, 13 May 2009 12:43:32 +0000

Thanks, I'm glad you like it! My doctorate is in another field so I was trying to find a handy but very competent reference and that seemed to do the trick for me. It's way near the top of my bookmarks.

By: profvrr

profvrr — Wed, 13 May 2009 00:30:21 +0000

Wow, that's some book. By the head of the Department of Theoretical
Biology, Institute for Advanced Study, Princeton. Some smart people
there. I'm talking Friday on TWiV with a former scientist from that
Institute, on the new flu sequences.

By: Matt Dubuque

Matt Dubuque — Wed, 13 May 2009 00:20:03 +0000

Oh oh. Looks like I better brush up on my eigenvectors!

(Page 88)

http://tinyurl.com/pteeq4

By: Matt Dubuque

Matt Dubuque — Wed, 13 May 2009 00:05:07 +0000

I'm wondering if you would use Wiener's statistical mechanics to describe it. Seems likely.

http://en.wikipedia.org/wiki/Statistical_mechanics

By: profvrr

profvrr — Tue, 12 May 2009 23:35:25 +0000

Variation would be a fair way to describe it; just remember that some
variations are neutral, some are lethal, and some advantageous.

By: profvrr

profvrr — Tue, 12 May 2009 23:34:29 +0000

You are absolutely correct – viral populations, not individual
mutants, are the target of selection. As you will see, if you limit
diversity, the population suffers.

By: profvrr

profvrr — Tue, 12 May 2009 23:32:20 +0000

I'm not a mathematician, but you can imagine that quasispecies,
dealing with population biology, has its share of mathematical
analyses.

By: Matt Dubuque

Matt Dubuque — Tue, 12 May 2009 23:09:49 +0000

Is it therefore fair to describe the “error-prone” ways of RNA synthesis as the “variation-prone ways of RNA synthesis?

By: Viral quasispecies and bottlenecks

Viral quasispecies and bottlenecks — Tue, 12 May 2009 14:54:49 +0000

[...] genome sequence of an RNA virus population clusters around a consensus or average sequence, but each genome is different. A rare genome with a [...]

By: Massey

Massey — Tue, 12 May 2009 13:18:57 +0000

I've never understood what quantitative difference separates prokaryotic and eukarytoic species from viral quasispecies, given that most prokaryotic/eukaryotic species also exist as a spectrum of mutants ie. are polymorphic. Also, why are RNA viruses regarded as quasispecies, but not DNA viruses?

By: Ben Hyde

Ben Hyde — Tue, 12 May 2009 10:27:58 +0000

That's just so cool. There is a tempting analogy to be made. It's as if that population (and it's statistics) are the infectious agent, that agent the individual representative of the quasispecies – analagous to how the individual animal is a representative of his species. The entire population is then what evolves. And it's statistics are a work around for the errors at the level of reproducing a single particle. But the analogy looks more fun or tempting than useful.

Thanks!

By: Snicklefritz

Snicklefritz — Tue, 12 May 2009 10:27:24 +0000

Facinating! It tastes like a 'sum over histories' interpretatioin of quantum mechanics where the wave functions for all the probablities are present, and some cancel each other out and what is left is the 'consensus' reality that is determined by the observer (who is the 'host'

I'm strictly an amateur scientist, so you don't need to pay much attention to my musings. But, it facinates me anyway. Thanks for the article.

By: profvrr

profvrr — Tue, 12 May 2009 01:06:16 +0000

Infections of animals are never initiated by a single particle; almost
always by many (I shouldn't say never, it always comes back to get me,
but it's likely extremely rare). A single particle, even a few hundred
or thousand, are not enough - viral infection is quite inefficient in
an animal host. Probably millions of particles are needed, but it
depends on the virus and host. So your statement below is absolutely
correct: "in most cases significant representative sample of the
entire quasispecies moves on to the next victim".

By: Ben Hyde

Ben Hyde — Tue, 12 May 2009 00:54:15 +0000

I'm very much enjoying this series, thanks.

You write: "consequence of a quasispecies is that most viral infections are initiated not by a single virion, but a population of particles"

I'm confused. Presumably the population diversity is very high in an infected animal. Presumably when the infection is passed from one animal only some sample of that population moves over into the next animal. The quote seems to be saying something about how complete a sample is usually passed on. Of course the story book version of viral infection involves a single infective viral particle doing the job. If I'm reading that quoted bit right your saying that in most cases significant representative sample of the entire quasispecies moves onto the next victim.