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how many segments per virus ? (+)
by: gs
Wed Jan 16, 2008 at 16:53:07 PM EST
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uhh, I'd always thought there were just one of each segment
in a virus, 8 strains in total.
Of course, I'd been puzzled what the HA,NA-peaks on the surface
were made of.
However, now I read for the first time since 2005, that there
are multiple copies of each segment included in one virus ?!?!?!
PB2:30-60
PB1:30-60
PA:30-60
HA:500
NP:1000
NA:100
M:20-60
NS:130-200
but also:
PB1-F2:2650
M1:3000
NS1:NA
???????
from
Cox,Neumann,Donis,Kawaoka: Orthomyxoviruses:influenza
http://www.topleyandwilson.com...
table 32.2 , page 10
so, can there be several mutation-variants of each of the segments present in one virus ?
Also, they say that HA contributes 25% to the virus mass. I can't verify this.
shame on me. Shame on all those authors who didn't make this clearer.
Honestly, who of you had thought the same (1 copy of each segment, <15000 nucleotides in total
per virus ) ?
gs :: how many segments per virus ?
Poll
did you also think there were only 8 RNA-strains in a fluA virus ?
* yes - 2 votes (100%)
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how many segments per virus ? | 27 comments | Post A Comment
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Nice chapter!
I don't think that table shows the number of copies of each RNA molecule that are in each virion - if it did, how would you account for the numbers being so different for PB1 and PB1-F2, which are encoded by the same RNA molecule? And how would you interpret "not applicable" for NS1?
I think what it shows is the copy number per virion, in the sense of "how many copies of this bit of RNA does it take to make one new virion?".
I'm confused by your mention of the HA and NA spikes, though. They are not made of RNA - they are made of the proteins haemagluttinin and neuraminidase that are encoded by the RNA. You knew that, surely, but then I find your post difficult to interpret...
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by: Mathematician @ Thu Jan 17, 2008 at 11:58:02 AM EST
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or to be more accurate and clearer
"how many copies FROM this bit of RNA does it take..."
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by: Mathematician @ Thu Jan 17, 2008 at 11:59:04 AM EST
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I don't know whether I knew that,
when I wrote it. So the proteins are needed for special (unknown) purposes
not just receptor and genetical code.
A flu-virus consists of RNA(1%),protein(73%:M1(40%)+HA(25%)+NA(5%)...),lip id(20%),carbohydrate(6%)
The RNA contains the 8 segments and is transported to the cell-nucleus for replication.
500 HA molecules (protein) as spikes on the virus surface and one HA as RNA-strain as part of the RNA-unit.
Their is no exchange of genetic material with the 500 spike HA-proteins and no mutations
can be stored and later released in these proteins.
Although, I think it could be somehow useful for the virus to store different RNAs
-------------------------------
http://www.haverford.edu/biolo...
The influenza virus is globular in shape, and is approximately 100 nanometers in diameter. The sheath of the virus is made up of a lipid bilayer, taken from the plasma membrane of the original host. Within the central core of this bilayer are located about 3000 matrix proteins (which differ depending on the type of the influenza), and 8 RNA genes. The surface membrane is spiked with protein molecules of two kinds: about 500 hemagglutinin ("H") and 100 neuraminidase ("N") molecules. Hemagglutinin molecules appear as pointed spikes, which are used to bind the virus to a cell and inject contents into it. Neuraminidase appear as blunt spikes, and possesses specialized enzymes which cause the infected cell to release the new viruses. (Silverstein: 50-52 and Flu)
Silverstein, Arthur M. Pure Politics and Impure Science: The Swine Flu Affair. Baltimore and London: The John Hopkins University Press, 1981.
uncoating. The nucleocapsid migrates to the nucleus where viral mRNA is transcribed. Viral mRNA is transcribed by a unique mechanism in which viral endonuclease cleaves the capped 5'-terminus from cellular heterologous mRNAs which then serve as primers for transcription of viral RNA templates by the viral transcriptase. Transcripts terminate at sites 15 to 22 bases from the ends of their templates, where oligo(U) sequences act as signals for the addition of poly(A) tracts. Of the eight viral RNA molecules so produced, six are monocistronic messages that are translated directly into the proteins representing HA, NA, NP and the viral polymerase proteins, PB2, PB1 and PA. The other two transcripts undergo splicing, each yielding two mRNAs which are translated in different reading frames to produce M1, M2, NS1 and NEP. In other words, the eight viral RNA segments code for ten proteins: nine structural and one nonstructural. A summary of the genes of the influenza virus and their protein products is shown in Table I below.
TABLE I
INFLUENZA VIRUS GENOME RNA SEGMENTS AND CODING
ASSIGNMENTSa
Lengthb Encoded Lengthd Molecules
Segment (Nucleotides) Polypeptidec (Amino Acids) Per Virion
Comments
1 2341 PB2 759 30-60 RNA
transcriptase component; host
cell RNA cap
binding
2 2341 PB1 757 30-60 RNA
transcriptase component;
initiation of
transcription
3 2233 PA 716 30-60 RNA
transcriptase component
4 1778 HA 566 500 Hemagglutinin;
trimer; envelope
glycoprotein;
mediates attachment to
cells
5 1565 NP 498 1000 Nucleoprotein;
associated with
RNA; structural
component of RNA
transcriptase
6 1413 NA 454 100 Neuraminidase;
tetramer; envelope
glycoprotein
7 1027 M1 252 3000 Matrix protein;
lines inside of
envelope
M2 96 ? Structural
protein in plasma
membrane;
spliced mRNA
8 890 NS1 230 Nonstructural
protein;function
unknown
NEP 121 ? Nuclear export
protein; spliced
mRNA
a Adapted from R.A. Lamb and P. W. Choppin (1983), Annual Review of
Biochemistry, Volume 52, 467-506.
b For A/PR/8/34 strain
c Determined by biochemical and genetic approaches
d Determined by nucleotide sequence analysis and protein sequencing
The influenza A virus genome contains eight segments of single-stranded RNA of negative polarity, coding for one nonstructural and nine structural proteins. The nonstructural protein NS1 is abundant in influenza virus infected cells, but has not been detected in virions. NS1 is a phosphoprotein found in the nucleus early during infection and also in the cytoplasm at later times of the viral cycle (King et al., 1975, Virology 64: 378)
http://books.google.com/books?...
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by: gs @ Thu Jan 17, 2008 at 14:46:09 PM EST
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polymerase
I can somehow understand/imagine the purpose of the HA-spikes,
but what are the 30-60 polymerase "proteins" good for ?
Does the virus manufacture its own proteins without the help
of the host-cell-nucleus ?
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by: gs @ Thu Jan 17, 2008 at 15:41:00 PM EST
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No, but it does a lot of the work itself
Influenza, like many viruses, has an RDRP - RNA dependent RNA polymerase - complex, meaning that it has the basic mechanism for copying its own RNA. That's what the polymerase proteins are good for. However, it seems it nevertheless can't do it without help from the host-cell-nucleus. See for example http://jvi.asm.org/cgi/reprint...
This is all about transcription - making one RNA molecule from another RNA molecule. The process that makes the viral proteins is translation. For that, the virus is (even) more dependent on the host-cell-mechanisms. See for example
http://jvi.asm.org/cgi/reprint...
These little virions are jolly complicated machines :-(
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by: Mathematician @ Fri Jan 18, 2008 at 10:46:00 AM EST
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yes, and that with only 3K of code.
Seems that the answer to the original question is 10 (in average):
From: Evidence for Segment-Nonspecific Packaging of the Influenza A Virus Genome
http://jvi.asm.org/cgi/content...
"Our results are therefore most compatible with the view that, on average, each influenza A virus virion packages 9 to 11 vRNAs and does so in a nonspecific manner."
So, in addition to all these proteins, there is one place inside the virus, where the viral RNA is stored.
~10 segments in total.
I'm puzzled, why the virus does this all.
What are the 30-60 polymerase (-proteins?) for ?
I wished, there were short summaries of such articles. Better than the abstracts.
And a good short survey which describes all this, without having to read the
details of the experiments.
can we continue this in email or on another board ?
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by: gs @ Fri Jan 18, 2008 at 13:21:44 PM EST
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Virus can do it on its own? Not just a hijacker?
Mathematician,
Hi. As a layman we where taught "virus are just strands of DNA that need a host cell to replicate. They can not do this on their own but hijack the internals of other living cells"
Where am I wrong (Probably just after the word Hi)
BTW I did try and read the article but all the Pol II, C-termnal domain, etc was confusing. The only C-terminal domain I know of is at HeartsField airport in Atlanta :o)
Kobie
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by: Kobie @ Fri Jan 18, 2008 at 13:47:14 PM EST
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I'd rather keep discussion on FW
and if I can help, I'd be happy to try writing explanations of some of the things I understand (though I wish we had a real virologist to do this kind of thing!).
However, the Wiki page
http://www.fluwikie.com/pmwiki...
seems pretty good for starters. I could maybe go into more detail about some particular area if you like, and put that in as a subsidiary page. Maybe on polymerase etc.? That page's recent edits seem to have been removing spam, I don't know who wrote it in the first place.
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by: Mathematician @ Fri Jan 18, 2008 at 15:12:27 PM EST
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I think you start being wrong at "just" :-)
and then at "DNA" it gets worse ;-) Influenza is an RNA virus, no DNA in sight. And there's more to it than just the strands of RNA - those are packaged up in an envelope that helps it get in and out of cells, and with other stuff that it needs to do the hijacking. (Pistol, black mask...) The wiki has a primer:
http://www.fluwikie.com/pmwiki...
and as I just said to gs I'd be happy to try to help expand it, if that would help. (But not to summarise the whole state of current knowledge about influenza, because life is too short!)
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by: Mathematician @ Fri Jan 18, 2008 at 15:15:11 PM EST
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...
lots of other stuff in the virus, only 1% is RNA.
It doesn't seem, that the virus can make it's own proteins without
help from the cell's RNA/DNA.
The wiki-article doesn't mention, that there are 500 HA-proteins, 30-60PB1-proteins,...
in addition to the 9-11 vRNA-segments.
Also transcription,translation,transduction,packaging,r eporters,...
how the vRNA goes to the nucleus
how many viruses per cell (1e5-1e6, but only enough cell-membrane for 10000 viruses ?)
99% of viruses are defect ?
how many cells are infected , how many viruses per human ?
virus inside liposomes
why polymorphic
the whole immunity things are also complicated and hard to grasp/remember
some people are banned here, some only post to other boards.
They should be included IMO.
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by: gs @ Fri Jan 18, 2008 at 15:35:14 PM EST
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Polymorphic I understand
GS and Mathematitian,
HI and thanks.
Let me read the articel to see what is so confusing.
As a computer geek the polymorphic thing is easy to understand. I write short little subroutines that do differnt things depending on what is fed them.
If its feed positive numbers it does one thing
It if is feed charectors or letters it does something else
If its fed letters and numbers it does something diffeent
If its fed numbers and letter than something else happens.
So the bundles of RNA from different viruses seemed as normal as subrutines or tool in a mechanics tool box. Tools you can assemble to make other tools. A socket does not do much but sit around, but socket and wrench do!
The whole thing on having some RNA for assembling parts threw me.
Ok. I was wrong with "Just" Laymen often get the abbriviated lecture :o)
kobie
Someone who thinks logically is a nice contrast to the real world.
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by: Kobie @ Fri Jan 18, 2008 at 15:47:08 PM EST
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they are talking about glycoproteins
not the RNA. That's my take, looking at the diagram and the caption. Also the RNP ribonucleoprotein complex.
But the nature of representative government often means that to finally get the answer of 'yes', you have to be the last person who has not yet given up when the government said 'no'. ITW
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by: SusanC @ Fri Jan 18, 2008 at 15:47:14 PM EST
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60
> Within the viral envelope one finds ribonucleoprotein (RNP)
> consisting of RNA-segments associated with nucleoprotein (NP)
> and the PA,PB1 and PB2 polymerase proteins.
> Three polymerase proteins are associated with the ends of vRNAs(insert).
so, a protein "consists" of RNA-segments ?
Which in turn are "associated" with other proteins.
But there are only 9-11 vRNAs in the virus, right ?
So, 3 polymerase proteins for each(?) end of the vRNAs
(including non-polymerase-segments) still makes only
60 polymerase proteins in total, but 90-180 are reported.
And 1000 nucleoproteins in total...
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by: gs @ Fri Jan 18, 2008 at 16:00:19 PM EST
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Interesting
Mathematician,
Wow. The last picture shows "a budding virus" as opposed to an exploding cell. I always thought virus took over a cell making thousands of copies untill the cell was full and exploded.
In my mind that is a bad thing. Virus could consume all the supplies or machinery of a cell adn then kill the replicator. This way the cell stays in tact like a mini virus factory pumping out new copies and then some variations. I assume virus mutates during replication.
At least if the cell died that would shut down some production. Yes I know I am made of cells so it is some of me that is dying. If too much of that happens it is a really bad thing.
But I am thinking that only some cells are good for viral reproduction. Not all cells. So if only some cells make the virus then I could get by without them for a while. Laymen oversimpliy things.
KObie
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by: Kobie @ Fri Jan 18, 2008 at 16:03:07 PM EST
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30
well, in the picture it's only on one end of the vRNA,
so I'm back to 30 polymerase-proteins inside
the virus in total.
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by: gs @ Fri Jan 18, 2008 at 16:04:01 PM EST
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many
Kobie, you are made of an awful lot of cells.
60 Trillion. So just a tiny fraction of these
gives the viruses lots of room for replication.
And then count 100000-1000000 viruses per cell !
(although I don't know, where they get all the lipid from)
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by: gs @ Fri Jan 18, 2008 at 16:08:09 PM EST
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I'm not sure I understand your question n/t
But the nature of representative government often means that to finally get the answer of 'yes', you have to be the last person who has not yet given up when the government said 'no'. ITW
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by: SusanC @ Fri Jan 18, 2008 at 16:11:40 PM EST
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multi-tasking
if it infects a bird, it uses its alpha2,3 receptor HA
if it infects a human, it uses its alpha2,6 receptor HA
if I were the virus-God, I'd make
viruses with 250 2,3-HA-proteins and 250 2,6-HA-proteins
and two HA-vRNAs.
Or viruses that just randomly choose 2,3 or 2,6 for all 500 HAs.
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by: gs @ Fri Jan 18, 2008 at 16:13:58 PM EST
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...
the picture shows that each vRNA (usually 9-11 per virus, at most
8 different ones) encircles one (or more ?) NP-proteins
with PB2,PB1,PA - proteins at its (3'?)end.
That makes 27-33 polymerase proteins and 9-11 NP-proteins.
Plus some polymerase vRNAs.
But several sources report that there are 30-60 proteins
of each of PB2,PB1,PA in a virus.
And 1000 NP-proteins and 500 HA-proteins and 100 NA-proteins
and 3000 M1-proteins and 20-60 M2-proteins and 130-200 NS2-proteins
and 2650 PB2-F1 proteins
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by: gs @ Fri Jan 18, 2008 at 16:22:01 PM EST
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there are 11 viral proteins
encoded by 8 RNA segments. Each of these 8 segments have to be 'packaged' inside the virus. The following diagram describes the structure of this package, also called the ribonucleoprotein or RNP.
The core of this package is the NP, nucleoprotein (not the NP gene, but the protein itself). The gene segment (the vRNA) wraps around this nucleoprotein, at the end of which you have the polymerase complex, consisting of PA, PB1 PB2, all of which are proteins not genes. The confusion may have arisen from our use of these same letters to designate genes as well as proteins, sometimes.
But the nature of representative government often means that to finally get the answer of 'yes', you have to be the last person who has not yet given up when the government said 'no'. ITW
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by: SusanC @ Fri Jan 18, 2008 at 16:49:40 PM EST
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well, yes there can be many protein molecules
if that is what you mean. There are 11 different TYPES of these molecules, but obviously one spike of HA is one molecule of HA protein, and there are lots of them.
That's the 'easy' part of the question.
The more complicated part is how exactly are the 8 different vRNAs packaged inside the virus, and whether there is at any moment exactly one strand of each RNA in each virion. This is a big question because how exactly do you define the structure of a virus anyway, given that it is constantly changing, and that the moment it enters a cell, this structure falls apart. It's like taking a freeze-frame of a movie, and trying to understand the rest of the story from that one frame!
What we can construct is a structure that we think exists from many different types of research, and a lot of the studies involve techniques eg to extract a particular part of the virus, or to dissolve the envelope, which one can imagine may alter the state of whatever it is that is inside. So are we actually able to say what exactly is inside each virion? More importantly, even if we do know, does that virus stay in that form anyway?
I have heard scientists refer to this notion of 'viral soup' where in avian species, maybe all that exist are just a bunch of these vRNA and proteins and they are so loosely constructed and constantly reassorting and changing, that maybe the idea of 'virion' as a particle is only a transient state of existence, and that the process of trying to observe it in the lab changes it so that all we have are indirect inferences, maybe?
But the nature of representative government often means that to finally get the answer of 'yes', you have to be the last person who has not yet given up when the government said 'no'. ITW
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by: SusanC @ Fri Jan 18, 2008 at 16:52:42 PM EST
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polymorphic
for viruses is simpler than for computers. It just means literally, having many shapes. E.g. influenza viruses can be long strands (filomorphic) or almost spherical.
(and you don't have to worry about whether it's parametric or adhoc polymorphism, neither ;-)
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by: Mathematician @ Fri Jan 18, 2008 at 17:16:59 PM EST
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some viruses do just that
- explode the cell, releasing lots of virions. Others do this budding thing, releasing new virions over a longer period. The cell does die (by apoptosis) in the end (ISTR about 2 days after infection?) but I don't remember exactly why it dies (i.e. what signals make it do so, e.g., is it "simply" because of the damage the virus has done to it, or is it more because it's set off some "alarm bell" that says this cell is sabotaging the body and would be better off dead), and I vaguely think I may remember having read that nobody's sure.
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by: Mathematician @ Fri Jan 18, 2008 at 17:21:16 PM EST
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they are very very small compared to the cell
so even for that kind of number of them there's plenty of lipid in the cell to scavenge? ISTR they get it from the cell's own bilipid layer, though haven't checked that.
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by: Mathematician @ Fri Jan 18, 2008 at 17:24:34 PM EST
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searching,searching,searching,....
http://cmr.asm.org/cgi/content...
http://www.pubmedcentral.nih.g...
early in the infectious cycle (4 h postinfection) of influenza virus, PB1 and PB2 are present mainly in the nucleus, whereas PA is predominantly present in the cytoplasm of the virus-infected cells. Later, at 6 to 8 h postinfection, all three polymerase proteins are apparent both in the cytoplasm as well as the nucleus.
The three polymerase proteins remain physically associated as a complex in either the presence or the absence of ribonucleoproteins. In the cytoplasm, the majority of the polymerase proteins remain unassociated, whereas in the nucleus they are present as a complex of three polymerase proteins.
PB1 alone, in the absence of the other polymerase proteins or the nucleoprotein, accumulates in the nucleus.This suggests that the formation of a complex with other viral protein(s) is not required for either nuclear transport or nuclear accumulation of PB1 protein and that the PB1 protein may contain an intrinsic signal(s) for nuclear transport.
------------------------------
These results suggest that a direct interaction of NP with polymerase proteins may be involved in regulating the switch of viral RNA synthesis from transcription to replication
----------------------------------
The ribonucleoprotein complex comprises a viral RNA segment associated with the nucleoprotein (NP) and three polymerase proteins (PA, PB1 and PB2). The matrix (M1) protein is associated with both ribonucleoprotein and the viral envelope.
----------------------------------
Much has also been learned about the viral proteins involved in RNA transcription and replication. They consist of the three polymerase proteins (PB1, PB2 ad PA) and the nucleoprotein (NP) which is wrapped around the virion template RNA. The NP is also required for the import of viral RNA from the cytoplasm into the nucleus (see below). The M1 protein appears to have a structural role: it inhibits viral transcription and it is involved in the nucleocytoplasmic transport of RNP as well as in virus maturation and budding. Finally, the NS1 protein has pleiotropic characteristics affecting RNA transport, splicing and translation
-----------------------------------
Here, we present a structured model for the single-cell reproductive cycle of influenza A virus in animal cells that accounts for the individual steps of the process such as attachment, internalization, genome replication and translation, and progeny virion assembly. The model describes an average cell surrounded by a small quantity of medium and infected by a low number of virus particles. The model allows estimation of the cellular resources consumed by virus replication. Simulation results show that the number of cellular surface receptors and endosomes, as well as other resources, such as the number of free nucleotides or amino acids, is not significantly influenced by influenza virus propagation. A factor that limits the growth rate of progeny viruses and their release is the total amount of matrix proteins (M1) in the nucleus while other newly synthesized viral proteins (e.g., nucleoprotein NP) and viral RNAs accumulate. During budding, synthesis of vRNPs (viral ribonucleoprotein complexes) represents another limiting factor
----------------------------------------
triggers uncoating. The nucleocapsid migrates to the nucleus where viral mRNA is transcribed as the essential initial event in infection. Transcription and replication of influenza RNA take place in the nucleus of infected cells and assembly into virions occurs by budding out of or through the plasma membrane
Replication of influenza virus RNAs is dependent on four viral gene products: PB1, PB2, PA, and NP. The three polymerase proteins, PB1, PB2, and PA, form a trimolecular complex in the nuclei of infected cells. Each protein has its own nuclear localization signal
PB1 appears to be primarily involved in the enzymatic polymerization process, i.e. the elongation step. It shares regions of amino acid homology with other RNA-dependent RNA polymerase proteins. The precise function of PA is unknown. The PB2 protein binds to the 5'-terminal cap structure present on host cell mRNAs; the mRNAs are then cleaved, producing a capped 9 to 15-mer oligoribonucleotide which serves as a primer for transcription of influenza mRNAs. The PB2 amino acid sequence contains a region of limited homology with the cellular cap-binding protein, eIF-4E. See de la Luna, Virus Res 13 :143-56 (1989). While PB2 is not absolutely required for replication of viral RNA, mRNAs transcribed from viral template in cells expressing only PB1, PA, and NP are uncapped and thus cannot be translated. See Nakagawa, J Virol 69 :728-33 (1995). Transcripts terminate at sites 15-22 bases from the ends of their templates, where oligo(U) sequences act as signals for the template-independent addition of poly(A) tracts. At a later stage of infection, instead of making mRNAs, the polymerase proteins PB1, PB2 and PA are used to make new viral RNA genomes. The polymerase complex first transcribes cRNA, which then serves as template for production of more vRNA. The plus-stranded cRNA copies differ from the plus-stranded mRNA transcripts by lacking capped and methylated 5'-termini. Also, they are not truncated or polyadenylated at the 3' termini. Thus, the cRNAs are coterminal with their negative strand templates and contain all the genetic information in each genomic segment in the complementary form.
The negative strand genomes (vRNAs) and antigenomes (cRNAs) are always encapsidated by viral nucleocapsid proteins; the only unencapsidated RNA species are virus mRNAs. Nucleocapsid assembly appears to take place in the nucleus. The virus matures by budding from the apical surface of the cell incorporating the M1 protein on the cytoplasmic side or inner surface of the budding envelope. The HA and NA glycoproteins are incorporated into the lipid envelope. In permissive cells, HA is post-translationally cleaved, but the two resulting chains remain associated by disulfide bonds.
-------------------------------------------------
extensive description of NP here:
http://vir.sgmjournals.org/cgi...
-----------------------------------------------
Each influenza RNA segment is encapsidated by nucleoproteins (NP) to form ribonucleotidenucleoprotein (RNP) complexes. The three polymerase proteins are associated with one end of the RNP complex. RNPs are surrounded by a membrane with the matrix protein (matrix 1 ) as an integral part.
-----------------------------------------------
aha. here it is:
http://www.jstage.jst.go.jp/ar...
"within the viral particle the 8 RNA segments {9-11 in average according to the other paper}
are coated with numerous copies of the nucleocapsid protein (NP).
Each nucleocapsid includes 3 polymerase proteins ... and an RNA genome coated with NP."
(?)
some strangeness still, but the only source, which I could find that mentions the
involvement of multiple NP-proteins in one RNP
-----------------------------------------------
http://cmr.asm.org/cgi/content...
http://cmr.asm.org/cgi/content...
FIG. 2. Structure of influenza A virus virions. Two glycoprotein spikes, HA and NA, and the M2 protein are embedded in the lipid bilayer derived from the host plasma membrane. The RNP consists of a viral RNA segment associated with the NP and the three polymerase proteins (PA, PB1, and PB2). The M1 protein is associated with both RNP and the viral envelope, while NS2 is associated with RNP through interaction with M1. NS1 is the only nonstructural protein of influenza A virus.
-------------------------------------------------
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by: gs @ Fri Jan 18, 2008 at 17:54:03 PM EST
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not sooo small
virus:100nm in diameter
cell : 10000nm
so I calculate the cell has 10000-fold surface.
Well, maybe the cell-envelope is thicker and the
virus only grasps a small layer. (how??)
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by: gs @ Fri Jan 18, 2008 at 17:57:21 PM EST
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better picture, 3d, zoom,rotate
in the picture at:
http://cmr.asm.org/content/vol...
I count about 3000 M1s inside the virus. (3000 is correct)
8 mRNAs (instead of 9-11)
21+19+17+17+15+13+11+9 = 122 NPs (instead of 1000)
8 PB2s (instead of 30-60)
8 PB1s (instead of 30-60)
8 PAs (instead of 30-60)
25 HAs (instead of 500)
13 NAs (instead of 100)
7 M2s (instead of 20-60)
0 NS1s (0 is correct)
16 NS2s (instead of 130-200)
someone please make a better picture, where the counts
and proportions match !
Rotatable with mouse-dragging, zoomable with click, option to look through walls.
Plus a table with the % of weight, estimated number of C,H,O,..-Atoms
of the components.
"encapsidated" - no such English word according to Merrian-Webster
how many segments per virus ? (+)
by: gs
Wed Jan 16, 2008 at 16:53:07 PM EST
[edit diary]
uhh, I'd always thought there were just one of each segment
in a virus, 8 strains in total.
Of course, I'd been puzzled what the HA,NA-peaks on the surface
were made of.
However, now I read for the first time since 2005, that there
are multiple copies of each segment included in one virus ?!?!?!
PB2:30-60
PB1:30-60
PA:30-60
HA:500
NP:1000
NA:100
M:20-60
NS:130-200
but also:
PB1-F2:2650
M1:3000
NS1:NA
???????
from
Cox,Neumann,Donis,Kawaoka: Orthomyxoviruses:influenza
http://www.topleyandwilson.com...
table 32.2 , page 10
so, can there be several mutation-variants of each of the segments present in one virus ?
Also, they say that HA contributes 25% to the virus mass. I can't verify this.
shame on me. Shame on all those authors who didn't make this clearer.
Honestly, who of you had thought the same (1 copy of each segment, <15000 nucleotides in total
per virus ) ?
gs :: how many segments per virus ?
Poll
did you also think there were only 8 RNA-strains in a fluA virus ?
* yes - 2 votes (100%)
* no - 0 votes (0%)
Total votes: 2
Results
Tags: 3000, 20-60, 100, 500, 30-60, (All Tags) :: Add/Edit Tags on this Post
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Nice chapter!
I don't think that table shows the number of copies of each RNA molecule that are in each virion - if it did, how would you account for the numbers being so different for PB1 and PB1-F2, which are encoded by the same RNA molecule? And how would you interpret "not applicable" for NS1?
I think what it shows is the copy number per virion, in the sense of "how many copies of this bit of RNA does it take to make one new virion?".
I'm confused by your mention of the HA and NA spikes, though. They are not made of RNA - they are made of the proteins haemagluttinin and neuraminidase that are encoded by the RNA. You knew that, surely, but then I find your post difficult to interpret...
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by: Mathematician @ Thu Jan 17, 2008 at 11:58:02 AM EST
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or to be more accurate and clearer
"how many copies FROM this bit of RNA does it take..."
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by: Mathematician @ Thu Jan 17, 2008 at 11:59:04 AM EST
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I don't know whether I knew that,
when I wrote it. So the proteins are needed for special (unknown) purposes
not just receptor and genetical code.
A flu-virus consists of RNA(1%),protein(73%:M1(40%)+HA(25%)+NA(5%)...),lip id(20%),carbohydrate(6%)
The RNA contains the 8 segments and is transported to the cell-nucleus for replication.
500 HA molecules (protein) as spikes on the virus surface and one HA as RNA-strain as part of the RNA-unit.
Their is no exchange of genetic material with the 500 spike HA-proteins and no mutations
can be stored and later released in these proteins.
Although, I think it could be somehow useful for the virus to store different RNAs
-------------------------------
http://www.haverford.edu/biolo...
The influenza virus is globular in shape, and is approximately 100 nanometers in diameter. The sheath of the virus is made up of a lipid bilayer, taken from the plasma membrane of the original host. Within the central core of this bilayer are located about 3000 matrix proteins (which differ depending on the type of the influenza), and 8 RNA genes. The surface membrane is spiked with protein molecules of two kinds: about 500 hemagglutinin ("H") and 100 neuraminidase ("N") molecules. Hemagglutinin molecules appear as pointed spikes, which are used to bind the virus to a cell and inject contents into it. Neuraminidase appear as blunt spikes, and possesses specialized enzymes which cause the infected cell to release the new viruses. (Silverstein: 50-52 and Flu)
Silverstein, Arthur M. Pure Politics and Impure Science: The Swine Flu Affair. Baltimore and London: The John Hopkins University Press, 1981.
uncoating. The nucleocapsid migrates to the nucleus where viral mRNA is transcribed. Viral mRNA is transcribed by a unique mechanism in which viral endonuclease cleaves the capped 5'-terminus from cellular heterologous mRNAs which then serve as primers for transcription of viral RNA templates by the viral transcriptase. Transcripts terminate at sites 15 to 22 bases from the ends of their templates, where oligo(U) sequences act as signals for the addition of poly(A) tracts. Of the eight viral RNA molecules so produced, six are monocistronic messages that are translated directly into the proteins representing HA, NA, NP and the viral polymerase proteins, PB2, PB1 and PA. The other two transcripts undergo splicing, each yielding two mRNAs which are translated in different reading frames to produce M1, M2, NS1 and NEP. In other words, the eight viral RNA segments code for ten proteins: nine structural and one nonstructural. A summary of the genes of the influenza virus and their protein products is shown in Table I below.
TABLE I
INFLUENZA VIRUS GENOME RNA SEGMENTS AND CODING
ASSIGNMENTSa
Lengthb Encoded Lengthd Molecules
Segment (Nucleotides) Polypeptidec (Amino Acids) Per Virion
Comments
1 2341 PB2 759 30-60 RNA
transcriptase component; host
cell RNA cap
binding
2 2341 PB1 757 30-60 RNA
transcriptase component;
initiation of
transcription
3 2233 PA 716 30-60 RNA
transcriptase component
4 1778 HA 566 500 Hemagglutinin;
trimer; envelope
glycoprotein;
mediates attachment to
cells
5 1565 NP 498 1000 Nucleoprotein;
associated with
RNA; structural
component of RNA
transcriptase
6 1413 NA 454 100 Neuraminidase;
tetramer; envelope
glycoprotein
7 1027 M1 252 3000 Matrix protein;
lines inside of
envelope
M2 96 ? Structural
protein in plasma
membrane;
spliced mRNA
8 890 NS1 230 Nonstructural
protein;function
unknown
NEP 121 ? Nuclear export
protein; spliced
mRNA
a Adapted from R.A. Lamb and P. W. Choppin (1983), Annual Review of
Biochemistry, Volume 52, 467-506.
b For A/PR/8/34 strain
c Determined by biochemical and genetic approaches
d Determined by nucleotide sequence analysis and protein sequencing
The influenza A virus genome contains eight segments of single-stranded RNA of negative polarity, coding for one nonstructural and nine structural proteins. The nonstructural protein NS1 is abundant in influenza virus infected cells, but has not been detected in virions. NS1 is a phosphoprotein found in the nucleus early during infection and also in the cytoplasm at later times of the viral cycle (King et al., 1975, Virology 64: 378)
http://books.google.com/books?...
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by: gs @ Thu Jan 17, 2008 at 14:46:09 PM EST
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polymerase
I can somehow understand/imagine the purpose of the HA-spikes,
but what are the 30-60 polymerase "proteins" good for ?
Does the virus manufacture its own proteins without the help
of the host-cell-nucleus ?
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by: gs @ Thu Jan 17, 2008 at 15:41:00 PM EST
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No, but it does a lot of the work itself
Influenza, like many viruses, has an RDRP - RNA dependent RNA polymerase - complex, meaning that it has the basic mechanism for copying its own RNA. That's what the polymerase proteins are good for. However, it seems it nevertheless can't do it without help from the host-cell-nucleus. See for example http://jvi.asm.org/cgi/reprint...
This is all about transcription - making one RNA molecule from another RNA molecule. The process that makes the viral proteins is translation. For that, the virus is (even) more dependent on the host-cell-mechanisms. See for example
http://jvi.asm.org/cgi/reprint...
These little virions are jolly complicated machines :-(
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by: Mathematician @ Fri Jan 18, 2008 at 10:46:00 AM EST
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yes, and that with only 3K of code.
Seems that the answer to the original question is 10 (in average):
From: Evidence for Segment-Nonspecific Packaging of the Influenza A Virus Genome
http://jvi.asm.org/cgi/content...
"Our results are therefore most compatible with the view that, on average, each influenza A virus virion packages 9 to 11 vRNAs and does so in a nonspecific manner."
So, in addition to all these proteins, there is one place inside the virus, where the viral RNA is stored.
~10 segments in total.
I'm puzzled, why the virus does this all.
What are the 30-60 polymerase (-proteins?) for ?
I wished, there were short summaries of such articles. Better than the abstracts.
And a good short survey which describes all this, without having to read the
details of the experiments.
can we continue this in email or on another board ?
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by: gs @ Fri Jan 18, 2008 at 13:21:44 PM EST
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Virus can do it on its own? Not just a hijacker?
Mathematician,
Hi. As a layman we where taught "virus are just strands of DNA that need a host cell to replicate. They can not do this on their own but hijack the internals of other living cells"
Where am I wrong (Probably just after the word Hi)
BTW I did try and read the article but all the Pol II, C-termnal domain, etc was confusing. The only C-terminal domain I know of is at HeartsField airport in Atlanta :o)
Kobie
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by: Kobie @ Fri Jan 18, 2008 at 13:47:14 PM EST
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I'd rather keep discussion on FW
and if I can help, I'd be happy to try writing explanations of some of the things I understand (though I wish we had a real virologist to do this kind of thing!).
However, the Wiki page
http://www.fluwikie.com/pmwiki...
seems pretty good for starters. I could maybe go into more detail about some particular area if you like, and put that in as a subsidiary page. Maybe on polymerase etc.? That page's recent edits seem to have been removing spam, I don't know who wrote it in the first place.
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by: Mathematician @ Fri Jan 18, 2008 at 15:12:27 PM EST
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I think you start being wrong at "just" :-)
and then at "DNA" it gets worse ;-) Influenza is an RNA virus, no DNA in sight. And there's more to it than just the strands of RNA - those are packaged up in an envelope that helps it get in and out of cells, and with other stuff that it needs to do the hijacking. (Pistol, black mask...) The wiki has a primer:
http://www.fluwikie.com/pmwiki...
and as I just said to gs I'd be happy to try to help expand it, if that would help. (But not to summarise the whole state of current knowledge about influenza, because life is too short!)
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by: Mathematician @ Fri Jan 18, 2008 at 15:15:11 PM EST
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...
lots of other stuff in the virus, only 1% is RNA.
It doesn't seem, that the virus can make it's own proteins without
help from the cell's RNA/DNA.
The wiki-article doesn't mention, that there are 500 HA-proteins, 30-60PB1-proteins,...
in addition to the 9-11 vRNA-segments.
Also transcription,translation,transduction,packaging,r eporters,...
how the vRNA goes to the nucleus
how many viruses per cell (1e5-1e6, but only enough cell-membrane for 10000 viruses ?)
99% of viruses are defect ?
how many cells are infected , how many viruses per human ?
virus inside liposomes
why polymorphic
the whole immunity things are also complicated and hard to grasp/remember
some people are banned here, some only post to other boards.
They should be included IMO.
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by: gs @ Fri Jan 18, 2008 at 15:35:14 PM EST
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Polymorphic I understand
GS and Mathematitian,
HI and thanks.
Let me read the articel to see what is so confusing.
As a computer geek the polymorphic thing is easy to understand. I write short little subroutines that do differnt things depending on what is fed them.
If its feed positive numbers it does one thing
It if is feed charectors or letters it does something else
If its fed letters and numbers it does something diffeent
If its fed numbers and letter than something else happens.
So the bundles of RNA from different viruses seemed as normal as subrutines or tool in a mechanics tool box. Tools you can assemble to make other tools. A socket does not do much but sit around, but socket and wrench do!
The whole thing on having some RNA for assembling parts threw me.
Ok. I was wrong with "Just" Laymen often get the abbriviated lecture :o)
kobie
Someone who thinks logically is a nice contrast to the real world.
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by: Kobie @ Fri Jan 18, 2008 at 15:47:08 PM EST
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they are talking about glycoproteins
not the RNA. That's my take, looking at the diagram and the caption. Also the RNP ribonucleoprotein complex.
But the nature of representative government often means that to finally get the answer of 'yes', you have to be the last person who has not yet given up when the government said 'no'. ITW
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by: SusanC @ Fri Jan 18, 2008 at 15:47:14 PM EST
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60
> Within the viral envelope one finds ribonucleoprotein (RNP)
> consisting of RNA-segments associated with nucleoprotein (NP)
> and the PA,PB1 and PB2 polymerase proteins.
> Three polymerase proteins are associated with the ends of vRNAs(insert).
so, a protein "consists" of RNA-segments ?
Which in turn are "associated" with other proteins.
But there are only 9-11 vRNAs in the virus, right ?
So, 3 polymerase proteins for each(?) end of the vRNAs
(including non-polymerase-segments) still makes only
60 polymerase proteins in total, but 90-180 are reported.
And 1000 nucleoproteins in total...
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by: gs @ Fri Jan 18, 2008 at 16:00:19 PM EST
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Interesting
Mathematician,
Wow. The last picture shows "a budding virus" as opposed to an exploding cell. I always thought virus took over a cell making thousands of copies untill the cell was full and exploded.
In my mind that is a bad thing. Virus could consume all the supplies or machinery of a cell adn then kill the replicator. This way the cell stays in tact like a mini virus factory pumping out new copies and then some variations. I assume virus mutates during replication.
At least if the cell died that would shut down some production. Yes I know I am made of cells so it is some of me that is dying. If too much of that happens it is a really bad thing.
But I am thinking that only some cells are good for viral reproduction. Not all cells. So if only some cells make the virus then I could get by without them for a while. Laymen oversimpliy things.
KObie
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30
well, in the picture it's only on one end of the vRNA,
so I'm back to 30 polymerase-proteins inside
the virus in total.
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many
Kobie, you are made of an awful lot of cells.
60 Trillion. So just a tiny fraction of these
gives the viruses lots of room for replication.
And then count 100000-1000000 viruses per cell !
(although I don't know, where they get all the lipid from)
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by: gs @ Fri Jan 18, 2008 at 16:08:09 PM EST
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I'm not sure I understand your question n/t
But the nature of representative government often means that to finally get the answer of 'yes', you have to be the last person who has not yet given up when the government said 'no'. ITW
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by: SusanC @ Fri Jan 18, 2008 at 16:11:40 PM EST
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multi-tasking
if it infects a bird, it uses its alpha2,3 receptor HA
if it infects a human, it uses its alpha2,6 receptor HA
if I were the virus-God, I'd make
viruses with 250 2,3-HA-proteins and 250 2,6-HA-proteins
and two HA-vRNAs.
Or viruses that just randomly choose 2,3 or 2,6 for all 500 HAs.
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by: gs @ Fri Jan 18, 2008 at 16:13:58 PM EST
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...
the picture shows that each vRNA (usually 9-11 per virus, at most
8 different ones) encircles one (or more ?) NP-proteins
with PB2,PB1,PA - proteins at its (3'?)end.
That makes 27-33 polymerase proteins and 9-11 NP-proteins.
Plus some polymerase vRNAs.
But several sources report that there are 30-60 proteins
of each of PB2,PB1,PA in a virus.
And 1000 NP-proteins and 500 HA-proteins and 100 NA-proteins
and 3000 M1-proteins and 20-60 M2-proteins and 130-200 NS2-proteins
and 2650 PB2-F1 proteins
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by: gs @ Fri Jan 18, 2008 at 16:22:01 PM EST
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there are 11 viral proteins
encoded by 8 RNA segments. Each of these 8 segments have to be 'packaged' inside the virus. The following diagram describes the structure of this package, also called the ribonucleoprotein or RNP.
The core of this package is the NP, nucleoprotein (not the NP gene, but the protein itself). The gene segment (the vRNA) wraps around this nucleoprotein, at the end of which you have the polymerase complex, consisting of PA, PB1 PB2, all of which are proteins not genes. The confusion may have arisen from our use of these same letters to designate genes as well as proteins, sometimes.
But the nature of representative government often means that to finally get the answer of 'yes', you have to be the last person who has not yet given up when the government said 'no'. ITW
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well, yes there can be many protein molecules
if that is what you mean. There are 11 different TYPES of these molecules, but obviously one spike of HA is one molecule of HA protein, and there are lots of them.
That's the 'easy' part of the question.
The more complicated part is how exactly are the 8 different vRNAs packaged inside the virus, and whether there is at any moment exactly one strand of each RNA in each virion. This is a big question because how exactly do you define the structure of a virus anyway, given that it is constantly changing, and that the moment it enters a cell, this structure falls apart. It's like taking a freeze-frame of a movie, and trying to understand the rest of the story from that one frame!
What we can construct is a structure that we think exists from many different types of research, and a lot of the studies involve techniques eg to extract a particular part of the virus, or to dissolve the envelope, which one can imagine may alter the state of whatever it is that is inside. So are we actually able to say what exactly is inside each virion? More importantly, even if we do know, does that virus stay in that form anyway?
I have heard scientists refer to this notion of 'viral soup' where in avian species, maybe all that exist are just a bunch of these vRNA and proteins and they are so loosely constructed and constantly reassorting and changing, that maybe the idea of 'virion' as a particle is only a transient state of existence, and that the process of trying to observe it in the lab changes it so that all we have are indirect inferences, maybe?
But the nature of representative government often means that to finally get the answer of 'yes', you have to be the last person who has not yet given up when the government said 'no'. ITW
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by: SusanC @ Fri Jan 18, 2008 at 16:52:42 PM EST
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polymorphic
for viruses is simpler than for computers. It just means literally, having many shapes. E.g. influenza viruses can be long strands (filomorphic) or almost spherical.
(and you don't have to worry about whether it's parametric or adhoc polymorphism, neither ;-)
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some viruses do just that
- explode the cell, releasing lots of virions. Others do this budding thing, releasing new virions over a longer period. The cell does die (by apoptosis) in the end (ISTR about 2 days after infection?) but I don't remember exactly why it dies (i.e. what signals make it do so, e.g., is it "simply" because of the damage the virus has done to it, or is it more because it's set off some "alarm bell" that says this cell is sabotaging the body and would be better off dead), and I vaguely think I may remember having read that nobody's sure.
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they are very very small compared to the cell
so even for that kind of number of them there's plenty of lipid in the cell to scavenge? ISTR they get it from the cell's own bilipid layer, though haven't checked that.
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searching,searching,searching,....
http://cmr.asm.org/cgi/content...
http://www.pubmedcentral.nih.g...
early in the infectious cycle (4 h postinfection) of influenza virus, PB1 and PB2 are present mainly in the nucleus, whereas PA is predominantly present in the cytoplasm of the virus-infected cells. Later, at 6 to 8 h postinfection, all three polymerase proteins are apparent both in the cytoplasm as well as the nucleus.
The three polymerase proteins remain physically associated as a complex in either the presence or the absence of ribonucleoproteins. In the cytoplasm, the majority of the polymerase proteins remain unassociated, whereas in the nucleus they are present as a complex of three polymerase proteins.
PB1 alone, in the absence of the other polymerase proteins or the nucleoprotein, accumulates in the nucleus.This suggests that the formation of a complex with other viral protein(s) is not required for either nuclear transport or nuclear accumulation of PB1 protein and that the PB1 protein may contain an intrinsic signal(s) for nuclear transport.
------------------------------
These results suggest that a direct interaction of NP with polymerase proteins may be involved in regulating the switch of viral RNA synthesis from transcription to replication
----------------------------------
The ribonucleoprotein complex comprises a viral RNA segment associated with the nucleoprotein (NP) and three polymerase proteins (PA, PB1 and PB2). The matrix (M1) protein is associated with both ribonucleoprotein and the viral envelope.
----------------------------------
Much has also been learned about the viral proteins involved in RNA transcription and replication. They consist of the three polymerase proteins (PB1, PB2 ad PA) and the nucleoprotein (NP) which is wrapped around the virion template RNA. The NP is also required for the import of viral RNA from the cytoplasm into the nucleus (see below). The M1 protein appears to have a structural role: it inhibits viral transcription and it is involved in the nucleocytoplasmic transport of RNP as well as in virus maturation and budding. Finally, the NS1 protein has pleiotropic characteristics affecting RNA transport, splicing and translation
-----------------------------------
Here, we present a structured model for the single-cell reproductive cycle of influenza A virus in animal cells that accounts for the individual steps of the process such as attachment, internalization, genome replication and translation, and progeny virion assembly. The model describes an average cell surrounded by a small quantity of medium and infected by a low number of virus particles. The model allows estimation of the cellular resources consumed by virus replication. Simulation results show that the number of cellular surface receptors and endosomes, as well as other resources, such as the number of free nucleotides or amino acids, is not significantly influenced by influenza virus propagation. A factor that limits the growth rate of progeny viruses and their release is the total amount of matrix proteins (M1) in the nucleus while other newly synthesized viral proteins (e.g., nucleoprotein NP) and viral RNAs accumulate. During budding, synthesis of vRNPs (viral ribonucleoprotein complexes) represents another limiting factor
----------------------------------------
triggers uncoating. The nucleocapsid migrates to the nucleus where viral mRNA is transcribed as the essential initial event in infection. Transcription and replication of influenza RNA take place in the nucleus of infected cells and assembly into virions occurs by budding out of or through the plasma membrane
Replication of influenza virus RNAs is dependent on four viral gene products: PB1, PB2, PA, and NP. The three polymerase proteins, PB1, PB2, and PA, form a trimolecular complex in the nuclei of infected cells. Each protein has its own nuclear localization signal
PB1 appears to be primarily involved in the enzymatic polymerization process, i.e. the elongation step. It shares regions of amino acid homology with other RNA-dependent RNA polymerase proteins. The precise function of PA is unknown. The PB2 protein binds to the 5'-terminal cap structure present on host cell mRNAs; the mRNAs are then cleaved, producing a capped 9 to 15-mer oligoribonucleotide which serves as a primer for transcription of influenza mRNAs. The PB2 amino acid sequence contains a region of limited homology with the cellular cap-binding protein, eIF-4E. See de la Luna, Virus Res 13 :143-56 (1989). While PB2 is not absolutely required for replication of viral RNA, mRNAs transcribed from viral template in cells expressing only PB1, PA, and NP are uncapped and thus cannot be translated. See Nakagawa, J Virol 69 :728-33 (1995). Transcripts terminate at sites 15-22 bases from the ends of their templates, where oligo(U) sequences act as signals for the template-independent addition of poly(A) tracts. At a later stage of infection, instead of making mRNAs, the polymerase proteins PB1, PB2 and PA are used to make new viral RNA genomes. The polymerase complex first transcribes cRNA, which then serves as template for production of more vRNA. The plus-stranded cRNA copies differ from the plus-stranded mRNA transcripts by lacking capped and methylated 5'-termini. Also, they are not truncated or polyadenylated at the 3' termini. Thus, the cRNAs are coterminal with their negative strand templates and contain all the genetic information in each genomic segment in the complementary form.
The negative strand genomes (vRNAs) and antigenomes (cRNAs) are always encapsidated by viral nucleocapsid proteins; the only unencapsidated RNA species are virus mRNAs. Nucleocapsid assembly appears to take place in the nucleus. The virus matures by budding from the apical surface of the cell incorporating the M1 protein on the cytoplasmic side or inner surface of the budding envelope. The HA and NA glycoproteins are incorporated into the lipid envelope. In permissive cells, HA is post-translationally cleaved, but the two resulting chains remain associated by disulfide bonds.
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extensive description of NP here:
http://vir.sgmjournals.org/cgi...
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Each influenza RNA segment is encapsidated by nucleoproteins (NP) to form ribonucleotidenucleoprotein (RNP) complexes. The three polymerase proteins are associated with one end of the RNP complex. RNPs are surrounded by a membrane with the matrix protein (matrix 1 ) as an integral part.
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aha. here it is:
http://www.jstage.jst.go.jp/ar...
"within the viral particle the 8 RNA segments {9-11 in average according to the other paper}
are coated with numerous copies of the nucleocapsid protein (NP).
Each nucleocapsid includes 3 polymerase proteins ... and an RNA genome coated with NP."
(?)
some strangeness still, but the only source, which I could find that mentions the
involvement of multiple NP-proteins in one RNP
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http://cmr.asm.org/cgi/content...
http://cmr.asm.org/cgi/content...
FIG. 2. Structure of influenza A virus virions. Two glycoprotein spikes, HA and NA, and the M2 protein are embedded in the lipid bilayer derived from the host plasma membrane. The RNP consists of a viral RNA segment associated with the NP and the three polymerase proteins (PA, PB1, and PB2). The M1 protein is associated with both RNP and the viral envelope, while NS2 is associated with RNP through interaction with M1. NS1 is the only nonstructural protein of influenza A virus.
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ask experts for their panflu probability estimates and report the replies
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by: gs @ Fri Jan 18, 2008 at 17:54:03 PM EST
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not sooo small
virus:100nm in diameter
cell : 10000nm
so I calculate the cell has 10000-fold surface.
Well, maybe the cell-envelope is thicker and the
virus only grasps a small layer. (how??)
ask experts for their panflu probability estimates and report the replies
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by: gs @ Fri Jan 18, 2008 at 17:57:21 PM EST
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better picture, 3d, zoom,rotate
in the picture at:
http://cmr.asm.org/content/vol...
I count about 3000 M1s inside the virus. (3000 is correct)
8 mRNAs (instead of 9-11)
21+19+17+17+15+13+11+9 = 122 NPs (instead of 1000)
8 PB2s (instead of 30-60)
8 PB1s (instead of 30-60)
8 PAs (instead of 30-60)
25 HAs (instead of 500)
13 NAs (instead of 100)
7 M2s (instead of 20-60)
0 NS1s (0 is correct)
16 NS2s (instead of 130-200)
someone please make a better picture, where the counts
and proportions match !
Rotatable with mouse-dragging, zoomable with click, option to look through walls.
Plus a table with the % of weight, estimated number of C,H,O,..-Atoms
of the components.
"encapsidated" - no such English word according to Merrian-Webster
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