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Topic: Virions

  Posterior midgut and hindgut are both sites of acquisition of Cucurbit aphid-borne yellows virus in Myzus persicae and ...
Observation of virions in the gut lumen (Lu), cytoplasm (Cyto) or basal lamina (BL) of epithelial cells of the anterior midgut (stomach), posterior midgut and hindgut of M.
The ultrastructure of the alimentary canal of A.
(a) Virions free in the lumen (lu) or adsorbed in a linear array on the surface of the apical plasmalemma (apl) (arrow).
vir.sgmjournals.org /cgi/content/full/84/12/3473   (4260 words)

 Viruses   (Site not responding. Last check: 2007-10-08)
The virion is inert, because it lacks many of the components that are necessary for independent life and reproduction; it does, however, provide for the transfer of the nucleic acid from host cell to host cell.
Many virions having a simple rod or polygonal shape are composed of several types of proteins, and some of these virions are surrounded by a less regularly shaped envelope, which often includes components of the host-cell membrane.
At the other extreme of complexity, bacteriophage T4 has a virion composed of at least 25 different types of protein that make up a hollow head in which a DNA molecule is enclosed, and a tubular tail by which the virion attaches to its host cell and injects its DNA into it.
www.accreditationservices.com /Viruses.htm   (2025 words)

 Structural organization of authentic, mature HIV-1 virions and cores   (Site not responding. Last check: 2007-10-08)
Virions are released from the cell surface as immature, non-infectious particles containing a spherical layer of Gag polyproteins underneath the viral membrane.
The frequent observation of multiple cores within single virions, combined with the calculation of the CA protein concentrations during core formation, suggests that the assembly process is template-mediated rather than concentration-driven as it is in vitro.
Virions with a single core were clearly smaller in diameter than virions with two cores (marked with double arrows).
www.nature.com /emboj/journal/v22/n7/full/7595054a.html   (7286 words)

 Virus - Wikipedia, the free encyclopedia
A capsid is composed of proteins encoded by the viral genome and its shape serves as the basis for morphological distinction.
The virions are counted and the number extrapolated to estimate the number of virions in the undiluted mixture.
The neologism virion or viron is used to refer to a single infective viral particle.
en.wikipedia.org /wiki/Virion   (4586 words)

 CEPCEB - Center for Plant Cell Biology at UC Riverside
Assembly of infectious virions has long been recognized to be an important phase in the life cycle of a given virus pathogenic to plants, humans and animals.
Since BMV is amenable for in vitro reconstruction of infectious virions from dissociated coat protein subunits and RNA, we initiated a project to unravel the mechanism of RNA packaging in BMV.
Analysis of virion RNA profiles obtained from barley protoplasts transfected with a RNA3 variant lacking the PE provides the first genetic evidence that de novo synthesized RNA4 is incompetent for autonomous assembly whereas prior packaging of RNA3 is a prerequisite for RNA4 to co-package.
www.cepceb.ucr.edu /members/rao.htm   (638 words)

 Virology Immunology 1
Antibodies (Abs) are elicited by the surface components of intact virions as well by the internal components of disrupted virions.
It is thought that reversible neutralization is due to the interference with attachment of virions to the cellular receptors.
Virion sites for neutralization - only epitopes on molecules involved in the release of the viral genome into the cells are targets of neutralization.
www.nlv.ch /Virologytutorials/Immunology.htm   (1046 words)

 Microbe Magazine
A fraction of the virions, most likely those that are bound instead to cholesterol receptors, remain intact and retain their infectivity.
After binding virions, the DCs contract their dendrites and transform into round cells with ¡°sails,¡± that are also known as ¡°veiled¡± cells.
During that period, the virions are proteolytically degraded in the HLA class II compartment and by the cytoplasmic proteasomes, loading the HLA class I molecules in the endoplasmic reticulum.
www.asm.org /microbe/index.asp?bid=32036   (2516 words)

 Herpes Simplex Virus Tegument Protein VP16 Is a Component of Primary Enveloped Virions -- Naldinho-Souto et al. 80 (5): ...
it is a component of primary virions (18).
Immunoelectron microscopy of extracellular and primary enveloped virions observed in cells infected with recombinant viruses expressing VP16gpf (a to c), VP22gfp (d to f), or VP13/14yfp (g to i).
The UL48 tegument protein of pseudorabies virus is critical for intracytoplasmic assembly of infectious virions.
jvi.asm.org /cgi/content/full/80/5/2582   (1945 words)

 The Big Picture Book of Viruses - Rhabdoviruses
Distinct viral structures visible in thin sections of infected tissue; virions enveloped, or not enveloped (in viruses that are considered possible species of the family); virions slightly pleomorphic; virions in unfixed preparations bullet-shaped, or bacilliform (in cases of plant viruses when fixed prior to negative staining); virions 45-100 nm in diameter; virions 100-430 nm long.
Virions only of one kind (that is a virus with defective genome, usually significantly shorter than the full length).
With electron microscopy, rabies virion shows a 75 nm mean diameter, and a length varying between 130 and 300 nm (mean: 180 nm); spike-like projections (9 nm long) can be seen on the viral envelope.
www.tulane.edu /~dmsander/Big_Virology/BVRNArhabdo.html   (560 words)

 The Big Picture Book of Viruses - Baculoviruses
Virions occluded by protein bodies or crystals in thin sections, or not occluded.
Many enveloped extracellular virions have budded through the cytoplasmic membrane and are visible outside the cell.
A portion of the nucleus containing enveloped virions in the process of being occluded into a developing polyhedron is shown.
www.tulane.edu /~dmsander/Big_Virology/BVDNAbaculo.html   (377 words)

 The Scripps Research Institute - News and Views
Finn saw these virions as "supramolecular" chemical reagents that can be manipulated to display a number of interesting molecules by attaching other chemicals to the side chains of the viral component proteins.
One key to this is the fact that the virions are polyvalent, and multiple copies of some endocytosis "effector" molecule can be displayed on their surface in well-defined patterns and distances.
In a different twist, Finn and his laboratory are trying to use Johnson's virions to make new materials, and they have made progress in getting the virions to assemble themselves into supermolecular assemblies, aggregates, and other nanostructures by putting different molecules on the outside of the virions.
www.scripps.edu /newsandviews/e_20030512/finn2.html   (1026 words)

 Incorporation of Vpr into human immunodeficiency virus type 1 virions: requirement for the p6 region of gag and ...
Incorporation of Vpr into human immunodeficiency virus type 1 virions: requirement for the p6 region of gag and mutational analysis.
The tagged Vpr expression vector and a vpr mutant HIV-1 provirus were used to cotransfect COS cells, and the resulting virions were tested for the presence of the tagged protein on immunoblots probed with monoclonal antibody against the hemagglutinin peptide.
The COS-produced virions were found to contain readily detectable amounts of tagged Vpr and smaller amounts of a putative tagged Vpr dimer.
www.aegis.com /aidsline/1994/feb/M9420387.html   (553 words)

 Vpr-mediated Incorporation of UNG2 into HIV-1 Particles Is Required to Modulate the Virus Mutation Rate and for ...
Vpr lane corresponds to purified virions produced from cells transfected with vpr-defective HIV-1 vector alone as indicated under "Experimental Procedures." B, analysis of UNG activity in the presence of uracil-DNA glycosylase inhibitor (UGI).
Virions were produced, as indicated under "Experimental Procedures," from 293T cells cotransfected with an HIV-1-based vector lacking the vpr gene in combination with plasmids for expression of HA-tagged Vpr-UNG or VprW54R-UNG fusions.
Virions produced from cells expressing either Vpr-UNG or VprW54R-UNG were collected from cell supernatants and prepared as described under "Experimental Procedures." UNG enzymatic activity was assayed as in Fig.
www.jbc.org /cgi/content/full/279/27/28419   (5357 words)

Once complete virions are produced within the host cell, they leave the cell in a variety of ways.
In this way the number of virions in a sample can be quantitated by counting the number of plaques formed on a host lawn.
Following induction the new phage virions are rapidly made and the host cell is lysed.
www.towson.edu /users/gekpenyo/315lab21.htm   (769 words)

 Cathepsin S Supports Acid-independent Infection by Some Reoviruses -- Golden et al. 279 (10): 8547 -- Journal of ...
3 from the virions of wild-type reovirus strains in
B, purified Lang or c43 virions (as labeled) were incubated with purified Cat S for the indicated times (in h), and the reactions were then terminated.
C, purified Lang or c43 virions (as labeled) were incubated with chymotrypsin (CHT) for the indicated times (in min), and the reactions were then terminated.
www.jbc.org /cgi/content/full/279/10/8547   (7072 words)

 Atomic Force Microscopy Investigation of Fibroblasts Infected with Wild-Type and Mutant Murine Leukemia Virus (MuLV) -- ...
In (c) and (d) are virions emerging from the cells, presumably with intact envelopes.
The virions in (a)-(c) are defective or damaged and a sector of surface proteins is missing in each case, resulting in a cavity and channel leading deeper into the interior of the virus particle.
The virions of the mutant are unable, in general, to properly mature and separate from the cell and instead form prominent tubelike protrusions from the cell surfaces.
www.biophysj.org /cgi/content/full/83/6/3665   (4355 words)

 Of the three tegument proteins that package mRNA in herpes simplex virions, one (VP22) transports the mRNA to ...
Wild-type and recombinant virus virions were purified as described elsewhere (3, 7).
virion proteins of the R7105 mutant (lane 2, Fig.
A central question arising from these studies is whether the RNA carried in virions is expressed in newly infected cells.
www.pnas.org /cgi/content/full/99/12/8318   (4578 words)

 Time-resolved Imaging of HIV-1 Env-mediated Lipid and Content Mixing between a Single Virion and Cell Membrane -- ...
The average fraction of individual virions exhibiting lipid mixing alone or in association with content mixing was determined from multiple experiments and plotted against C34 concentration.
The total number of double-labeled virions analyzed for each C34 concentration were as follows: 1658 particles in the absence of C34; 75 for 25 nM C34; 458 for 50 nM; 104 for 100 nM; and 610 for 200 nM.
The kinetics of lipid mixing for virions that did not transfer their contents is shown by open triangles.
www.molbiolcell.org /cgi/content/full/16/12/5502   (7993 words)

Virions range in size from as small as the poliovirus shown above magnified some 450,000 times (courtesy of A. Taylor), which is 30 nm in diameter (about the size of a ribosome) to as large as the vaccinia virus which, at 230 nm, is larger than some bacteria.
The virion attaches to the surface of the host cell (usually binding to a specific cell surface molecule that accounts for the specificity of the infection).
In fact, when the phage is "rescued", the released virions may contain some host genes as well as their own.
home.comcast.net /~john.kimball1/BiologyPages/V/Viruses.html   (1649 words)

 Analysis of Human Immunodeficiency Virus Type 1 Reverse Transcriptase Subunit Structure/Function in the Context of ...
Virions were analyzed for infectivity using the TZM-bl reporter cell line.
The virions were examined for (B) p66 and (C) CA using a MAb specific for either the RNase H subdomain (7E5) or CA, respectively.
Virions derived by transfection with proviral SG3 or cotransfection with M7, vpr-p51/p66, and vpr-IN were used to infect the TZM-bl reporter cell line in the presence of 0.008 to 5.0 µM (A) 3TC or (B) NVP, and inhibition of infectivity was determined as described in Materials and Methods.
aac.asm.org /cgi/content/full/49/9/3762   (5494 words)

 Morphological changes and fusogenic activity of influenza virus hemagglutinin -- Shangguan et al. 74 (1): 54 -- ...
Note that the spikes on the virions have become disorganized and are no longer well defined or distinct.
Many of the virions incubated under these conditions had blebs and discontinuities visible on their surfaces.
The arrowhead indicates a virion that retains an organized spike layer, which is extremely rare under these conditions (see text).
www.biophysj.org /cgi/content/full/74/1/54   (5432 words)

 Lecture Notes MCB 229. Viruses.
Virions are the transmissible state of a virus.
Virions must be able to adhere and allow entry into some host cell(s).
Some virions more hardy than others (e.g., hepatitis virus can withstand short periods of boiling; most virions are destroyed by this).
www.sp.uconn.edu /~terry/229sp03/lectures/viruses.html   (3012 words)

 Retrovirology | Full text | Generation of H9 T-cells stably expressing a membrane-bound form of the cytoplasmic tail of ...   (Site not responding. Last check: 2007-10-08)
The infectivities of the virions in the supernatants of the infected H9 cells were analysed in a single-round assay in Tzm-bl reporter cells [13-15].
This observation of gp120 incorporation into pNL-Tr712 virions stands in contrast to two studies in the literature [1,17] which report that Env incorporation into pNL-Tr712 virions is defective when these are produced in non-permissive cells.
The presence of the membrane-bound Env-TMD-CT protein in the H9 cells was not sufficient to transcomplement the replication block of virions encoding C-terminally truncated Env proteins.
www.retrovirology.com /content/3/1/27   (2575 words)

 BioS 353
Because there are typically about a hundred million or so virions in the body, we conclude that at any given time, there are thousands of virions in the body with the particular change, and thus these virions are already partially resistant to the drug before the patient starts taking it.
If the patient starts taking two drugs that require separate mutations to give partial resistance to each drug, the fraction of double-resistant virions already present in the body will be something like 1 in 10,000 times 1 in 10,000, which is 1 in a hundred million.
If the patient starts taking three drugs that each require separate mutations to give partial resistance to each drug, the fraction of triple-resistant virions already present in the body is expected to be something like 1 in a trillion (one in ten to 12'th power).
www.lehigh.edu /~jas0/V17.html   (896 words)

 Retrovirology | Full text | APOBEC3G targets human T-cell leukemia virus type 1   (Site not responding. Last check: 2007-10-08)
During reverse transcription, it deaminates deoxycytidine (dC) into deoxyuridine (dU) in newly synthesized minus strand DNA, resulting in either G-to-A hypermutation of the viral plus strand DNA or degradation of dU-rich reverse transcripts [3,6-8], though several resent studies suggest cytidine deaminase adtivity is essential but not a sole determinant for antiviral activity of APOBEC3G.
The fact that infusion of fresh frozen plasma from the seropositive individuals did not cause the transmission also supports the notion that living infected cells are essential for the transmission in vivo [18,19].
To confirm the incorporation of APOBEC3G into virion, HTLV-1 K30 virions were purified by sucrose density equilibrium gradients as previously reported with slight modifications [30].
www.retrovirology.com /content/2/1/32   (4415 words)

 Movements of vaccinia virus intracellular enveloped virions with GFP tagged to the F13L envelope protein -- Geada et ...
Movements of vaccinia virus intracellular enveloped virions with GFP tagged to the F13L envelope protein -- Geada et al.
the movements of enveloped virions in the infected cells.
Vaccinia virus intracellular enveloped virions move to the cell periphery on microtubules in the absence of the A36R protein
vir.sgmjournals.org /cgi/content/full/82/11/2747   (6209 words)

 BioS 353
That is, about half the virions in a person's blood are ones that were produced within the past day or so.
In the body as a whole, perhaps a hundred million (or so) new virions are being produced every day.
Essentially all of the virions present in the blood at any time were produced within the past week or so.
www.lehigh.edu /~jas0/V16.html   (1106 words)

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