The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
Rashid Bashir - One of the best experts on this subject based on the ideXlab platform.
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single Virus Particle mass detection using microresonators with nanoscale thickness
Applied Physics Letters, 2004Co-Authors: Amit K Gupta, Demir Akin, Rashid BashirAbstract:In this letter, we present the microfabrication and application of arrays of silicon cantilever beams as microresonator sensors with nanoscale thickness to detect the mass of individual Virus Particles. The dimensions of the fabricated cantilever beams were in the range of 4–5 μm in length, 1–2 μm in width and 20–30 nm in thickness. The Virus Particles we used in the study were vaccinia Virus, which is a member of the Poxviridae family and forms the basis of the smallpox vaccine. The frequency spectra of the cantilever beams, due to thermal and ambient noise, were measured using a laser Doppler vibrometer under ambient conditions. The change in resonant frequency as a function of the Virus Particle mass binding on the cantilever beam surface forms the basis of the detection scheme. We have demonstrated the detection of a single vaccinia Virus Particle with an average mass of 9.5 fg. These devices can be very useful as components of biosensors for the detection of airborne Virus Particles.
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Single Virus Particle mass detection using microresonators with nanoscale thickness
Applied Physics Letters, 2004Co-Authors: A Gupta, Darcin Akin, Demir Akin, Rashid BashirAbstract:In this letter, we present the microfabrication and application of arrays of silicon cantilever beams as microresonator sensors with nanoscale thickness to detect the mass of individual Virus Particles. The dimensions of the fabricated cantilever beams were in the range of 4–5 μm in length, 1–2 μm in width and 20–30 nm in thickness. The Virus Particles we used in the study were vaccinia Virus, which is a member of the Poxviridae family and forms the basis of the smallpox vaccine. The frequency spectra of the cantilever beams, due to thermal and ambient noise, were measured using a laser Doppler vibrometer under ambient conditions. The change in resonant frequency as a function of the Virus Particle mass binding on the cantilever beam surface forms the basis of the detection scheme. We have demonstrated the detection of a single vaccinia Virus Particle with an average mass of 9.5 fg. These devices can be very useful as components of biosensors for the detection of airborne Virus Particles. © 2004 American Institute of Physics.
Demir Akin - One of the best experts on this subject based on the ideXlab platform.
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single Virus Particle mass detection using microresonators with nanoscale thickness
Applied Physics Letters, 2004Co-Authors: Amit K Gupta, Demir Akin, Rashid BashirAbstract:In this letter, we present the microfabrication and application of arrays of silicon cantilever beams as microresonator sensors with nanoscale thickness to detect the mass of individual Virus Particles. The dimensions of the fabricated cantilever beams were in the range of 4–5 μm in length, 1–2 μm in width and 20–30 nm in thickness. The Virus Particles we used in the study were vaccinia Virus, which is a member of the Poxviridae family and forms the basis of the smallpox vaccine. The frequency spectra of the cantilever beams, due to thermal and ambient noise, were measured using a laser Doppler vibrometer under ambient conditions. The change in resonant frequency as a function of the Virus Particle mass binding on the cantilever beam surface forms the basis of the detection scheme. We have demonstrated the detection of a single vaccinia Virus Particle with an average mass of 9.5 fg. These devices can be very useful as components of biosensors for the detection of airborne Virus Particles.
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Single Virus Particle mass detection using microresonators with nanoscale thickness
Applied Physics Letters, 2004Co-Authors: A Gupta, Darcin Akin, Demir Akin, Rashid BashirAbstract:In this letter, we present the microfabrication and application of arrays of silicon cantilever beams as microresonator sensors with nanoscale thickness to detect the mass of individual Virus Particles. The dimensions of the fabricated cantilever beams were in the range of 4–5 μm in length, 1–2 μm in width and 20–30 nm in thickness. The Virus Particles we used in the study were vaccinia Virus, which is a member of the Poxviridae family and forms the basis of the smallpox vaccine. The frequency spectra of the cantilever beams, due to thermal and ambient noise, were measured using a laser Doppler vibrometer under ambient conditions. The change in resonant frequency as a function of the Virus Particle mass binding on the cantilever beam surface forms the basis of the detection scheme. We have demonstrated the detection of a single vaccinia Virus Particle with an average mass of 9.5 fg. These devices can be very useful as components of biosensors for the detection of airborne Virus Particles. © 2004 American Institute of Physics.
Aaron Klug - One of the best experts on this subject based on the ideXlab platform.
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the tobacco mosaic Virus Particle structure and assembly
Philosophical Transactions of the Royal Society B, 1999Co-Authors: Aaron KlugAbstract:A short account is given of the physical and chemical studies that have led to an understanding of the structure of the tobacco mosaic Virus Particle and how it is assembled from its constituent coat protein and RNA. The assembly is a much more complex process than might have been expected from the simplicity of the helical design of the Particle. The protein forms an obligatory intermediate (a cylindrical disk composed of two layers of protein units), which recognizes a specific RNA hairpin sequence. This extraordinary mechanism simultaneously fulfils the physical requirement for nucleating the growth of the helical Particle and the biological requirement for specific recognition of the viral DNA.
Karen L Mossman - One of the best experts on this subject based on the ideXlab platform.
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the ifn independent response to Virus Particle entry provides a first line of antiviral defense that is independent of tlrs and retinoic acid inducible gene i
Journal of Immunology, 2006Co-Authors: Patrick Paladino, Derek Cummings, Ryan S Noyce, Karen L MossmanAbstract:The innate immune system responds to pathogen infection by eliciting a nonspecific immune response following the recognition of various pathogen-associated molecular patterns. TLRs and the RNA helicases retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated gene 5 recognize foreign nucleic acid within endosomal and cytoplasmic compartments, respectively, initiating a signaling cascade that involves the induction of type I IFN through the transcription factors IFN regulatory factor (IRF) 3 and NF-B. However, a recent paradigm has emerged in which bacterial DNA and double-stranded B-form DNA trigger type I IFN production through an uncharacterized TLR- and RIG-I-independent pathway. We have previously described a response in primary fibroblasts wherein the entry of diverse RNA- and DNA-enveloped Virus Particles is sufficient to induce a subset of IFN-stimulated genes and a complete antiviral response in an IRF3-dependent, IFN-independent manner. In this study, we show that the innate immune response to Virus Particle entry is independent of both TLR and RIG-I pathways, confirming the existence of novel innate immune mechanisms that result in the activation of IRF3. Furthermore, we propose a model of innate antiviral immunity in which exposure to increasing numbers of Virus Particles elevates the complexity of the cellular response from an intracellular, IFN-independent response to one involving secretion of cytokines and activation of infiltrating immune cells. The Journal of Immunology, 2006, 177: 8008 – 8016.
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innate cellular response to Virus Particle entry requires irf3 but not Virus replication
Journal of Virology, 2004Co-Authors: Susan E Collins, Ryan S Noyce, Karen L MossmanAbstract:Mammalian cells respond to Virus infections by eliciting both innate and adaptive immune responses. One of the most effective innate antiviral responses is the production of alpha/beta interferon and the subsequent induction of interferon-stimulated genes (ISGs), whose products collectively limit Virus replication and spread. Following viral infection, interferon is produced in a biphasic fashion that involves a number of transcription factors, including the interferon regulatory factors (IRFs) 1, 3, 7, and 9. In addition, Virus infection has been shown to directly induce ISGs in the absence of prior interferon production through the activation of IRF3. This process is believed to require Virus replication and results in IRF3 hyperphosphorylation, nuclear localization, and proteasome-mediated degradation. Previously, we and others demonstrated that herpes simplex Virus type 1 (HSV-1) induces ISGs and an antiviral response in fibroblasts in the absence of both interferon production and Virus replication. In this report, we show that the entry of enveloped Virus Particles from diverse Virus families elicits a similar innate response. This process requires IRF3, but not IRF1, IRF7, or IRF9. Following Virus replication, the large DNA Viruses HSV-1 and vaccinia Virus effectively inhibit ISG mRNA accumulation, whereas the small RNA Viruses Newcastle disease Virus, Sendai Virus, and vesicular stomatitis Virus do not. In addition, we found that IRF3 hyperphosphorylation and degradation do not correlate with ISG and antiviral state induction but instead serve as a hallmark of productive Virus replication, particularly following a high-multiplicity infection. Collectively, these data suggest that Virus entry triggers an innate antiviral response mediated by IRF3 and that subsequent Virus replication results in posttranslational modification of IRF3, such as hyperphosphorylation, depending on the nature of the incoming Virus.
John E. Johnson - One of the best experts on this subject based on the ideXlab platform.
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Virus Particle maturation insights into elegantly programmed nanomachines
Current Opinion in Structural Biology, 2010Co-Authors: John E. JohnsonAbstract:Similar modes of Virus maturation have been observed in dsDNA bacteriophages and the structurally related herpes Viruses and some type of maturation occur in most animal Viruses. Recently a variety of biophysical studies of maturation intermediates of bacteriophages P22, λ, and HK97 have suggested an energy landscape that drives the transitions and structure-based mechanisms for its formation. Near-atomic resolution models of subunit tertiary structures in an early intermediate of bacteriophage HK97 maturation revealed a remarkable distortion of the secondary structures when compared to the mature Particle. Scaffolding proteins may induce the distortion that is maintained by quaternary structure interactions following scaffold release, making the intermediate Particle metastable.
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Model-based 3-D Reconstructions for the Structural Biology of Viruses Exhibiting Incompatible Symmetries
2006 IEEE International Conference on Electro Information Technology, 2006Co-Authors: Cory J. Prust, Peter C. Doerschuk, John E. JohnsonAbstract:A model-based approach to 3-D reconstruction from cryo electron microscope images is presented for the case of a Virus Particle lacking total Particle symmetry. In particular, we consider the reconstruction of a tailed bacteriophage where the symmetries of the capsid and tail are incompatible. We describe a model-based statistical approach and a two-stage reconstruction algorithm. Numerical results from synthetic data are presented
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Virus Particle explorer viper a website for Virus capsid structures and their computational analyses
Journal of Virology, 2001Co-Authors: Vijay S Reddy, Padmaja Natarajan, Brian Okerberg, Kevin Li, K V Damodaran, Ryan T Morton, Charles L Brooks, John E. JohnsonAbstract:The number of icosahedral-capsid structures determined at a near-atomic level of resolution is growing rapidly as advances in synchrotron radiation sources, fast-readout detectors, and computer hardware and software are made. Hence, there is an increasing need to organize these mega-assemblies into a uniform and easy-to-use database. The coordinates of the icosahedral-capsid structures deposited in the Protein Data Bank (PDB) (2) follow a variety of conventions in which the icosahedral symmetry axes are oriented differently in the orthogonal coordinate system. While trying to analyze the various capsid structures en masse, we became aware of the need for a database in which all capsid structures (coordinates) are stored in a standard icosahedral orientation. Such a structural database of viral capsids would indeed facilitate the development of tools for high-throughput analyses of the Virus structures. We report here the creation of a web-base (website and database) of Virus structures, the Virus Particle Explorer (VIPER), which can be accessed through the World Wide Web (WWW) at the uniform resource locator (URL) http://mmtsb.scripps.edu /viper/. The organization of the VIPER database is shown in Fig. Fig.1.1. FIG. 1 Flow chart showing the organization of the contents of the VIPER site. The VIPER database contains the structures of viral capsids determined at a nearly atomic-level resolution. Coordinates of the capsid structures are stored in the z(2)-3-5-x(2) convention. ...
