scholarly journals Optical Trapping, Sizing, and Probing Acoustic Modes of a Small Virus

2020 ◽  
Vol 10 (1) ◽  
pp. 394 ◽  
Author(s):  
Jeffrey Burkhartsmeyer ◽  
Yanhong Wang ◽  
Kam Sing Wong ◽  
Reuven Gordon
Keyword(s):  
Optical Trapping ◽  
Local Fields ◽  
Plasmonic Enhancement ◽  
Virus Particles ◽  
Acoustic Modes ◽  
Analysis Technique ◽  
Viral Particles ◽  
Large Ensembles ◽  
Small Virus ◽  
Good Agreement

Prior opto-mechanical techniques to measure vibrational frequencies of viruses work on large ensembles of particles, whereas, in this work, individually trapped viral particles were studied. Double nanohole (DNH) apertures in a gold film were used to achieve optical trapping of one of the smallest virus particles yet reported, PhiX174, which has a diameter of 25 nm. When a laser was focused onto these DNH apertures, it created high local fields due to plasmonic enhancement, which allowed stable trapping of small particles for prolonged periods at low powers. Two techniques were performed to characterize the virus particles. The particles were sized via an established autocorrelation analysis technique, and the acoustic modes were probed using the extraordinary acoustic Raman (EAR) method. The size of the trapped particle was determined to be 25 ± 3.8 nm, which is in good agreement with the established diameter of PhiX174. A peak in the EAR signal was observed at 32 GHz, which fits well with the predicted value from elastic theory.

scholarly journals Identification and Characterization of a Poliovirus Capsid Mutant with Enhanced Thermal Stability

2018 ◽  
Vol 93 (6) ◽  
Author(s):  
Y Nguyen ◽  
Palmy R. Jesudhasan ◽  
Elizabeth R. Aguilera ◽  
Julie K. Pfeiffer
Keyword(s):  
Thermal Stability ◽  
High Temperatures ◽  
Oral Route ◽  
Mutant Virus ◽  
Single Amino Acid ◽  
Bacterial Surface ◽  
Virus Particles ◽  
Heat Resistant ◽  
Viral Particles ◽  
Very High

ABSTRACTEnteric viruses, including poliovirus, are spread by the fecal-oral route. In order to persist and transmit to a new host, enteric virus particles must remain stable once they are in the environment. Environmental stressors such as heat and disinfectants can inactivate virus particles and prevent viral transmission. It has been previously demonstrated that bacteria or bacterial surface glycans can enhance poliovirus virion stability and limit inactivation from heat or bleach. While investigating the mechanisms underlying bacterially enhanced virion thermal stability, we identified and characterized a poliovirus (PV) mutant with increased resistance to heat inactivation. The M132V mutant harbors a single amino acid change in the VP1 capsid coding that is sufficient to confer heat resistance but not bleach resistance. Although the M132V virus was stable in the absence of bacteria or feces at most temperatures, M132V virus was stabilized by feces at very high temperatures. M132V PV had reduced specific infectivity and RNA uncoating compared with those of wild-type (WT) PV, but viral yields in HeLa cells were similar. In orally inoculated mice, M132V had a slight fitness cost since fecal titers were lower and 12.5% of fecal viruses reverted to the WT. Overall, this work sheds light on factors that influence virion stability and fitness.IMPORTANCEViruses spread by the fecal-oral route need to maintain viability in the environment to ensure transmission. Previous work indicated that bacteria and bacterial surface polysaccharides can stabilize viral particles and enhance transmission. To explore factors that influence viral particle stability, we isolated a mutant poliovirus that is heat resistant. This mutant virus does not require feces for stability at most temperatures but can be stabilized by feces at very high temperatures. Even though the mutant virus is heat resistant, it is susceptible to inactivation by treatment with bleach. This work provides insight into how viral particles maintain infectivity in the environment.

scholarly journals Abundant Defective Viral Particles Budding from Microglia in the Course of Retroviral Spongiform Encephalopathy

2000 ◽  
Vol 74 (4) ◽  
pp. 1775-1780 ◽  
Author(s):  
Regine Hansen ◽  
Stefanie Czub ◽  
Evi Werder ◽  
Jens Herold ◽  
Georg Gosztonyi ◽  
...  
Keyword(s):  
Infectious Virus ◽  
Protein Translocation ◽  
Neuronal Damage ◽  
Ex Vivo ◽  
Spongiform Encephalopathy ◽  
Microglia Cell ◽  
Virus Particles ◽  
Viral Particles ◽  
Type C ◽  
Retroviral Infections

ABSTRACT A pathogenetic hallmark of retroviral neurodegeneration is the affinity of neurovirulent retroviruses for microglia cells, while degenerating neurons are excluded from retroviral infections. Microglia isolated ex vivo from rats peripherally infected with a neurovirulent retrovirus released abundant mature type C virions; however, infectivity associated with microglia was very low. In microglia, viral transcription was unaffected but envelope proteins were insufficiently cleaved into mature viral proteins and were not detected on the microglia cell surface. These microglia-specific defects in envelope protein translocation and processing not only may have prevented formation of infectious virus particles but also may have caused further cellular defects in microglia with the consequence of indirect neuronal damage. It is conceivable that similar events play a role in neuro-AIDS.

scholarly journals What is in a Viral Stock: Perspectives and Current Limitations of Flow Virometry

2020 ◽  
Author(s):  
Timothy K. Soh ◽  
Jens B. Bosse
Keyword(s):  
Flow Cytometry ◽  
Full Potential ◽  
Multiple Objects ◽  
Virus Particles ◽  
Viral Particles ◽  
Viral Stock ◽  
Infected Cells ◽  
A Minor ◽  
Unique Capability

Herpesviruses produce a plethora of pleomorphic and heterogeneous particle populations. The composition and biological role of these is not understood. Detailed analysis has been challenging due to the lack of multidimensional identification and purification methodologies. Fluorescence-activated cell sorting (FACS), originally developed to sort objects with at least ten thousand-fold larger volumes, has recently been applied to cellular exosomes as well as viral particles and has been dubbed nanoscale flow cytometry or “flow virometry”. In comparison to other nanoparticles, herpesvirus concentrations can be measured with high precision using simple culturing methods. Here, we used this unique capability to evaluate a standard FACS sorter. We demonstrate that detection and separation capabilities were insufficient to distinguish infectious fluorescent viral populations from populations lacking fluorescence and infectivity. Moreover, fluorescent populations did not contain single virus particles but mostly aggregates. On top, analysis of viral samples by flow cytometry was confounded by swarm detection, as multiple objects are measured simultaneously and interpreted as a single object. Despite these technical difficulties, comparison of crude supernatant to gradient purified HCMV revealed that infectious virus is a minor proportion of the particles released from infected cells. Our data stress the need for a set of standardized controls and protocols when applying FACS to biological nanoparticles and highlights technical challenges that need to be solved before flow virometry can achieve its full potential.

scholarly journals Are There 1031 Virus Particles on Earth, or More, or Fewer?

2020 ◽  
Vol 202 (9) ◽  
Author(s):  
A. R. Mushegian
Keyword(s):  
Scientific Literature ◽  
General Interest ◽  
Virus Particles ◽  
Know How ◽  
Link Type ◽  
Best Estimate ◽  
Viral Particles ◽  
History Of ◽  
New Evidence

ABSTRACT The number of virus particles on Earth is frequently reported in the scientific literature and in general-interest publications as being on the order of 1031, with some confusion about whether this is a high or low estimate. This number is often given without a source, although it should be attributed to a paper by Hendrix et al. published in 1999 (R. W. Hendrix, M. C. Smith, R. N. Burns, M. E. Ford, and G. F. Hatfull, Proc Natl Acad Sci U S A 96:2192–2197, 1999, https://doi.org/10.1073/pnas.96.5.2192). As with any oft-repeated statistic, it is informative to know how it has been derived and whether it should be revised in the light of new evidence. I review the history of the 1031 estimate and use more recent assessments of the number of bacterial and viral particles in various habitats to conclude that the best estimate of the number of virus particles on Earth (“the Hendrix product”) remains close to 1031 and is unlikely to be either much less or much more than that.

scholarly journals Differential Biophysical Properties of Infectious Intracellular and Secreted Hepatitis C Virus Particles

2006 ◽  
Vol 80 (22) ◽  
pp. 11074-11081 ◽  
Author(s):  
Pablo Gastaminza ◽  
Sharookh B. Kapadia ◽  
Francis V. Chisari
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Buoyant Density ◽  
Infection Model ◽  
Virus Particles ◽  
Viral Egress ◽  
Viral Particles ◽  
A Cell ◽  
Infected Cells

ABSTRACT The recent development of a cell culture infection model for hepatitis C virus (HCV) permits the production of infectious particles in vitro. In this report, we demonstrate that infectious particles are present both within the infected cells and in the supernatant. Kinetic analysis indicates that intracellular particles constitute precursors of the secreted infectious virus. Ultracentrifugation analyses indicate that intracellular infectious viral particles are similar in size (∼65 to 70 nm) but different in buoyant density (∼1.15 to 1.20 g/ml) from extracellular particles (∼1.03 to 1.16 g/ml). These results indicate that infectious HCV particles are assembled intracellularly and that their biochemical composition is altered during viral egress.

scholarly journals Fast NO<sub>2</sub> retrievals from Odin-OSIRIS limb scatter measurements

2011 ◽  
Vol 4 (5) ◽  
pp. 965-972 ◽  
Author(s):  
A. E. Bourassa ◽  
C. A. McLinden ◽  
C. E. Sioris ◽  
S. Brohede ◽  
A. F. Bathgate ◽  
...  
Keyword(s):  
Infrared Imaging ◽  
Imaging System ◽  
Computational Cost ◽  
Data Sets ◽  
Proof Of Concept ◽  
Spectral Fitting ◽  
Analysis Technique ◽  
Order Of Magnitude ◽  
Very High ◽  
Good Agreement

Abstract. The feasibility of retrieving vertical profiles of NO2 from space-based measurements of limb scattered sunlight has been demonstrated using several different data sets since the 1980's. The NO2 data product routinely retrieved from measurements made by the Optical Spectrograph and InfraRed Imaging System (OSIRIS) instrument onboard the Odin satellite uses a spectral fitting technique over the 437 to 451 nm range, over which there are 36 individual wavelength measurements. In this work we present a proof of concept technique for the retrieval of NO2 using only 4 of the 36 OSIRIS measurements in this wavelength range, which reduces the computational cost by almost an order of magnitude. The method is an adaptation of a triplet analysis technique that is currently used for the OSIRIS retrievals of ozone at Chappuis band wavelengths. The results obtained are shown to be in very good agreement with the spectral fit method, and provide an important alternative for applications where the computational burden is very high. Additionally this provides a baseline for future instrument design in terms of cost effectiveness and reducing spectral range requirements.

A CYTOPLASMIC POLYHEDROSIS OF HYALOPHORA CECROPIA (LINNAEUS)

1965 ◽  
Vol 11 (4) ◽  
pp. 703-707 ◽  
Author(s):  
W. A. Smirnoff
Keyword(s):  
Electron Microscope ◽  
Viral Infection ◽  
Cytoplasmic Polyhedrosis Virus ◽  
Virus Particles ◽  
Protein Mass ◽  
Viral Particles ◽  
Polyhedrosis Virus ◽  
Hyalophora Cecropia

Hyalophora cecropia (Linnaeus) is susceptible to infection by a cytoplasmic polyhedrosis virus. Electron microscope studies showed spherical viral particles known as "cores" which remain in groups of 12 to 17 subunits. The virus particles were embedded in a protein mass located in craters of the polyhedra. Larvae of the first, second, and third instars were more susceptible to viral infection than later instars. However, up to 50% of the larvae of later instars sometimes survived. The larvae of subsequent instars and the pupa were very resistant and periodic injections of strong dosages of virus material produced no ill effect. In general, larvae infected by this cytoplasmic virus shrank to less than half normal size before death.

Virus Particles Infected the Erythrocytes of Cultured Eel in Taiwan

1981 ◽  
Vol 39 ◽  
pp. 608-609
Author(s):  
Kuo-chun Liu
Keyword(s):  
Viral Particle ◽  
Electron Microscopic Observation ◽  
Field Trips ◽  
Fish Farms ◽  
Electron Microscopic ◽  
Internal Organs ◽  
Virus Particles ◽  
Pathological Conditions ◽  
Viral Particles ◽  
Electron Lucent

The erythrocytes infected by viral particles and the pathological conditions by the presence of those viral particles were reported in cod, herring and few other species of fish in the western waters. This report will present the evidence that the erythrocytes of some of the cultured eel in Taiwan were infected by virus particles.In the summer of 1980, in one of the field trips to the fish farms in Lotung county, northeastern of Taiwan, the author was informed that dead eels from unknown cause were picked up from eel ponds every morning. Samples were collected the following morning. There was no observable external symptom.The internal organs showed a red coloration (Fig. 1,2). Tissues from the livers and gills were processed for electron microscopic observation. Virus particles were found in some of the erythrocytes in both organs (Fig.3).The viral particles aggregated together as an inclusion body in the cytoplasm only. No intranuclear viral particle was found. In a single viral aggregate 1 to 40 particles were observed. A electron lucent ring separated the viral aggregate from the hemoglobin cytoplasm.

Dynamical analysis of B-train vehicle combination with liquid cargo

2019 ◽  
Vol 233 (14) ◽  
pp. 3871-3881
Author(s):  
Nilson Barbieri ◽  
Rubem Penteado de Melo ◽  
Key Fonseca de Lima ◽  
Gabriel de Sant’Anna Vitor Barbieri
Keyword(s):  
Lateral Acceleration ◽  
Dynamical Analysis ◽  
Curved Trajectories ◽  
Straight Line ◽  
Analysis Technique ◽  
Liquid Load ◽  
The Moment ◽  
Experimental Values ◽  
Acceleration Signals ◽  
Good Agreement

In this work, a combination of B-train type vehicle is dynamically analysed through lateral movement at low speed manoeuvre known as Lane Change Manoeuvre. The analyses were conducted for a vehicle with liquid loads of 100%, 80%, 60% and 40% capacity. The analyses involve adjusting the steer angle through an objective function taking into account the numerical and experimental lateral acceleration of the tractor vehicle. The movement of the liquid (slosh) during the manoeuvres are approximated using the software Pasimodo and trammel pendulum. Considering the upper surface of the liquid inside the tank as a straight line, it is possible to obtain the centre of gravity variation and the moment of inertia through polynomial adjustments. In this way, it is possible to analyse numerically the behaviour of the vehicle with liquid load in a curved trajectory. To obtain modal parameters, the operational modal analysis technique is used. With the applied methodology, it was possible to find good agreement between the numerical and experimental values of the acceleration signals in four different positions in the vehicle combination. Through the analyses of the vehicle with fluid in movement, it was possible to verify a great variation of load in the wheels due to transfer of load of the vehicle travelling by curved trajectories or due to evasive manoeuvres. This is a critical condition that can lead the vehicle to rollover condition. The experimental data were obtained for the vehicle at constant speed (between 30 and 40 km/h) and under these conditions, the vehicle is considered stable by analysing the eigenvalues.

Deep Drawing of Square-Shaped Sheet Metal Parts, Part 1: Finite Element Analysis

1993 ◽  
Vol 115 (1) ◽  
pp. 102-109 ◽  
Author(s):  
S. A. Majlessi ◽  
D. Lee
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Membrane Properties ◽  
Computationally Efficient ◽  
Element Analysis ◽  
Sheet Metal Parts ◽  
Part Geometry ◽  
Analysis Technique ◽  
The Finite Element Analysis ◽  
Good Agreement

The process of square-cup drawing is modeled employing a simplified finite element analysis technique. In order to make the algorithm computationally efficient, the deformation (total strain) theory of plasticity is adopted. The solution scheme is comprised of specifying a mesh of two-dimensional finite elements with membrane properties over the deformed configuration of the final part geometry. The initial positions of these elements are then computed by minimization of the potential energy, and therefore the strain distributions are determined. In order to verify predictions made by the finite element analysis method, a drawing apparatus is built and various drawing experiments are carried out. A number of circular and square cups are drawn and strain distributions measured. It is observed that there is generally a good agreement between computed and measured results for both axisymmetric and nonaxisymmetric cases.

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