scholarly journals SARS-CoV-2 Spike Pseudoviruses: A Useful tool to study virus entry and address emerging neutralization escape phenotypes

2021 ◽  
Author(s):  
Raj Kalkeri ◽  
Zhaohui Cai ◽  
Shuling Lin ◽  
John Farmer ◽  
Yury V Kuzmichev ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Virus Entry ◽  
Unmet Need ◽  
High Sensitivity ◽  
Cost Effective ◽  
Neutralization Assay ◽  
Preclinical Models ◽  
Post Vaccination ◽  
Angiotensin Converting Enzyme 2 ◽  
Neutralization Ability

SARS-CoV-2 genetic variants are emerging around the globe. Unfortunately, several SARS-CoV-2 variants, especially, variants of concern (VOC) are less susceptible to neutralization by the convalescent and post-vaccination sera, raising concerns of increased disease transmissibility and severity. Recent data suggests the SARS-CoV-2 neutralizing anti-body levels as a good correlate of vaccine mediated protection. However, currently used BSL3 based virus micro-neutralization (MN) assays are more laborious, time consuming and expensive, underscoring the need for BSL2 based, cost effective neutralization assays against SARS-CoV-2 variants. In light of this unmet need, we have developed a BSL2 pseudovirus based neutralization assay (PBNA) in cells expressing Angiotensin Converting Enzyme-2 (ACE2) receptor for SARS-CoV-2. The assay is reproducible (R2=0.96), demonstrates a good dynamic range and high sensitivity. Our data suggests that the biological Anti-SARS-CoV-2 research reagents such as NIBSC 20/130 show lower neutralization against B.1.351 RSA and B1.1.7 UK VOC, whereas a commercially available monoclonal antibody MM43 retains activity against both these variants. SARS-CoV-2 Spike Pseudovirus based neutralization assays for VOC would be useful tools to measure the neutralization ability of candidate vaccines in both preclinical models and clinical trials and further help develop effective prophylactic countermeasures against emerging neutralization escape phenotypes.

scholarly journals SARS-CoV-2 Spike Pseudoviruses: A Useful Tool to Study Virus Entry and Address Emerging Neutralization Escape Phenotypes

2021 ◽  
Vol 9 (8) ◽  
pp. 1744
Author(s):  
Raj Kalkeri ◽  
Zhaohui Cai ◽  
Shuling Lin ◽  
John Farmer ◽  
Yury V. Kuzmichev ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Unmet Need ◽  
Neutralizing Antibody ◽  
High Sensitivity ◽  
Cost Effective ◽  
Neutralization Assay ◽  
Post Vaccination ◽  
Angiotensin Converting Enzyme 2 ◽  
Antibody Levels ◽  
Neutralization Ability

SARS-CoV-2 genetic variants are emerging around the globe. Unfortunately, several SARS-CoV-2 variants, especially variants of concern (VOCs), are less susceptible to neutralization by the convalescent and post-vaccination sera, raising concerns of increased disease transmissibility and severity. Recent data suggests that SARS-CoV-2 neutralizing antibody levels are a reliable correlate of vaccine-mediated protection. However, currently used BSL3-based virus micro-neutralization (MN) assays are more laborious, time-consuming, and expensive, underscoring the need for BSL2-based, cost-effective neutralization assays against SARS-CoV-2 variants. In light of this unmet need, we have developed a BSL-2 pseudovirus-based neutralization assay (PBNA) in cells expressing the human angiotensin-converting enzyme-2 (hACE2) receptor for SARS-CoV-2. The assay is reproducible (R2 = 0.96), demonstrates a good dynamic range and high sensitivity. Our data suggest that the biological Anti-SARS-CoV-2 research reagents such as NIBSC 20/130 show lower neutralization against B.1.351 SA (South Africa) and B.1.1.7 UK (United Kingdom) VOC, whereas a commercially available monoclonal antibody MM43 retains activity against both these variants. SARS-CoV-2 spike PBNAs for VOCs would be useful tools to measure the neutralization ability of candidate vaccines in both preclinical models and clinical trials and would further help develop effective prophylactic countermeasures against emerging neutralization escape phenotypes.

Rapid, targeted and culture-free viral infectivity assay in drop-based microfluidics

Lab on a Chip ◽  
2015 ◽  
Vol 15 (19) ◽  
pp. 3934-3940 ◽  
Author(s):  
Ye Tao ◽  
Assaf Rotem ◽  
Huidan Zhang ◽  
Connie B. Chang ◽  
Anindita Basu ◽  
...  
Keyword(s):  
High Throughput ◽  
Dynamic Range ◽  
High Sensitivity ◽  
Cost Effective ◽  
Serial Dilution ◽  
Viral Infectivity ◽  
Large Dynamic Range ◽  
Infectivity Assay ◽  
Dilution Experiments

We developed a rapid, targeted and culture-free infectivity assay using high-throughput drop-based microfluidics. The high sensitivity and large dynamic range of our cost effective assay alleviates the need for serial dilution experiments.

A novel approach to design electrochemical aptamer-based biosensor for ultrasensitive detecting of zearalenone as a prevalent estrogenic mycotoxin

2021 ◽  
Vol 28 ◽  
Author(s):  
Shokoufeh Hassani ◽  
Armin Salek Maghsoudi ◽  
Milad Rezaei Akmal ◽  
Shahram Shoeibi ◽  
Fatemeh Ghadipasha ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Electrochemical Impedance ◽  
Fusarium Species ◽  
High Sensitivity ◽  
High Specificity ◽  
Cost Effective ◽  
Differential Pulse ◽  
Electrode Position ◽  
Novel Approach ◽  
Modified Surface

Background: Zearalenone is a well-known estrogenic mycotoxin produced by Fusarium species, a serious threat to the agricultural and food industries worldwide. Zearalenone, with its known metabolites, are biomarkers of exposure to certain fungi, primarily through food. It has considerable toxic effects on biological systems due to its carcinogenicity, mutagenicity, renal toxicity, teratogenicity, and immunotoxicity. Introduction: This study aims to design a simple, quick, precise, and cost-effective method on a biosensor platform to evaluate the low levels of this toxin in foodstuffs and agricultural products. Methods: An aptamer-based electrochemical biosensor was introduced that utilizes screen-printed gold electrodes instead of conventional electrodes. The electrode position process was employed to develop a gold nanoparticle-modified surface to enhance the electroactive surface area. Thiolated aptamers were immobilized on the surface of gold nanoparticles, and subsequently, the blocker and analyte were added to the modified surface. In the presence of a redox probe, electrochemical characterization of differential pulse voltammetry, cyclic voltammetry, and electrochemical impedance spectroscopy were used to investigate the various stages of aptasensor fabrication. Results: The proposed aptasensor for zearalenone concentration had a wide linear dynamic range covering the 0.5 pg/mL to 100 ng/mL with a 0.14 pg/mL detection limit. Moreover, this aptasensor had high specificity so that a non-specific analyte cannot negatively affect the selectivity of the aptasensor. Conclusion: Overall, due to its simple design, high sensitivity, and fast performance, this aptasensor showed a high potential for assessing zearalenone in real samples, providing a clear perspective for designing a portable and cost-effective device.

scholarly journals Yn-situ: a robust single RNA molecule in situ detection method

2021 ◽  
Author(s):  
Yunming Wu ◽  
Wenjing Xu ◽  
Limei Ma ◽  
Zulin Yu ◽  
Yongfu Wang ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Signal To Noise Ratio ◽  
High Sensitivity ◽  
Cost Effective ◽  
Hybridization Chain Reaction ◽  
Single Pair ◽  
Rna Molecules ◽  
Key Steps ◽  
In Situ Detection

We describe a cost-effective, highly sensitive, and quantitative method for in situ detection of single RNA molecules in tissue sections. This method, dubbed Yn situ, standing for Y-branched probe in situ hybridization, uses a single-strand DNA preamplifier with multiple initiation sites that trigger hybridization chain reaction (HCR) to detect polynucleotide. We characterized the performance of this method and compared it to other approaches in the postnatal mouse olfactory epithelia. We find that the Yn situ method, in conjunction with an improved fixation step, is sensitive enough to allow detection of single molecules using a single pair of probes targeting a short nucleotide sequence. A set of 5-probes can produce quantitative results with smaller puncta and higher signal-to-noise ratio than the 20-probe sets commonly required for HCR and RNA-Scope. We show that the high sensitivity and wide dynamic range allow quantification of genes expressed at different levels in the olfactory sensory neurons. We describe key steps of this method to enable broad utility by individual laboratories.

Slow-Scan CCD Observation of Backscattering Patterns in SEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1308-1309
Author(s):  
F. Ouyang ◽  
D. A. Ray ◽  
O. L. Krivanek
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Dynamic Range ◽  
High Sensitivity ◽  
Lens System ◽  
Wide Dynamic Range ◽  
Peltier Cooler ◽  
Diffraction Patterns ◽  
Scanning Electron

Electron backscattering Kikuchi diffraction patterns (BKDP) reveal useful information about the structure and orientation of crystals under study. With the well focused electron beam in a scanning electron microscope (SEM), one can use BKDP as a microanalysis tool. BKDPs have been recorded in SEMs using a phosphor screen coupled to an intensified TV camera through a lens system, and by photographic negatives. With the development of fiber-optically coupled slow scan CCD (SSC) cameras for electron beam imaging, one can take advantage of their high sensitivity and wide dynamic range for observing BKDP in SEM.We have used the Gatan 690 SSC camera to observe backscattering patterns in a JEOL JSM-840A SEM. The CCD sensor has an active area of 13.25 mm × 8.83 mm and 576 × 384 pixels. The camera head, which consists of a single crystal YAG scintillator fiber optically coupled to the CCD chip, is located inside the SEM specimen chamber. The whole camera head is cooled to about -30°C by a Peltier cooler, which permits long integration times (up to 100 seconds).

Development of imaging plate for a TEM and its characteristics

1989 ◽  
Vol 47 ◽  
pp. 100-101
Author(s):  
N. Mori ◽  
T. Oikawa ◽  
Y. Harada ◽  
J. Miyahara ◽  
T. Matsuo
Keyword(s):  
Dynamic Range ◽  
Protective Layer ◽  
High Sensitivity ◽  
Imaging Plate ◽  
Phosphor Layer ◽  
Imaging Device ◽  
X Ray Imaging ◽  
New Type ◽  
Basic Characteristics ◽  
Reading System

The Imaging Plate (IP) is a new type imaging device, which was developed for diagnostic x ray imaging. We have reported that usage of the IP for a TEM has many merits; those are high sensitivity, wide dynamic range, and good linearity. However in the previous report the reading system was prototype drum-type-scanner, and IP was also experimentally made, which phosphor layer was 50μm thick with no protective layer. So special care was needed to handle them, and they were used only to make sure the basic characteristics. In this article we report the result of newly developed reading, printing system and high resolution IP for practical use. We mainly discuss the characteristics of the IP here. (Precise performance concerned with the reader and other system are reported in the other article.)Fig.1 shows the schematic cross section of the IP. The IP consists of three parts; protective layer, phosphor layer and support.

The WHO World Mental Health (WMH) Surveys

2009 ◽  
Vol 06 (01) ◽  
pp. 5-9 ◽  
Author(s):  
S. Aguilar-Gaxiola ◽  
J. Alonso ◽  
S. Chatterji ◽  
S. Lee ◽  
T. B. Üstün ◽  
...  
Keyword(s):  
Mental Health ◽  
Mental Disorders ◽  
Treatment Effectiveness ◽  
Age Of Onset ◽  
Common Mental Disorders ◽  
Mental Health Policy ◽  
Unmet Need ◽  
Cost Effective ◽  
World Mental Health ◽  
Prevalence Estimates

SummaryThe paper presents an overview of the WHO World Mental Health (WMH) Survey Initiative and summarizes recent WMH results regarding the prevalence and societal costs of mental disorders. The WMH surveys are representative community surveys that were carried out in 28 countries throughout the world aimed at providing information to mental health policy makers about the prevalence, burden, and unmet need for treatment of common mental disorders. Results show that mental disorders are commonly occurring in all participating countries. The inter-quartile range (IQR: 25th-75th percentiles) of lifetime DSM-IV disorder prevalence estimates (combining anxiety, mood, disruptive behavior, and substance disorders) is 18.1-36.1%. The IQR of 12-month prevalence estimates is 9.8-19.1%. Analysis of age-of-onset reports shows that many mental disorders begin in childhood-adolescence and have significant adverse effects on subsequent role transitions. Adult mental disorders are found in the WMH data to be associated with high levels of role impairment. Despite this burden, the majority of mental disorders go untreated. Although these results suggest that expansion of treatment could be cost-effective from both the employer perspective and the societal perspective, treatment effectiveness trials are needed to confirm this suspicion. The WMH results regarding impairments are being used to target several such interventions.

scholarly journals High-frequency rectifiers based on type-II Dirac fermions

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Libo Zhang ◽  
Zhiqingzi Chen ◽  
Kaixuan Zhang ◽  
Lin Wang ◽  
Huang Xu ◽  
...  
Keyword(s):  
High Frequency ◽  
Dynamic Range ◽  
High Sensitivity ◽  
High Dynamic Range ◽  
Anisotropy Ratio ◽  
Dirac Fermions ◽  
Topological States ◽  
Topological Semimetals ◽  
Polarized Surface ◽  
Symmetry Protected

AbstractThe advent of topological semimetals enables the exploitation of symmetry-protected topological phenomena and quantized transport. Here, we present homogeneous rectifiers, converting high-frequency electromagnetic energy into direct current, based on low-energy Dirac fermions of topological semimetal-NiTe2, with state-of-the-art efficiency already in the first implementation. Explicitly, these devices display room-temperature photosensitivity as high as 251 mA W−1 at 0.3 THz in an unbiased mode, with a photocurrent anisotropy ratio of 22, originating from the interplay between the spin-polarized surface and bulk states. Device performances in terms of broadband operation, high dynamic range, as well as their high sensitivity, validate the immense potential and unique advantages associated to the control of nonequilibrium gapless topological states via built-in electric field, electromagnetic polarization and symmetry breaking in topological semimetals. These findings pave the way for the exploitation of topological phase of matter for high-frequency operations in polarization-sensitive sensing, communications and imaging.

scholarly journals Multiplexed detection of SARS-CoV-2 and other respiratory infections in high throughput by SARSeq

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ramesh Yelagandula ◽  
◽  
Aleksandr Bykov ◽  
Alexander Vogt ◽  
Robert Heinen ◽  
...  
Keyword(s):  
Influenza A ◽  
Respiratory Infections ◽  
High Sensitivity ◽  
Cost Effective ◽  
Massively Parallel ◽  
Rt Pcr ◽  
Viral Spread ◽  
Saliva Analysis ◽  
Double Blinded ◽  
Generation Sequencing

AbstractThe COVID-19 pandemic has demonstrated the need for massively-parallel, cost-effective tests monitoring viral spread. Here we present SARSeq, saliva analysis by RNA sequencing, a method to detect SARS-CoV-2 and other respiratory viruses on tens of thousands of samples in parallel. SARSeq relies on next generation sequencing of multiple amplicons generated in a multiplexed RT-PCR reaction. Two-dimensional, unique dual indexing, using four indices per sample, enables unambiguous and scalable assignment of reads to individual samples. We calibrate SARSeq on SARS-CoV-2 synthetic RNA, virions, and hundreds of human samples of various types. Robustness and sensitivity were virtually identical to quantitative RT-PCR. Double-blinded benchmarking to gold standard quantitative-RT-PCR performed by human diagnostics laboratories confirms this high sensitivity. SARSeq can be used to detect Influenza A and B viruses and human rhinovirus in parallel, and can be expanded for detection of other pathogens. Thus, SARSeq is ideally suited for differential diagnostic of infections during a pandemic.

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