bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Study of the Unsteady Blade Forces in an Oscillating Annular Compressor Cascade
Authors: Keerthi M. C. , Kushari Abhijit
Published: February 2016

The benefits of minimizing the weight of an aircraft are substantial, due to which all aircraft components are designed so as to perform acceptably with minimal weight. As a result, modern compressor, fan and turbine blades are increasingly being designed with thinner airfoil profiles, while also being subjected to high loading, so as to improve the thrust-to-weight ratio of the engine. These conditions make the blades extremely likely to result in large-amplitude vibrations. A class of critical vibrations are caused due to aeroelastic instabilities within the turbomachinery blade rows. Forced response or the self-excited flutter can lead to high-cycle fatigue which can cause a catastrophic failure of the blades. The absence of a reliable prediction methodology for the occurrence of these instabilities signify the importance of unsteady aerodynamic studies in turbomachine cascades. The present experiments are conducted on a newly commissioned annular cascade tunnel. The test section consisting of 14 compressor blades is studied under subsonic conditions. The profiles of the blades have a constant span design, and the cascade parameters are chosen as EPFL’s Second Standard Test Configuration at the mid-span location. A set of guide vanes upstream of this blade row set the required incidence to the cascade by imparting a circumferential component to the velocity. For the present unsteady studies, selected blades are subjected to controlled vibrations while the unsteady response on a reference stationery blade is measured. Two blades are connected to individual servo motors through a mechanism so as to execute controlled, low-amplitude, torsional (pitching) oscillations about its mid-chord axis. A reference blade is mounted on a load cell to enable measurement of both the axial and transverse forces and moments. In order to simulate the effect of the inter-blade phase angle prevalent in a rotating turbomachine blade row, the phase angle between the vibrating blades is varied to all admissible values. The fundamental parameters for evaluating the stability are the phase difference between blade position and the forces responses. This is estimated from the Fourier transform of the displacement and load signals. The parameters are evaluated for a range of reduced frequencies and inlet velocities to evaluate the stability of the cascade at all specified flow conditions.
Experimental Study on the Flow Past Sinusoidal Leading Edge Serrations in a Compressor Cascade
Authors: Rajeshwaran M. S. , Kushari Abhijit
Published: February 2016

The leading edge serrations are a type of passive flow control techniques in a compressor cascade. They are particularly attractive as they have been observed to increase the stall angle. This stall postponing character of the serrations is helpful in preventing compressor surge and widens the operational window of the compressor. Due to the simpler geometry of the serration type used in this study, it can be easily implemented onto the existing compressor blades. An experimental study on the flow modifications and losses due to these serrations are conducted in a linear cascade tunnel. The experiments are conducted on blades of NACA 65209 airfoil with and without leading edge serrations at Re of 120,000. Four serration profiles of various width and amplitude are compared. End plane measurements taken with 5-hole probe are studied for the better serration profile and surface flow visualizations are conducted to study the variation in the surface flow pattern on the suction side. The surface flow visualization reveals the presence of local recirculation zones and stream wise vortices created from each wave of the serration leading to flow attachment. These serrated blades have higher losses at 0 deg incidence; the reason for the same is found to be the flat leading edge surfaces formed from serration.
Casing Treatment of Centrifugal Compressors
Authors: Noushad Jisha , Dhamarla Anand Babu , Kumar Pavan
Published: February 2016

The operating range of any compressor is controlled by Surge and Choke. Surge occurs at lower mass flow rates with large pressure fluctuations and flow reversals, while choke occurs at higher mass flow rates when the flow rate reaches the limit which compressor can discharge. Ported shroud is a cost effective casing treatment that can greatly improve operating range of centrifugal compressors. By removing the stagnant and reverse flow from shroud wall boundary-layer region and recirculating it to impeller inlet, it has been demonstrated that larger range of operability can be achieved without much loss on compressor efficiency. This paper demonstrates the improvement of a centrifugal compressor operational range with ported shroud configuration.

A series of CFD simulations were carried out with open source centrifugal compressor geometry (NASA HPCC 4:1) to create performance characteristics/speed-lines. The CFD methodology and practices were validated by comparing the results with the experimental data. Performance evaluation of ported shroud configuration is done with respect to solid shroud.

Ported shroud compressor is proven to give higher choke mass flow and also a better surge margin compared to the Solid shroud model. The phenomena of in-flowing and out-flowing port have also been demonstrated. Emphasis was given to understand how ported shroud helps to achieve a better performance. A design optimization study has also been carried out in order to establish the optimum ported shroud configuration. Design parameter such as port location has been selected and the effect of this parameter on the performance of the compressor is studied using CFD. Optimum port geometry was proposed.
Open Loop Active Control of Combustion Noise in Gas Turbine Combustor
Authors: Kumar Juvva Srihari Dinesh , Mariappan Sathesh , Kushari Abhijit
Published: February 2016

The presented study is on a laboratory scaled industrial gas turbine combustor of intensity 25MW/m3 atm, where an open loop active control technique is investigated. Combustion noise is classified as direct and in-direct combustion noise. The present study is focused on the investigation of direct combustion noise. It occurs when the volume of the gas fluctuates due to the fluctuations in heat release rate, caused perhaps due to flow turbulence. This results in sound waves, which propagate outside the boundary of the flame. The radiated acoustic waves are reflected from the boundaries of the combustion chamber, perturbing the fuel flow rate and hence the spray characteristics. This eventually leads to perturbation in the heat release rate and thus a feedback loop is established. At certain conditions, if the unsteady heat release rate drives the acoustic oscillations, satisfying Rayleigh criterion, pressure oscillations grow leading to discrete tonal sound and this phenomena is termed as combustion instability.

Experiments are performed in a scaled down swirl stabilized liquid fueled gas turbine combustor, where a new scheme for open-loop control of combustion noise using periodic fuel injection is employed without drastically altering the combustor design or forfeiting its performance. Fuel is modulated in the frequency range of 0.6 to 5 Hz with various duty cycles [25–75%] using square wave. Fuel modulation is achieved by passing fuel through a direct current (DC) powered solenoid valve, which is being controlled using a custom-made circuit. The modulated fuel enters the combustor through an air-blast atomizer and is metered through a turbine flow meter.

The main objective of this paper is to investigate the potential of active control to reduce combustion noise in laboratory scaled gas turbine combustor. Pressure transducer is used to capture the sound pressure level inside the combustor. A reduction in overall sound pressure level of 14dB is achieved by modulating fuel with 50% duty cycle at 1.5Hz.
Parametric Study and Meanline Design of Multistage Axial Flow Compressor for Process Application
Authors: Singh Ambrish , Singh Nand Kumar
Published: February 2016

An industrial axial compressor has to meet a wide range of operation requirements. These machines have to run continuously for four to five years before going for overhaul. Hence, overall high level of efficiency may be slightly relaxed to meet this requirement. This requires axial flow compressor design to be more conservative and flexible to accommodate changes required for process industry through modern design & development approaches.

This paper deals with finding of optimum flow path configuration that will allow a successful detailed design to follow. The effect of various parameters such as hub to tip ratio, proper selection of design rpm, reactions, work coefficient & flow coefficient has been investigated and selected for optimal performance of the machine. Last stage of the compressor is selected as radial stage with the advantage of reduction in axial length and to provide radial outlet, which is more suitable outlet configuration. Meanline design and streamline analysis for each configuration is determined to find out good operating range (stall-free operation) before starting the detailed design.
Development of Plasma Spray Coatings Using Linz-Donawitz (LD) Slag Particles
Authors: Pati Pravat Ranjan , Satapathy Alok
Published: February 2016

LD slag (LDS) is a major solid waste generated in huge quantities during steel making. It comes from slag formers such as burned lime/dolomite and from oxidising of silica, iron etc., while refining the iron into steel in the LD furnace. This work aims at utilization of waste LDS to develop surface coatings by plasma spraying technique. This technology has the advantage of being able to process various low-grade ore minerals to obtain value-added products and also to deposit materials, generating near homogeneous coatings with the desired microstructure. Coatings prepared for this investigation are characterized in terms of their thickness, hardness, adhesion strength and porosity. Coating deposition efficiency is calculated in order to assess the coatability of LDS and XRD is carried out in order to ascertain the various phases present in the coating. Premixing of TiO2 powder with LDS is found to substantially improve the interfacial adhesion. It is also found that the operating power levels of the plasma torch affect the adhesion strength, coating deposition efficiency and mean thickness of the coatings. This work reveals that LD slag is eminently coatable and can be gainfully used as a potential cost-effective material for deposition of plasma spray coatings on metallic substrates.
Response of Cracked Cantilever Beam Subjected to Traversing Mass
Authors: Jena Shakti P. , Parhi Dayal R. , Mishra Devasis
Published: February 2016

The present work emphasizes the dynamic response of double cracked cantilever beam subjected to a traversing mass. The cracks are located at different positions of the beam with random crack depths. The response of the damaged structure has been evaluated employing a numerical procedure of Runge-Kuuta method. The effects of crack depth, traversing mass, traversing speed and crack location on the response of the structure are studied. Finite element analysis (FEA) using the commercial ANSYS 15 has been presented to validate the adopted numerical method.
Transient Response of Mixed Flow Variable Geometry Turbine for a Turbocharger
Authors: Kannan Ramesh , Prasad Bhamidi , Koppa Sridhara
Published: February 2016

A specific design of mixed flow variable geometry turbine for an automotive sub 1.5 litre diesel engine turbocharger is proposed in this paper. An experimental set up is developed for measuring the steady state and transient response behaviour of the turbine at different nozzle vane opening positions. The rotor speed, pressure and temperature before and after the turbine are measured and recorded using high frequency data logging system. The steady state performance for mass flow, efficiency, velocity ratio, specific speed and the transient response behaviour of the mixed flow variable geometry turbine (MFVGT) are compared against the same parameters of a radial flow variable geometry turbine (RFVGT) of similar dimensions. Typical result indicates that the transient response of the MFVGT is faster by about 350 milliseconds than the radial at turbine inlet pressure of 0.2 bar (g).
Aerodynamics of Contra-Rotating Fans With Swept Blades
Authors: Vijayraj K. , Govardhan M.
Published: February 2016

A Counter-Rotating System (CRS) is composed of a front rotor and a rear rotor which rotates in the opposite direction. Compared with traditional rotor-stator system, the rear rotor is used not only to recover the static head but also to supply energy to the fluid. Therefore, to achieve the same performance, the use of a CRS may lead to a reduction of the rotational speed and may generate better homogeneous flow downstream of the stage. On the other hand, the mixing area in between the two rotors induces complicated interacting flow structures.

Blade sweep has attracted the turbomachinery blade designers owing to a variety of performance benefits it offers. However, the effect of blade sweep on the performance, stall margin improvements whether it is advantageous/disadvantageous to sweep one or both rotors has not been studied till now. In the current investigation blade sweep on the performance characteristics of contra rotating axial flow fans are studied. Two sweep schemes (axial sweeping and tip chord line sweeping) are studied for two sweep angles (20° and 30°). Effect of blade sweep on front rotor and rear rotor are dealt separately by sweeping one at a time. Both rotors are swept together and effect of such sweep scheme on the aerodynamic performance of the stage is also reported here. The performance of contra rotating fan is significantly affected by all these parameters. Blade sweep improved the pressure rise and stall margin of front rotors. Axially swept rotors are found to have higher pressure rise with reduced incidence losses near the tip for front rotors. Sweeping the rear rotor is not effective since the pressure rise is less than that of unswept rotor and also has less stall margin.
Experimental Investigation of Adiabatic Film Cooling Effectiveness Over a Circular Fan and Laidback Fan Shaped Hole Flat Plate Test Models
Authors: Yepuri Giridhara Babu , Jesuraj Felix , Batchu Suresh , Venkataraman Kesavan
Published: February 2016

The experimental investigation of adiabatic film cooling effectiveness is carried out on a flat plates with 4:1 scaled up hole geometries, similar to that of typical turbine nozzle guide vane film cooling holes. Under this study, three flat plate models are considered with the two rows of holes having circular, fan and laidback fan shapes arranged in a staggered manner. These flat plate models are generated using solid works design software and fabricated using low thermal conductivity nylon based material using RPT technique. The mass flow results indicated the average nominal coefficient of discharge for the cooling holes as 0.71, for all these three models based on the inlet hole area and length of the holes. The laterally averaged adiabatic film cooling effectiveness is found along the stream wise direction at a density ratio of 1.62 by varying the blowing ratio in the range of 0.5 to 2.5. The surface temperatures of the test models are captured using the infrared camera, to evaluate the film cooling effectiveness. The experimentally evaluated results shows that, there is no increase in cooling effectiveness for the blowing ratio of 2.0 to 2.5 in the stream wise direction up to the X/d of 25 and there is a marginal increase above the X/d of 25 in the cases of these type of two row circular and Fan shaped hole models. Where as in the Laidback fan shaped hole model, the increase in cooling effectiveness is found significant up to the blowing ratio of 2.5 in the considered range. From the comparative results of adiabatic film cooling effectiveness of these three models, the laidback fan shaped hole model shows the higher film cooling effectiveness than the circular and fan shaped holes model at all the considered blowing ratios.
Black-wax assisted lift-off and transfer of CVD grown graphene from copper foil substrates to various foreign substrates
Authors: Liu Hongfei , Chew Ah Bian , Tan Lee Kheng , Teng Jinghua , Chi Dongzhi
Published: February 2016

The authors have lifted-off and transferred graphene nanosheets, which were grown by chemical vapor deposition on copper foil substrates, to flat, nanostructured, and microscale-patterned substrates. Black-wax, instead of the conventional polymethyl methacrylate, was used as the protective layer in the lift-off and transfer process. Quartz wafers, with and without coating of gold nanoparticle thin films, and surface grooved Si wafers were used as the target substrates. Structural, electrical, and optical characterizations revealed that the lift-off and transfer process, protected by the black-wax, is repeatable, even for graphene stacking, and the transferred graphene nanosheets are uniform and free of damage on flat substrates. Their electrical and optical properties are greatly affected by the target substrates; on quartz coated with gold nanoparticle thin film, coupling between graphene and the plasmon resonance of gold nanoparticles has been observed. The authors also demonstrated that the transferred graphene nanosheets can apparently tune the spectral polarization properties of surface grooved Si.
The stress regulator FKBP51 drives chronic pain by modulating spinal glucocorticoid signaling
Authors: Maiarù Maria , Tochiki Keri K. , Cox Marc B. , Annan Leonette V. , Bell Christopher G. , Feng Xixi , Hausch Felix , Géranton Sandrine M.
Published: February 2016

Interfering with the stress protein FKBP51 can block chronic pain in mice and rats, suggesting its potential as a therapeutic target.
Filaggrin inhibits generation of CD1a neolipid antigens by house dust mite–derived phospholipase
Authors: Jarrett Rachael , Salio Mariolina , Lloyd-Lavery Antonia , Subramaniam Sumithra , Bourgeois Elvire , Archer Charles , Cheung Ka Lun , Hardman Clare , Chandler David , Salimi Maryam , Gutowska-Owsiak Danuta , de la Serna Jorge Bernardino , Fallon Padraic G. , Jolin Helen , Mckenzie Andrew , Dziembowski Andrzej , Podobas Ewa Izabela , Bal Wojciech , Johnson David , Moody D. Branch , Cerundolo Vincenzo , Ogg Graham
Published: February 2016

Lack of the skin barrier protein filaggrin worsens atopic dermatitis by allergenic activation of CD1a-reactive T cells.
Silence of the GUCY2C tumor suppressor
Authors: Alvarez Jessica
Published: February 2016

Excess calories promote colon cancer by silencing a key tumor suppressor.
The Human Microbiome during Bacterial Vaginosis
Authors: Onderdonk Andrew B. , Delaney Mary L. , Fichorova Raina N.
Published: February 2016

Bacterial vaginosis (BV) is the most commonly reported microbiological syndrome among women of childbearing age. BV is characterized by a shift in the vaginal flora from the dominant
Lactobacillus
to a polymicrobial flora. BV has been associated with a wide array of health issues, including preterm births, pelvic inflammatory disease, increased susceptibility to HIV infection, and other chronic health problems. A number of potential microbial pathogens, singly and in combinations, have been implicated in the disease process. The list of possible agents continues to expand and includes members of a number of genera, including
Gardnerella
,
Atopobium
,
Prevotella
,
Peptostreptococcus
,
Mobiluncus
,
Sneathia
,
Leptotrichia
,
Mycoplasma
, and BV-associated bacterium 1 (BVAB1) to BVAB3. Efforts to characterize BV using epidemiological, microscopic, microbiological culture, and sequenced-based methods have all failed to reveal an etiology that can be consistently documented in all women with BV. A careful analysis of the available data suggests that what we term BV is, in fact, a set of common clinical signs and symptoms that can be provoked by a plethora of bacterial species with proinflammatory characteristics, coupled to an immune response driven by variability in host immune function.
Potent
In Vitro
and
In Vivo
Activity of Plantibody Specific for Porphyromonas gingivalis FimA
Authors: Choi Young-Suk , Moon Ji-Hoi , Kim Tae-Geum , Lee Jin-Yong
Published: February 2016

Fimbrial protein fimbrillin (FimA), a major structural subunit of
Porphyromonas gingivalis
, has been suggested as a vaccine candidate to control
P. gingivalis
-induced periodontal disease. Previously, cDNAs encoding IgG monoclonal antibodies (MAbs) against purified FimA from
P. gingivalis
2561 have been cloned, and the MAbs have been produced in rice cell suspension. Here we examined the biological activities of the plant-produced MAb specific for FimA (anti-FimA plantibody) of
P. gingivalis
in vitro
and
in vivo
. The anti-FimA plantibody recognized oligomeric/polymeric forms of native FimA in immunoblot analysis and showed high affinity for native FimA (

K
D

= 0.11 nM). Binding of
P. gingivalis
(10
8
cells) to 2 mg of saliva-coated hydroxyapatite beads was reduced by 53.8% in the presence of 1 μg/ml plantibody. Anti-FimA plantibody (10 μg/ml) reduced invasion of periodontal ligament cells by
P. gingivalis
(multiplicity of infection, 100) by 68.3%. Intracellular killing of
P. gingivalis
opsonized with the anti-FimA plantibody by mouse macrophages was significantly increased (77.1%) compared to killing of bacterial cells with irrelevant IgG (36.7%). In a mouse subcutaneous chamber model, the number of recoverable
P. gingivalis
cells from the chamber fluid was significantly reduced when the numbers of bacterial cells opsonized with anti-FimA plantibody were compared with the numbers of bacterial cells with irrelevant IgG, 66.7% and 37.1%, respectively. These
in vitro
and
in vivo
effects of anti-FimA plantibody were comparable to those of the parental MAb. Further studies with
P. gingivalis
strains with different types of fimbriae are needed to investigate the usefulness of anti-FimA plantibody for passive immunization to control
P. gingivalis
-induced periodontal disease.
Cellular Immune Responses in Humans Induced by Two Serogroup B Meningococcal Outer Membrane Vesicle Vaccines Given Separately and in Combination
Authors: Oftung Fredrik , Korsvold Gro Ellen , Aase Audun , Næss Lisbeth M.
Published: February 2016

MenBvac and MeNZB are safe and efficacious outer membrane vesicle (OMV) vaccines against serogroup B meningococcal disease. Antibody responses have previously been investigated in a clinical trial with these two OMV vaccines given separately (25 μg/dose) or in combination (12.5 and 12.5 μg/dose) in three doses administered at 6-week intervals. Here, we report the results from analyzing cellular immune responses against MenBvac and MeNZB OMVs in terms of antigen-specific CD4+T cell proliferation and secretion of cytokines. The proliferative CD4+T cell responses to the combined vaccine were of the same magnitude as the homologous responses observed for each individual vaccine. The results also showed cross-reactivity in the sense that both vaccine groups receiving separate vaccines responded to both homologous and heterologous OMV antigen when assayed for antigen-specific cellular proliferation. In addition, a multiplex bead array assay was used to analyze the presence of Th1 and Th2 cytokines in cell culture supernatants. The results showed that gamma interferon, interleukin-4 (IL-4), and IL-10 responses could be detected as a result of vaccination with both the MenBvac and the MeNZB vaccines given separately, as well as when given in combination. With respect to cross-reactivity, the cytokine results paralleled the observations made for proliferation. In conclusion, the results demonstrate that cross-reactive cellular immune responses involving both Th1 and Th2 cytokines can be induced to the same extent by different tailor-made OMV vaccines given either separately or in combination with half the dose of each vaccine.
Humoral and Cell-Mediated Immune Responses to Alternate Booster Schedules of Anthrax Vaccine Adsorbed in Humans
Authors: Quinn Conrad P. , Sabourin Carol L. , Schiffer Jarad M. , Niemuth Nancy A. , Semenova Vera A. , Li Han , Rudge Thomas L. , Brys April M. , Mittler Robert S. , Ibegbu Chris C. , Wrammert Jens , Ahmed Rafi , Parker Scott D. , Babcock Janiine , Keitel Wendy , Poland Gregory A. , Keyserling Harry L. , El Sahly Hana , Jacobson Robert M. , Marano Nina , Plikaytis Brian D. , Wright Jennifer G.
Published: February 2016

Protective antigen (PA)-specific antibody and cell-mediated immune (CMI) responses to annual and alternate booster schedules of anthrax vaccine adsorbed (AVA; BioThrax) were characterized in humans over 43 months. Study participants received 1 of 6 vaccination schedules: a 3-dose intramuscular (IM) priming series (0, 1, and 6 months) with a single booster at 42 months (4-IM); 3-dose IM priming with boosters at 18 and 42 months (5-IM); 3-dose IM priming with boosters at 12, 18, 30, and 42 months (7-IM); the 1970 licensed priming series of 6 doses (0, 0.5, 1, 6, 12, and 18 months) and two annual boosters (30 and 42 months) administered either subcutaneously (SQ) (8-SQ) or IM (8-IM); or saline placebo control at all eight time points. Antibody response profiles included serum anti-PA IgG levels, subclass distributions, avidity, and lethal toxin neutralization activity (TNA). CMI profiles included frequencies of gamma interferon (IFN-γ)- and interleukin 4 (IL-4)-secreting cells and memory B cells (MBCs), lymphocyte stimulation indices (SI), and induction of IFN-γ, IL-2, IL-4, IL-6, IL-1β, and tumor necrosis factor alpha (TNF-α) mRNA. All active schedules elicited high-avidity PA-specific IgG, TNA, MBCs, and T cell responses with a mixed Th1-Th2 profile and Th2 dominance. Anti-PA IgG and TNA were highly correlated (e.g., month 7,
r
2
= 0.86,
P
< 0.0001, log
10
transformed) and declined in the absence of boosters. Boosters administered IM generated the highest antibody responses. Increasing time intervals between boosters generated antibody responses that were faster than and superior to those obtained with the final month 42 vaccination. CMI responses to the 3-dose IM priming remained elevated up to 43 months. (This study has been registered at ClinicalTrials.gov under registration no. NCT00119067.)
Commentary: Identification of Low-Level Vancomycin Resistance in Staphylococcus aureus in the Era of Informatics
Authors: Ford Bradley A.
Published: February 2016

Vancomycin-intermediate
Staphylococcus aureus
(VISA) and heteroresistant VISA (hVISA) are pathogens for which accurate antimicrobial susceptibility testing (AST) would rule out standard treatment with vancomycin. Unfortunately, AST for vancomycin is relatively slow and standard methods are unable to reliably detect VISA and hVISA. An article in this issue (C. A. Mather, B. J. Werth, S. Sivagnanam, D. J. SenGupta, and S. M. Butler-Wu, J Clin Microbiol 54:883–890, 2016, doi:
http://dx.doi.org/10.1128/JCM.02428-15
) describes a rapid whole-cell matrix-assisted laser desorption ionization–time of flight proxy susceptibility method that highlights current innovations and challenges with rapid AST, VISA/hVISA identification, and clinical bioinformatics.
Antemortem Detection of Chronic Wasting Disease Prions in Nasal Brush Collections and Rectal Biopsy Specimens from White-Tailed Deer by Real-Time Quaking-Induced Conversion
Authors: Haley Nicholas J. , Siepker Chris , Walter W. David , Thomsen Bruce V. , Greenlee Justin J. , Lehmkuhl Aaron D. , Richt Jürgen A.
Published: February 2016

Chronic wasting disease (CWD), a transmissible spongiform encephalopathy of cervids, was first documented nearly 50 years ago in Colorado and Wyoming and has since spread to cervids in 23 states, two Canadian provinces, and the Republic of Korea. The expansion of this disease makes the development of sensitive diagnostic assays and antemortem sampling techniques crucial for the mitigation of its spread; this is especially true in cases of relocation/reintroduction of farmed or free-ranging deer and elk or surveillance studies of private or protected herds, where depopulation is contraindicated. This study sought to evaluate the sensitivity of the real-time quaking-induced conversion (RT-QuIC) assay by using recto-anal mucosa-associated lymphoid tissue (RAMALT) biopsy specimens and nasal brush samples collected antemortem from farmed white-tailed deer (
n
= 409). Antemortem findings were then compared to results from ante- and postmortem samples (RAMALT, brainstem, and medial retropharyngeal lymph nodes) evaluated by using the current gold standard
in vitro
assay, immunohistochemistry (IHC) analysis. We hypothesized that the sensitivity of RT-QuIC would be comparable to IHC analysis in antemortem tissues and would correlate with both the genotype and the stage of clinical disease. Our results showed that RAMALT testing by RT-QuIC assay had the highest sensitivity (69.8%) compared to that of postmortem testing, with a specificity of >93.9%. These data suggest that RT-QuIC, like IHC analysis, is an effective assay for detection of PrP
CWD
in rectal biopsy specimens and other antemortem samples and, with further research to identify more sensitive tissues, bodily fluids, or experimental conditions, has potential for large-scale and rapid automated testing for CWD diagnosis.
Analytical and Clinical Evaluation of the Epistem Genedrive Assay for Detection of Mycobacterium tuberculosis
Authors: Shenai Shubhada , Armstrong Derek T. , Valli Eloise , Dolinger David L. , Nakiyingi Lydia , Dietze Reynaldo , Dalcolmo Margareth Pretti , Nicol Mark P. , Zemanay Widaad , Manabe Yuka , Hadad David Jamil , Marques-Rodrigues Patricia , Palaci Moises , Peres Renata L. , Gaeddert Mary , Armakovitch Sandra , Nonyane Bareng A. S. , Denkinger Claudia M. , Banada Padmapriya , Joloba Moses L. , Ellner Jerrold , Boehme Catharina , Alland David , Dorman Susan E.
Published: February 2016

The Epistem Genedrive assay rapidly detects the
Mycobacterium tuberculosis
complex from sputum and is currently available for clinical use. However, the analytical and clinical performance of this test has not been fully evaluated. The analytical limit of detection (LOD) of the Genedrive PCR amplification was tested with genomic DNA; the performance of the complete (sample processing plus amplification) system was tested by spiking
M. tuberculosis
mc
2
6030 cells into distilled water and
M. tuberculosis
-negative sputum. Specificity was tested using common respiratory pathogens and nontuberculosis mycobacteria. A clinical evaluation enrolled adults with suspected pulmonary tuberculosis, obtained three sputum samples from each participant, and compared the accuracy of the Genedrive to that of the Xpert MTB/RIF assay using
M. tuberculosis
cultures as the reference standard. The Genedrive assay had an LOD of 1 pg/μl (100 genomic DNA copies/reaction). The LODs of the system were 2.5 × 10
4
CFU/ml and 2.5 × 10
5
CFU/ml for cells spiked into water and sputum, respectively. False-positive
rpoB
probe signals were observed in 3/32 (9.4%) of the negative controls and also in few samples containing
Mycobacterium abscessus
,
Mycobacterium gordonae
, or
Mycobacterium thermoresistibile
. In the clinical study, among 336 analyzed participants, the overall sensitivities for the tuberculosis case detection of Genedrive, Xpert, and smear microscopy were 45.4% (95% confidence interval [CI], 35.2% to 55.8%), 91.8% (95% CI, 84.4% to 96.4%), and 77.3% (95% CI, 67.7% to 85.2%), respectively. The sensitivities of Genedrive and Xpert for the detection of smear-microscopy-negative tuberculosis were 0% (95% CI, 0% to 15.4%) and 68.2% (95% CI, 45.1% to 86.1%), respectively. The Genedrive assay did not meet performance standards recommended by the World Health Organization for a smear microscopy replacement tuberculosis test. Epistem is working on modifications to improve the assay.
Emergence of a Multidrug-Resistant Shiga Toxin-Producing Enterotoxigenic Escherichia coli Lineage in Diseased Swine in Japan
Authors: Kusumoto Masahiro , Hikoda Yuna , Fujii Yuki , Murata Misato , Miyoshi Hirotsugu , Ogura Yoshitoshi , Gotoh Yasuhiro , Iwata Taketoshi , Hayashi Tetsuya , Akiba Masato
Published: February 2016

Enterotoxigenic
Escherichia coli
(ETEC) and Shiga toxin-producing
E. coli
(STEC) are important causes of diarrhea and edema disease in swine. The majority of swine-pathogenic
E. coli
strains belong to a limited range of O serogroups, including O8, O138, O139, O141, O147, O149, and O157, which are the most frequently reported strains worldwide. However, the circumstances of ETEC and STEC infections in Japan remain unknown; there have been few reports on the prevalence or characterization of swine-pathogenic
E. coli
. In the present study, we determined the O serogroups of 967
E. coli
isolates collected between 1991 and 2014 from diseased swine in Japan, and we found that O139, O149, O116, and OSB9 (O serogroup of
Shigella boydii
type 9) were the predominant serogroups. We further analyzed these four O serogroups using pulsed-field gel electrophoresis (PFGE), multilocus sequence typing, and virulence factor profiling. Most of the O139 and O149 strains formed serogroup-specific PFGE clusters (clusters I and II, respectively), whereas the O116 and OSB9 strains were grouped together in the same cluster (cluster III). All of the cluster III strains belonged to a single sequence type (ST88) and carried genes encoding both enterotoxin and Shiga toxin. This PFGE cluster III/ST88 lineage exhibited a high level of multidrug resistance (to a median of 10 antimicrobials). Notably, these bacteria were resistant to fluoroquinolones. Thus, this lineage should be considered a significant risk to animal production due to the toxigenicity and antimicrobial resistance of these bacteria.
Evaluation of Luminex xTAG Gastrointestinal Pathogen Panel Assay for Detection of Multiple Diarrheal Pathogens in Fecal Samples in Vietnam
Authors: Duong Vu Thuy , Phat Voong Vinh , Tuyen Ha Thanh , Dung Tran Thi Ngoc , Trung Pham Duc , Minh Pham Van , Tu Le Thi Phuong , Campbell James I. , Le Phuc Hoang , Ha Ton Thi Thanh , Ngoc Nguyen Minh , Huong Nguyen Thi Thanh , Tam Pham Thi Thanh , Huong Dang Thao , Xang Nguyen Van , Dong Nguyen , Phuong Le Thi , Hung Nguyen Van , Phu Bui Duc , Phuc Tran My , Thwaites Guy E. , Vi Lu Lan , Rabaa Maia A. , Thompson Corinne N. , Baker Stephen
Published: February 2016

Diarrheal disease is a complex syndrome that remains a leading cause of global childhood morbidity and mortality. The diagnosis of enteric pathogens in a timely and precise manner is important for making treatment decisions and informing public health policy, but accurate diagnosis is a major challenge in industrializing countries. Multiplex molecular diagnostic techniques may represent a significant improvement over classical approaches. We evaluated the Luminex xTAG gastrointestinal pathogen panel (GPP) assay for the detection of common enteric bacterial and viral pathogens in Vietnam. Microbiological culture and real-time PCR were used as gold standards. The tests were performed on 479 stool samples collected from people admitted to the hospital for diarrheal disease throughout Vietnam. Sensitivity and specificity were calculated for the xTAG GPP for the seven principal diarrheal etiologies. The sensitivity and specificity for the xTAG GPP were >88% for
Shigella
spp.,
Campylobacter
spp., rotavirus, norovirus genotype 1/2 (GI/GII), and adenovirus compared to those of microbiological culture and/or real-time PCR. However, the specificity was low (∼60%) for
Salmonella
species. Additionally, a number of important pathogens that are not identified in routine hospital procedures in this setting, such as
Cryptosporidium
spp. and
Clostridium difficile
, were detected with the GPP. The use of the Luminex xTAG GPP for the detection of enteric pathogens in settings, like Vietnam, would dramatically improve the diagnostic accuracy and capacity of hospital laboratories, allowing for timely and appropriate therapy decisions and a wider understanding of the epidemiology of pathogens associated with severe diarrheal disease in low-resource settings.
The Past, Present, and (Possible) Future of Serologic Testing for Lyme Disease
Authors: Theel Elitza S.
Published: February 2016

Lyme disease prevails as the most commonly transmitted tick-borne infection in the United States, and serologic evaluation for antibodies to
Borrelia burgdorferi
remains the recommended modality for diagnosis. This review presents a brief historical perspective on the evolution of serologic assays for Lyme disease and provides a summary of the performance characteristics for the currently recommended two-tiered testing algorithm (TTTA). Additionally, a recently proposed alternative to the traditional TTTA is discussed, and novel methodologies, including immuno-PCR and metabolic profiling for Lyme disease, are outlined.
Impact of Heparan Sulfate Binding on Transduction of Retina by Recombinant Adeno-Associated Virus Vectors
Authors: Boye Sanford L. , Bennett Antonette , Scalabrino Miranda L. , McCullough K. Tyler , Van Vliet Kim , Choudhury Shreyasi , Ruan Qing , Peterson James , Agbandje-McKenna Mavis , Boye Shannon E.
Published: February 2016

Adeno-associated viruses (AAVs) currently are being developed to efficiently transduce the retina following noninvasive, intravitreal (Ivt) injection. However, a major barrier encountered by intravitreally delivered AAVs is the inner limiting membrane (ILM), a basement membrane rich in heparan sulfate (HS) proteoglycan. The goal of this study was to determine the impact of HS binding on retinal transduction by Ivt-delivered AAVs. The heparin affinities of AAV2-based tyrosine-to-phenylalanine (Y-F) and threonine-to-valine (T-V) capsid mutants, designed to avoid proteasomal degradation during cellular trafficking, were established. In addition, the impact of grafting HS binding residues onto AAV1, AAV5, and AAV8(Y733F) as well as ablation of HS binding by AAV2-based vectors on retinal transduction was investigated. Finally, the potential relationship between thermal stability of AAV2-based capsids and Ivt-mediated transduction was explored. The results show that the Y-F and T-V AAV2 capsid mutants bind heparin but with slightly reduced affinity relative to that of AAV2. The grafting of HS binding increased Ivt transduction by AAV1 but not by AAV5 or AAV8(Y733F). The substitution of any canonical HS binding residues ablated Ivt-mediated transduction by AAV2-based vectors. However, these same HS variant vectors displayed efficient retinal transduction when delivered subretinally. Notably, a variant devoid of canonical HS binding residues, AAV2(4pMut)ΔHS, was remarkably efficient at transducing photoreceptors. The disparate AAV phenotypes indicate that HS binding, while critical for AAV2-based vectors, is not the sole determinant for transduction via the Ivt route. Finally, Y-F and T-V mutations alter capsid stability, with a potential relationship existing between stability and improvements in retinal transduction by Ivt injection.

IMPORTANCE
AAV has emerged as the vector of choice for gene delivery to the retina, with attention focused on developing vectors that can mediate transduction following noninvasive, intravitreal injection. HS binding has been postulated to play a role in intravitreally mediated transduction of retina. Our evaluation of the HS binding of AAV2-based variants and other AAV serotype vectors and the correlation of this property with transduction points to HS affinity as a factor controlling retinal transduction following Ivt delivery. However, HS binding is not the only requirement for improved Ivt-mediated transduction. We show that AAV2-based vectors lacking heparin binding transduce retina by subretinal injection and display a remarkable ability to transduce photoreceptors, indicating that other receptors are involved in this phenotype.
Distinct Entry Mechanisms for Nonenveloped and Quasi-Enveloped Hepatitis E Viruses
Authors: Yin Xin , Ambardekar Charuta , Lu Yurong , Feng Zongdi
Published: February 2016

The hepatitis E virus (HEV) sheds into feces as nonenveloped virions but circulates in the blood in a membrane-associated, quasi-enveloped form (eHEV). Since the eHEV virions lack viral proteins on the surface, we investigated the entry mechanism for eHEV. We found that compared to nonenveloped HEV virions, eHEV attachment to the cell was much less efficient, requiring a longer inoculation time to reach its maximal infectivity. A survey of cellular internalization pathways identified clathrin-mediated endocytosis as the main route for eHEV entry. Unlike nonenveloped HEV virions, eHEV entry requires Rab5 and Rab7, small GTPases involved in endosomal trafficking, and blocking endosomal acidification abrogated eHEV infectivity. However, low pH alone was not sufficient for eHEV uncoating, suggesting that additional steps are required for entry. Supporting this concept, eHEV infectivity was substantially reduced in cells depleted of Niemann-Pick disease type C1, a lysosomal protein required for cholesterol extraction from lipid, or in cells treated with an inhibitor of lysosomal acid lipase. These data support a model in which the quasi-envelope is degraded within the lysosome prior to virus uncoating, a potentially novel mechanism for virus entry.

IMPORTANCEThe recent discovery of quasi-enveloped viruses has shifted the paradigm of virus-host interactions. The impact of quasi-envelopment in the virus life cycle and pathogenesis is largely unknown. HEV is a highly relevant model to study these questions. HEV circulates as quasi-enveloped virions in the blood that are hidden from neutralizing antibodies. eHEV particles most likely are responsible for the cell-to-cell spread of the virus. Given the increasing concerns about persistent HEV infection and its potential for transmission via the blood supply, understanding how eHEV infects cells is important for understanding its pathogenesis and developing therapies. Our data provide evidence that eHEV uses a potentially novel mechanism for cellular entry. Several steps critical to eHEV entry were identified and may provide a basis for developing treatments for hepatitis E. Because quasi-enveloped viruses resemble exosomes, these data also may provide insights into the exosome-mediated intercellular communications.
MicroRNA-Detargeted Mengovirus for Oncolytic Virotherapy
Authors: Ruiz Autumn J. , Hadac Elizabeth M. , Nace Rebecca A. , Russell Stephen J.
Published: February 2016

Mengovirus, a member of the
Picornaviridae
family, has a broad cell tropism and can cause encephalitis and myocarditis in multiple mammalian species. Attenuation has been achieved by shortening the polycytidine tract in the 5′ noncoding region (NCR). A poly(C)-truncated strain of mengovirus, vMC
24
, resulted in significant tumor regression in immunocompetent BALB/c mice bearing syngeneic MPC-11 plasmacytomas, but the associated toxicities were unacceptable. To enhance its safety profile, microRNA target sequences complementary to miR-124 or miR-125 (enriched in nervous tissue), miR-133 and miR-208 (enriched in cardiac tissue), or miR-142 (control; enriched in hematopoietic tissues) were inserted into the vMC
24
NCRs. The microRNA-detargeted viruses showed reduced replication and cell killing specifically in cells expressing the cognate microRNAs, but certain insertions additionally were associated with nonspecific suppression of viral fitness
in vivo. In vivo
toxicity testing confirmed that miR-124 targets within the 5′ NCR suppressed virus replication in the central nervous system while miR-133 and miR-208 targets in the 3′ NCR suppressed viral replication in cardiac tissue. A dual-detargeted virus named vMC
24
-NC, with miR-124 targets in the 5′ NCR and miR-133 plus miR-208 targets in the 3′ NCR, showed the suppression of replication in both nervous and cardiac tissues but retained full oncolytic potency when administered by intratumoral (10
6
50% tissue culture infectious doses [TCID
50
]) or intravenous (10
7
to 10
8
TCID
50
) injection into BALB/c mice bearing MPC-11 plasmacytomas. Overall survival of vMC
24
-NC-treated tumor-bearing mice was significantly improved compared to that of nontreated mice. MicroRNA-detargeted mengoviruses offer a promising oncolytic virotherapy platform that merits further development for clinical translation.

IMPORTANCE
The clinical potential of oncolytic virotherapy for cancer treatment has been well demonstrated, justifying the continued development of novel oncolytic viruses with enhanced potency. Here, we introduce mengovirus as a novel oncolytic agent. Mengovirus is appealing as an oncolytic virotherapy platform because of its small size, simple genome structure, rapid replication cycle, and broad cell/species tropism. However, mengovirus can cause encephalomyelitis and myocarditis. It can be partially attenuated by shortening the poly(C) tract in the 5′ NCR but remains capable of damaging cardiac and nervous tissue. Here, we further enhanced the safety profile of a poly(C)-truncated mengovirus by incorporating muscle- and neuron-specific microRNA target sequences into the viral genome. This dual-detargeted virus has reduced pathogenesis but retained potent oncolytic activity. Our data show that microRNA targeting can be used to further increase the safety of an attenuated mengovirus, providing a basis for its development as an oncolytic platform.
Hepatitis B Virus Infection of a Mouse Hepatic Cell Line Reconstituted with Human Sodium Taurocholate Cotransporting Polypeptide
Authors: Lempp Florian A. , Qu Bingqian , Wang Yong-Xiang , Urban Stephan
Published: February 2016

Hepatitis B virus (HBV) enters hepatocytes via its receptor, human sodium taurocholate cotransporting polypeptide (hNTCP). So far, HBV infection has been achieved only in human hepatic cells reconstituted with hNTCP and not in cells of mouse origin. Here, the first mouse liver cell line (AML12) which gains susceptibility to HBV upon hNTCP expression is described. Thus, HBV infection of receptor-expressing mouse hepatocytes does not principally require a human cofactor but can be triggered by endogenous murine determinants.