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Background & objectives: The pandemic of SARS-COV-2 began in Wuhan, China in December 2019 and has caused more than 101 million cases worldwide. Diagnostic technologies possessing sensitivity and specificity equivalent to real-time reverse-transcriptase polymerase chain reaction (rRT-PCR) assays are needed to ramp up testing capacity in most countries. Newer platforms need to be technically less demanding, require minimum equipment and reduce turn-around time for reporting results. The objective of this study was to exploit loop-mediated isothermal amplification (LAMP) for the detection of SARS-CoV-2 and evaluate its performance by comparison with rRT-PCR. Methods: Reverse-transcription LAMP (RT-LAMP) assay primers were designed to detect envelop (E) and nucleocapsid (N) genes of SARS-CoV-2. Positive control RNA was prepared by in vitro transcription of E and N genes clones. RT-LAMP amplification reactions were incubated at 65°C for 30 min. Results were recorded visually. RT-LAMP results were evaluated by comparing the results obtained with a commercial rRT-PCR kit. Results: The RT-LAMP assay for E and N genes was carried out in separate tubes. RT-LAMP detected about 40 copies of SARS-CoV-2 RNA per reaction. A total of 253 throat swabs were tested using the RT-LAMP assay. The overall diagnostic sensitivity and specificity of the LAMP assay were 98.46 and 100 per cent, respectively, as compared to the rRT-PCR. Interpretation & conclusions: SARS-CoV-2 RT-LAMP assay was designed, standardized and evaluated. The assay showed diagnostic sensitivity and specificity equivalent to rRT-PCR assays. The assay will be useful to increase testing capacity for the detection of SARS-CoV-2 in the country.
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Objective@#To establish an ultra-sensitive, ultra-fast, visible detection method for Vibrio parahaemolyticus (VP) .@*Methods@#We established a new method for detecting the tdh and trh genes of VP using clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 12a (CRISPR/Cas12a) combined with recombinase polymerase amplification and visual detection (CRISPR/Cas12a-VD).@*Results@#CRISPR/Cas12a-VD accurately detected target DNA at concentrations as low as 10 -18 M (single molecule detection) within 30 min without cross-reactivity against other bacteria. When detecting pure cultures of VP, the consistency of results reached 100% compared with real-time PCR. The method accurately analysed pure cultures and spiked shrimp samples at concentrations as low as 10 2 CFU/g.@*Conclusion@#The novel CRISPR/Cas12a-VD method for detecting VP performed better than traditional detection methods, such as real-time PCR, and has great potential for preventing the spread of pathogens.
Subject(s)
CRISPR-Cas Systems , Nucleic Acid Amplification Techniques/methods , Recombinases/genetics , Vibrio parahaemolyticus/geneticsABSTRACT
Objective To develop a rapid, accurate, visual, and portable detection method for adenovirus types B (AdvB) and E ( AdvE).Methods Universal primers were targeted on type-specific conserved regions to allow the simultaneous detection of both human Adv (HAdV) species.A detection method based on the combination of recombinase polymerase amplification ( RPA) and lateral flow dipstick ( LFD) was established the sensitivity and specificity evaluated , and throat swab specimens of 19 patients infected with AdvB and AdvE as well as 10 healthy volunteers were detected with this method.Results The detection limit of the method was 10 copies/μl Adv DNA, which was close to that of qPCR , and there were no cross-reactions with other species of Adv and unrelated virus .The detection could be finished within 15 to 20 min within the temperature range of 25 to 45℃.When applied to clinical samples , this method showed 100% sensitivity and specificity.Conclusion This detection assay is a sensitive , specific, rapid and simple method that eliminates the need for expensive equipment , trained personnel or laboratories .The characteristics of this system render it suitable for use in grass-roots healthcare departments , and the system is especially effective for field testing and on-site testing.
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A photochromic sensing platform composing of emeraldine salt of polyaniline ( ES-PANI ) and titanium dioxide nanoparticles ( TiO2 NPs) for visual detection of trace copper was developed. Under ultraviolet light irradiation, the greenish ES-PANI could be oxidized to dark blue pernigraniline salt by the photogenerated hole of excited TiO2 NPs. In the presence of Cu2+, a light yellow leucoemeraldine salt was visually observed. The overall mechanism of color change was verified to be corresponding to the different redox states of PANI regulated by Cu species during the photochromic process. By integrating the advantages of both photoelectric property and visual detection, the redox reaction-based sensing mechanism led to a good sensitivity and high selectivity in the detection of Cu2+ with the detection limit of 0. 4 μmol/L. Besides the naked eye, two color recognition methods including reading mean green intensities in Photoshop and recording ultraviolet absorbance in microplate reader were also studied. This method was successfully applied to Cu2+ detection in human hair with satisfactory recoveries. More significantly, this sensing platform was really simple, low-cost and able to detect an array of analytes within several minutes without requiring sophisticated equipment. This photoelectron-regulated colorimetric strategy provided a novel concept for the design of visual sensing platform, and could develop the portable test kits for rapid detection in clinical diagnosis.
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Objective To develop a rapid, accurate, visual, and portable detection method for adenovirus types B (AdvB) and E ( AdvE).Methods Universal primers were targeted on type-specific conserved regions to allow the simultaneous detection of both human Adv (HAdV) species.A detection method based on the combination of recombinase polymerase amplification ( RPA) and lateral flow dipstick ( LFD) was established the sensitivity and specificity evaluated , and throat swab specimens of 19 patients infected with AdvB and AdvE as well as 10 healthy volunteers were detected with this method.Results The detection limit of the method was 10 copies/μl Adv DNA, which was close to that of qPCR , and there were no cross-reactions with other species of Adv and unrelated virus .The detection could be finished within 15 to 20 min within the temperature range of 25 to 45℃.When applied to clinical samples , this method showed 100% sensitivity and specificity.Conclusion This detection assay is a sensitive , specific, rapid and simple method that eliminates the need for expensive equipment , trained personnel or laboratories .The characteristics of this system render it suitable for use in grass-roots healthcare departments , and the system is especially effective for field testing and on-site testing.
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Objective To establish a Loop-mediated Isothermal Amplification (LAMP) for Pseudomonas aeruginosa rapid detection. Method 152 P. aeruginosa strains isolated from nasal swabs and 30 reference strains were applied. P. aeruginosa ATCC15442 was used to develop LAMP amplification and evaluate sensitivity and specificity. Results Sensitivity of LAMP was 103 times higher than PCR, with DNA amount as 132 fg. When LAMP was applied to 30 reference strains and 152 P. aeruginosa strains , the specification was 100% while iden-tification rate reached 94.7%. Conclusion The establishment LAMP showed a promising prospect in P. aerugi-nosa rapid detection.
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Se realizó una investigación analítica y prospectiva, de casos y controles, de los niños con glaucoma o estrabismo, o ambos, atendidos en la consulta de Oftalmología del Hospital Infantil Sur de Santiago de Cuba, de enero a junio del 2011, a fin de evaluar la percepción visual del movimiento coherente en ellos. El grupo de casos incluyó 72 pacientes escogidos de forma aleatoria, y el de controles, igual cantidad de integrantes que presentaban toda su capacidad visual. Se determinó que los niños con afecciones en la visión cometían más errores, omisiones y menos aciertos, además de ser menos rápidos en la solución de los ensayos orientados, pues tuvieron mayor tiempo de reacción para ejecutarlos.
A prospective analytic case-control study was carried out in children with glaucoma or strabismus or both, treated at the Department of Ophthalmology of the Southern Children Hospital in Santiago de Cuba, from January to June 2011, with the purpose of assessing the visual perception of coherent motion in them. The case group included 72 randomly selected patients, and control group with the same number of members who had all their vision. It was determined that children with visual disorders made more errors, omissions and fewer hits, besides being less rapid in solving oriented tests, as they had longer reaction time to do them.
ABSTRACT
Se aplicó una tarea de detección visual del movimiento coherente, confeccionada en el Centro de Neurociencias y Procesamiento de Imágenes y Señales de la Universidad de Oriente, en Santiago de Cuba, mediante la cual se determinó que los escolares disléxicos estudiados podían detectar el movimiento visual, pero cometían muchos errores y omisiones, indicativos de un ligero debilitamiento del proceso de detección visual. También se observaron deficiencias perceptivas en ellos, relacionadas con el incremento de la densidad de los puntos que se movían en los paneles y su disminución porcentual, así como también con el aumento del tiempo de respuesta, reveladores de una reducción de la sensibilidad a la percepción visual del movimiento en estos alumnos con dislexia del desarrollo.
A task of visual detection of the coherent movement, made in the Neurosciences and Processing of Images and Signs Center from Oriente University was applied in Santiago de Cuba, by means of which it was determined that the dyslexic students studied, could detect the visual movement, but they made many mistakes and omissions, indicative of a slight weakening of the visual detection process. Perceptive deficiencies were also observed in them, related with the increment of the density of the points which moved in the panels and their percentage decrease, as well as with the increase of the response time, showing of a reduction of the sensibility to the visual perception of movement in these students with development dyslexia.