scholarly journals Rapid Point-of-Care Isothermal Amplification Assay for the Detection of Malaria without Nucleic Acid Purification

2016 ◽  
Vol 9 ◽  
pp. IDRT.S32162 ◽  
Author(s):  
Sayli S. Modak ◽  
Cheryl A. Barber ◽  
Eran Geva ◽  
William R. Abrams ◽  
Daniel Malamud ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Point Of Care ◽  
Isothermal Amplification ◽  
Blood Smears ◽  
Circulating Antigen ◽  
Amplification Assay ◽  
Amplification Loop ◽  
Nucleic Acid Purification ◽  
Antigen Tests ◽  
Mitochondrial Cytochrome Oxidase

Malaria remains one of the most prevalent infectious diseases and results in significant mortality. Isothermal amplification (loop-mediated isothermal amplification) is used to detect malarial DNA at levels of ~1 parasite/μL blood in ≥30 minutes without the isolation of parasite nucleic acid from subject's blood or saliva. The technique targets the mitochondrial cytochrome oxidase subunit 1 gene and is capable of distinguishing Plasmodium falciparum from Plasmodium vivax. Malarial diagnosis by the gold standard microscopic examination of blood smears is generally carried out only after moderate-to-severe symptoms appear. Rapid diagnostic antigen tests are available but generally require infection levels in the range of 200–2,000 parasites/μL for a positive diagnosis and cannot distinguish if the disease has been cleared due to the persistence of circulating antigen. This study describes a rapid and simple molecular assay to detect malarial genes directly from whole blood or saliva without DNA isolation.

scholarly journals Comparison of four commercial, automated antigen tests to detect SARS-CoV-2 variants of concern

2021 ◽  
Author(s):  
Andreas Osterman ◽  
Maximilian Iglhaut ◽  
Andreas Lehner ◽  
Patricia Späth ◽  
Marcel Stern ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Point Of Care ◽  
Study Cohort ◽  
Operating Characteristics ◽  
Testing Strategies ◽  
Level 3 ◽  
Amino Acid Mutations ◽  
Antigen Tests ◽  
Roche Diagnostics ◽  
Analytical Sensitivities

AbstractA versatile portfolio of diagnostic tests is essential for the containment of the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) pandemic. Besides nucleic acid-based test systems and point-of-care (POCT) antigen (Ag) tests, quantitative, laboratory-based nucleocapsid Ag tests for SARS-CoV-2 have recently been launched. Here, we evaluated four commercial Ag tests on automated platforms and one POCT to detect SARS-CoV-2. We evaluated PCR-positive (n = 107) and PCR-negative (n = 303) respiratory swabs from asymptomatic and symptomatic patients at the end of the second pandemic wave in Germany (February–March 2021) as well as clinical isolates EU1 (B.1.117), variant of concern (VOC) Alpha (B.1.1.7) or Beta (B.1.351), which had been expanded in a biosafety level 3 laboratory. The specificities of automated SARS-CoV-2 Ag tests ranged between 97.0 and 99.7% (Lumipulse G SARS-CoV-2 Ag (Fujirebio): 97.03%, Elecsys SARS-CoV-2 Ag (Roche Diagnostics): 97.69%; LIAISON® SARS-CoV-2 Ag (Diasorin) and SARS-CoV-2 Ag ELISA (Euroimmun): 99.67%). In this study cohort of hospitalized patients, the clinical sensitivities of tests were low, ranging from 17.76 to 52.34%, and analytical sensitivities ranged from 420,000 to 25,000,000 Geq/ml. In comparison, the detection limit of the Roche Rapid Ag Test (RAT) was 9,300,000 Geq/ml, detecting 23.58% of respiratory samples. Receiver-operating-characteristics (ROCs) and Youden’s index analyses were performed to further characterize the assays’ overall performance and determine optimal assay cutoffs for sensitivity and specificity. VOCs carrying up to four amino acid mutations in nucleocapsid were detected by all five assays with characteristics comparable to non-VOCs. In summary, automated, quantitative SARS-CoV-2 Ag tests show variable performance and are not necessarily superior to a standard POCT. The efficacy of any alternative testing strategies to complement nucleic acid-based assays must be carefully evaluated by independent laboratories prior to widespread implementation.

scholarly journals Accuracy of Two Circulating Antigen Tests for the Diagnosis and Surveillance of Schistosoma mansoni Infection in Low-Endemicity Settings of Côte d’Ivoire

2021 ◽  
Author(s):  
Rufin K. Assaré ◽  
Mathieu I. Tra-Bi ◽  
Jean T. Coulibaly ◽  
Paul L. A. M. Corstjens ◽  
Mamadou Ouattara ◽  
...  
Keyword(s):  
Schistosoma Mansoni ◽  
Cote D'ivoire ◽  
Côte D’Ivoire ◽  
Point Of Care ◽  
Urine Specimen ◽  
Cote D’Ivoire ◽  
Côte D'ivoire ◽  
Circulating Antigen ◽  
Antigen Tests ◽  
True Infection

In low-endemicity settings, current tools for diagnosis and surveillance of schistosomiasis are often inaccurate in detecting true infection. We assessed the accuracy of an up-converting phosphor lateral flow circulating anodic antigen (UCP-LF CAA) test and a point-of-care circulating cathodic antigen (POC-CCA) urine cassette test for the diagnosis of Schistosoma mansoni. Our study was conducted in eight schools of western Côte d’Ivoire. Fifty children, aged 9 to 12 years, were enrolled per school. From each child, a single urine specimen and two stool specimens were collected over consecutive days for diagnostic workup. Urine samples were subjected to UCP-LF CAA and POC-CCA tests. From each stool sample, triplicate Kato-Katz thick smears were examined. Overall, 378 children had complete data records. The prevalence of S. mansoni, as assessed by six Kato-Katz thick smears, was 4.0%. The UCP-LF CAA and POC-CCA tests revealed S. mansoni prevalence of 25.4% and 30.7%, respectively, when considering trace results as positive, and prevalence of 23.3% and 10.9% when considering trace results as negative. In the latter case, based on a composite gold standard, the sensitivity of UCP-LF CAA (80.7%) was considerably higher than that of POC-CCA (37.6%) and six Kato-Katz thick smears (13.8%). The negative predictive value of UCP-LF CAA, POC-CCA, and six Kato-Katz thick smears was 92.8%, 79.8%, and 74.1%, respectively. Our results confirm that UCP-LF CAA is more accurate than Kato-Katz and POC-CCA for the diagnosis of S. mansoni in low-endemicity settings.

Long-term dry storage of enzyme-based reagents for isothermal nucleic acid amplification in a porous matrix for use in point-of-care diagnostic devices

The Analyst ◽  
2020 ◽  
Vol 145 (21) ◽  
pp. 6875-6886 ◽  
Author(s):  
Sujatha Kumar ◽  
Ryan Gallagher ◽  
Josh Bishop ◽  
Enos Kline ◽  
Joshua Buser ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Glass Fiber ◽  
Point Of Care ◽  
Porous Matrix ◽  
Isothermal Amplification ◽  
Nucleic Acid Amplification ◽  
Isothermal Nucleic Acid Amplification ◽  
Dry Storage

Long-term dry storage of enzyme-based isothermal amplification reagents in glass fiber porous matrix for use in point-of-care devices.

One-step purification and concentration of DNA in porous membranes for point-of-care applications

Lab on a Chip ◽  
2015 ◽  
Vol 15 (12) ◽  
pp. 2647-2659 ◽  
Author(s):  
S. A. Byrnes ◽  
J. D. Bishop ◽  
L. Lafleur ◽  
J. R. Buser ◽  
B. Lutz ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Point Of Care ◽  
Porous Membranes ◽  
Complex Samples ◽  
One Step ◽  
Single User ◽  
Nucleic Acid Purification

Nucleic acid purification in porous membranes at the point-of-care from complex samples including nasal matrix and blood using a single-user step.

scholarly journals Loop-Mediated Isothermal Amplification (LAMP) as a Promising Point-of-Care Diagnostic Strategy in Avian Virus Research

Animals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 76
Author(s):  
Faiz Padzil ◽  
Abdul Razak Mariatulqabtiah ◽  
Wen Siang Tan ◽  
Kok Lian Ho ◽  
Nurulfiza Mat Isa ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Nucleic Acid ◽  
Point Of Care ◽  
Rolling Circle Amplification ◽  
Isothermal Amplification ◽  
Screening Methods ◽  
Diagnostic Strategy ◽  
Chain Reaction ◽  
Loop Mediated Isothermal Amplification ◽  
Polymerase Chain

Over the years, development of molecular diagnostics has evolved significantly in the detection of pathogens within humans and their surroundings. Researchers have discovered new species and strains of viruses, while mitigating the viral infections that occur, owing to the accessibility of nucleic acid screening methods such as polymerase chain reaction (PCR), qualitative (real-time) polymerase chain reaction (qPCR) and reverse-transcription qPCR (RT-qPCR). While such molecular detection methods are widely utilized as the benchmark, the invention of isothermal amplifications has also emerged as a reliable tool to improvise on-field diagnosis without dependence on thermocyclers. Among the established isothermal amplification technologies are loop-mediated isothermal amplification (LAMP), recombinant polymerase amplification (RPA), strand displacement activity (SDA), nucleic acid sequence-based amplification (NASBA), helicase-dependent amplification (HDA) and rolling circle amplification (RCA). This review highlights the past research on and future prospects of LAMP, its principles and applications as a promising point-of-care diagnostic method against avian viruses.

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