Droplet LAMP based point-of-care assay for SARS-CoV-2 viral load quantification v2 (protocols.io.bpn2mmge)

Remote areas of many low and middle income (LMI) countries have poor access to HIV viral load (HIV VL) testing. The SAMBA-II (Simple Amplification-based Assay) Semi-Q Whole Blood Test (Diagnostics for the Real World (DRW), Cambridge, UK) is a point of care assay which uses leucodepletion technology to allow whole blood testing in remote settings. 1540 consecutive HIV-positive clinic patients in Cameroon (250), UK (633), Ukraine (412) and Zimbabwe (245) donated venous blood (all countries) and finger-prick blood (all except UK) for testing on SAMBA-II. SAMBA II results were compared with simultaneous plasma results on the Abbott RealTime HIV-1 (Abbott Molecular, Des Plaines, IL) viral load assay and interpreted as either <1000 RNA copies/ml or ≥1000 RNA copies/ml. For 1528 venous whole-blood samples tested on SAMBA II, overall percent agreement with the reference test at a cut-off of HIV VL ≥1000 cps/ml was 96.9% (1480/1528 95% CI 95.9-97.7), negative percent agreement 97.7% (1259/1289 95% CI 96.7-98.4), positive percent agreement 92.5% (221/239 95% CI 88.4-95.5). For 854 finger-prick samples there was 95.0% (811/854 95% CI 93.3-96.3) overall percent agreement; negative percent agreement 98.0% (625/638, 95% CI 96.5-98.9); positive percent agreement 86.1% (186/216 95% CI 80.8-90.4). These rose to 93.5% (82.1, 98.6), 97.6% (95.6, 98.8) and 95.6% (93.3, 97.3) after exclusion of aberrant results from the Ukraine centre. These results show a high level of agreement between SAMBA-II and a laboratory-based assay. SAMBA-II has a performance that is suitable to use as a VL point of care assay in remote settings

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The Practicability of the Xpert HCV Viral Load Fingerstick Point-of-Care Assay in Primary Care Settings

Viruses ◽

10.3390/v13112327 ◽

2021 ◽

Vol 13 (11) ◽

pp. 2327

Author(s):

David Petroff ◽

Olaf Bätz ◽

Katrin Jedrysiak ◽

Jan Kramer ◽

Thomas Berg ◽

...

Keyword(s):

Primary Care ◽

Viral Load ◽

Primary Care Physicians ◽

Point Of Care ◽

Linkage To Care ◽

Hcv Rna ◽

Primary Care Settings ◽

Hcv Screening ◽

The Individual ◽

Point Of Care Assay

Linkage to care presents one obstacle toward eliminating HCV, and the current two-step pathway (anti-HCV, followed by HCV-RNA testing) results in the loss of patients. HCV screening was tested in the primary care setting with the fingerstick Xpert HCV viral load point-of-care assay to analyze the practicability of immediate diagnosis. Anti-HCV (Cobas) and HCV-RNA (Cobas Amplicor version 2.0, only performed if anti-HCV was positive) were analyzed centrally as the gold standard. The Xpert assay was performed by 10 primary care private practices. In total, 622 patients were recruited. Five individuals (0.8%) were anti-HCV positive, and one was HCV-RNA positive. The Xpert test was valid in 546/622 (87.8%) patients. It was negative in 544 and positive in 2 cases, both of whom were anti-HCV negative. The HCV-RNA PCR and the Xpert test were both negative in 4/5 anti-HCV-positive cases, and the individual with HCV-RNA 4.5 × 106 IU/mL was not detected by the Xpert test. Primary care physicians rated the Xpert test practicability as bad, satisfactory, or good in 6%, 13%, and 81%, respectively, though 14/29 (48%) bad test ratings were assigned by a single practice. Despite adequate acceptance, interpretability and diagnostic performance in primary care settings should be further evaluated before its use in HCV screening can be recommended.

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Faculty Opinions recommendation of Evaluation of the Xpert HCV Viral Load point-of-care assay from venepuncture-collected and finger-stick capillary whole-blood samples: a cohort study.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.727572363.793553789 ◽

2018 ◽

Author(s):

Norah Terrault

Keyword(s):

Cohort Study ◽

Viral Load ◽

Whole Blood ◽

Point Of Care ◽

Blood Samples ◽

Load Point ◽

Whole Blood Samples ◽

Finger Stick ◽

Point Of Care Assay

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Methods of Respiratory Virus Detection: Advances towards Point-of-Care for Early Intervention

Micromachines ◽

10.3390/mi12060697 ◽

2021 ◽

Vol 12 (6) ◽

pp. 697

Author(s):

Siming Lu ◽

Sha Lin ◽

Hongrui Zhang ◽

Liguo Liang ◽

Shien Shen

Keyword(s):

Viral Load ◽

Respiratory Virus ◽

Viral Infections ◽

Point Of Care ◽

Human Life ◽

Low Cost ◽

Virus Detection ◽

Frequent Monitoring ◽

User Friendly ◽

New Strategies

Respiratory viral infections threaten human life and inflict an enormous healthcare burden worldwide. Frequent monitoring of viral antibodies and viral load can effectively help to control the spread of the virus and make timely interventions. However, current methods for detecting viral load require dedicated personnel and are time-consuming. Additionally, COVID-19 detection is generally relied on an automated PCR analyzer, which is highly instrument-dependent and expensive. As such, emerging technologies in the development of respiratory viral load assays for point-of-care (POC) testing are urgently needed for viral screening. Recent advances in loop-mediated isothermal amplification (LAMP), biosensors, nanotechnology-based paper strips and microfluidics offer new strategies to develop a rapid, low-cost, and user-friendly respiratory viral monitoring platform. In this review, we summarized the traditional methods in respiratory virus detection and present the state-of-art technologies in the monitoring of respiratory virus at POC.

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Validity of a point-of-care viral load test for hepatitis B in a low-income setting

Journal of Virological Methods ◽

10.1016/j.jviromet.2020.114057 ◽

2021 ◽

Vol 289 ◽

pp. 114057

Author(s):

Gezahegn Mekonnen Woldemedihn ◽

Corina Silvia Rueegg ◽

Hailemichael Desalegn ◽

Hanna Aberra ◽

Nega Berhe ◽

...

Keyword(s):

Viral Load ◽

Hepatitis B ◽

Low Income ◽

Point Of Care ◽

Load Test ◽

Viral Load Test ◽

Low Income Setting

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Essential properties and pitfalls of colorimetric Reverse Transcription Loop-mediated Isothermal Amplification as a point-of-care test for SARS-CoV-2 diagnosis

Molecular Medicine ◽

10.1186/s10020-021-00289-0 ◽

2021 ◽

Vol 27 (1) ◽

Author(s):

Bruna de Oliveira Coelho ◽

Heloisa Bruna Soligo Sanchuki ◽

Dalila Luciola Zanette ◽

Jeanine Marie Nardin ◽

Hugo Manuel Paz Morales ◽

...

Keyword(s):

Viral Load ◽

Internal Control ◽

Reverse Transcription ◽

Color Change ◽

Point Of Care ◽

Colorimetric Detection ◽

False Negative ◽

Isothermal Amplification ◽

Clinical Samples ◽

Loop Mediated Isothermal Amplification

Abstract Background SARS-CoV-2 Reverse Transcription Loop-mediated Isothermal Amplification (RT-LAMP) colorimetric detection is a sensitive and specific point-of-care molecular biology technique used to detect the virus in only 30 min. In this manuscript we have described a few nuances of the technique still not properly described in the literature: the presence of three colors clusters; the correlation of the viral load with the color change; and the importance of using an internal control to avoid false-negative results. Methods To achieve these findings, we performed colorimetric RT-LAMP assays of 466 SARS-CoV-2 RT-qPCR validated clinical samples, with color quantification measured at 434 nm and 560 nm. Results First we determinate a sensitivity of 93.8% and specificity of 90.4%. In addition to the pink (negative) and yellow (positive) produced colors, we report for the first time the presence of an orange color cluster that may lead to wrong diagnosis. We also demonstrated using RT-qPCR and RT-LAMP that low viral loads are related to Ct values > 30, resulting in orange colors. We also demonstrated that the diagnosis of COVID-19 by colorimetric RT-LAMP is efficient until the fifth symptoms day when the viral load is still relatively high. Conclusion This study reports properties and indications for colorimetric RT-LAMP as point-of-care for SARS-CoV-2 diagnostic, reducing false results, interpretations and optimizing molecular diagnostics tests application.

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