Correlation between cycle threshold and viral load through comparison of RT-PCR qualitative <em>versus</em> quantitative assay for SARS-CoV-2

Background and aims. Real-time reverse transcription polymerase chain reaction (RT-PCR) is the gold-standard assay to detect SARS-CoV-2, but it has limitations compared to viral load analysis. Quantitative detection improves surveillance, diagnosis, and prevention. We performed a comparative study of qualitative and quantitative tests for the diagnosis of COVID-19 on respiratory samples from patients screened for SARS-CoV-2 infection, and explored the correlation between viral load compared to the threshold cycle (Ct) value obtained in RT-PCR.Materials and methods. Sixty respiratory samples from patients affected by SARS-CoV-2 were subjected to both the qualitative (Allplex ™ 2019-nCoV Seegene) and the quantitative (Clonit® Quanty COVID-19) assays, and the relationship between viral load and Ct value was assessed by Spearman correlation analysis (ρ). In addition, the viral load of samples collected from a patient with symptomatic cancer was monitored. Results. The results show 100% agreement between the results obtained with quantitative assay and the reference standards, whereas 99.2% agreement was found for the qualitative test. A strong negative Spearman’s correlation between the Ct values of the N genes and RdRP gene was observed from qualitative assay values and viral loads.Conclusions. Quantitative assay has a higher sensitivity than qualitative assay, and viral load testing allows the clinicians to better orient themself in the choice of therapeutic treatment to be adopted. The constantly higher viral load of clinical cases considered, irrespective of the different therapies used, confirms that viral load monitoring could represent a great advantage in clinical practice.

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Field evaluation of an open and polyvalent universal HIV-1/SIVcpz/SIVgor quantitative RT-PCR assay for HIV-1 viral load monitoring in comparison to Abbott RealTime HIV-1 in Cameroon

Journal of Virological Methods ◽

10.1016/j.jviromet.2016.09.005 ◽

2016 ◽

Vol 237 ◽

pp. 121-126 ◽

Cited By ~ 2

Author(s):

Emilande Guichet ◽

Avelin Aghokeng ◽

Sabrina Eymard-Duvernay ◽

Nicole Vidal ◽

Ahidjo Ayouba ◽

...

Keyword(s):

Viral Load ◽

Field Evaluation ◽

Rt Pcr ◽

Pcr Assay ◽

Viral Load Monitoring ◽

Load Monitoring ◽

Hiv 1

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Point-of-Care HIV Viral Load Testing: an Essential Tool for a Sustainable Global HIV/AIDS Response

Clinical Microbiology Reviews ◽

10.1128/cmr.00097-18 ◽

2019 ◽

Vol 32 (3) ◽

Cited By ~ 12

Author(s):

Paul K. Drain ◽

Jienchi Dorward ◽

Andrew Bender ◽

Lorraine Lillis ◽

Francesco Marinucci ◽

...

Keyword(s):

Viral Load ◽

Point Of Care ◽

Load Testing ◽

Hiv Viral Load ◽

Viral Load Testing ◽

Essential Tool ◽

Aids Pandemic ◽

Viral Load Monitoring ◽

Load Monitoring ◽

Hiv Aids

SUMMARYThe global public health community has set ambitious treatment targets to end the HIV/AIDS pandemic. With the notable absence of a cure, the goal of HIV treatment is to achieve sustained suppression of an HIV viral load, which allows for immunological recovery and reduces the risk of onward HIV transmission. Monitoring HIV viral load in people living with HIV is therefore central to maintaining effective individual antiretroviral therapy as well as monitoring progress toward achieving population targets for viral suppression. The capacity for laboratory-based HIV viral load testing has increased rapidly in low- and middle-income countries, but implementation of universal viral load monitoring is still hindered by several barriers and delays. New devices for point-of-care HIV viral load testing may be used near patients to improve HIV management by reducing the turnaround time for clinical test results. The implementation of near-patient testing using these new and emerging technologies may be an essential tool for ensuring a sustainable response that will ultimately enable an end to the HIV/AIDS pandemic. In this report, we review the current and emerging technology, the evidence for decentralized viral load monitoring by non-laboratory health care workers, and the additional considerations for expanding point-of-care HIV viral load testing.

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HBV viral load monitoring in HIV coinfected patients on lamivudine therapy: early emergence of HBV polymerase mutants

Journal of Hepatology ◽

10.1016/s0168-8278(01)80500-6 ◽

2001 ◽

Vol 34 (0) ◽

pp. 137

Author(s):

A Rogue Afonso

Keyword(s):

Viral Load ◽

Lamivudine Therapy ◽

Early Emergence ◽

Viral Load Monitoring ◽

Load Monitoring ◽

Polymerase Mutants

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Viral Dynamics and Real-Time RT-PCR Ct Values Correlation with Disease Severity in COVID-19

Diagnostics ◽

10.3390/diagnostics11061091 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1091

Author(s):

Ali A. Rabaan ◽

Raghavendra Tirupathi ◽

Anupam A Sule ◽

Jehad Aldali ◽

Abbas Al Mutair ◽

...

Keyword(s):

Viral Load ◽

Real Time ◽

Disease Severity ◽

False Negative ◽

Influential Factors ◽

Confirmatory Test ◽

Acid Extraction ◽

Rt Pcr ◽

Viral Kinetics ◽

Ct Value

Real-time RT-PCR is considered the gold standard confirmatory test for coronavirus disease 2019 (COVID-19). However, many scientists disagree, and it is essential to understand that several factors and variables can cause a false-negative test. In this context, cycle threshold (Ct) values are being utilized to diagnose or predict SARS-CoV-2 infection. This practice has a significant clinical utility as Ct values can be correlated with the viral load. In addition, Ct values have a strong correlation with multiple haematological and biochemical markers. However, it is essential to consider that Ct values might be affected by pre-analytic, analytic, and post-analytical variables such as collection technique, specimen type, sampling time, viral kinetics, transport and storage conditions, nucleic acid extraction, viral RNA load, primer designing, real-time PCR efficiency, and Ct value determination method. Therefore, understanding the interpretation of Ct values and other influential factors could play a crucial role in interpreting viral load and disease severity. In several clinical studies consisting of small or large sample sizes, several discrepancies exist regarding a significant positive correlation between the Ct value and disease severity in COVID-19. In this context, a revised review of the literature has been conducted to fill the knowledge gaps regarding the correlations between Ct values and severity/fatality rates of patients with COVID-19. Various databases such as PubMed, Science Direct, Medline, Scopus, and Google Scholar were searched up to April 2021 by using keywords including “RT-PCR or viral load”, “SARS-CoV-2 and RT-PCR”, “Ct value and viral load”, “Ct value or COVID-19”. Research articles were extracted and selected independently by the authors and included in the present review based on their relevance to the study. The current narrative review explores the correlation of Ct values with mortality, disease progression, severity, and infectivity. We also discuss the factors that can affect these values, such as collection technique, type of swab, sampling method, etc.

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Performance of Self-Collected Saliva Testing Compared with Nasopharyngeal Swab Testing for the Detection of SARS-CoV-2

Viruses ◽

10.3390/v13050895 ◽

2021 ◽

Vol 13 (5) ◽

pp. 895

Author(s):

Florence Carrouel ◽

Martine Valette ◽

Hervé Perrier ◽

Maude Bouscambert-Duchamp ◽

Claude Dussart ◽

...

Keyword(s):

Viral Load ◽

Quantitative Pcr ◽

Statistical Analyses ◽

Fair Agreement ◽

Quantitative Detection ◽

Nasopharyngeal Swab ◽

Rt Pcr ◽

Noninvasive Techniques ◽

Concordance Probability ◽

Salivary Test

The aim of this study was to determine whether self-collected pure saliva (SCPS) is comparable to nasopharyngeal (NP) swabs in the quantitative detection of SARS-CoV-2 by RT-PCR in asymptomatic, mild patients with confirmed COVID-19. Thirty-one patients aged from 18 to 85 years were included between 9 June and 11 December 2020. A SCPS sample and a NP sample were taken for each patient. Quantitative PCR was performed to detect SARS-CoV-2 viral load. Results of SCPS vs NP samples testing were compared. Statistical analyses were performed. Viral load was significantly correlated (r = 0.72). The concordance probability was estimated at 73.3%. In symptomatic adults, SCPS performance was similar to that of NP swabs (Percent Agreement = 74.1%; p = 0.11). Thus, the salivary test based on pure oral saliva samples easily obtained by noninvasive techniques has a fair agreement with the nasopharyngeal one in asymptomatic, mild patients with a confirmed diagnosis of COVID-19.

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