RT-qPCR half reaction optimization for the detection of SARS-CoV-2

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Abstract

BACKGROUND

The main laboratory test for the diagnosis of COVID-19 is the reverse transcription real-time polymerase chain reaction (RT-qPCR). However, the RT-qPCR is an expensive method due to the number of tests required.

OBJECTIVES

To evaluate an alternative RT-qPCR approach for the detection of SARS-CoV-2 sing half of the total volume currently recommended by the US Centers for Disease Control and Prevention.

METHODS

The analytical limit of detection (LoD) and the reaction efficiency using half volumes of RT-qPCR assay were evaluated for both the N1 and N2 regions by using a synthetic control RNA. A panel of 76 SARS-CoV-2-positive and 26 SARS-CoV-2-negative clinical samples were evaluated to establish the clinical sensitivity and specificity.

FINDINGS

The RT-qPCR assay efficiency was 105% for both the half and standard reactions considering the N2 target and 84% (standard) and 101% (half) for N1. The RT-qPCR half reaction LoD for N1 and N2 were 20 and 80 copies/µL, respectively. Clinical sensitivity and specificity were 100%. The half reaction presented a decrease of up to 5.5 cycle thresholds when compared with the standard RT-qPCR.

CONCLUSIONS

The use of RT-qPCR half reaction proved to be a feasible and economic strategy for detection of SARS-CoV-2 RNA.

Sponsorship

This work was supported by FAPERGS (20/2551-0000265-9) and by Fundo de Incentivo a Pesquisa e Eventos do Hospital de Clínicas de Porto Alegre (FIPE/HCPA) (Project no. 2020-0163).

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  1. SciScore for 10.1101/2021.05.19.21257470: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    EthicsIRB: Ethical approval: The study was approved by the Ethics Committees from Hospital de Clínicas de Porto Alegre (CAAE: 30767420.2.0000.5327).
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    Nucleic acid extraction: RNA was extracted from 600 μL of respiratory specimens using the Abbott mSample Preparation System (Promega, Madison, WI, USA) with an Abbott M2000 instrument (Abbott, Chicago, EUA), following the manufacturer’s instructions.
    Abbott
    suggested: (Abbott, RRID:SCR_010477)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).


    Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    Results from TrialIdentifier: No clinical trial numbers were referenced.


    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.


    Results from JetFighter: We did not find any issues relating to colormaps.


    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    Results from scite Reference Check: We found no unreliable references.


    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.