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An optimisation of four SARS-CoV-2 qRT-PCR assays in a Kenyan laboratory to support the national COVID-19 rapid response teams.

ABSTRACT: Background: The global COVID-19 outbreak relies on a quantitative real-time polymerase chain reaction (qRT-PCR) for the detection of severe acute respiratory syndrome coronavirus (SARS-CoV-2), to facilitate the roll-out of patient care and infection control measures. There are several qRT-PCR assays with little evidence on their comparability. We report alterations to the developers' recommendations to sustain the testing capability in our setting, where the supply of testing reagents is limited. Methods: Standards generated from a serially-diluted positive control and previously identified positive/negative samples were used to determine the optimal volumes of the qRT-PCR reagents and to evaluate the validity and performance of four assays: Charité Berlin and European Virus Archive - GLOBAL (EVAg) primer-probe sets, and DAAN and Beijing Genomics Institute (BGI) premixed commercial kits. A multiplex and singleplex RT-PCR kit was used with the two primer-probe sets and the recommended assay volumes of the two premixed kits were altered. Results: In comparison to the multiplex RT-PCR kit, the singleplex RT-PCR kit combined with the primer-probe sets yielded consistent cycle threshold (Ct) values across the different titrations tested. The DAAN premixed kit produced comparable Ct values across the titrations, while the BGI kit showed incomparable Ct values and inconsistent results between batches using the manufacturer's recommended volumes. Conclusion: We achieved a 2.5-fold and 4-fold increase in the number of tests/kit for the premixed kits and the primer-probe sets, respectively. The primer-probe set assays were reliable and consistent, and we preferred a combination of an EVAg and a Berlin target. Any inconclusive result was repeated by different individuals following the same protocol. DAAN was a consistent and reliable assay even at lower concentrations from the stated recommendations. BGI in contrast, required dilution to improve its performance and was hence an assay that was used in combination with EVAg or Berlin targets.

SUBMITTER: Mohammed KS

PROVIDER: S-EPMC8921690 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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An optimization of four SARS-CoV-2 qRT-PCR assays in a Kenyan laboratory to support the national COVID-19 rapid response teams.

Mohammed Khadija Said KS de Laurent Zaydah R ZR Omuoyo Donwilliams O DO Lewa Clement C Gicheru Elijah E Cheruiyot Robinson R Bartilol Brian B Mutua Shadrack S Musyoki Jennifer J Gumba Horace H Mwacharo Jedidah J Riako Debra D Mwangi Shaban J SJ Gichuki Bonface M BM Nyamako Lydia L Karani Angela A Karanja Henry H Mugo Daisy D Gitonga John N JN Njuguna Susan S Gumbi Wilson W Tawa Brian B Tendwa Metrine M Cheruiyot Wesley W Sein Yiakon Y Nyambu John K JK Patta Shem O SO Thani Thani Suleiman TS Maitha Eric K EK Kitole Benson B Mwakinangu Mohamed S MS Muslih Barke S BS Otieno John Ochieng JO Nyiro Joyce U JU Kiyuka Patience P Ndwiga Leonard L Ndwiga Leonard L Wamae Kevin K Kimani Domtila D Makale Johnstone J Morobe John Mwita JM Osoti Victor V Lambisia Arnold W AW Odundo Calleb C Mwarumba Salim S Mutunga Martin M Bejon Philip P Tsofa Benjamin B Agoti Charles N CN Ochola-Oyier Lynette Isabella LI

Wellcome open research 20200101

<b>Background:</b> The COVID-19 pandemic relies on real-time polymerase chain reaction (qRT-PCR) for the detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), to facilitate roll-out of patient care and infection control measures. There are several qRT-PCR assays with little evidence on their comparability. We report alterations to the developers' recommendations to sustain the testing capability in a resource-limited setting. <b>Methods:</b> We used a SARS-CoV-2 positive con ...[more]

PMID: 35330938

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Project description:The coronavirus infectious disease (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viruses. The pandemic has emerged as a global public health crisis, and the threat of fast-spreading of the latest variants of the coronavirus (such as omicron, delta) is rampant. Therefore, a fast and reliable diagnostic assay is needed to make the clinical decision for further treatment. The study aims to develop a Centers for Disease and Prevention (CDC)-modified qualitative real-time reverse transcriptase PCR (RT-qPCR) assay and parallel assessment of commercially available RT-qPCR assay (Altona, Seegene, BD, and GBC) to detect SARS-CoV-2. Two hundred nine samples were chosen randomly out of around two hundred thousand samples. The panel consisted of SARS-CoV-2-positive (n = 156) and SARS-CoV-2-negative (n = 52) nasopharyngeal swab specimens for a primary clinical evaluation. Furthermore, 29 positive samples were sequenced using Oxford Nanopore Minion technology. Two hundred nine patient sample data of the cycle threshold (Ct) readings for target genes of five assays are 100% sensitive for Ct values. Mean Ct values for N1, N2, RdRp, S, and E of the positive controls in CDC assay, RealStar®, Allplex, GBC, and SD Biosensor were 17.5 ± 0.49, 16.9 ± 0.51, 20 ± 0.49, 21.7 ± 0.38, and 23.1 ± 0.43, respectively. F test value shows ≥ 1, which was statistically significant. All assays showed an efficiency of < 120% and R squares were < 0.99, which is well above the required threshold value. Thus, when taking the CDC-modified assay as a gold standard, the other four assays demonstrated a p value of 0.0000, concordance at 100%, and a Kappa at 1.000. A maximum-likelihood (ML) tree was constructed and compared based on full-length SARS-CoV-2 with Wuhan isolate. These isolates are closely related to the B.1.617 lineage and reference sequences. Therefore, we conclude that all RT-PCR kits assessed in this study shall be used for routine diagnostics of COVID-19 in patients.Supplementary informationThe online version contains supplementary material available at 10.1007/s00580-022-03356-y.

Project description:BackgroundViral hemorrhagic fevers (VHFs) are a group of animal and human illnesses that are mostly caused by several distinct families of viruses including bunyaviruses, flaviviruses, filoviruses and arenaviruses. Although specific signs and symptoms vary by the type of VHF, initial signs and symptoms are very similar. Therefore rapid immunologic and molecular tools for differential diagnosis of hemorrhagic fever viruses (HFVs) are important for effective case management and control of the spread of VHFs. Real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) assay is one of the reliable and desirable methods for specific detection and quantification of virus load. Multiplex PCR assay has the potential to produce considerable savings in time and resources in the laboratory detection.ResultsPrimers/probe sets were designed based on appropriate specific genes for each of 28 HFVs which nearly covered all the HFVs, and identified with good specificity and sensitivity using monoplex assays. Seven groups of multiplex one-step real-time qRT-PCR assays in a universal experimental system were then developed by combining all primers/probe sets into 4-plex reactions and evaluated with serial dilutions of synthesized viral RNAs. For all the multiplex assays, no cross-reactivity with other HFVs was observed, and the limits of detection were mainly between 45 and 150 copies/PCR. The reproducibility was satisfactory, since the coefficient of variation of Ct values were all less than 5% in each dilution of synthesized viral RNAs for both intra-assays and inter-assays. Evaluation of the method with available clinical serum samples collected from HFRS patients, SFTS patients and Dengue fever patients showed high sensitivity and specificity of the related multiplex assays on the clinical specimens.ConclusionsOverall, the comprehensive multiplex one-step real-time qRT-PCR assays were established in this study, and proved to be specific, sensitive, stable and easy to serve as a useful tool for rapid detection of HFVs.

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An optimisation of four SARS-CoV-2 qRT-PCR assays in a Kenyan laboratory to support the national COVID-19 rapid response teams.

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An optimization of four SARS-CoV-2 qRT-PCR assays in a Kenyan laboratory to support the national COVID-19 rapid response teams.

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