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Brief Report

Laboratory Evaluation of a SARS-CoV-2 RT-LAMP Test

by
Sandra Menting
1,
Annette Erhart
2 and
Henk D. F. H. Schallig
1,*
1
Amsterdam University Medical Centres, Academic Medical Centre at the University of Amsterdam, Laboratory for Experimental Parasitology, Department of Clinical Microbiology and Infection Prevention, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
2
MRC Unit The Gambia at the LSHTM, Atlantic Boulevard, Fajara, Banjul P.O. Box 273, The Gambia
*
Author to whom correspondence should be addressed.
Trop. Med. Infect. Dis. 2023, 8(6), 320; https://doi.org/10.3390/tropicalmed8060320
Submission received: 21 March 2023 / Revised: 30 May 2023 / Accepted: 8 June 2023 / Published: 13 June 2023
(This article belongs to the Special Issue COVID-19: Current Situation and Future Trends)

Abstract

:
There is a need to have more accessible molecular diagnostic tests for the diagnosis of severe acute respiratory syndrome coronavirus 2 disease in low- and middle-income countries. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) may provide an attractive option as this technology does not require a complex infrastructure. In this study, the diagnostic performance of a SARS-CoV-2 RT-LAMP was evaluated using RT-PCR-confirmed clinical specimens of COVID-19-positive (n = 55) and -negative patients (n = 55) from the Netherlands. The observed sensitivity of the RT-LAMP test was 97.2% (95% CI: 82.4–98.0%) and the specificity was 100% (95% CI: 93.5–100%). The positive predictive value of the RT-LAMP was 100%, the negative predictive value 93.2% (95% CI: 84.3–97.3%), and the diagnostic accuracy was 96.4% (95% CI: 91.0–99.0%). The agreement between the RT-LAMP and the RT-PCR was “almost perfect” (κ-value: 0.92). The evaluated RT-LAMP might provide an attractive alternative molecular diagnostic tool for SARS-CoV-2 in resource limited settings.

1. Introduction

Many low- and middle-income countries (LMICs) have a fragile health system and the latter are under even greater pressure since the COVID-19 pandemic [1]. There is a need to establish and improve diagnostic and disease surveillance capacity in LMICs. With limited material and human resources available, accurate, simple, and rapid diagnostic methods for virus detection are needed to test as many individuals as possible, to promptly isolate confirmed cases, and to support rapid contact tracing for the surveillance and understanding of the local epidemiology [1]. The reference standard for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is a real-time reverse transcription polymerase chain reaction (real-time RT-PCR) [2]. However, the implementation of real-time RT-PCR requires specialized laboratories, infrastructure and personnel, and costly reagents and equipment, which are often not widely available in LMICs. Antigen detection based rapid diagnostic tests (Ag-RDTs) represent an attractive alternative, because of their low cost and ease of operation, but concerns about their sensitivity limit their use at particularly low viral loads [3,4,5,6,7,8,9].
The development of loop-mediated isothermal amplification (LAMP) represents an interesting advance in nucleic acid-based diagnostics [10,11] with several advantages. First, the amplification reaction is isothermal (between 60 and 65 °C) and does not require the use of a thermocycler. Second, the specificity of the reaction is high because of the design of four to six primers recognizing distinct sequences on the target. Third, the product can be visualized directly using simple detection methods, from fluorescence to colorimetric to lateral flow assay. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) assays have now also been developed for the diagnosis of SARS-CoV-2 [10,11]. RT-LAMP combines the advantages of Ag-RDTs as they are easy, rapid, and do not require specialized infrastructures [10] or real-time RT-PCR (high sensitivity) [10,11,12,13]. These properties make RT-LAMP an attractive candidate diagnostic test for implementation in LMICs. However, the diagnostic performance of such a test needs to be independently established under controlled laboratory conditions before implementation.
The aim of the current study was to evaluate the performance of the SARS-CoV-2 RT-LAMP kit (Coris BioConcept, Gembloux, Belgium; CE marked) against gold standard real-time RT-PCR using both positive and negative clinical samples of the SARS-CoV-2 virus.

2. Materials and Methods

2.1. Ethical Statement

The use of clinical specimens from the Amsterdam University Medical Centre (Amsterdam UMC) was approved by the Biobank Review Committee (approval: 2021.0259) for the protocol: “Enhancing Diagnostic & Surveillance Capacity in Low-Middle Income Countries.” Informed consent was obtained before the storage and usage of residual materials from COVID-19 patients. Ethical review was waved for the anonymized use of stored diagnostic specimens for diagnostic evaluation in accordance with Dutch law.

2.2. Clinical Samples

The clinical samples comprised nasopharyngeal swabs from 110 Dutch suspected cases of COVID-19 (based on clinical symptoms) stored at the departmental biobank of the department of Medical Microbiology and Infection Prevention of the Amsterdam UMC. Specimens were obtained as part of the routine clinical diagnostic practice for SARS-CoV-2 in place at Amsterdam UMC [14]. Nasopharyngeal swabs were taken from patients admitted at AMSTERDAM UMC with the clinical suspicion of having COVID-19 diseases. All had respiratory complaints and were hospitalized (not to the IC unit) during the peak of the pandemic in the Netherlands. Nasopharyngeal swabs were collected in a 3 mL UTM viral transport medium (COPAN ITALIA spa Brescia, Italy). In total, 110 swabs were available for analysis. Cases were confirmed as being positive or negative using an established SARS-CoV-2 real-time RT-PCR targeting the E-gene with a confirmed sensitivity of >95 and specificity of 100%, which was performed by complying to the established protocol [2].

2.3. Sample Size Calculation

The RT-LAMP test under evaluation should have a minimally acceptable sensitivity and specificity of 97%. To make a precise estimation of the sensitivity and specificity, the desired 95% confidence interval is ±5%. With these assumptions, the number of samples to be analysed can be estimated following WHO/TDR guidelines for the evaluation of diagnostics [15]:
p ± z × √[p(1 − p)/n]
where p = sensitivity (or specificity) measured as a proportion, n = number of samples from infected people (or for specificity from non-infected) and z = 1.96 (if we use a 95% confidence interval).
According to this equation, at least 44 SARS-CoV-2 positive or negative samples should be included to be able to determine with 95% confidence, as recommended by the Standards for Reporting Diagnostic accuracy studies [16], if the sensitivity or specificity is 97% ± 5%.

2.4. Procedures

SARS-CoV-2 RNA was extracted using an EMag (bioMérieux SA, Marcy-l′Étoile, France). Next, a SARS-CoV-2 real-time RT-PCR (gold standard for this study) targeted at the E-gene, which was performed according to a previously established protocol [2], was performed on all 110 clinical samples. Samples with a Ct value > 37.0 were considered to be negative.
Subsequently, a Reverse transcription loop-mediated isothermal amplification (SARS-CoV-2 RT-LAMP) assay (Coris BioConcept, Gembloux, Belgium; Lot: 47980H2208; expiration date: 20 October 2022) utilizing a primer mix targeting the SARS-CoV-2 ORF1ab region, the N gene, and the E gene was used as the test under investigation. The samples were subjected to RT-LAMP without having the final results of the gold standard real-time RT-PCR available. RT-LAMP was performed according to the manufacturer’s instructions. The RT-LAMP assay is based on fluorometric detection using a DNA intercalating agent. The RT-LAMP assay was performed at 63 °C for 30 min using a CFX-96 (Bio-Rad, Veenendaal, The Netherlands) real-time thermocycler. The RT-LAMP conditions consisted of a temperature of 63 °C, maintained during 30 cycles of 60 s each for a total running time of 30 min. The fluorescence signal was collected at each of the 30 repeats. The fluorescence channel to use for the dye was the SYBR Green/FAM channel (450–490 nm for excitation, 510–530 nm for detection). The volume of the reaction mix including the sample was 20 μL (5 μL of extracted RNA or 5 μL of positive control to 15 μL of reaction mix). The test was performed in 0.2 mL (PCR) tubes.
A positive control provided in the kit was used to confirm that the test was performed with effective reagents and in correct experimental conditions. A negative control (No Template Control, NTC) was performed with 5 μL of molecular biology grade water as the sample. The positive control was analysed as positive if it displayed a fluorescence growth curve with a Ct value < 30. The negative control could not display a fluorescence growth curve.

2.5. Data Analysis

The performance of the RT-LAMP was evaluated against the gold standard real-time RT-PCR, using both results to calculate the sensitivity, specificity, and negative and positive predictive value of the RT-LAMP using the MedCalc Software Ltd. diagnostic test evaluation calculator, https://www.medcalc.org/calc/diagnostic_test.php (Version 20.013; accessed on 30 December 2022). The agreement between the RT-LAMP and real-time RT-PCR was determined by calculating the kappa (k) value with 95% confidence intervals using GraphPad software, https://www.graphpad.com/quickcalcs/ (Version 12/2022; accessed on 30 December 2022).

3. Results

The 110 samples were first analysed by gold standard SARS-CoV-2 real-time RT-PCR and subsequently by RT-LAMP. PCR revealed that there were 55 cases positive and 55 cases negative for SARS-CoV-2. The positive SARS-CoV-2 PCR samples had a mean Ct value of 24.0 (range: 15.0–33.7). Nine of these samples had a Ct value > 30.0.
All clinical samples were next tested by RT-LAMP (operator was blinded from the PCR results) and these results are presented in Table 1. Positive and negative controls were included in each test and there were no amplification deviations observed.
In total, 51 out of 55 real-time RT-PCR positive samples were also found positive with the RT-LAMP test, while 4 samples tested negative. The latter were found to have relatively low viral loads as their cycle threshold (Ct) values ranged from 30.54 to 33.66. However, 5 other samples with a Ct value > 30.0 were found positive with RT-LAMP. All 55 negative real-time RT-PCR samples were also found negative by RT-LAMP.
The observed sensitivity of the RT-LAMP test was 97.2% (95% CI: 82.4–98.0%) and the specificity was 100% (95% CI: 93.5–100%). The positive predictive value of the RT-LAMP was 100% and the negative predictive value was 93.2% (95% CI: 84.3–97.3%). The diagnostic accuracy (i.e., the overall probability that a patient is correctly classified) of the RT-LAMP was 96.4% (95% CI: 91.0–99.0%).
The agreement between the RT-LAMP and the real-time RT-PCR was considered “almost perfect,” with a κ-value of 0.93 (95% CI: 0.86–0.99; SE of kappa = 0.04).

4. Discussion

The observed diagnostic performance of the RT-LAMP test under evaluation (sensitivity 97.2%; specificity 100%) exceeded the WHO recommendations for Ag-RDTs, which should have a minimal sensitivity of 80% and a minimal specificity of 97% [6]. The RT-LAMP test also met the sample size assumptions of having a sensitivity and specificity of >97%. In total, 4 positive RT-PCR samples were not detected by RT-LAMP, probably due to their low viral load, hence confirming prior reports showing a slightly lesser sensitivity compared to RT-LAMP for the diagnosis of SARS-CoV-2[10,11].
On the other hand, the RT-LAMP was able to detect SARS-CoV-2 in 5 positive samples with a Ct > 30. These might have been missed by Ag-RDTs since the latter often have a poorer performance when testing samples with Ct values > 25 [17] and thus, these might have been missed while using an antigen detection test and this underpins the added value of the RT-LAMP.
A limitation of the current evaluation is the fact that we did not specifically assess the diagnostic performance of the RT-LAMP on the clinical specimens of patients with other confirmed lung diseases. However, all tested samples were collected at the height of the COVID-19 pandemic in the Netherlands from cases with clinical suspicion of disease caused by SARS-CoV-2, as all had respiratory symptoms and can, as such, be considered a representative sample.
The present study confirms the good diagnostic performance of the RT-LAMP under evaluation as compared to real-time RT-PCR, with the advantages of having much less technical and costs requirements than real-time RT-PCR. Moreover, there are several options to further simplify the RT-LAMP procedure to enable its implementation as a molecular diagnostic in resource-limited settings. First, there is no need to use a sophisticated real-time machine for amplification. As the amplification reaction is isothermal, it can be performed in a simple Loopamp incubator (Eiken Chemical Co., Tokyo, Japan) [18]. Even the use of water baths has been proposed to facilitate the isothermal amplification process. Secondly, the current protocol uses fluorescence detection via a real-time PCR machine. This can be circumvented by visualising the amplification results under the illumination of UV light, which can be observed by the naked eye [18]. A slightly more sophisticated read-out method is the use of lateral flow-based strips for the detection of amplified SARS-CoV-2 viral mRNA [19,20]. A further simplification could be sought by using less sophisticated (or even non) nucleic acid extraction methods [21], but these will need further validation, particularly for RNA.

5. Conclusions

The RT-LAMP for SARS-CoV-2 evaluated in the present study has good diagnostic performance (sensitivity: 97.2%; specificity: 100%) compared to the gold standard reference, real-time RT-PCR. With some adaptations, such as simplifying the results read-out, this assay could be implemented as a simple molecular diagnostic tool in resource-limited settings.

Author Contributions

H.D.F.H.S. and A.E. designed the study. S.M. performed the experiments. S.M. and H.D.F.H.S. analysed the data. H.D.F.H.S. wrote the manuscript with the contributions of S.M. and A.E. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the European Developing Countries Clinical Trial Partnership EDCTP2 programme, supported by the European Union (grant number: RIA2020EF-3012; COVID-19 epidemic in West Africa: infection dynamics and diagnostic approaches [COVADIS]).

Institutional Review Board Statement

The use of clinical specimens from Amsterdam UMC was approved by the Biobank Review Committee (approval: 2021.0259) for the protocol “Enhancing Diagnostic & Surveillance Capacity in Low-Middle Income Countries”.

Informed Consent Statement

Informed consent was obtained before the storage and usage of residual materials from COVID-19 patients in accordance with the Amsterdam UMC COVID-19 Biobank protocol approved by the local institutional review boards. Ethical review was waved for the anonymized use of stored diagnostic specimens for diagnostic evaluation in accordance with Dutch law.

Data Availability Statement

The data that support the findings of this study are contained within this article.

Acknowledgments

We acknowledge the efforts of the departmental biobank of the Department of Medical Microbiology & Infection Prevention of Amsterdam UMC for providing samples according to good clinical practice and modern ethical standards.

Conflicts of Interest

The authors declare no conflict of interest. The funder and the manufacturer of the evaluated LAMP test were not involved in the design of the study or the interpretation of the study data.

References

  1. Hopman, J.; Allegranzi, B.; Mehtar, S. Managing COVID-19 in Low- and Middle-Income Countries. JAMA 2020, 323, 1549–1550. [Google Scholar] [CrossRef] [PubMed]
  2. Corman, V.M.; Landt, O.; Kaiser, M.; Molenkamp, R.; Meijer, A.; Chu, D.K.; Bleicker, T.; Brünink, S.; Schneider, J.; Schmidt, M.L.; et al. Detection of 2019 novel coronavirus (2019-nCoV) by real-time RT-PCR. Euro Surveill. 2020, 25, 2000045. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  3. Badawy, E.R.; Ezz El-Din, A.M.; El Zohne, R.A. Evaluation of diagnostic performance of a rapid antigen test in diagnosing COVID-19. Egypt J Immunol. 2023, 30, 14–19. [Google Scholar] [CrossRef] [PubMed]
  4. Dobrynin, D.; Polischuk, I.; Pokroy, B. A Comparison Study of the Detection Limit of Omicron SARS-CoV-2 Nucleocapsid by Various Rapid Antigen Tests. Biosensors 2022, 12, 1083. [Google Scholar] [CrossRef]
  5. Faffe, D.S.; Byrne, R.L.; Body, R.; Castiñeiras, T.M.P.; Castiñeiras, A.P.; Finch, L.S.; Kontogianni, K.; Bengey, D.; Galliez, R.M.; Ferreira, O.C., Jr.; et al. Multicenter Diagnostic Evaluation of a Novel Coronavirus Antigen Lateral Flow Test among Symptomatic Individuals in Brazil and the United Kingdom. Microbiol Spectr. 2022, 10, e0201222. [Google Scholar] [CrossRef]
  6. Irungu, J.K.; Munyua, P.; Ochieng, C.; Juma, B.; Amoth, P.; Kuria, F.; Kiiru, J.; Makayotto, L.; Abade, A.; Bulterys, M.; et al. Diagnostic accuracy of the Panbio COVID-19 antigen rapid test device for SARS-CoV-2 detection in Kenya, 2021: A field evaluation. PLoS ONE 2023, 18, e0277657. [Google Scholar] [CrossRef]
  7. Juniastuti Furqoni, A.H.; Amin, M.; Restifan, Y.D.; Putri, S.M.D.; Ferandra, V.A.; Lusida, M.I. The evaluation results of proposed antigen rapid diagnostic tests for COVID-19: Some possible factors might influence. Infection 2023, 2, 1–7. [Google Scholar] [CrossRef]
  8. Matsumura, Y.; Yamazaki, W.; Noguchi, T.; Yamamoto, M.; Nagao, M. Analytical and clinical performances of seven direct detection assays for SARS-CoV-2. J. Clin. Virol. Plus 2023, 3, 100138. [Google Scholar] [CrossRef]
  9. Pillet, S.; Courtieux, J.; Gonzalo, S.; Bechri, I.; Bourlet, T.; Valette, M.; Bal, A.; Pozzetto, B. Evaluation of Rapid Lateral-Flow Tests Directed against the SARS-CoV-2 Nucleoprotein Using Viral Suspensions Belonging to Different Lineages of SARS-CoV-2. Viruses 2022, 14, 2628. [Google Scholar] [CrossRef]
  10. Choi, G.; Moehling, T.J.; Meagher, R.J. Advances in RT-LAMP for COVID-19 testing and diagnosis. Expert Rev. Mol. Diagn. 2023, 25, 9–28. [Google Scholar] [CrossRef]
  11. Tapia-Sidas, D.A.; Vargas-Hernández, B.Y.; Ramírez-Pool, J.A.; Núñez-Muñoz, L.A.; Calderón-Pérez, B.; González-González, R.; Brieba, L.G.; Lira-Carmona, R.; Ferat-Osorio, E.; López-Macías, C.; et al. Starting from scratch: Step-by-step development of diagnostic tests for SARS-CoV-2 detection by RT-LAMP. PLoS ONE 2023, 18, e0279681. [Google Scholar] [CrossRef] [PubMed]
  12. Cao, G.; Lin, K.; Ai, J.; Cai, J.; Zhang, H.; Yu, Y.; Liu, Q.; Zhang, X.; Zhang, Y.; Fu, Z.; et al. A diagnostic accuracy study comparing RNA LAMP, direct LAMP, and rapid antigen testing from nasopharyngeal swabs. Front. Microbiol. 2022, 13, 1063414. [Google Scholar] [CrossRef] [PubMed]
  13. Prakash, S.; Priyatma Aasarey, R.; Pandey, P.K.; Mathur, P.; Arulselvi, S. An inexpensive and rapid diagnostic method for detection of SARS-CoV-2 RNA by loop-mediated isothermal amplification (LAMP). MethodsX 2023, 10, 102011. [Google Scholar] [CrossRef] [PubMed]
  14. Zonneveld, R.; Jurriaans, S.; van Gool, T.; Hofstra, J.J.; Hekker, T.A.M.; Defoer, P.; Broekhuizen van Haaften, P.E.; Wentink-Bonnema, E.M.; Boonkamp, L.; Teunissen, C.E.; et al. Head-to-head validation of six immunoassays for SARS-CoV-2 in hospitalized patients. J. Clin. Virol. 2021, 139, 104821. [Google Scholar] [CrossRef]
  15. Banoo, S.; Bell, D.; Bossuyt, P.; Herring, A.; Mabey, D.; Poole, F.; Smith, P.G.; Sriram, N.; Wongsrichanalai, C.; Linke, R.; et al. Evaluation of diagnostic tests for infectious diseases: General principles. Nat. Rev. Microbiol. 2006, 4 (Suppl. 9), S21–S31. [Google Scholar] [CrossRef]
  16. Cohen, J.F.; Korevaar, D.A.; Altman, D.G.; Bruns, D.E.; Gatsonis, C.A.; Hooft, L.; Irwig, L.; Levine, D.; Reitsma, J.B.; de Vet, H.C.; et al. STARD 2015 guidelines for reporting diagnostic accuracy studies: Explanation and elaboration. BMJ Open 2016, 6, e012799. [Google Scholar] [CrossRef] [Green Version]
  17. Ng, Q.X.; Lim, Y.L.; Han, M.X.; Teoh, S.E.; Thumboo, J.; Tan, B.H. The Performance of Lateral Flow Tests in the Age of the Omicron: A Rapid Systematic Review. Life 2022, 12, 1941. [Google Scholar] [CrossRef]
  18. Vink, M.M.T.; Nahzat, S.M.; Rahimi, H.; Buhler, C.; Ahmadi, B.A.; Nader, M.; Zazai, F.R.; Yousufzai, A.S.; van Loenen, M.; Schallig, H.D.F.H.; et al. Evaluation of point-of-care tests for cutaneous leishmaniasis diagnosis in Kabul, Afghanistan. EBioMedicine 2018, 37, 453–460. [Google Scholar] [CrossRef] [Green Version]
  19. Saxena, A.; Rai, P.; Mehrotra, S.; Baby, S.; Singh, S.; Srivastava, V.; Priya, S.; Sharma, S.K. Development and Clinical Validation of RT-LAMP-Based Lateral-Flow Devices and Electrochemical Sensor for Detecting Multigene Targets in SARS-CoV-2. Int. J. Mol. Sci. 2022, 23, 13105. [Google Scholar] [CrossRef]
  20. Zheng, C.; Wang, K.; Zheng, W.; Cheng, Y.; Li, T.; Cao, B.; Jin, Q.; Cui, D. Rapid developments in lateral flow immunoassay for nucleic acid detection. Analyst 2021, 146, 1514–1528. [Google Scholar] [CrossRef]
  21. Taki, K.; Yokota, I.; Fukumoto, T.; Iwasaki, S.; Fujisawa, S.; Takahashi, M.; Negishi, S.; Hayasaka, K.; Sato, K.; Oguri, S.; et al. SARS-CoV-2 detection by fluorescence loop-mediated isothermal amplification with and without RNA extraction. J. Infect. Chemother. 2021, 27, 410–412. [Google Scholar] [CrossRef] [PubMed]
Table 1. Comparison of diagnostic testing with real-time RT-PCR (gold standard) and RT-LAMP on RNA samples isolated from nasopharyngeal swabs collected from COVID-19-positive and -negative patients.
Table 1. Comparison of diagnostic testing with real-time RT-PCR (gold standard) and RT-LAMP on RNA samples isolated from nasopharyngeal swabs collected from COVID-19-positive and -negative patients.
RT-LAMPReal-time RT–PCR
PositiveNegativeTotal
Positive51051
Negative45559
5555110
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MDPI and ACS Style

Menting, S.; Erhart, A.; Schallig, H.D.F.H. Laboratory Evaluation of a SARS-CoV-2 RT-LAMP Test. Trop. Med. Infect. Dis. 2023, 8, 320. https://doi.org/10.3390/tropicalmed8060320

AMA Style

Menting S, Erhart A, Schallig HDFH. Laboratory Evaluation of a SARS-CoV-2 RT-LAMP Test. Tropical Medicine and Infectious Disease. 2023; 8(6):320. https://doi.org/10.3390/tropicalmed8060320

Chicago/Turabian Style

Menting, Sandra, Annette Erhart, and Henk D. F. H. Schallig. 2023. "Laboratory Evaluation of a SARS-CoV-2 RT-LAMP Test" Tropical Medicine and Infectious Disease 8, no. 6: 320. https://doi.org/10.3390/tropicalmed8060320

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