发布: 2021年03月20日第11卷第6期 DOI: 10.21769/BioProtoc.3964 浏览次数: 5531
评审: Kenji SugiyamaNathan Rhys JamesSonali ChaturvediAnonymous reviewer(s)
Abstract
During pandemics, such as the one caused by SARS-CoV-2 coronavirus, simple methods to rapidly test large numbers of people are needed. As a faster and less resource-demanding alternative to detect viral RNA by conventional qPCR, we used reverse transcription loop-mediated isothermal amplification (RT-LAMP). We previously established colorimetric RT-LAMP assays on both purified and unpurified SARS-CoV-2 clinical specimens and further developed a multiplexed sequencing protocol (LAMP-sequencing) to analyze the outcome of many RT-LAMP reactions at the same time (Dao Thi et al., 2020). Extending on this work, we hereby provide step-by-step protocols for both RT-LAMP assays and read-outs.
Keywords: RT-LAMP (逆转录环介导等温扩增)Background
The new SARS-CoV-2 coronavirus poses a major public health problem (reviewed in Li et al., 2020). In the absence of efficient antiviral treatments and a protective vaccine, preventing local outbreaks by mass testing is critical. The standard diagnostic pipeline to detect SARS-CoV-2 infections is based on the isolation of viral RNA from clinical specimens, a reverse-transcription (RT) reaction to transcribe the RNA into cDNA, and detection by a semi-quantitative DNA polymerase chain reaction (qPCR) (Corman et al., 2020). Yet, commercial RNA isolation and RT-qPCR kits are costly, time-consuming, and shortages of supplies during the pandemics limit high-throughput testing requiring alternative solutions (Klein et al., 2020 ).
In our recent study (Dao Thi et al., 2020), we used reverse transcription loop-mediated isothermal amplification (RT-LAMP) (Notomi et al., 2020) as an alternative to detect SARS-CoV-2 RNA in clinical specimens. We developed and characterized colorimetric RT-LAMP assays on both purified and unpurified pharyngeal swab specimens. We also developed a multiplexed sequencing protocol based on tagmentation for enzymatic addition of barcoded sequencing library adapters. This enables the analysis of many RT-LAMP reactions at the same time. Here, we present detailed step-by-step protocols to further facilitate the application of RT-LAMP for mass testing.
Materials and Reagents
1.5 ml tubes (Eppendorf), room temperature
Filter tips (for pipettes and liquidator), room temperature
96-well plate (Eppendorf, catalog number: 00 30128672 ), room temperature
Nuclease-free water (Ambion, catalog number: AM9937 ), room temperature
Ethanol for Molecular Biology
WarmStart Colorimetric RT-LAMP 2× Master Mix (New England Biolabs, catalog number: M1800 ), -20 °C
10× primer mix for RT-LAMP assay as in Table 1 (Sigma-Aldrich), -20 °C
Table 1. N gene primer for RT-LAMP assay. Primer sequences were designed by Zhang et al. (2020).
Name | Sequence | Concentration in 10× primer mix (µM) |
GeneN-A-F3 | TGGCTACTACCGAAGAGCT | 2 |
GeneN-A-B3 | TGCAGCATTGTTAGCAGGAT | 2 |
GeneN-A-FIP | TCTGGCCCAGTTCCTAGGTAGTCCAGACGAATTCGTGGTGG | 16 |
GeneN-A-BIP | AGACGGCATCATATGGGTTGCACGGGTGCCAATGTGATCT | 16 |
GeneN-A-LF | GGACTGAGATCTTTCATTTTACCGT | 4 |
GeneN-A-LB | ACTGAGGGAGCCTTGAATACA | 4 |
LAMP-sequencing primers as in Table 2 (Sigma-Aldrich), -20 °C
Table 2. LAMP-sequencing primers. The full table is available as Table S4 in Dao Thi et al. (2020). [Phos] = phosphorylation, [SpcC3] = C3 spacer group, N, X, Y indicate one of the bases [GATC] (N are random bases while X and Y belong to respective inline barcodes used for multiplexing).
Name | Sequence |
Tn5hY-Rd2-Wat-SC3 | [Phos]CTGTCTCTTATACACATCT[SpcC3] |
P5-UMI-xi5XXX-ME.fw | CGGCGACCACCGAGATCTACACNNNNNNNNNXXXXXXXXXXXXCGTCGGCAGCG TCAGATGTGTATAAGAGACAG |
P5.fw | AATGATACGGCGACCACCGAGATC |
P7nxt-GeneN-A-LBrc | GTCTCGTGGGCTCGGAGATGTGTATAAGAGACAGTGTATTCAAGGCTCCCTCAG T |
P7-xi7YYY | CAAGCAGAAGACGGCATACGAGATYYYYYYYYYYYYTCTCGTGGGCTCGGAG |
Optically clear adhesive seal (Kisker Biotech, catalog number: GK480-OS ), room temperature
Adhesive aluminum foil seal (Steinbrenner Laborsysteme, catalog number: SL-AM0550 ), room temperature
Pierceable foil (Brooks Life Sciences, catalog number: 4ti-0566/96 ), room temperature
200 ng/µl Tn5 (E54K, L372P) Transposase (purified according to Hennig et al., 2018 , -80 °C)
0.2% SDS solution (room temperature)
AMPureXP bead (Beckman Coulter, catalog number: A63881 ), 4 °C
NEBNext Q5 HotStart polymerase (New England Biolabs, catalog number: M0543 ), -20 °C
NucleoSpin Gel and PCR Clean-up mini kit (Macherey-Nagel, catalog number: 740609 ), room temperature
NEBNext Library Quant Kit for Illumina (New England Biolabs, catalog number: E7630 ), -20 °C
[Tris(hydroxymethyl)methylamino]propanesulfonic acid (TAPS)
MgCl2
Dimethylformamide (DMF)
Freshly prepared 5× tagmentation buffer (see Recipes)
Note: All chemicals purchased from Sigma-Aldrich except when indicated otherwise.
Equipment
Pipetman L P2L, 0.2-2 μl (Gilead, catalog number: FA10001M )
Pipetman L P20L, 2-20 μl (Gilead, catalog number: FA10003M )
Pipetman L P200L, 20-200 μl (Gilead, catalog number: FA10005M )
Pipetman L P1000L, 100-1,000 μl (Gilead, catalog number: FA10006M )
Pipetman L Multichannel P8 x 20L, 2-20 μl (Gilead, catalog number: FA10009 )
Liquidator 96 2-20 μl (Mettler Toledo, catalog number: LIQ-96-20 )
Thermocycler (Biometra, TAdvanced 96 S )
Absorbance reader (Tecan, model: Infinite M200/Spark Cyto )
Centrifuge (Eppendorf, model: 5430 R )
Table top centrifuge (Heraeus, model: Pico 21 )
Magnetic stand (6 Tube Magnetic Stand; Ambion, catalog number: 10055 )
NextSeq 550 machine (Illumina)
Procedure
文章信息
版权信息
© 2021 The Authors; exclusive licensee Bio-protocol LLC.
如何引用
Readers should cite both the Bio-protocol article and the original research article where this protocol was used:
分类
分子生物学 > RNA > RNA 检测
微生物学 > 病原体检测 > RT-LAMP
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