scholarly journals Development of Two-Tube Loop-Mediated Isothermal Amplification Assay for Differential Diagnosis of Plasmodium falciparum and Plasmodium vivax and Its Comparison with Loopamp™ Malaria

Diagnostics ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1689
Author(s):  
Mudsser Azam ◽  
Kirti Upmanyu ◽  
Ratan Gupta ◽  
Karugatharayil Sasi Sruthy ◽  
Monika Matlani ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Plasmodium Vivax ◽  
Sensitivity And Specificity ◽  
Limit Of Detection ◽  
Lamp Assay ◽  
Repeat Sequence ◽  
Isothermal Amplification ◽  
Malaria Surveillance ◽  
Loop Mediated Isothermal Amplification ◽  
Closed Tube

To strengthen malaria surveillance, field-appropriate diagnostics requiring limited technical resources are of critical significance. Loop-mediated isothermal amplification (LAMP) based malaria diagnostic assays are potential point-of-care tests with high sensitivity and specificity and have been used in low-resource settings. Plasmodium vivax–specific consensus repeat sequence (CRS)-based and Plasmodium falciparum–specific 18S rRNA primers were designed, and a two-tube LAMP assay was developed. The diagnostic performance of a closed-tube LAMP assay and Loopamp™ Malaria Detection (Pan/Pf, Pv) kit was investigated using nested PCR confirmed mono- and co-infections of P. vivax and P. falciparum positive (n = 149) and negative (n = 67) samples. The closed-tube Pv LAMP assay showed positive amplification in 40 min (limit of detection, LOD 0.7 parasites/µL) and Pf LAMP assay in 30 min (LOD 2 parasites/µL). Pv LAMP and Pf LAMP demonstrated a sensitivity and specificity of 100% (95% CI, 95.96–100% and 89.85–100%, respectively). The LoopampTM Pan/Pf Malaria Detection kit demonstrated a sensitivity and specificity of 100%, whereas LoopampTM Pv showed a sensitivity of 98.36% (95% CI, 91.28–99.71%) and specificity of 100% (95% CI, 87.54–100%). The developed two-tube LAMP assay is highly sensitive (LOD ≤ 2 parasite/µL), demonstrating comparable results with the commercial Loopamp™ Malaria Detection (Pf/pan) kit, and was superior in detecting the P. vivax co-infection that remained undetected by the Loopamp™ Pv kit. The developed indigenous two-tube Pf/Pv malaria detection can reliably be used for mass screening in resource-limited areas endemic for both P. falciparum and P. vivax malaria.

scholarly journals Colorimetric Reverse Transcription–Loop-Mediated Isothermal Amplification Assay for Rapid Detection of SARS-CoV-2

2021 ◽  
Author(s):  
Meng Yee Lai ◽  
Soo Nee Tang ◽  
Yee Ling Lau
Keyword(s):  
Sensitivity And Specificity ◽  
Reverse Transcription ◽  
Virus Detection ◽  
Lamp Assay ◽  
Isothermal Amplification ◽  
Clinical Sensitivity ◽  
Loop Mediated Isothermal Amplification ◽  
Resource Limited ◽  
Detection Technology ◽  
Simple Detection

Coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been spreading rapidly all over the world. In the absence of effective treatments or a vaccine, there is an urgent need to develop a more rapid and simple detection technology of COVID-19. We describe a WarmStart colorimetric reverse transcription–loop-mediated isothermal amplification (RT-LAMP) assay for the detection of SARS-CoV-2. The detection limit for this assay was 1 copy/µL SARS-CoV-2. To test the clinical sensitivity and specificity of the assay, 37 positive and 20 negative samples were used. The WarmStart colorimetric RT-LAMP had 100% sensitivity and specificity. End products were detected by direct observation, thereby eliminating the need for post-amplification processing steps. WarmStart colorimetric RT-LAMP provides an opportunity to facilitate virus detection in resource-limited settings without a sophisticated diagnostic infrastructure.

scholarly journals Rapid detection of cytochrome cd1-containing nitrite reductase encoding gene nirS of denitrifying bacteria with loop-mediated isothermal amplification assay

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Xuzhi Zhang ◽  
Qianqian Yang ◽  
Qingli Zhang ◽  
Xiaoyu Jiang ◽  
Xiaochun Wang ◽  
...  
Keyword(s):  
Nitrite Reductase ◽  
Genomic Dna ◽  
Limit Of Detection ◽  
Lamp Assay ◽  
Denitrifying Bacteria ◽  
Isothermal Amplification ◽  
Target Sequence ◽  
Bacterial Cells ◽  
Loop Mediated Isothermal Amplification ◽  
Order Of Magnitude

Abstract The cytochrome cd1-containing nitrite reductase, nirS, plays an important role in biological denitrification. Consequently, investigating the presence and abundance of nirS is a commonly used approach to understand the distribution and potential activity of denitrifying bacteria, in addition to denitrifier communities. Herein, a rapid method for detecting nirS gene with loop-mediated isothermal amplification (LAMP) was developed, using Pseudomonas aeruginosa PAO1 (P. aeruginosa PAO1) as model microorganism to optimize the assay. The LAMP assay relied on a set of four primers that were designed to recognize six target sequence sites, resulting in high target specificity. The limit of detection for the LAMP assay under optimized conditions was 1.87 pg/reaction of genomic DNA, which was an order of magnitude lower than that required by conventional PCR assays. Moreover, it was validated that P. aeruginosa PAO1 cells as well as genomic DNA could be directly used as template. Only 1 h was needed from the addition of bacterial cells to the reaction to the verification of amplification success. The nirS gene of P. aeruginosa PAO1 in spiked seawater samples could be detected with both DNA-template based LAMP assay and cell-template based LAMP assay, demonstrating the practicality of in-field use.

scholarly journals Rapid and Extraction-Free Detection of SARS-CoV-2 from Saliva by Colorimetric Reverse-Transcription Loop-Mediated Isothermal Amplification

2020 ◽  
Author(s):  
Matthew A Lalli ◽  
Joshua S Langmade ◽  
Xuhua Chen ◽  
Catrina C Fronick ◽  
Christopher S Sawyer ◽  
...  
Keyword(s):  
Reverse Transcription ◽  
Limit Of Detection ◽  
Colorimetric Assay ◽  
Quantitative Polymerase Chain Reaction ◽  
Rna Extraction ◽  
Lamp Assay ◽  
Isothermal Amplification ◽  
Clinical Samples ◽  
Viral Detection ◽  
Loop Mediated Isothermal Amplification

Abstract Background Rapid, reliable, and widespread testing is required to curtail the ongoing COVID-19 pandemic. Current gold-standard nucleic acid tests are hampered by supply shortages in critical reagents including nasal swabs, RNA extraction kits, personal protective equipment, instrumentation, and labor. Methods To overcome these challenges, we developed a rapid colorimetric assay using reverse-transcription loop-mediated isothermal amplification (RT-LAMP) optimized on human saliva samples without an RNA purification step. We describe the optimization of saliva pretreatment protocols to enable analytically sensitive viral detection by RT-LAMP. We optimized the RT-LAMP reaction conditions and implemented high-throughput unbiased methods for assay interpretation. We tested whether saliva pretreatment could also enable viral detection by conventional reverse-transcription quantitative polymerase chain reaction (RT-qPCR). Finally, we validated these assays on clinical samples. Results The optimized saliva pretreatment protocol enabled analytically sensitive extraction-free detection of SARS-CoV-2 from saliva by colorimetric RT-LAMP or RT-qPCR. In simulated samples, the optimized RT-LAMP assay had a limit of detection of 59 (95% confidence interval: 44–104) particle copies per reaction. We highlighted the flexibility of LAMP assay implementation using 3 readouts: naked-eye colorimetry, spectrophotometry, and real-time fluorescence. In a set of 30 clinical saliva samples, colorimetric RT-LAMP and RT-qPCR assays performed directly on pretreated saliva samples without RNA extraction had accuracies greater than 90%. Conclusions Rapid and extraction-free detection of SARS-CoV-2 from saliva by colorimetric RT-LAMP is a simple, sensitive, and cost-effective approach with broad potential to expand diagnostic testing for the virus causing COVID-19.

scholarly journals q-LAMP Assays for the Detection of Botryosphaeria dothidea Causing Chinese Hickory Canker in Trunk, Water, and Air Samples

Plant Disease ◽  
2019 ◽  
Vol 103 (12) ◽  
pp. 3142-3149
Author(s):  
Q. W. Wang ◽  
C. Q. Zhang
Keyword(s):  
Limit Of Detection ◽  
Lamp Assay ◽  
Isothermal Amplification ◽  
Botryosphaeria Dothidea ◽  
Canker Disease ◽  
Air Samples ◽  
Loop Mediated Isothermal Amplification ◽  
Optimum Reaction ◽  
Epidemiological Characteristics ◽  
Trunk Canker

Trunk canker disease caused by Botryosphaeria dothidea with a prolonged latent infection phase poses a serious threat to Chinese hickory production. To further understand the epidemiological characteristics and develop reasonable management techniques, a quantitative loop-mediated isothermal amplification (q-LAMP) assay was developed to quantitatively monitor B. dothidea in hickory plants, water, and air samples. Specific primers were designed based on the different sites of the β-tubulin sequence between B. dothidea and other fungi commonly found on Chinese hickory. At the optimum reaction temperature of 65.9°C, this loop-mediated isothermal amplification (LAMP) assay can specifically distinguish B. dothidea from other tested fungi. The limit of detection of LAMP assays for B. dothidea was 0.001 ng/µl of pure genomic DNA and 10 spores per 1 ml of water. The q-LAMP assay enables rapid detection of B. dothidea within 60 min in hickory trunk, water in hickory forests, and spores captured on tapes. These results provide a powerful and convenient tool for monitoring B. dothidea, which could be applied widely in epidemiology, forecast, and management of tree canker disease.

Detection of Plasmodium vivax and Plasmodium falciparum DNA in human saliva and urine: Loop-mediated isothermal amplification for malaria diagnosis

Acta Tropica ◽  
2014 ◽  
Vol 136 ◽  
pp. 44-49 ◽  
Author(s):  
Zahra Ghayour Najafabadi ◽  
Hormozd Oormazdi ◽  
Lame Akhlaghi ◽  
Ahmad Reza Meamar ◽  
Mehdi Nateghpour ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Plasmodium Vivax ◽  
Malaria Diagnosis ◽  
Human Saliva ◽  
Isothermal Amplification ◽  
Loop Mediated Isothermal Amplification

scholarly journals Rapid detection of cytochromecd1-containing nitrite reductase encoding genenirSwith loop-mediated isothermal amplification assay

2018 ◽  
Author(s):  
Qianqian Yang ◽  
Xuzhi Zhang ◽  
Xiaoyu Jiang ◽  
Xiaochun Wang ◽  
Yang Li ◽  
...  
Keyword(s):  
Nitrite Reductase ◽  
Genomic Dna ◽  
Limit Of Detection ◽  
Bacterial Species ◽  
Lamp Assay ◽  
Isothermal Amplification ◽  
Target Sequence ◽  
Bacterial Cells ◽  
Conventional Pcr ◽  
Loop Mediated Isothermal Amplification

AbstractThe cytochromecd1-containing nitrite reductase,nirS, plays an important role in biological denitrification. Consequently, investigating the presence and abundance ofnirSis a commonly used approach to understand the distribution and potential activity of denitrifying bacteria, in addition to denitrifier communities. Herein, a new molecular biology technique termed loop-mediated isothermal amplification (LAMP) was developed to rapidly detectnirSgene using those ofPseudomonas aeruginosato optimize the assay. The LAMP assay relied on a set of four primers that were designed to recognize six target sequence sites, resulting in high target specificity. The specificity of the assay was confirmed by the lack of amplification when using DNA from 15 other bacterial species lackingnirSgene. The limit of detection for the LAMP assay under optimized conditions was 1.87 pg/reaction of genomic DNA, which was an order of magnitude lower than that required by conventional PCR assays. Moreover, a cell-template based LAMP assay was also developed for detectingnirSgene that directly used bacterial cells as template rather than genomic DNA. Only 1 h was needed from the addition of bacterial cells to the reaction to the verification of amplification success, and bulky and sophisticated equipment were not needed. Further, thenirSgene ofP. aeruginosain spiked seawater samples could be detected with both the DNA-template based LAMP assay and the cell-template based LAMP assay, thereby demonstrating the practicality of in-field use of them. In summary, the LAMP assays described here represent a rapid, user-friendly, and cost-effective alternative to conventional PCR.

scholarly journals Loop-Mediated Isothermal Amplification (LAMP) Assay for Detecting Burkholderia cepacia Complex in Non-Sterile Pharmaceutical Products

Pathogens ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1071
Author(s):  
Soumana Daddy Gaoh ◽  
Ohgew Kweon ◽  
Yong-Jin Lee ◽  
John J. LiPuma ◽  
David Hussong ◽  
...  
Keyword(s):  
Burkholderia Cepacia ◽  
Limit Of Detection ◽  
Free Water ◽  
Lamp Assay ◽  
Pharmaceutical Products ◽  
Isothermal Amplification ◽  
Burkholderia Cenocepacia ◽  
Burkholderia Cepacia Complex ◽  
Loop Mediated Isothermal Amplification ◽  
Consumer Safety

Simple and rapid detection of Burkholderia cepacia complex (BCC) bacteria, a common cause of pharmaceutical product recalls, is essential for consumer safety. In this study, we developed and evaluated a ribB-based colorimetric loop-mediated isothermal amplification (LAMP) assay for the detection of BCC in (i) nuclease-free water after 361 days, (ii) 10 μg/mL chlorhexidine gluconate (CHX) solutions, and (iii) 50 μg/mL benzalkonium chloride (BZK) solutions after 184 days. The RibB 5 primer specifically detected 20 strains of BCC but not 36 non-BCC strains. The limit of detection of the LAMP assay was 1 pg/μL for Burkholderia cenocepacia strain J2315. Comparison of LAMP with a qPCR assay using 1440 test sets showed higher sensitivity: 60.6% in nuclease-free water and 42.4% in CHX solution with LAMP vs. 51.3% and 31.1%, respectively, with qPCR. These results demonstrate the potential of the ribB-based LAMP assay for the rapid and sensitive detection of BCC in pharmaceutical manufacturing.

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