Specific and sensitive detection of the guava fruit anthracnose pathogen (Colletotrichum gloeosporioides) by loop-mediated isothermal amplification (LAMP) assay

2020 ◽  
Vol 66 (1) ◽  
pp. 17-24
Author(s):  
Chengzhong Lan ◽  
Jinai Yao ◽  
Xiujuan Yang ◽  
Hongchun Ruan ◽  
Deyi Yu ◽  
...  

Anthracnose of guava, caused by the fungus Colletotrichum gloeosporioides, is a major factor limiting worldwide guava production. Timely and accurate detection of the pathogen is important in developing a disease management strategy. Herein, a loop-mediated isothermal amplification (LAMP) assay for the specific and sensitive detection of C. gloeosporioides was developed using primers targeting the β-tubulin 2 (TUB2) gene. The optimal reaction conditions were 64 °C for 60 min. The specificity of the method was tested against C. gloeosporioides isolates, Colletotrichum spp. isolates, and isolates of other genera. Positive results were obtained only in the presence of C. gloeosporioides, whereas no cross-reaction was observed for other species. The detection limit of the LAMP assay was 10 fg of genomic DNA in a 25 μL reaction. The LAMP assay successfully detected C. gloeosporioides in guava fruit collected in the field. The results indicate that the developed LAMP assay is a simple, cost-effective, rapid, highly sensitive, and specific tool for the diagnosis of guava anthracnose caused by C. gloeosporioides and could be useful for disease management.

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Daniel Moreira de Avelar ◽  
Débora Moreira Carvalho ◽  
Ana Rabello

Visceral leishmaniasis (VL) is considered a major public health concern in Brazil and several regions of the world. A recent advance in the diagnosis of infectious diseases was the development of loop-mediated isothermal amplification (LAMP). The aim of this study was to develop and evaluate a new LAMP assay for detection of K26 antigen-coding gene of L. donovani complex. A total of 219 blood samples of immunocompetent patients, including 114 VL cases and 105 non-VL cases, were analyzed for the diagnosis of VL in the present study. Diagnostic accuracy was calculated against a combination of parasitological and/or serological tests as a reference standard. The results were compared to those of kDNA Leishmania-PCR. The detection limit for the K26-Lamp assay was 1fg L. infantum purified DNA and 100 parasites/mL within 60 min of amplification time with visual detection for turbidity. The assay was specific for L. donovani complex. Sensitivity, specificity, and accuracy were 98.2%, 98.1%, and 98.2%, respectively, for K26-LAMP and 100%, 100%, and 100%, respectively, for kDNA Leishmania-PCR. Excellent agreement was observed between K26-LAMP and kDNA Leishmania-PCR assays (K = 0.96). A highly sensitive and specific LAMP assay targeting K26 antigen-coding gene of L. donovani complex was developed for diagnosis in peripheral blood samples of VL patients.


2017 ◽  
Vol 07 (03) ◽  
pp. 042-048
Author(s):  
Gunimala Chakraborty ◽  
Indrani Karunasagar ◽  
Anirban Chakraborty

AbstractDelivery of quality healthcare in case of an infectious disease depends on how efficiently and how quickly the responsible pathogens are detected from the samples. Molecular methods can detect the presence of pathogens in a rapid and sensitive manner. Over the years, a number of such assays have been developed. However, these methods, although highly reliable and efficient, require use of expensive equipment, reagents, and trained personnel. Therefore, development of molecular assays that are simple, rapid, cost-effective, yet sensitive, is highly warranted to ensure efficient management or treatment strategies. Loop-mediated isothermal amplification (LAMP), a technique invented in the year 2000, is a novel method that amplifies DNA at isothermal conditions. Since its invention, this technique has been one of the most extensively used molecular diagnostic tools in the field of diagnostics offering rapid, accurate and cost-effective diagnosis of infectious diseases. Using the LAMP principle, many commercial kits have been developed in the last decade for a variety of human pathogens including bacteria, viruses and parasites. Currently LAMP assay is being considered as an effective diagnostic tool for use in developing countries because of its simple working protocol, allowing even an onsite application. The focus of this review is to describe the salient features of this technique the current status of development of LAMP assays with an emphasis on the pathogens of clinical significance.


Viruses ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 972 ◽  
Author(s):  
Mohammed A. Rohaim ◽  
Emily Clayton ◽  
Irem Sahin ◽  
Julianne Vilela ◽  
Manar E. Khalifa ◽  
...  

Until vaccines and effective therapeutics become available, the practical solution to transit safely out of the current coronavirus disease 19 (CoVID-19) lockdown may include the implementation of an effective testing, tracing and tracking system. However, this requires a reliable and clinically validated diagnostic platform for the sensitive and specific identification of SARS-CoV-2. Here, we report on the development of a de novo, high-resolution and comparative genomics guided reverse-transcribed loop-mediated isothermal amplification (LAMP) assay. To further enhance the assay performance and to remove any subjectivity associated with operator interpretation of results, we engineered a novel hand-held smart diagnostic device. The robust diagnostic device was further furnished with automated image acquisition and processing algorithms and the collated data was processed through artificial intelligence (AI) pipelines to further reduce the assay run time and the subjectivity of the colorimetric LAMP detection. This advanced AI algorithm-implemented LAMP (ai-LAMP) assay, targeting the RNA-dependent RNA polymerase gene, showed high analytical sensitivity and specificity for SARS-CoV-2. A total of ~200 coronavirus disease (CoVID-19)-suspected NHS patient samples were tested using the platform and it was shown to be reliable, highly specific and significantly more sensitive than the current gold standard qRT-PCR. Therefore, this system could provide an efficient and cost-effective platform to detect SARS-CoV-2 in resource-limited laboratories.


2014 ◽  
Vol 77 (9) ◽  
pp. 1593-1598 ◽  
Author(s):  
HEE-JIN DONG ◽  
AE-RI CHO ◽  
TAE-WOOK HAHN ◽  
SEONGBEOM CHO

Campylobacter jejuni is a leading cause of bacterial foodborne disease worldwide. The detection of this organism in cattle and their environment is important for the control of C. jejuni transmission and the prevention of campylobacteriosis. Here, we describe the development of a rapid and sensitive method for the detection of C. jejuni in naturally contaminated cattle farm samples, based on real-time loop-mediated isothermal amplification (LAMP) of the hipO gene. The LAMP assay was specific (100%inclusivity and exclusivity for 84 C. jejuni and 41 non–C. jejuni strains, respectively), sensitive (detection limit of 100 fg/μl), and quantifiable (R2 = 0.9133). The sensitivity of the LAMP assay was then evaluated for its application to the naturally contaminated cattle farm samples. C. jejuni strains were isolated from 51 (20.7%) of 246 cattle farm samples, and the presence of the hipO gene was tested using the LAMP assay. Amplification of the hipO gene by LAMP within 30 min (mean =10.8 min) in all C. jejuni isolates (n = 51) demonstrated its rapidity and accuracy. Next, template DNA was prepared from a total of 186 enrichment broth cultures of cattle farm samples either by boiling or using a commercial kit, and the sensitivity of detection of C. jejuni was compared between the LAMP and PCR assays. In DNA samples prepared by boiling, the higher sensitivity of the LAMP assay (84.4%) compared with the PCR assay (35.5%) indicates that it is less susceptible to the existence of inhibitors in sample material. In DNA samples prepared using a commercial kit, both the LAMP and PCR assays showed 100% sensitivity. We anticipate that the use of this rapid, sensitive, and simple LAMP assay, which is the first of its kind for the identification and screening of C. jejuni in cattle farm samples, may play an important role in the prevention of C. jejuni contamination in the food chain, thereby reducing the risk of human campylobacteriosis.


2017 ◽  
Vol 14 (2) ◽  
pp. 727-734
Author(s):  
Saba Aslani ◽  
Ghasemali Garoosi ◽  
Hossein Jafary

ABSTRACT: Verticillium wilt, which is caused by the fungus Verticillium dahliae, is one of the most important olive diseases worldwide. There are many ways to extract DNA from plant pathogenic fungi and from plant tissues for molecular-based diagnostic assays. LAMP is a new and sensitive molecular-based technique used for detection of plant pathogenic agents with minimum requirements needed. In this study, we tried to achieve a simple, cost effective and efficient method of DNA extraction from both Verticillium dahliae fungus and from infected wood samples in order to run a loop-mediated isothermal amplification (LAMP) assay. Efficiency of three DNA isolation methods from both mycelia and infected wood samples was evaluated. For this purpose, wood samples from infected olive trees were collected from Tarom region in Zanjan province and the samples were cultured on the media. The fungus was isolated and identified as V. dahliae based on morphological features. Then the genomic DNA was extracted using traditional CTAB method, fast NaOH method and direct isolation method from infected wood samples. After assessment of the quality and the quantity of the extracted DNA samples, a LAMP assay was ran using specific primer pairs and the DNA templates extracted using three different methods. In spite of the significant differences in the quantity of DNA samples, LAMP assay could successfully detect the fungus in all samples. The improved direct isolation of the DNA of V. dahlia from infected wood, followed by a LAMP assay could considerably shortened the detection process of the fungus and hence is a suitable method for screening of olive trees and saplings against Verticillium wilt disease.


2020 ◽  
Author(s):  
Mohammed A Rohaim ◽  
Emily Clayton ◽  
Irem Sahin ◽  
Julianne Vilela ◽  
Manar E Khalifa ◽  
...  

Until vaccines and effective therapeutics become available, the practical way to transit safely out of the current lockdown may include the implementation of an effective testing, tracing and tracking system. However, this requires a reliable and clinically validated diagnostic platform for the sensitive and specific identification of SARS-CoV-2. Here, we report on the development of a de novo, high-resolution and comparative genomics guided reverse-transcribed loop-mediated isothermal amplification (LAMP) assay. To further enhance the assay performance and to remove any subjectivity associated with operator interpretation of result, we engineered a novel hand-held smart diagnostic device. The robust diagnostic device was further furnished with automated image acquisition and processing algorithms, and the collated data was processed through artificial intelligence (AI) pipelines to further reduce the assay run time and the subjectivity of the colorimetric LAMP detection. This advanced AI algorithm-implemented LAMP (ai-LAMP) assay, targeting the RNA-dependent RNA polymerase gene, showed high analytical sensitivity and specificity for SARS-CoV-2. A total of ~200 coronavirus disease (CoVID-19)-suspected patient samples were tested using the platform and it was shown to be reliable, highly specific and significantly more sensitive than the current gold standard qRT-PCR. The system could provide an efficient and cost-effective platform to detect SARS-CoV-2 in resource-limited laboratories.


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