scholarly journals Rapid Detection of Burkholderia pseudomallei with a Lateral Flow Recombinase Polymerase Amplification Assay

2019 ◽  
Author(s):  
Yao Peng ◽  
Zheng Xiao ◽  
Biao Kan ◽  
Wei Li ◽  
Wen Zhang ◽  
...  

AbstractMelioidosis is a severe infectious disease caused by gram-negative, facultative intracellular pathogen Burkholderia pseudomallei (B. pseudomallei). Although cases are increasing reported from other parts of the world, it is an illness of tropical and subtropical climates primarily found in southeast Asia and northern Australia. Because of a 40% mortality rate, this life-threatening disease poses a public health risk in endemic area. Early detection of B. pseudomallei infection benefits greatly to implement effective treatment timely, which is vital for prognosis of a melioidosis patient. In this study, a novel isothermal recombinase polymerase amplification combined with lateral flow dipstick (LF-RPA) assay was established for rapid detection of B.pseudomallei. A set of probe and primers targeting orf2 gene of B. pseudomallei were generated and parameters for the LF-RPA assay were optimized. Result can be easy visualized in 30 minutes with the limit of detection (LoD) as low as 20 femtogram (ca. 25.6 copies) of B. pseudomallei genomic DNA. The assay is highly specific as no cross amplification was observed with 35 non-B. pseudomallei pathogens. Isolates (N=19) from patients of Hainan province of China were retrospectively confirmed by the newly developed method. LoD for B. pseudomallei spiked soil and blood samples were 2.1×103 CFU/g and 4.2×103 CFU/ml respectively. Sensitivity of the LF-RPA assay was comparable to TaqMan Real-Time PCR, however, the LF-RPA assay exhibited a better tolerant to inhibitors in blood than the later. Our results showed that the LF-RPA assay is an alternative to existing PCR-based methods for detection of B. pseudomallei with a potentiality of early accurate diagnosis of melioidosis at point of care or in-field use.

2020 ◽  
Author(s):  
Thomas R Shelite ◽  
Ashanti C Uscanga-Palomeque ◽  
Alejandro Castellanos ◽  
Peter C Melby ◽  
Bruno L Travi

Abstract The rapid detection of novel pathogens necessitates the development of easy-to-use diagnostic tests that can be readily adapted and utilized in both clinical laboratories and field settings. In December of 2019, novel coronavirus, SARS-CoV-2 (2019-nCoV), was isolated from a cluster of pneumonia patients in the Chinese city of Wuhan. The virus rapidly spread throughout the world and the first fatal cases of COVID-19 in the United States occurred in late February. The lack of testing and delay in diagnosis has facilitated the spread of this novel virus. Development of point-of-care diagnostic assays that can be performed in rural or decentralized health care centers to expand testing capacity is needed. We developed a qualitative test based on recombinase-polymerase-amplification coupled with lateral flow reading (RPA-LF) for rapid detection of SARS-CoV-2. The RPA-LF detected SARS-CoV-2 with a limit of detection of 35.4 viral nucleocapsid (N) gene copies/µL. Additionally, the RPA-LF was able to detect 0.25-2.5 copies/µL of SARS-CoV-2 N gene containing plasmid. We evaluated 37 clinical samples using CDC’s N3, N1 and N2 RT-real-time PCR assays for SARS-CoV-2 as reference test. We found a 100% concordance between RPA-LF and RT-qPCR reference test as determined by 18/18 positive and 19/19 negative samples. All positive samples had Ct values between 19-37 by RT-qPCR. The RPA-LF primers and probe did not cross react with other relevant betacoronaviruses such as SARS and MERS. This is the first isothermal amplification test paired with lateral flow developed for qualitative detection of COVID-19 allowing rapid viral detection and with prospective applicability in resource limited and decentralized laboratories.


2020 ◽  
Author(s):  
Thomas R Shelite ◽  
Ashanti C Uscanga-Palomeque ◽  
Alejandro Castellanos ◽  
Peter C Melby ◽  
Bruno L Travi

Abstract The rapid detection of novel pathogens necessitates the development of easy-to-use diagnostic tests that can be readily adapted and utilized in both clinical laboratories and field settings. In December of 2019, novel coronavirus, SARS-CoV-2 (2019-nCoV), was isolated from a cluster of pneumonia patients in the Chinese city of Wuhan. The virus rapidly spread throughout the world and the first fatal cases of COVID-19 in the United States occurred in late February. The lack of testing and delay in diagnosis has facilitated the spread of this novel virus. Development of point-of-care diagnostic assays that can be performed in rural or decentralized health care centers to expand testing capacity is needed. We developed a qualitative test based on recombinase-polymerase-amplification coupled with lateral flow reading (RPA-LF) for rapid detection of SARS-CoV-2. The RPA-LF detected SARS-CoV-2 with a limit of detection of 35.4 viral nucleocapsid (N) gene copies/µL. Additionally, the RPA-LF was able to detect 0.25-2.5 copies/µL of SARS-CoV-2 N gene containing plasmid. We evaluated 37 clinical samples using CDC’s N3, N1 and N2 RT-real-time PCR assays for SARS-CoV-2 as reference test. We found a 100% concordance between RPA-LF and RT-qPCR reference test as determined by 18/18 positive and 19/19 negative samples. All positive samples had Ct values between 19-37 by RT-qPCR. The RPA-LF primers and probe did not cross react with other relevant betacoronaviruses such as SARS and MERS. This is the first isothermal amplification test paired with lateral flow developed for qualitative detection of COVID-19 allowing rapid viral detection and with prospective applicability in resource limited and decentralized laboratories.


Plant Disease ◽  
2020 ◽  
Author(s):  
Zhiqiang Song ◽  
Xiai Yang ◽  
Xiaowei Zhang ◽  
Mingbao Luan ◽  
Bing Guo ◽  
...  

The northern root-knot nematode, Meloidogyne hapla, is a biotrophic parasite that infects many crops and causes severe economic losses worldwide. Rapid and accurate detection of M. hapla is crucial for disease forecasting and control. We developed a recombinase polymerase amplification combined with a lateral flow dipstick (RPA-LFD) assay for rapid detection of M. hapla. The primers and a probe were designed based on the effector gene 16D10 sequence and were highly specific to M. hapla. The RPA reaction was performed at a wide range of temperatures from 25 to 45°C within 5 to 25 min, and the amplicon was visualized directly on the LFD within 5 min. The detection limits of the RPA-LFD assay were 10-3 female and 10-2 J2/0.5 g of soil, which was 10 times more sensitive than the conventional PCR assay. In addition, the RPA-LFD assay can detect M. hapla from infested plant roots and soil samples, and the entire detection process can be completed within 1.5 h. These results indicate that the RPA-LFD assay is a simple, rapid, specific, sensitive, and visual method that can be used for rapid detection of M. hapla in the field and in resource-limited conditions.


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