Rapid detection of Banna virus by reverse transcription-loop-mediated isothermal amplification (RT-LAMP)

Development and Validation of a Colorimetric Reverse Transcriptase Loop-Mediated Isothermal Amplification Assay for Detection of Eastern Equine Encephalitis Virus in Mosquitoes

Eastern equine encephalitis virus (EEEV) is a highly pathogenic alphavirus that causes periodic outbreaks in the eastern USA. Mosquito abatement programs are faced with various challenges with surveillance and control of EEEV and other mosquito-borne illnesses. Environmental sampling of mosquito populations can be technically complex. Here we report the identification of biomarkers, development and validation of a colorimetric reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for the detection of EEEV. Positive samples are easily visualized by a color change from pink to yellow. The assay was validated using EEEV from viral culture, experimentally spiked mosquito pools, and previously tested mosquito pools. The RT-LAMP assay detected viral titers down to approximately 10% of what would be present in a single infectious mosquito, based upon EEEV viral titers determined by previous competency studies. The RT-LAMP assay efficiently detected EEEV in combined aliquots from previously homogenized pools of mosquitoes, allowing up to 250 individual mosquitoes to be tested in a single reaction. No false positive results were obtained from RNA prepared from negative mosquito pools acquired from known and potential EEEV vectors. The colorimetric RT-LAMP assay is highly accurate, technically simple, and does not require sophisticated equipment, making it a cost-effective alternative to real time reverse transcriptase-polymerase chain reaction (RT-PCR) for vector surveillance.

Microfluidics for sepsis early diagnosis and prognosis: a review of recent methods

Sepsis is a complex disorder of immune system response to infections that can be caused by a wide range of clinical contexts. Traditional methods for sepsis detection include molecular diagnosis, biomarkers either based on protein concentration or cell surface expression, and microbiological cultures. Development of point-of-care (POC) instruments, which can provide high accuracy and consume less time, is in unprecedented demand. Within the past few years, applications of microfluidic systems for sepsis detection have achieved excellent performance. In this review, we discuss the most recent microfluidic applications specifically in sepsis detection, and propose their advantages and disadvantages. We also present a comprehensive review of other traditional and current sepsis diagnosis methods to obtain a general understanding of the present conditions, which can hopefully direct the development of a new sepsis roadmap.

Molecular Approaches for Low-Cost Point-of-Care Pathogen Detection in Agriculture and Forestry

Early detection of plant diseases is a crucial factor to prevent or limit the spread of a rising infection that could cause significant economic loss. Detection test on plant diseases in the laboratory can be laborious, time consuming, expensive, and normally requires specific technical expertise. Moreover, in the developing countries, it is often difficult to find laboratories equipped for this kind of analysis. Therefore, in the past years, a high effort has been made for the development of fast, specific, sensitive, and cost-effective tests that can be successfully used in plant pathology directly in the field by low-specialized personnel using minimal equipment. Nucleic acid-based methods have proven to be a good choice for the development of detection tools in several fields, such as human/animal health, food safety, and water analysis, and their application in plant pathogen detection is becoming more and more common. In the present review, the more recent nucleic acid-based protocols for point-of-care (POC) plant pathogen detection and identification are described and analyzed. All these methods have a high potential for early detection of destructive diseases in agriculture and forestry, they should help make molecular detection for plant pathogens accessible to anyone, anywhere, and at any time. We do not suggest that on-site methods should replace lab testing completely, which remains crucial for more complex researches, such as identification and classification of new pathogens or the study of plant defense mechanisms. Instead, POC analysis can provide a useful, fast, and efficient preliminary on-site screening that is crucial in the struggle against plant pathogens.

Development of loop-mediated isothermal amplification combined with a chromatographic lateral-flow dipstick for rapid detection of Chattonella marina

Harmful algal blooms caused by Chattonella marina recently have caused severe negative effect on coastal economy worldwide, with increased occurrence frequency and scale. It is therefore vital to establish new methods for rapid detection of this alga. In this study, the internal transcribed spacer (ITS) sequence was used as the target gene for molecular detection of C. marina. First, four loop-mediated isothermal amplification (LAMP) primers were designed based on the six regions of ITS, and the LAMP reaction system was established using these primers. Next, a probe was designed to detect the LAMP products by lateral-flow dipstick (LFD). Finally, a new method for rapid and sensitive detection of C. marina that is referred to as LAMP-LFD was established. The LAMP reaction system, amplification time, and amplification temperature were particularly optimized. The optimal parameters are as follows: Mg²⁺ concentration, 10 mM；dNTP concentration, 1.2 mM；ratio of internal primer concentration to outer primer concentration, 8:1；reaction time, 60 min；and reaction temperature, 60 °C. Both specificity and sensitivity were tested using the optimized LAMP reaction system in combination with LFD (LAMP-LFD). The established LAMP-LFD displayed good specificity and no cross reaction was detected with non-target algal species. The detection limit of LAMP-LFD was 3.4 × 10^-4 ng μL^-1 (3.4 × 10^-4 ng per reaction) for the genomic DNA of target algae, and 1.3 copies μL^-1 (1.3 copies per reaction) for the plasmid DNA containing the target ITS. Sensitivity tests using genomic DNA and plasmid DNA as templates consistently revealed that LAMP-LFD is 100 times more sensitive than regular PCR. The established LAMP-LFD was applied to analyze the simulated samples and the results showed that the detection limit of LAMP-LFD could reach 1 cell mL^-1. LAMP-LFD also demonstrated good specificity and sensitivity in the analysis of natural samples. The whole procedure of LAMP-LFD could be completed within 1.5 h. Taken together, the LAMP-LFD assay developed here is characterized by simplicity, high specificity and sensitivity, and rapidity and therefore is promising for rapid detection of C. marina.

Rapid Visual Detection of Getah Virus Using a Loop-Mediated Isothermal Amplification Method

Getah virus (GETV) is a mosquito-borne alphavirus that is considered to be an emerging pathogen. To date, reverse transcription loop-mediated isothermal amplification (RT-LAMP) has not been used to detect GETV. Therefore, we describe a novel, fast, and sensitive LAMP method to detect GETV. Amplification of GETV RNA can be obtained within 50 min at 65°C. This RT-LAMP method was verified to be highly specific for GETV, with no cross detection of other viruses. The assay was 10³ and 10¹ times more sensitive than RT-PCR and RT-qPCR, respectively, for the detection of GETV RNA. This novel RT-LAMP method provides a practical and economical alternative for detecting GETV in mosquitoes and serum samples that can be used even in the field.