A real-time isothermal amplification based portable microfluidic system for simple and reliable detection of Vibrio splendidus

A loop-mediated isothermal amplification-based microfluidic chip for triplex detection of shrimp pathogens

Decapod iridescent virus 1 (DIV1), White spot syndrome virus (WSSV), and Enterocytozoon hepatopenaei (EHP) pose serious threats to the shrimp farming. To date, early detection remains an important way to control the occurrence and diffusion of these pathogens. Here, we developed for the first time, a loop-mediated isothermal amplification (LAMP)-based microfluidic chip detection system, which could detect DIV1, WSSV, and EHP simultaneously. The limits of detection (LoD) of the system were 10 copies/reaction for EHP and DIV1, and 10² copies/reaction for WSSV. The entire detection procedure could be completed rapidly in 40 min at 63°C with 100% specificity and had no cross-reaction with other common shrimp pathogens. This newly established method was further validated using 94 Penaeus vannamei clinical samples, which were comparable to a typical qPCR assay and revealed good stability and reproducibility. These results illustrate that this LAMP microfluidic chip detection system allows rapid triplex pathogen analysis and could satisfy the demands of the field and routine diagnoses in aquaculture.

A real-time LAMP-based dual-sample microfluidic chip for rapid and simultaneous detection of multiple waterborne pathogenic bacteria from coastal waters

Waterborne pathogens are becoming a serious worldwide health hazard; thus, the regular monitoring of epidemic pathogens is urgently required for public safety. In the present study, we developed a microfluidic chip integrated loop-mediated isothermal amplification technique (on-chip LAMP) to simultaneously detect 10 waterborne pathogenic bacteria, Campylobacter jejuni, Listeria monocytogenes, Salmonella enterica, Shigella flexneri, Staphylococcus aureus, Vibrio alginolyticus, V. cholerae, V. parahemolyticus, V. vulnificus, and Yersinia enterocolitica. This method was capable of simultaneously completing 22 genetic analyses of two specimens and achieved limits of detection ranging from 7.92 × 10-3 to 9.54 × 10-1 pg of genomic DNA of pure bacteria per reaction. The processes from sample loading to microfluidic operation were in a highly automated format, and the LAMP reaction ran to completion within 35 minutes, with a minimal volume of 22 μl per each half of a single chip. The coefficient of variation for the time-to-positive value was less than 0.1, indicating an excellent reproducibility of the dual-sample on-chip LAMP assay. The clinical sensitivity and specificity in analyses of coastal water samples were 93.1% and 98.0%, respectively, in comparison with traditional microbiological methods. Our established dual-sample on-chip LAMP assay provides an effective multiple-pathogen analysis of waterborne bacterial pathogens. This indicates that the method is applicable for on-site detection and routine monitoring of waterborne bacteria in aquatic environments.

Simultaneous detection of multiple bacterial and viral aquatic pathogens using a fluorogenic loop-mediated isothermal amplification-based dual-sample microfluidic chip

Rapid and user-friendly diagnostic tests are necessary for early diagnosis and immediate detection of diseases, particularly for on-site screening of pathogenic microorganisms in aquaculture. In this study, we developed a dual-sample microfluidic chip integrated with a real-time fluorogenic loop-mediated isothermal amplification assay (dual-sample on-chip LAMP) to simultaneously detect 10 pathogenic microorganisms, that is Aeromonas hydrophila, Edwardsiella tarda, Vibrio harveyi, V. alginolyticus, V. anguillarum, V. parahaemolyticus, V. vulnificus, infectious hypodermal and haematopoietic necrosis virus, infectious spleen and kidney necrosis virus, and white spot syndrome virus. This on-chip LAMP provided a nearly automated protocol that can analyse two samples simultaneously, and the tests achieved limits of detection (LOD) ranging from 10⁰ to 10^-1  pg/μl for genomic DNA of tested bacteria and 10^-4 to 10^-5  pg/μl for recombinant plasmid DNA of tested viruses, with run times averaging less than 30 min. The coefficient of variation for the time-to-positive value was less than 10%, reflecting a robust reproducibility. The clinical sensitivity and specificity were 93.52% and 85.53%, respectively, compared to conventional microbiological or clinical methods. The on-chip LAMP assay provides an effective dual-sample and multiple pathogen analysis, and thus would be applicable to on-site detection and routine monitoring of multiple pathogens in aquaculture.