Fast identification of foodborne pathogenic viruses using continuous-flow reverse transcription-PCR with fluorescence detection

Being beneficial from dramatic process in bio-chemical and micro-electro-mechanical technologies, this study presents an integrated microfluidic system capable of performing a continuous-flow reverse transcription-polymerase chain reaction (RT-PCR) combined with fluorescence microscopy for rapid diagnosis of RNA-based viruses. The device consists of two heated cylinders for heating the different reaction zones of the reverse transcription and the amplification. In the amplification cylinder, bath refrigerating is used for thermal protection of the annealing region, which is heated possibly due to the thermal effects of radiation, conduction, and/or convection from denaturation and extension regions, thus resulting in a space-saving design of the whole device. Detection of the amplified products is performed on-line by a fluorescence microscopy with SybrGreen I, a widely used intercalating dye. In this article, the proposed miniature RT-PCR system is used to amplify and detect two RNA-based viruses (Noroviruses (NVs) and Rotaviruses (RVs)), which are now recognized as the most common etiological agents of acute viral gastroenteritis causing numerous outbreaks worldwide. The experimental data have demonstrated the ability of the presented system to perform a two-step or one-step RT-PCR process. On this device, the NVs and RVs RNA samples were successfully reverse transcribed and amplified within 1 h, and the limit of detection of the RNA concentration was 6.4 x 10(4) copies mu l(-1) using one-step RT-PCR process. Consequently, the developed microfluidic system can provide a promising platform for fast diagnosis of RNA-based viruses.