Detection of shrimp Taura syndrome virus by loop-mediated isothermal amplification using a designed portable multi-channel turbidimeter

In this study, a portable turbidimetric end-point detection method was devised and tested for the detection of Taura syndrome virus (TSV) using spectroscopic measurement of a loop-mediated isothermal amplification (LAMP) by-product: magnesium pyrophosphate (Mg2P2O7). The device incorporated a heating block that maintained an optimal temperature of 63 degrees C for the duration of the RI-LAMP reaction. Turbidity of the RT-LAMP by-product was measured when light from a light-emitting diode (LED) passed through the tube to reach a light dependent resistance (LDR) detector. Results revealed that turbidity measurement of the RI-LAMP reactions using this device provided the same detection sensitivity as the agarose gel electrophoresis detection of RI-LAMP and nested RT-PCR (IQ2000 (TM)) products. Cross reactions with other shrimp viruses were not found, indicating that the RT-LAMP-turbidity measurement was highly specific to TSV. The combination of 10 min for rapid RNA preparation with 30 min for RI-LAMP amplification followed by turbidity measurement resulted in a total assay time of less than 1 h compared to 4-8 h for the nested RT-PCR method. RI-LAMP plus turbidity measurement constitutes a platform for the development of more rapid and user-friendly detection of TSV in the field. (C) 2011 Elsevier B.V. All rights reserved.