RT-LAMP detection of shrimp Taura syndrome virus (TSV) by combination with a nanogold-oligo probe Jurairat Phromjai 1 , Thitima Mathuros 1 , Ditsayuth Phokharatkul 1 , Potchanathorn Prombun 2 , Rungkarn Suebsing 2,3 , Adisorn Tuantranont 1 & Wansika Kiatpathomchai 2,3 1 National Center of Electronic and Computer (NECTEC), National Science and Technology Development Agency, Pathumthani, Thailand 2 CENTEX Shrimp, Faculty of Science, Mahidol University, Bangkok, Thailand 3 National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency, Pathumthani, Thailand Correspondence: A Tuantranont and W Kiatpathomchai, National Center of Electronic and Computer (NECTEC); National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency, Pathumthani 12120, Thailand. E-mails: adisorn.tuantranont@nectec.or.th; wansika@biotec.or.th Abstract This study describes the application and optimiza- tion of a newly developed specific gold nanoparticle (AuNP) visual detection method to detect a reverse transcription loop-mediated isothermal amplifica- tion (RT-LAMP) product of Taura syndrome virus (TSV) in shrimp with simple and cheaper in com- parison to conventional gel electrophoresis. Briefly, the visual detection method is based on prevention of a salt induced DNA-labelled AuNP colour change from red to blue–purple due to hybridiza- tion with complementary DNA amplicons that arise from a positive TSV RT-LAMP reaction. RT- LAMP combined with visual amplicon detection using the DNA-labelled AuNP-probe had high sen- sitivity and the probe did not cross react with amplicons obtained using specific LAMP methods with other shrimp viruses. The advantages of this assay include simplicity, short analysis time and low-cost, suitable for field laboratory applica- tions. Keywords: TSV, LAMP, gold nanoparticles, col- orimetric Introduction Taura syndrome virus (TSV) is a non-enveloped icosahedral virus containing a single-stranded positive-sense RNA genome (Bonami, Hasson, Mari, Poulos & Lightner 1997; Mari, Poulos, Lightner & Bonami 2002). It causes Taura syn- drome, a disease that was first described in Ecua- dor as the cause of high mortality in cultivated Penaeus (Litopenaeus) vannamei (C^ ot e, Navarro, Tang, Noble & Lightner 2008; Tang & Lightner 2005). Detection of TSV has been conducted using polymerase chain reaction (PCR) assays such as reverse transcriptase PCR (RT-PCR) (Nunan, Poulos & Lightner 1998) and a commercial nested RT-PCR kit. However, these methods involve several time-consuming steps and expensive equip- ment. Reverse transcription loop-mediated isother- mal amplication (RT-LAMP) overcomes some of these problems by allowing amplification of DNA and RNA with high specificity, sensitivity and rapidity under isothermal conditions using an inexpensive heating block (Notomi, Okayama, Masubuchi, Yonekawa, Watanabe, Amino & Hase 2000). RT-LAMP assays for TSV have been successfully developed using amplicon detection using gel elec- trophoresis and staining with the carcinogen ethi- dium bromide (Kiatpathomchai, Jaroenram, Jitrapakdee & Flegel 2007), using a lateral flow dipstick (LFD) (Kiatpathomchai, Jaroenram, Arun- rut, Jitrapakdee & Flegel 2008) or by measuring turbidity of the white magnesium pyrophosphate precipitate formed as a LAMP by-product (Sappat, Jaroenram, Puthawibool, Lomas, Tuantranont & Kiatpathomchai 2011). These amplicon detection methods had various disadvantages such as time required for gel electrophoresis, high cost of the © 2013 John Wiley & Sons Ltd 1 Aquaculture Research, 2013, 1–12 doi: 10.1111/are.12345