Real-time quantitative loop-mediated isothermal amplification as a simple method for detecting white spot syndrome virus

White spot syndrome virus (WSSV) continues to be the most pathogenic virus among the crustacean aquaculture causing mass mortality. In the present study, we established a one-step, single tube, real-time accelerated loop-mediated isothermal amplification (real-time LAMP) for quantitative detection of WSSV. A set of six specially designed primers that recognize eight distinct sequences of the target. The whole process can be completed in 1 h under isothermal conditions at 63 degrees C. Detection and quantification can be achieved by real-time monitoring in an inexpensive turbidimeter based on threshold time required for turbidity in the LAMP reaction. A standard curve was constructed by plotting viral titre against the threshold time (T-t) using plasmid standards with high correlation coefficient (R-2 = 0.988). Sensitivity analysis using 10-fold dilutions (equivalent to 35 ng mu l(-1) to 35 ag mu l(-1)) of plasmid standards revealed this method is capable of detecting upto 100 copies of template DNA. Cross-reactivity analysis with DNA/cDNA of IHHNV, TSV, YHV-infected and healthy shrimp showed this method is highly specific for quantitative detection of WSSV. WSSV real-time LAMP assay appears to be precise, accurate and a valuable tool for the detection and quantification of WSSV in large field samples and epidemiological studies.