Visual LAMP Method for Detection of White Spot Syndrome Virus in Shrimp and Crayfish

Abstract

White spot syndrome virus (WSSV) has caused large economic losses to the aquaculture industry, and thus far there are no efficient therapeutic treatments available against this lethal virus. Therefore, rapid detection of white spot syndrome virus (WSSV) in shrimp is crucial. This study was conducted to establish a rapid visual detection method for WSSV in shrimp and on the basis of loop-mediated isothermal amplification (LAMP). The color change of the amplification products was observed using a fluorescence amplification curve (with the SYTO-9 fluorescent dye) and LAMP visualization (with calcein), and the method`s specificity, sensitivity, and reproducibility were analyzed. It showed that this method can specifically detect WSSV, with a detection sensitivity of 1 fg/μL and has good reproducibility and reliability. This method was used to analyze cultured shrimp and crayfish samples; among 329 suspected clinical samples, the positive diagnostic rate of WSSV was 27.96%. The infection activity of WSSV was the highest at temperatures of 20–26°C. The LAMP-based method for rapid visual detection of WSSV does not need complex experimental instruments, and an equipment with a stable heat source is sufficient for the reaction. It is easy to use and can be used at shrimp breeding sites.