Development of a loop-mediated isothermal amplification assay for rapid detection of iridovirus in the Chinese giant salamander

A loop-mediated isothermal amplification (LAMP) assay based on the major caspid protein (MCP) gene has been developed to detect the Chinese giant salamander (Andrias davidianus) iridovirus (GSIV). Primer pairs for the LAMP assay were designed based on the GSIV MCP gene sequence (Fig. A). Amplification results indicated that under optimized conditions the LAMP assay had the ability to specifically detect the virus. The assay was able to detect concentrations of 10−9 (approximately 0.01 pg/μL) of GSIV DNA (Fig. B). The LAMP assay is relatively easy to perform and the amplification products can be observed directly via staining with SYBR Green I or under UV light (Fig. C). The LAMP reaction was able to detect viral DNA isolated from infected Chinese giant salamanders, but no for KHV, LCDV, EPC cells, or the two bacterial strains Aeromonas hydrophilia and Citrobacter freundii, isolated from Chinese giant salamanders (Fig. D). These results indicated that LAMP was a novel and important tool for the diagnosis of GSIV infection in farmed Chinese giant salamanders.