Detection of Nucleospora salmonis in cutthroat trout (Oncorhynchus clarki) and rainbow trout (Oncorhynchus mykiss) by loop-mediated isothermal amplification

Nucleospora salmonis is an intranuclear microsporidian parasite of salmonids that causes a chronic lymphoblastosis and a leukemic-like condition in both cultured and wild salmonids. Loop-mediated isothermal amplification (LAMP) is a novel method that amplifies DNA with high specificity and rapidity under isothermal conditions. Using the LAMP method, a protocol for detection of N. salmonis was developed. A set of four primers, two inner and two outer were designed based on the sequence of ribosomal RNA intermediate spacer of this parasite. Optimum time and temperature conditions for detection of N. salmonis by LAMP were 60 min at 63 °C, respectively. The detection-limit (DL) using LAMP was found to be similar to polymerase chain reaction (PCR). In this study, we have developed a highly sensitive and rapid diagnostic procedure for detection of N. salmonis infections in cutthroat trout(Oncorhynchus clarki) and rainbow trout (Oncorhynchus mykiss).