Development and evaluation of a loop-mediated isothermal amplification assay for rapid and simple detection of Flavobacterium psychrophilum.

Flavobacterium psychrophilum is the causative agent of bacterial cold-water disease and rainbow trout fry syndrome of salmonids. The pathogen has been reported from all regions in the world involved in salmonid aquaculture, but also from natural fresh-water environments. We established a quantitative loop-mediated isothermal amplification of DNA (LAMP) method to estimate quantities of F. psychrophilum. LAMP primers were designed based on the sequence of the DNA topoisomerase IV subunit B gene, parE, of F. psychrophilum. parE LAMP exhibited a high specificity for the parE gene of F. psychrophilum but not for other related species. parE LAMP detected the gene in a wide range of concentrations from 2.0 x 10(1) to 2.0 x 10(9) copies/reaction within 70 min and revealed a good correlation between threshold times and gene copy number.