A rapid purification-free LAMP assay for detection of largemouth Bass Ranavirus using minimally invasive samples

Largemouth Bass Ranavirus (LMBV) causes severe mortality in largemouth bass (Micropterus salmoides), significantly threatening aquaculture sustainability. Conventional PCR-based methods for LMBV detection are resource-intensive, requiring specialized equipment, skilled personnel, and purified DNA samples, thus limiting their practical applications. Here, we established a simplified, purification-free loop-mediated isothermal amplification (LAMP) assay integrated with a portable fluorescence detection device (WeD-1) for rapid and sensitive detection of LMBV. Using an in vitro infection model, we demonstrated that crude lysates from minimally invasive samples, particularly peritoneal fluid, could be directly used in LAMP assays without nucleic acid purification. The entire detection workflow—from sample collection to result interpretation—was completed within 40  minutes (min). This approach provides a sensitive, rapid, and cost-effective diagnostic method for early detection of LMBV and can potentially be extended for rapid detection of other aquatic pathogens.