Fluorochrome Uvitex 2b stain for detection of the microsporidian causing beko disease of yellowtail and goldstriped amberjack juveniles

Abstract

The fluorochrome Uvitex 2B [4,4-BIS(2-di(2-hyroxyethyl)-amino-4-(3-sulfophenylamino)-1,3,5-triazine-6- ylamino)-stilbene-2,2-disulfonic acid, sodium salt] stain was used for detection of Microsporidium seriolae (Protozoa: Microspora), the causative agent of beko disease of yellowtail Seriola quinqueradiata and goldstriped amberjack S. lalandi juveniles. For detection of the parasite, microscopical fluorescence examination for spores in the Uvitex 2B-stained smears of trunk muscle homogenates was much more sensitive than the conventional visual inspection for "cysts" in the trunk muscle. The Uvitex 2B-H & E stain of deparaffinized sections was applicable to the examination for the sporulation sequence in "cysts" and spore dispersal into adjacent tissues or other organs. Thus, Uvitex 2B stain was found to be useful not only for a rapid and sensitive diagnosis of beko disease but also for histopathological studies of microsporidian infections.