A new finding and range extension of bacilliform virus in the freshwater red claw crayfish in Utah, USA

Nuclear pathology of digestive tubules in the hepatopancreas was detected i n tissues collected during an inspection of red claw crayfish Cherax quadri -carinatus (also known as the tropical blue crayfish) at a farm in the stat e of Utah, USA. Signs of clinical disease in all age-classes were absent. F oci with hypertrophic, eosinophilic nuclei were detected in tissues from th e adult, but the intensity of nuclear abnormalities was low. Histological p reparations of hepatopancreas from juveniles showed a greater intensity of nuclear lesions than did preparations of tissues from the adult. Virus was not observed by use of electron microscopy on the adult crayfish; however, rod-shaped virions were detected within nuclei of the hepatopancreatic epit helium in juveniles. Virions had a rod-shaped nucleocapsid surrounded by a loose envelope and a faintly distinct taillike structure. Mean virion size was 224 +/- 14 nm x 74 +/- 4 nm, and nucleocapsids measured 180 +/- 9 nm x 38 +/- 3 nm (mean +/- SD). The virus is morphologically similar to the baci lliform virus in C. quadricarinatus reported in Australia and California. T he present report documents an extension of the known range of this virus.