A New Finding and Range Extension of Bacilliform Virus in the Freshwater Red Claw Crayfish in Utah, USA

Abstract

Nuclear pathology of digestive tubules in the hepatopancreas was detected in tissues collected during an inspection of red claw crayfish Cherax quadricarinatus (also known as the tropical blue crayfish) at a farm in the state of Utah, USA. Signs of clinical disease in all age-classes were absent. Foci with hypertrophic, eosinophilic nuclei were detected in tissues from the adult, but the intensity of nuclear abnormalities was low. Histological preparations 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 epithelium in juveniles. Virions had a rod-shaped nucleocapsid surrounded by a loose envelope and a faintly distinct tail-like structure. Mean virion size was 224 ± 14 nm × 74 ± 4 nm, and nucleocapsids measured 180 ± 9 nm × 38 ± 3 nm (mean ± SD). The virus is morphologically similar to the bacilliform virus in C. quadricarinatus reported in Australia and California. The present report documents an extension of the known range of this virus.