The General Characteristics of a Birnavirus Isolated from Cultured Loach(Misgurnus anguillicaudatus) in Taiwan

Abstract

A birnavirus was isolated from cultured loach (Misgurnus anguillicaudatus) in Taiwan with TO-2 cell line. Evident cytopathic effects of the virus, including karyopycnosis, cytoplasmic inclusion bodies and cell destruction, were observed in TO-2 cells by light microscopy. The naked icosahedral virion layered by a single capsid with a diameter of 69±4 nm was observed by electron microscopy. Sometimes, complete virions were found to be enclosed by lysosomes to form cytolysome. The virus propagated in several fish cell lines and its replication cycle was completed in 24 hours at its optimum multiplication temperature of 25°C. This virus has a two segmented double-stranded RNA genome and 3 structural proteins, showing 1.33 g/cm3 buoyant density in CsCl. The chemico-physical properties of the virus together with the result of cross neutralization test indicated that it is a birnavirus and is closely related to Ab serotype of infectious pancreatic necrosis virus (IPNV). © 1993, The Japanese Society of Fish Pathology. All rights reserved.