Taura syndrome of marine penaeid shrimp: characterization of the viral agent.

The causative agent of Taura syndrome (TS) was recognized in 1994 to be viral in nature and tentatively classified as belonging to either the family Picornaviridae or Nodaviridae. The work reported here has led to a more definitive classification of this new penaeid virus. Located within the cytoplasm of infected cuticular epithelial cells of penaeid shrimp, the virus is a 31 to 32 nm icosahedral particle with a buoyant density of 1.338+/-0.001 g/ml. Three major (55, 40 and 24 kDa) and one minor (58 kDa) polypeptides constitute its proteinic capsid. Its genome contains a single molecule of ssRNA, which is polyadenylated at the 3' end and approximately 9 kb in length. Based on these characteristics, we believe that TS virus should be included in the family Picornaviridae. Ecuadorian and Hawaiian TS virus isolates were found to be identical in their biophysical, biochemical and biological characteristics, and should be considered as the same virus.