Characteristics of a Previously Unidentified Virus from Channel Catfish (Ictalurus punctatus)

Abstract

A virus (strain F82-34) was isolated from channel catfish (Ictalurus punctatus) that was clearly distinct from channel catfish virus (CCV). The virus induced extensive syncytia in channel catfish ovary (CCO) cells incubated at 26 °C. The BB and CHSE-214 cell lines supported virus replication but the FHM line was refractory. Virus replication was optimal at 25 °C where, after 96 h, approximately 50% of the virus was found to be released from CCO cells. Virus infectivity was stable for 1 mo at4, 16, and 23 °C and for 5 mo at −20 and −8Q °C but was lost after 7 d at45 °C. Partially purified virions are double-shelled hexagonal capsids characteristic of reoviruses and have an average diameter of 75 nm. F82-34 was related to but distinct from two other reoviruses from fish in neutralization studies; these three viruses, and possibly a fourth from American oysters (Crassostrea virginica), appear to represent a new taxonomic group within the family Reoviridae. We therefore propose that this new virus be tentatively designated catfish reovirus (CRV).