Characterization, pathogenicity and neutralization studies of a nervous necrosis virus isolated from grouper, Epinephelus tauvina, in Singapore

A virus isolated from diseased marine fish, Grouper, Epinephelus tauvina, was cultured in sea bass (SB) cell line, characterized and its pathogenicity and neutralization studies were carried out. This isolated virus is an icosahedral virus with a mean diameter of 28-30 nm and has buoyant density of 1.30-1.35 g/ml. It replicates exclusively in the cytoplasm and forms paracrystalline array and inclusion bodies in the infected cells. SDS-PAGE analysis of purified virus structural proteins resolved one major polypeptide of approximately 42 kDa. This virus induces cytopathic effects such as rounding and granulation of cells, localized cell death and detachment of cells within 3-5 days postinfection on sea bass larval cell line. Typical histopathological changes in the virus-infected sea bass larvae under experimental conditions showed vacuolation of nervous tissue. Polyclonal antisera raised against the purified virus and the coat protein of this virus effectively neutralized virus infectivity in vitro suggesting the use of coat protein as a vaccine against this viral infection. (C) 2002 Elsevier Science B.V All rights reserved.