levels of infectivity were still detectable after 30 min exposure to 100 ppm of either disinfectant. Treatment with an acid peroxygen disinfectant rapidly reduced virus infectivity in both distilled
water and serum supplemented diluent within 5 min but infectious virus was not totally eliminated even after exposure for 30 min. q 2000 Elsevier Science B.V. All rights reserved.
Keywords: Disinfectant inactivation; Dicentrarchus labrax; Neuropathy nodavirus
1. Introduction
Nodavirus infection characterised by the development of a vacuolating encephalopa- thy and retinopathy with high mortality in larval and juvenile stages of affected fish was
Ž .
first recognised over 10 years ago in hatchery-reared sea bass Dicentrarchus labrax in Ž
. Martinique and the French Mediterranean Breuil et al., 1991 . The disease has since
been recorded in a wide variety of fish species from mariculture sites in Japan, southeast Asia, Australia, the south Pacific and Norway as well as the Mediterranean and is
probably the most serious disease threat to the marine finfish aquaculture industry at the present time.
In the development of effective control and eradication measures against virus diseases of international importance it is essential to establish the susceptibility of the
infectious agent to physical and chemical inactivation agents and evaluate the stability of the nodavirus under differing environmental conditions in order to implement rational
disinfection procedures. Although the virus could be classified as a member of the Nodaviridae following biochemical characterisation of the nucleic acid and structural
Ž .
proteins of virion material obtained directly from sea bass larvae Comps et al., 1994 , Ž
. and Arimoto et al.
1996 were able to assess a range of chemical and physical Ž
. treatments on virus purified directly from infected striped jack Pseudocaranx dentex
larvae, such studies have hitherto been hampered by the lack of an in vitro cell culture Ž
. system for piscine nodaviruses. The recently described snakehead cell line SSN-1
Ž .
culture system for the isolation and propagation of the nodavirus Frerichs et al., 1996 has now greatly facilitated the laboratory characterisation of this agent, and the present
in vitro study evaluates the efficacy of heat treatment, UV irradiation and chemical disinfectants for the inactivation of nodavirus isolated from Mediterranean sea bass and
the stability of the nodavirus under different environmental conditions.
2. Materials and methods
