DETECTION OF SERUM ANTIBODIES AGAINST NODAVIRUS IN WILD AND FARMED ADULT SEA BASS: APPLICATION TO THE SCREENING OF BROODSTOCK IN SEA BASS HATCHERIES
G. Breuil, J.F. Pepin, J. Castric, C. Fauvel, R. Thiery-2000
Bulletin of the European Association of Fish Pathologists, 20(3): 95-100
Abstract:
Antibodies to nodavirus were detected by ELISA in the serum of adult sea bass. Preliminary epidemiological analysis revealed no significant differences between wild (17% seropositive fish) and farmed reared (18% seropositive) adult fish in Palavas-les-Flots, France. A higher proportion of seropositive fish was found in farmed reared females (16%) compared to the males (3%). Furthermore, 30 fish were separated in two groups (seronegative and seropositive) with regard to their serological results following three successive analyses at 2 months intervals. All fish have been individually tested for two years at 2 months intervals. No fish belonging to the seronegative group have developed nodavirus antibodies for 2 years, and all the samples tested, ovarian biopsies, sperm, eggs and larvae have been found virus negative. The seropositive fish have remained seropositive for 2 years and developed a lower serum antibody level during winter. These observations suggest that the screening of the broodstock by repeated ELISA detection of the nodavirus antibodies could be a valuable method for the detection of seronegative fish. For optimal results in the sea bass, the broodstock should be screened during summer prior to the maturation period of the females. This method should also be used in conjunction with the antigen detection in ovarian biopsies.
(IFREMER, Laboratoire de Recherche Aquacole, Chemin de Maguelone 34250, Palavas-les-Flots, France)