ALTERATIONS IN TOTAL PROTEIN, IGM AND SPECIFIC ANTIBODY-ACTIVITY OF MALE AND FEMALE SEA BASS (DICENTRARCHUS-LABRAX L, 1758) SERA FOLLOWING INJECTION WITH KILLED VIBRIO-ANGUILLARUM

The relationship between the levels of total proteins, immunoglobulins and antibody activity in serum of sea bass broodstock, following one or two intraperitoneal injections of heat-killed Vibrio anguillarum (V 1), was studied over a period of 10 months. Determination of immunoglo bulin (IgM) level was carried out using a double monoclonal antibody s andwich ELISA and the specific antibody activity to V1 (AbV1) quantifi ed by indirect ELISA. IgM level decreased during the first month post- immunisation (p.i.), but persisted at a high level from the third mont h until the eighth month p.i. in injected fish and until the tenth mon th p.i. in boosted fish. AbV1 level increased after 2 weeks and remain ed elevated for longer than 10 months p.i. Neither the IgM nor the AbV 1 levels of control fish were changed following an injection of phosph ate-buffered saline. The V1 injection did not modify the protein level , but alteration of protein levels over time differed between males an d females. Moreover IgM production was significantly higher, but no si gnificant difference was found between males and females in AbV1 produ ction. The decrease of IgM level after injection may be explained by c onsumption of IgM, with paratopes close to the injected antigen epitop e, which are mobilised to compensate for the lack of the specific anti bodies. This early decrease is likely to be an adaptation rather than a deficiency of the immune system. (C) 1997 Academic Press Limited.