In vitrolevamisole fails to increase seabream (Sparus aurataL.) phagocyte functions

Groups of rainbow trout received two injections of the T-dependent antigenLimulus polyphemushaemocyanin (LPH) or the T-independent antigenEscherichia colilipopolysaccharide O 111:B4 (E.coliLPS), mixed with either Freundʹs complete adjuvant (FCA), or aVibrio salmonicidabacterin or phosphate buffered saline (PBS). One group that received an injection of PBS served as a negative control for both antigens. The antibody responses againstE. coliLPS and LPH were measured by enzyme linked immunosorbent assays 6, 10 and 14 weeks after the second immunisation. The groups injected withE. coliLPS or LPH in FCA responded with high antibody titers. The groups that receivedE. coliLPS or LPH mixed withV. salmonicidaor PBS, responded with relatively low antibody titers to the antigens. However, the fish injected with LPH andV. salmonicidabacterin responded significantly better to LPH six weeks post immunisation than the fish that received LPH and PBS. Ten and 14 weeks p.i. there were no significant differences between these groups. There was no difference in the response toE. coliLPS between the fish that receivedE. coliLPS mixed withV. salmonicidabacterin and those injected with LPS in PBS neither 6, 10 nor 14 weeks p.i. The results of the present study show that aV. salmonicidabacterin enhances the antibody response to a T-dependent antigen in rainbow trout.