Non specific immune parameters and resistance to Aeromonas Hydrophila infection in the asian dwarf cat fish (mystus vittatus, bloch 1974)

The present study investigates non specific immune parameters against Aeromonas hydrophila infection in the Asian dwarf catfish (Mystus vittatus). The infectious bacterial culture broth was made with PBS at varied concentrations (10³, 10⁵, 10⁸ cells/ml) and was injected to the fish intraperitoneally (200μl/fish) at room temperature. All the experimental tanks (10³, 10⁵, 10⁸ cells/ml) were monitored for symptoms of infection after every twelve hours of immersion of Aeromonas hydrophila including control tank for the LD50 concentration. Clinically-infected cat fishes exhibit hemorrhages at the base of fins, erosion of the pectoral fins, ulcers on the skin surface and septicemia after 72 hours of infection. Before infection, cell counts of all the experimental animals were approximately similar. Total WBC count was very high on 72 hrs after infection in B group. The plasma lysozyme activities of fishes infected with A. hydrophila of all concentration were increased gradually after 24 hrs and 48 hrs. We examined the effect of A. hydrophila infection on the oxidative burst capacity (NBT assay) of neutrophils from Asian dwarf catfish. Infection was induced by injection and sampling occurred at 24, 48, 72 and 96 hours. The number of circulating neutrophils per ml of blood increased after infection when compared with control, and as concentration of pathogen A. hydrophila was increased, the activities were also increased gradually.