Study of some specific and non-specific immune responses of grass carp (C. idella) to Aeromonas hydrophila and in the present of organophosphate, diazinon

Abstract

Some specific and non-specific immune variables of grass carp against Aeromonas hydropila and in the present of organophosphate, diazinon was studied at 18-20?C. Also, the toxicity of this toxicant was assessed in this species. Isolation and characterization of the fish IgM showed that fish possesses IgM with molecular weight of 480-640 KD having 15-20% of total serum protein. The LC50 96 hours of the toxicant was 15.13 mg/L and the survival fish showed erythropenia, leucopenia and a decrease in levels of blood enzymes, alanine aminotransferase, alkaline phosphatase, lactate dehydrogenase and total protein, while level of glucose increased. When fish were exposed to sublethal concentrations of diazinon (1, 2 and 4 mg/L) for 12 hours large change were then observed in hematological and biochemical variables of blood feaures plus a suppression of chemiluminuscence (CL) response by blood leucocytes during 45 days post-expposure. When fish were intraperitoneally immunized with Aeromonas hydrophila whole cell antigens and exposed to 2 mg/L of diazinon, the immunological responses consisting of lysozyme content, CL response, antibody titre were suppressed during one moth post-exposure. Also, light and electron microscopic examinations of tissues of kidney, liver, gill, spleen and nostril of fish exposed to acute and sublethal concentration of the toxicant revealded remarkable changes including hyperemia, heamorrhage, necrosis, damaging of reticulum endoplasmic of epithelial cells and vacuolation of club cell of nostril, and degeneration of mithochondria in kidney cells, reduction in excretion of amorphous proteinous materials and vesicle numbers on the cell surface and also blocking of cell surface cannals of nostril cells.