Characterization Of Histopathological And Ultrastructural Changes In Myxocyprinus Asiaticus Acutely Infected With Virulent Aeromonas Hydrophila

Aeromonas hydrophila is a common pathogenic bacterium that causes motile Aeromonas septicaemia (MAS), but the pathogenic mechanism of this species remains unclear. In the present study, histological and ultrastructural alterations of the trunk kidney, head kidney, spleen and liver in Myxocyprinus asiaticus experimentally infected with virulent A. hydrophila (vAh) were analysed. Histopathological observations showed damaged endothelial cell, haemolysis, melano-macrophage centre (MMC) response, necrosis, lymphocyte infiltration, vacuolization, concretion and acidophilic degeneration of hepatocytes and erythrocyte atrophy degeneration, etc. Notably, the strategy of MMC response indicated that the spleen plays a dominant role in the immune response. Ultrastructural pathological features of MAS showed collapsed blood capillary, mesangial cell swelling, podocyte hyperplasia, structure destruction of the glomerular filtration device. Severely damaged Disse space of liver, disappeared glycogen, swelling mitochondria, increased autophagic lysosomes in hepatocytes were also observed in infected juveniles. In conclusion, these results indicated that vAh infection would lead to serious pathological changes in tissues, which maybe in turn results in death from anoxia, energy shortage and metabolic waste accumulation. But meanwhile, MMC played an important role in immune response, which could represent a new tool for diagnosis of MAS and for gaining novel insight into some aspects of disease pathogenesis.