A decline in production of Puntius sarana worldwide and subsequent intensification of its culture as a measure for conservation and increase food fish production have led to emergence of diseases. Investigations on innate immunological changes in fish that survives an acute
bacterial infection are a few or lacking. An attempt was made to study the detailed changes in innate immune responses in P. sarana following an intraperitoneal challenge with Aeromonas hydrophila at 2.24 × 10(7)colony-forming unit (CFU)/fish. Sequential changes in transcription of immune related genes in liver and kidney, innate immune status, haematological profile and histopathology of major organs were studied after different time intervals post-challenge in the survivors. A significant increase in serum
myeloperoxidase,
ceruloplasmin activities and total leucocyte count, and decline in alternative
complement activity were observed at early
infection periods. A significant decline in plasma
glucose level, total erythrocyte count, haemoglobin content and packed cell volume in blood was noticed after challenge.
Superoxide radical production and serum
antiprotease activity increased significantly at later period of challenge. In addition, few immune related genes pertinent to
acute phase reactants and inflammatory response viz.,
complement component 3 (C3),
lysozyme G,
lysozyme C, β2-microglobulin (B2M),
transferrin,
interleukin 1β,
interleukin 8,
manganese superoxide dismutase (MnSOD), natural killer cell enhancing
factor-B and
chemokine CXCa were modulated after bacterial challenge. In liver, a significant up-regulation of C3 and
transferrin, and down-regulation of
lysozyme G,
interleukin 8, MnSOD and B2M were noticed in survivors. On the contrary,
lysozyme G,
lysozyme C,
interleukin 1β,
interleukin 8, CXCa, and MnSOD were found to be significantly up-regulated and C3 was down-regulated in the kidney. All these data suggest that the innate
immune factors were highly modulated during
infection process to render protection of P. sarana to this bacterium. This study also generated the primary information on many innate immune molecules/genes for this important medium carp species for the first time.