The Thai Journal of Veterinary Medicine


Immune response of Lion’s paw scallop Nodipecten subnodosus to the challenge of Vibrio alginolyticus strainAPSA2 was studied through the characterization of the activity of lysosomal enzymes and hemocyte size andnumber. Samples were obtained as hemocyte lysate supernatant (HLS) and plasma, after 6 and 24 hours, and 3, 6, and10 days after challenge. The enzymatic activity was tested by colorimetric and lysoplate assay techniques. Betweensampling times, significant differences in enzymatic activity determined by the colorimetric technique were found.The enzymatic activity was significantly higher in HLS than in plasma; in addition more enzymes were detected inHLS as compared with plasma. The enzymes with higher activity were leucyl arylamidase and esterase in both, HLSand plasma. Lysozyme-like activity did not show significant differences between the sampling times. However, inplasma the lysozyme-like activity was significantly higher than in HLS, suggesting that lysozyme was released fromhemocytes into plasma as a first response to the challenge. A significantly negative correlation was found betweenprotein concentration in plasma and in HLS. Based on the findings reported here, we can affirm that hemocytes andlysosomal enzymes are two of the mechanisms that this species has to fight bacterial attacks.

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