| Abstrakt: |
Using a chemiluminescence (CL) test, it had been previously demonstrated that Vibrio pectenicida,which is pathogenic to Pecten maximuslarvae, was able to inhibit completely the CL activity of P. maximushemocytes and partially inhibit those of Crassostrea gigas.Conversely, a Vibriosp. strain, S322, pathogenic to C. gigaslarvae was more active in reducing the CL activity of oyster hemocytes than of scallop hemocytes. Using this same CL biotest, V. pectenicidaand S322 cytoplasmic extracts were shown to reproduce CL inhibition while the cytoplasmic extract of a nonpathogenic strain (U1, Pseudoalteromonas) was without effect. Moreover, cytoplasmic extract as well as live V. pectenicidacells provoked, within a few hours, death of P. maximushemocytes adhering to a glass slide. After partial purification, it was shown that toxic activities of V. pectenicidacytoplasmic extract was due to a toxin, named VHKT (for vibrio hemocyte-killer toxin), which is heat stable, acid and protease resistant, and less than 3 kDa in molecular weight. Attempts to purify VHKT by reverse-phase (C18) HPLC separated activity into the fraction eluted by water at a retention time of 4.02 min. |
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