Effective inactivation of Edwardsiella tarda for the development of vaccine for fish

Abstract

To find out adequate inactivator in substitution for the high concentration of formalin, different organic and inorganic chemicals, heat and chemicals combined with heat were tested for the inactivation of a fish-pathogenic bacterium Edwardsiella tarda strain. The survivality, sustainability of the cell surface antigenicity, bacterial protein and the total cell antigens of E. tarda were determined after treated with those inactivators. A major antigen at 37 kDa was detected by Sodium Dodecyl Sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE) and Western blot analysis. Formalin (0.1%) with heat (71 C×10 min) and 0.9% citric acid killed E. tarda resulted moderate killing activity with enough antigen-sustainability. This study suggests that formalin (0.1 %) combined with heat (70°C×10 min) and citric acid (0.9%) killed E. tarda as a new vaccine candidate. © 2009 Asian Network for Scientific Information.