Pathogenicity Assay of Vibrio harveyi in Tiger Shrimp Larvae Employing Rifampicin-Resistant as A Molecular Marker

Abstract

<p>Rifampicin-resistant marker was employed as a reporter to assay pathogenicity of <em>Vibrio harveyi</em>  in shrimp larvae.  <em>V. harveyi</em> M. G₃ and G₇ that difference not schizotyping as shown by Pulsed-Filed Gel Electrophoresis (PFGE) used in this study. Spontaneous mutation was conducted to generate <em>V. harveyi</em> resistant to rifampicin. Two groups of shrimp post-larvae (PL₅) were immersed for 30 min in 106 CFU/ml of mutants and wild type of <em>V. harveyi</em>, respectively; and then placed in a 2 liter shrimp rearing tank for five days. A control group was immersed in sterile seawater. Growth curve analysis and pathogenicity assay of <em>V. harveyi </em> showed that each of the <em>V. harveyi</em> mutant exhibited almost identical profiles to that of the wild type parental strain and did not show alteration in their pathogenicity. Sample from dead shrimp larvae showed that the dead shrimp larvae were infected by <em>V. harveyi </em>Rf^R, indicated that rifampicin-resistant marker effective as a reporter to assay pathogenicity of <em>Vibrio harveyi </em>in shrimp larvae.</p> <p>Key words: shrimp larvae, <em>Vibrio harveyi</em>, rifampicin-resistant, molecular marker</p>