Genetic diversity between two Vibrio anguillarum strains exhibiting different virulence by suppression subtractive hybridization.

Objective And Methods: Vibrio anguillarum, a halophilic Gram-negative bacterium, is the causative agent of vibriosis in fish. V. anguillarum strain VIB72 was defined as having high virulence whereas strain CW1 was defined as having low virulence on the basis of their different LD50 values to zebra fish. Suppression subtractive hybridization (SSH) was used to identify genetic differences between these two strains.

Results: After screening, 59 subtracted library clones were isolated which were specific for strain VIB72, and the DNA sequences of these clones were determined. Seventeen fragments showed high homology to the genes of known functions in other bacteria. This includes soluble lytic murein transglycosylase, mobilization protein (MobA, MobC), transposase (IS66), resistance-related protein (metallo-beta-lactamase and acetyltransferase family), toxin protein (DT-201 and alveicin A immunity protein), ATP-dependent endonuclease of OLD family like protein, SocE and GTP-binding protein HflX (high frequency of lysogenization). These fragments may represent parts of putative pathogenicity islands (PAIs) in V. anguillarum. The remaining fragments showed no significant homology to any known genes.

Conclusion: The results indicated that SSH was successful in identifying genetic differences and putative virulence genes among different strains of V. anguillarum.