Comparative proteomics of two Vibrio anguillarum serotype O1 strains with different virulence phenotypes.

Vibrio anguillarum is part of the natural flora in the aquatic habitat, but under certain circumstances it can cause terminal hemorrhagic septicemia in marine fish due to the action of virulence-associated proteins. In our study, V. anguillarum MN and 3010 were identified as serotype O1 by AFLP analysis, and the virulence of V. anguillarum MN was shown 50-fold higher than that of the strain 3101 by LD(50) tests with Japanese flounder Paralichthys olivaceus. Nine spots were noted as differentially expressed proteins by comparing the cellular and extracellular protein profiles of V. anguillarum MN and 3101. Mass spectrometry results showed OmpU and PrtV were highly expressed in the virulent strain MN but lowly expressed in the less virulent strain 3101. Expression level confirmed by semiquantitative RT-PCR showed that ompU and prtV were indeed highly expressed in the virulent strain MN. Together with similar amino acid sequences of both OmpU and PrtV in V. anguillarum MN and 3101, our study indicated that the expression level of OmpU and PrtV may be associated with the virulence of V. anguillarum.