Swarming Differentiation of Vibrio vulnificus Downregulates the Expression of the vvhBA Hemolysin Gene via the LuxS Quorum-Sensing System

다국어 초록 (Multilingual Abstract)

Swarming has proven to be a good in vitro model for bacterial surface adherence and
colonization, and the swarming differentiation of a bacterium has been shown to be coupled
with changes in the expression of virulence factors associated with its invasiveness,
particularly in the early stages of infection. In this study, we attempted to determine
whether the expression of vvhA, which encodes for hemolysin/cytolysin (VvhA), is either
upregulated or downregulated during the swarming differentiation of V. vulnificus. The
insertional inactivation of vvhA itself exerted no detectable effect on the expression of V.
vulnificus swarming motility. However, in our lacZ-fused vvhA transcriptional reporter
assay, vvhA expression decreased in swarming V. vulnificus as compared to non-swarming
or planktonic V. vulnificus. The reduced expression of vvhA in swarming V. vulnificus
increased as a result of the deletional inactivation of luxS, a gene associated with
quorum sensing. These results show that vvhA expression in swarming V. vulnificus is
downregulated via the activity of the LuxS quorum-sensing system, suggesting that VvhA
performs no essential role in the invasiveness of V. vulnificus via the adherence to and
colonization on the body surfaces required in the early stages of the infection. However,
VvhA may play a significant role in the pathophysiological deterioration occurring after
swarming V. vulnificus is differentiated into planktonic V. vulnificus.

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