RESUMO
<p><b>OBJECTIVE</b>To explore the mechanism of virulence regulation in group B streptococcus (BGS) by studying LuxS-related AI-2 quorum-sensing pathway in GBS.</p><p><b>METHODS</b>luxS gene deletion mutants of GBS (Delta lusX) were characterized by reverse transcription (RT)-PCR, colony immunoblot analysis, growth curve measurement, and cAMP determination. Functional analysis of luxS in the deletion mutants was conducted by bioluminescence assay.</p><p><b>RESULTS</b>Genetic analysis results showed that the luxS deletion in the mutant 515-Delta lusX caused upregulation of scpB gene expression. Phenotypic analysis revealed that, in comparison with the wild strain, 515-Delta lusX mutant grew slowly in DCM media but quickly in THY media. An approximately two-fold decrement in bioluminescence was detected in the luxS deletion mutants as compared with the wild strain.</p><p><b>CONCLUSION</b>This study confirms the importance of LuxS molecule in the AI-2 quorum-sensing pathway in GBS and provides new insights into the virulence regulation mechanism of GBS.</p>