RESUMO
Objective To study the impact of QseBC on the motility of Salmonella enterica serovar Typhi ( S.Typhi ) . Methods The motility of wild-type ( WT) and null mutants (ΔqseB and ΔqseC) at mid-log phase was investigated by swimming assay.Quantitative RT-PCR was carried out to calculate the transcriptional variation of flhD and qseB among WT,ΔqseB andΔqseC.QseB overexpressing strain was constructed to compare its motility and flhD expression with the wild-type control.Results The result of motility assay showed that the motility of ΔqseB was similar to that of the WT strain , while the motility of ΔqseC was much lower than that of WT .qRT-PCR revealed that compared with WT , the expression of flhD was significantly decreased in ΔqseC while the expression of qseB was increased considerably .The motility of QseB overex-pressing strain was lower .Conclusion The expression of flhD may be regulated by QseBC which has an effect on the motil-ity of S.typhi, and the overexpression of QseB may inhibit the motility .