Abstract: ObjectiveTo study the effects of selenium on the vacolating cytotox in(VacA)and the recombinanted VacA of Helicobacter pylori(Hp).MethodsThe VacAof Hp was purified by salting out,dialysis,gel filtration and concentration.The pET 32a-vacA-E.coli BL21(DE3)bacteria were cultivated and the recombinanted plasmids were analysed by restriction endonuclease.The recombinanted VacAprotein was purified by Ni-TEDTM kit and identified by SDS-PAGE and Western blot.Different concentrations of VacA,recombinanted VacAand selenium(Se)were added into the SGC-7901 cells,then the changes of the cell cycle of SGC-7901 were obser ved by spectrophoto meter,inverted microssope,transmission electron microscope and Flow Cytometry.ResultsThe configuration of Hp was changed by Se(12 mmol/l).The proliferation inhibition of recombinanted VacA on the SGC-7901 cells was streng thened by Se.The percentage of G1 phase cells was increased and of the Sphase cells was decreased by Se.Brickred appeared after Se was added into the E.coli.ConclusionSe can inhibit the proliferation of Hp and decrease the production of VacA,butit fails to inhibit the cellular vacolation effect of VacA.Se can improve the inhibitive effects of the recombinant VacAon the SG C-7901 and decrease the VacAexpression by inhibiting the Hp proliferation.But Se fails to reduce the cellular vacolation of VacA directly.