Objective   To observe the effect of a Chinese Helicobacter pylori (Hp) iceA mutant strain on growth of gastric epithelial SGC7901 cells in vitro and study the iceA-related cytotoxicity.  Methods Morphological changes of cells were observed and compared after the wild or mutant strains of Hp were co-cultured for 48 h. Cell proliferation was detected and analyzed by methyl thiazoly1 tetrazolium (MTT) assay when the cells were co-cultured for 12-36 h. Cell cycle and apoptosis of SGC7901 cells were determined by flow

cytometry when the cells were co-cultured for 24 and 48h

respectively.  Results   The  morphological changes of cells were similar in wild and mutant strains groups. The cell proliferation was significantly different among different groups after the cells were co-cultured for 30 and 36 h

respectively （P0.05). The cell proliferation activity was significantly higher in mutant strain group （0.745±0.006）than in wild strain group（0.728±0.017）when the cells were co-cultured for 30 h（P0.05). The cell cycle was arrested at G

2

phase and S phase in wild strain group and mutant strain group

respectively. Significant apoptosis was observed both in wild strain group(33.04%±10.69%

52.28%±3.41%) and in mutant strain group(44.23%±11.34%

57.32%±0.88%) when the cells were cultured for 24 h and 48 h

respectively (P0.05). However

no significant difference was found in the ability of the two strains to induce apoptosis (P0.05).  Conclusion   Hp can significantly affect the growth of SGC7901 cells. The mutant of iceA gene has no important effect on the morphological changes and apoptosis of SGC7901 cells but can significantly affect their proliferation and cell cycle.