Objective    To construct the conditionally replicating adenovirus vector Ad-delE1b55kD-shRNA/Survivin-EGFP that can transfects into HT-29 effectually and selectively and contains shRNA targeting to human Survivin gene.     Methods    EGFP gene and shRNA gene were inserted into pAd-delE1b55kD

then pAd-delE1b55kD-shRNA/Survivin-EGFP was obtained. The plasmid and pBHGE3 were cotransfected into HEK-293 cell to obtain the conditionally replicating adenovirus vector Ad-delE1b55kD-shRNA/Survivin-EGFP. Then DNA of the adenovirus vector was extracted and identified. The  transfection efficiency of the vector to HT-29 and LO2 was detected. The expression of Survivin mRNA and protein was detected by RT-PCR and Western blot.     Results    EGFP gene and shRNA gene targeting to human Survivin mRNA were inserted into conditionally replicating adenovirus vector successfully

proven by sequencing. The transfection efficiency to HT-29 of Ad-delE1b55kD-shRNA/Survivin-EGFP was significantly higher than replication defective adenovirus and liposome vector (P0.01). After transfection of Ad-delE1b55kD-shRNA/Survivin-EGFP

mRNA and protein of Survivin gene in HT-29 cells were obviously reduced.     Conclusion    A conditionally replicating adenovirus vector was constructed and identified successfully. It can transfect to HT-29 and silence Survivin effectually and selectively.