Aim: The aim of this study was to observe the effect of attenuated Salmonella typhi as a tumor-targeting delivery vector for multidrug-resistance gene (MDR1) small interfering RNA (siRNA). Material and Methods: The cisplatin (DDP)-resistant ovarian cancer cell line SKOV-3/DDPwas established by treatment with gradually increasing concentrations of cisplatin. MDR1 siRNA expression plasmid contai…