Objective:To investigate whether expression of MxA gene could be enhanced by intravenous injection of gene and contrast agent with ultrasound wave irradiation in mice liver and to investigate the effects of different ultrasound parameters on gene expression.Methods:(1) Effect of different methods on transfection efficiency:24 Kunming mice were randomly divided into 4 groups as plasmid group

plasmid and microbubble group

ultrasound and plasmid group

and plasmid

ultrasound and microbubble group.After 7 days

the lungs

hearts

spleens

kidneys

lungs and skeletal muscles were harvested and half quantization of MxA protein was detected with immunofluorescence technique.(2) Effects of different parameters on gene expression:20 Kunming mice were randomly divided into 4 groups as 0.25 W/cm2 group

0.5 W/cm2 group

0.75 W/cm2 group and 1.0 W/cm2 group according to different ultrasound parameters.After 7 days

liver tissues were harvested for the half quantization of MxA by the same method described above.Results:(1) Number of liver cells with positive expression was the highest in plasmid

ultrasound and microbubble group

followed by ultrasound and plasmid group

plasmid and microbubble group

and plasmid group in order;There was significant statistical difference between either two groups(P<0.001).Positive expression of MxA was found in few spleen cells of plasmid

ultrasound and microbubble group while MxA positive expression cells were only found in livers of rest groups.(2) Number of liver cells with positive expression was the highest in 0.5W/cm2 group

followed by 0.75 W/cm2 group

1.0 W/cm2 and 0.25 W/cm2 group in order;There was significant statistical difference between either two groups(P<0.001).Conclusion:Local expression of exogenous MxA gene in mice liver could be significantly enhanced by ultrasound and microbubble destruction technique.In a certain range

expression of human MxA gene in mice liver can be enhanced with increased intensity of sound.Transfection efficiency was the highest with the intensity as 0.5W/cm2.The method may provide a safe and effective transfection method for genetic therapy of liver diseases.