Objective To construct the prokaryotic expression vector bearing fusion gene NT4-ADNF-9 and lay foundation for further study on genetic therapy of neurosensory deafness. Methods By means of asymmetrical primer/ template,double stranded cDNA of activity dependent neurotrophic factor-9 (ADNF-9) was obtained,which included restriction enzymes sites on the two extremities. ADNF-9 cDNA was ligated to the signal and leader peptides of neurotrophin 4 (NT4),and the fusion gene was named NT4-ADNF-9. Then it was subc...