The invention provides a self-processing RNA expression cassette which includes at least one pair of processing units, an RNAi effecter sequence of predetermined length that regulates target gene expression which is flanked by said pair of processing units; and at least one pair of cognate ribozyme cis-cleavage target sites located 5' and 3' of the RNAi effecter sequence. The self-processing RNA expression cassette is able to express in vivo and in vitro and the RNAi effecter sequence includes at least one target recognition sequence derived from the Hepatitis B Virus (HBV) X gene (HBx).
