为探索控制水稻条纹叶枯病毒（Ｒｉｃｅｓｔｒｉｐｅｖｉｒｕｓ，ＲＳＶ）设计合成了特异切割该病毒ＲＮＡ保守区及编码病害特异性蛋白（ＤｉｓｅａｓｅＳｐｅｃｉｆｉｃＰｒｏｔｅｉｎ，ＤＳＰ）基因的核酶，核酶基因的长度均为４０个碱基，用化学合成方法合成其正链及与其３＇－末端互补的１５个碱基引物，用ＴａｇＤＮＡ多聚酶合成其互补链。双链ＤＮＡ直接插入克隆载体ＰＧＥＭ３ｚｆ（＋）的Ｓｍａｌ位点。序列测定表明，克隆得到的核酶序列与设计的核酶序列完全一致。经ＳＰ６ＲＮＡ多聚酶体外转录得到核酶ＲＮＡ。当核酶ＲＮＡ与以同样方法转录得到的靶基因ＲＮＡ混合反应，可得到预期结果相同的切割片段，表明两种核酶在体外均具有特异性切割活性。

Rice stripe virus(RSV)genome is composed of four ssRNA species. The 5'-and 3'-terminal sequences of about 20 bases of each ssRNA were almost completely complementary to each otherand the 5'-terminal sequences of all four ssRNA have the some sequence of 11 nucleotides.Thoseconserved sequences were proposed to be involved in the replication,transcription or assembly ofRNAs into the particle.If those sequences are cleaved the virus would be lack of recognition sitesso that its reproduction will be destroyed.On the other hand,the diseasespecific protein (DSP)is related to the disease severity. Inhibition of its expression may reduce the disease severity.Basedon those considerations and the structure requirements of the hammer-head ribozymes,two ri-bozymes were designed,one was to cleave the conserved region of the 5'-terminal of the viral se-quence of RNA 4 or even all the regions of the 5'-terminals of the eight viral and viral complemen-tary sequences of the virus,and the another to cleave the DSP gene region.