Design and anti-HIV-1 activity of ribozymes that cleave HIV-1 LTR.

A hairpin ribozyme (HR112) and two hammerhead ribozymes (RZ115 and RZ119) containing a 5'C(UUCG)G3' loop were designed to cleave the long terminal repeat (LTR) of HIV-1. When the ribozyme catalyzed RNA cleavage reaction for a chemically synthesized 19 mer (LTR 19) was measured, the t 1/2 value of LTR 19 mediated by RZ115 was smaller than that of the RZ119 case. Moreover, the transformed CEM cells harboring the gene encoding these ribozymes were challenged with a HIV-1IIIB strain, two ribozymes, HR112 and RZ119 possessed strong anti-HIV-1 activity. However, the anti-HIV-1 activity displayed by RZ115 was weak. On the basis of secondary structure predictions of the RNA transcribed with the gene encoding ribozymes, the secondary structure of the transcribed RNA with RZ115 sequences was observed to be different from those with the other ribozymes. It has been demonstrated that the secondary structures of transcribed RNAs can possibly influence the anti-HIV-1 activity.