Sequence specific cleavage of the HIV-1 coreceptor CCR5 gene by a hammer-head ribozyme and a DNA-enzyme: Inhibition of the coreceptor function by DNA-enzyme

The chemokine receptor CCR5 is used as a major coreceptor for fusion and entry by non-syncytia inducing macrophage tropic isolates of HIV-1, which is mainly involved in transmission. Individuals who are homozygous for the Delta 32 allele of CCR5 are usually resistant to HIV-I infection and continue to lead a normal healthy life, Thus this gene is dispensable and is, therefore, an attractive target in the host cell for interfering specifically with the virus-host interaction. With the aim to develop a specific antiviral approach at the molecular level, we have synthesized a hammer-bead ribozyme and a DNA-enzyme. Both ribozyme and DNA-enzyme cleaved the CCR5 RNA in a sequence specific manner. This cleavage was protein independent hut Mg2+ dependent. The extent of cleavage increased with increasing concentration of magnesium chloride. DNA-enzyme was more effective in cleaving a full length (1376 bases) in vitro generated transcript of CCR5 gene. In this communication, we show that the DNA-enzyme when introduced into a mammalian cell, results in decreased CD4-CCR5-gp160 mediated fusion of cell membranes, Potential applications of these rr ans acting molecules are discussed. (C) 1998 Federation of European Biochemical Societies.