PRECLINICAL CHARACTERIZATION OF AN ANTI-TAT RIBOZYME FOR THERAPEUTIC APPLICATION

A hammerhead ribozyme retrovial construct, denoted RRz2, targeting the coding region of the human immunodeficiency virus type 1 (HIV-1) tat gene, has shown itself to be effective in a range of test systems. Inh ibition of the replication of HIV-1 IIIB and primary drug-resistant st rains in pooled transduced CEMT4 cells was consistently found to be mo re than 80% compared with the control-vector transduced cells, whereas a mutant RRz2 gave approximately 45% inhibition. A multiple HIV-X pas sage assay showed the absence of emergence of mutations within the spe cific viral RNA ribozyme target sequences. This lack of generation of ribozyme ''escape mutants'' occurred despite the almost complete disap pearance of a HIV-1 quasi-species in the testing virus. When RRz2 was tesed in peripheral blood lymphocytes (PBLs) from HIV-l-infected patie nts, paired analysis showed that cell viability in the ribozyme-transd uced HIV-1-infected PBLs was significantly higher than that in the vec tor-transduced cells. This difference in viability (vector versus RRz2 ) was not observed in PBLs from non-HIV-l-infected donors. Taken toget her, these results indicate that the transfer of an anti-HIV-l ribozym e gene into human T lymphocytes could have major impact on viral repli cation and T cell viability in the HIV-1-infected individual.