Targeted RNases: a feasibility study for use in HIV gene therapy

A targeted RNase would be ideal for gene therapy of several acquired and in herited disorders. Such an RNase may be engineered to contain a ribonucleol ytic domain and a specific target RNA binding domain. To demonstrate the fe asibility of this approach, an RNase targeted against human immunodeficienc y virus (HIV) RNA - Tev-RNase T1 - was designed and tested for its use in H IV-I gene therapy. A human CD4+ T lymphoid (MT4) cell line and human periph eral blood lymphocytes (PBLs) were transduced with retroviral vectors lacki ng or expressing the tevT1 gene. Expression of enzymatically functional Tev -RNase T1 protein and its lack of toxicity was demonstrated I in stable MT4 transductants. Compared with control cells lacking this protein, both tran sduced MT4 cells and PBLs expressing Tev-RNase T1 delayed HIV-1 replication . Tev-RNase TI was shown to act after integration, since HlV-1 proviral DNA could be detected but the amount of HIV-1 RNA produced in MT4 cells and PB Ls was significantly decreased. This study demonstrates the feasibility of a targeted RNase strategy for therapeutic use.