HAIRPIN RIBOZYME GENE THERAPY FOR HCV INFECTION

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Hepatitis C virus (HCV) is the major cause of non-A, non-B hepatitis, which is a serious worldwide health problem. Our long term objective is to develop hairpin Ribozyme (Rz) gene therapy for the treatment of HCV infection. Immusol's Rz core technology, developed as a result of the success of its HIV program, is based upon the ability to engineer and optimize hairpin Rz genes whose transcribed RNAs can specifically degrade almost any undesirable RNA molecule. HCV is especially suited for ribozyme-mediated therapy since the viral genome is present exclusively in the form of RNA. HCV encodes only one primary transcript, thus, cleavage of any target sequence within this RNA should abolish virus expression. Immusol has generated two hairpin ribozymes target at HCV (+) strand RNA as potential therapeutic agents for HCV infection (Gene Therapy, 1996, 3: 994). Immusol also plans to target the negative strand RNA that is an essential intermediate in HCV replication. Degradation of this RNA may be more effective, since its intracellular level is lower than that of the positive strand RNA. Therefore, we propose a Phase I SBIR studies aimed at: 1) to synthesize and optimize effective ribozymes that target HCV positive- (+) and negative- (-) strand RNA; 2) to generate viral vectors (AV and AAV) that express active hairpin ribozymes; and 3) to test vector- derived ribozyme activity in reducing HCV gene expression in liver cell culture Achieving these three Aims will generate the most effective ribozyme viral vector(s) for preclinical studies. PROPOSED COMMERCIAL APPLICATION: Immusol plans to commercially develop a Rz gene therapy approach to HBV infection. We will manufacture and provide Rz-expressing viral vectors in a vial. The vectors will then be provided to medical centers around the world that will carry out the in vivo vector-mediated gene transfer into patient liver cells to combat HBV virus.