Using a viral vector system, Strata Biosciences will compare and contrast the relative potentials of expressed hairpin and hammerhead ribozymes, as well as analogous antisense RNAs to selectively inactivate targeted model reporter genes (gene "knock-out" or "knock-down") in cell culture, thereby preventing expression of the selected protein. AAV vectors will be engineered to express ribozymes designed to target one of two reporter genes, the transfected enhanced GFP gene and the native hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene. Recombinant AAV will then be used to infect human cell lines expressing these genes and expression levels of the target proteins will be evaluated. The ultimate goal is to develop this technology to the point where it can be used to eliminate target protein function in human cells to test whether the target protein expression correlates to a particular state (such as a cancerous or transformed phenotype).