This proposal is an unsolicited submission. The goal of the research is to apply directed evolution and diversity approaches to address two major problems in gene delivery: (1) targeting delivery to specific cells, in this case CD34+ hematopoietic stem cells, and (2) targeted viral integration into specific loci of the human genome. The results will enhance the efficacy and safety of therapeutic gene delivery as well as yield fundamental insights into mechanisms of viral infection. Directed evolution emulates the process of natural evolution, in which large numbers of diverse variants, or mutants, are generated and screened for desired properties. Since it explores a vast number of possible solutions to a problem, it proves effective even in the absence of the detailed mechanistic knowledge necessary to rationally predict and design variants that can successfully achieve a specific goal. Importantly, the examination of the resulting successful variants can greatly enhance understanding of mechanism and open the possibility of further refinement by rational design.
