the gene therapy community with a versatile toolkit of AAV vectors. Our goal is to establish a thorough understanding of the structure-function correlates of the diverse tissue tropisms of AAV serotypes. To achieve such, we have devised a comprehensive, two- pronged approach to unravel structural attributes of AAV1-9, while simultaneously exploiting these serotypes as blueprints for novel AAV vector design. The approach exploits the ability of DNA shuffling to rapidly evolve novel phenotypes derived from parental serotypes followed by rational manipulation of novel AAV mutants to establish structural attributes at the amino acid level. The first strategy involves generation of a combinatorial AAV library through DNA shuffling of AAV serotype capsid sequences followed by directed evolution of cell type/receptor-specific mutants. The objective of this approach is to eliminate bias in the identification of so- called hot spots on the AAV capsid that impart a specific phenotype. The second approach is concerned with rational manipulation of such specific regions on AAV serotype capsids using