Abstract: The present invention discloses platforms for chemically modify AAV capsids with control over site and stoichiometry. An AAV packaging system is described that allows the introduction of site-directed natural and unnatural amino acid mutations into any subset of the three capsid proteins. These engineered residues can be subsequently used to chemically functionalize the resulting capsids with precise control over site and stoichiometry. Such controlled modification strategy can be used to attach a wide variety of entities to AAV capsids to engineer its tropism, immunogenicity, etc.

Abstract: The present invention involves the ability to 1) use a virus assisted directed evolution platform to significantly improve the activity of engineered nonsense-suppressor tRNAs in mammalian cells, 2) provide mutants of archaeal pyrrolysyl and E. coli leucyl tRNAs that show remarkably improved Uaa incorporation efficiency in mammalian cells, and 3) use these tRNAs to express recombinant proteins in mammalian cells incorporating Uaas at significantly improved yields.