Elastin‐Like Polypeptides Facilitate Adeno‐Associated Virus Transduction in the Presence of Pre‐Existing Neutralizing Antibodies

Adeno-associated virus (AAV) is successfully developed as a major gene therapy vector, but it is still susceptible to a significant delivery limitation specifically when the vector encounters neutralizing antibodies from a pre-existing immune response or at readministration. Here thermoresponsive polymer elastin-like polypeptides (ELPs) are utilized to crosslink with AAV serotypes 2, 8, and 9 and polyplex AAV vectors are formed by creating a shield of nonviral polymer around them in nanoscale. Neutralizing antibody (NAb) assays are performed which reveal that ELP-AAV nanoparticles significantly improve expression at high NAb titers for AAV 2 and 9. The ELP-AAV nanoparticles are stable for an extended period in neutralizing serum and ELP appears to follow the AAV capsid during uncoating and degradation. No toxicity is found after subretinal, intramuscular, and retro-orbital injections of ELP-AAV. After passive transfer of human NAbs in vivo, ELP-AAV significantly increases transduction at a low systemic AAV dose (1012 vg kg−1) in mice compared to free AAV. In an in vivo readministration paradigm, ELP-AAV significantly improves the reporter gene expression compared to free AAV and does not change the AAV tropism. This method has strong potential to overcome the AAV-associated neutralizing antibody response in gene therapy without redesigning the AAV virion.