Display of Self-Peptide on Adeno-Associated Virus Capsid Decreases Phagocytic Uptake in Vitro.

ABSTRACT

Adeno-associated virus (AAV) vectors are currently investigated as gene transfer agents for the treatment of a variety of diseases. However, activation of the host immune response upon vector administration limits the use of AAV in the clinical setting. To decrease host detection of AAVs, we tested the CD47-based "don't-eat-me" signal in the context of the AAV capsid. We genetically incorporated the bioactive region of CD47, named "self-peptide" (SP), onto the surface of the AAV2 capsid. AAV mutants were structurally and functionally characterized for vector production, SP and linker incorporation into the capsid, transduction efficiency, and phagocytic susceptibility. We demonstrate that utilizing linkers improves the AAV2 capsid's tolerance to SP insertion. Notably, the SP significantly decreases the phagocytic susceptibility of AAV2 in vitro. Collectively, these results suggest that display of the SP motif on the AAV capsid surface can inhibit phagocytosis of the vector in vitrovia the "don't-eat-me" signaling.