NEO-AAV: an engineered extracellular vesicle-enveloped AAV platform for activation-coupled T cell transduction and CAR-T cell generation

Efficient delivery of genetic cargo to primary human T cells remains a critical barrier for cell-based immunotherapies. AAVs are widely used but limited by immune neutralization and poor T cell transduction efficiency. We present NEO-AAV, an engineered fusion protein (PH–ALG2–PKD12) that recruits AAV capsids into endogenous extracellular vesicles (EVs) via PI(4,5)P2-directed membrane targeting, multivalent PKD12–capsid clustering, and ALG2-mediated ESCRT machinery recruitment, yielding EV-enveloped particles with improved AAV loading compared with passive EV-AAV controls. NEO-AAV displayed enhanced resistance to an anti-AAV6 neutralizing antibody (ADK6), maintaining transduction at concentrations that neutralized naked AAV6 and outperformed passively formed EV-AAV6. Surface display of a CD7/CD3/CD28 tri-chimera enabled single-step activation and transduction of CD7⁺ T cells within PBMCs, reaching ∼38% eGFP⁺ cells without exogenous pre-activation. As a proof-of-concept, NEO-AAV generated functional CAR-T cells from primary human PBMCs, exhibiting antigen-specific IFN-γ release and cytotoxicity against CD19 ⁺ target cells. CAR expression peaked at day 5 and declined by day 15, consistent with episomal AAV kinetics, framing NEO-AAV as an activation-coupled delivery module rather than a durable solution. Together, NEO-AAV provides a programmable EV-enveloped AAV platform with improved immune shielding and single-step T cell transduction, offering a building block for immune cell engineering with in vivo potential.