AAV-mediated delivery of humanized anti-ricin antibody enabled by tolerogenic exosomes for repeat dosing and controllable expression

Nucleic acid-encoded antibody passive immunotherapy, facilitated by recombinant adeno-associated virus (AAV) vectors, represents a promising therapeutic approach for combating infectious diseases and biotoxin exposure. In response to ricin intoxication, we developed a single-dose solution to achieve sustained systemic serum levels of protein immunotherapeutics through AAV-mediated gene transfer. We provide proof-of-concept using a ricin exposure model, in which a single intramuscular dose of AAV encoding the humanized Ricin antibody effectively demonstrated long-term protection. This platform presents a versatile and expandable framework for biotoxin defense. To overcome the challenge of carrier immunogenicity that limits vector re-administration, we co-administered AAV vectors with milk-derived exosomes encapsulating rapamycin, successfully preventing the induction of anti-capsid immune responses, which enabled successful vector re-administration in mice. Additionally, we developed an inducible system employing an exon skipping strategy, achieving on-demand, repeated expression of the therapeutic transgene following AAV injection. This platform could be adapted for the short-term or repeated expression of other immunotherapeutic transgenes, with potential applications in the treatment of infectious diseases or tumors.