# Mechanism of immune response to muscle-directed AAV gene transfer

> **NIH NIH R01** · INDIANA UNIVERSITY INDIANAPOLIS · 2024 · $759,377

## Abstract

Muscle-directed gene transfer is integral to the treatment of severe muscle degenerative disorders such as
Duchenne muscular dystrophy (DMD). Adeno-associated viral (AAV) vectors represent the most advanced
platform for in vivo gene delivery through intramuscular (IM) injection or systemic delivery to various types of
muscles. A major hurdle for this approach is the potential for immune responses, which may limit the efficacy
and duration of therapy and can also be a source of serious immunotoxicities. Cytotoxic T cell responses against
viral capsid and transgene products and complement activation have been observed in patients. The latter is
likely caused by antibody-capsid complexes that form within days after high-dose systemic delivery. Neutralizing
antibodies (NAb) that form after vector administration persist long-term, tend to be cross-reactive with various
serotypes, and preclude re-administration of the vector. Our most recent collaborative studies in the canine DMD
models illustrate the potential for CD8+ T cell responses against Cas9 nuclease employed in gene editing to
correct muscular dystrophy. It is therefore imperative that we better understand the immune response
mechanisms in AAV muscle gene transfer. To take on this task, we formed a collaborative team that combines
the expertise in basic immune mechanisms of AAV muscle gene transfer with expertise in translational research
in animal models of DMD. Our preliminary studies directly support the hypothesis that innate immune sensing
drives adaptive immunity against the transgene product upon muscle-directed AAV gene transfer, and in
particular CD8+ T cell responses. Depending on vector dose, multiple innate signaling pathways have either
critical or redundant roles. We further hypothesize that vector engineering combined with specific interventions
minimizes deleterious immune responses, thereby preserving therapy. We specifically propose to i) define the
mechanisms that link innate immune sensing to adaptive immune responses in AAV muscle gene transfer; ii)
prevent deleterious immune responses against transduced/gene-edited muscle following systemic AAV vector
delivery, and iii) develop a novel protocol for re-administration of systemic AAV delivery. We will continue to use
a model antigen (ovalbumin) to dissect the response mechanisms in skeletal muscle upon genetic or
pharmacological disruption of these pathways; combine engineering of the vector genome with targeted
interventions; and define the impact of dystrophic muscle on immune responses. We will use our ovalbumin
platform to determine if the mechanisms identified for intramuscular injection also apply to systemic delivery of
liver-detargeted AAV vectors to skeletal muscle. Further, we will evaluate the B and T cell responses against
therapeutic transgene products (micro-dystrophin and Cas9). Finally, we have developed a novel protocol based
on transient antibody-mediated depletion of B cells and the B-cell growth factor ...

## Key facts

- **NIH application ID:** 10844416
- **Project number:** 5R01AI177600-02
- **Recipient organization:** INDIANA UNIVERSITY INDIANAPOLIS
- **Principal Investigator:** Dongsheng Duan
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $759,377
- **Award type:** 5
- **Project period:** 2023-05-19 → 2028-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10844416

## Citation

> US National Institutes of Health, RePORTER application 10844416, Mechanism of immune response to muscle-directed AAV gene transfer (5R01AI177600-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10844416. Licensed CC0.

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