High Expression And Therapeutic Efficiency Of Systemic Delivery Of A Dual Aav Strategy In A Murine Model For Dysferlin Deficiencies

Recombinant AAV (rAAV) is currently the best vector for gene delivery into the skeletal muscle. However, the 5-kb packaging capacity of this virus is a major obstacle for large gene transfer. This past decade, many different strategies were developed to circumvent this issue (concatemerization-splicing, overlapping vectors, hybrid dual or fragmented AAV). In this study, we compared large gene transfer techniques to deliver the DYSF gene into the skeletal muscle. Loss of function mutations in the DYSF gene whose coding sequence is 6.2 kb lead to progressive muscular dystrophies (LGMD2B, MM; DMAT). After rAAV8 intramuscular injection into dysferlin deficient mice of vectors corresponding to all existing strategies, we showed that the overlap strategy was the most effective approach to reconstitute a full-length messenger. After systemic administration, the level of dysferlin obtained on different muscles corresponded from 0.5 to 2 fold compared to the normal level. We further demonstrated that the overlapping vector set was efficient to correct the histopathology, resistance to eccentric contractions and whole body force in the dysferlin deficient mice up to one year after injection. Altogether, these data indicate that using overlapping vectors could be a promising approach for a potential clinical treatment of dysferlinopathies.