Membrane fusion FerA domains enhance adeno-associated virus vector transduction.

The recombinant adeno-associated virus (rAAV) vector has been successfully employed in clinical trials for patients with blindness and bleeding diseases as well as neuromuscular disorders. To date, it remains a major challenge to achieve higher transduction efficiency with a lower dose of rAAV vector. Our previous studies have demonstrated that serum proteins are able to directly interact with AAV virions for transduction enhancement. Herein, we explored the effect of the FerA domains, which are derived from ferlin proteins and possess membrane-fusion activity, on AAV transduction. Our results show that FerA domains from dysferlin, myoferlin, and otoferlin proteins are able to directly interact with AAV vectors and enhance AAV transduction in vitro and in mice through either intravenous or intramuscular injections. The enhanced AAV transduction induced by human/mouse FerA domains is achieved in various cell lines and in mice regardless of AAV serotypes. Mechanism studies demonstrated that the FerA domains could effectively enhance the ability of AAV vectors to bind to target cells and cross the vascular barrier. Additionally, FerA domains slow down the blood clearance of AAV. Systemic administration of AAV8/hFIX-FerA complex induced approximate 4-fold more human coagulation factor IX expression and improved hemostasis in hemophilia B mice than that of AAV8/hFIX. Collectively, we show, for the first time, that multiple FerA domains could be tethered on the AAV capsid and enhance widespread tissue distribution in an AAV serotypes-independent manner. This approach therefore holds a promise for future clinical application.