488. Adeno-Associated Viral Serotype 2/1 Is a Highly Efficient Vector for In Utero Gene Transfer to Hair Cell Precursors

Abstract

Gene transfer during gestational development represents a promising gene therapy strategy for correction of congenital developmental anomalies. Congenital hearing deficits may one day be treated in this manner as gene transfer to precursor hair cells may prove to be a highly efficient means of generating transgene expression in a high percentage of mature hair cells. Through exo-utero and transuterine microsurgical approaches, we tested delivery of lentivirus and an array of recombinant adeno-associated viral serotypes (rAAV) expressing enhanced green fluorescent protein (eGFP) to the E11-12.5 developing mouse otocyst. We examined the ability of these viral vectors to successfully infect hair cell precursors and to express eGFP by post-natal day 0 (P0). We noted successful infection of hair cells and eGFP expression from lentivirus, AAV 2/1 and AAV 2/8. We then studied the longer term expression of these viral vectors and found AAV 2/1 to be a highly efficient vector for transduction of both inner and outer hair cells. The hearing thresholds of mice injected with these viral vectors were tested by ABR response and with the exception of the lentivirus injected group, were found to be unchanged from uninjected controls. Thus, in utero microinjection of rAAV, especially AAV 2/1, into the developing mouse otocyst represents an exciting and highly efficient new approach to gene delivery to murine hair cells.