A novel bovine virus efficiently transduces inner ear neuroepithelial cells

Disruption of the cellular composition or arrangement of the sensory epithelia due to hair cell or supporting cell damage leads to hearing loss and vestibular dysfunctions. These peripheral hearing disorders make good targets for gene therapy; however, development requires efficient gene transfer methods for the inner ear. Here we characterized the cellular tropism of a novel adeno-associated bovine virus vector (BAAV) in cultured rat inner ear epithelia. To help identify transduced cells, we used beta-actin-GFP as a reporter gene. We found that BAAV efficiently transduced auditory and vestibular hair cells as well as all types of supporting cells with no apparent pathological effects. The number of transduced hair cells significantly increased in both a dose- and a time-dependent manner. Transduction was independent of the cells' maturation state and was observed in both P2 and P10 cultures. Interestingly, even after several days of incubation with BAAV, hair cells demonstrated varying progression of beta-actin-GFP incorporation into the stereocilia. This suggests that the onset of viral transduction can occur throughout the course of the experiment. Of the other tested AAVs, AAV2 and AAV5 transduced only a small percentage of inner and vestibular hair cells, respectively, whereas no transduction was detected with AAV4.