Role of histone modifications in the life cycle of AAV2 and recombinant AAV-mediated transgene expression

Adeno-associated virus (AAV) is a preferred vector for gene therapy. However, large doses are needed to achieve therapeutic effect. Due to similarities of rAAV gene expression to the latent phase of wild type AAV, where transcription is inhibited, a possible explanation for the low biological bioactivity is gene silencing of the recombinant vector. Several studies show episome formation and chromatization in both wild type and recombinant AAV. Previous research in our lab demonstrated that trimethylation of histone H3 Lysine 9 must be overcome in order for AAV2 to replicate. This raises the possibility that epigenetic phenomena potentially affect rAAV expression. In order to understand the epigenetic regulations of the AAV life cycle, this project will study histone modifications on wildtype AAV. A potential candidate to induce these histone modifications is cellular transcription co-factor HCF-1, which was identified as part of the virus-host interactome of AAV. The role of HCF-1 within the AAV life cycle will be determined. These studies will be extended to include various recombinant AAV vectors to investigate how histone modifications influence AAV-mediated transgene expression. This will allow the design of AAV gene therapy vectors that are less susceptible to histone modifications that reduce transgene expression.