| Popis: |
Adeno-associated virus (AAV) is a small, non-pathogenic virus, exploited as a vector for gene therapy applications, with many successful clinical trials. However, these vectors are based on human and non-human primate AAVs, to which there exists pre-existing immunity in the general population. We hypothesized AAVs having low seroprevalence in the human population can be isolated from alternate sources and can be an alternative to those used in current clinical trials. We also hypothesized that the close homology between pig and human tissues suggests that AAVs isolated from pigs would be able to transduce human cells efficiently. Porcine-derived AAVs preferred specific tissue targets when injected in vivo in mice and successfully transduced cells derived from humans. Immune responses generated against the AAV capsid are also important for determining the safety profile of the vectors; there still exists the possibility of the host mounting adverse immune responses against transduced cells, as seen in some of clinical trials. Although the transduction efficiency of AAV gene transfer has been extensively studied in animal models, the host’s immune response towards the gene product is still poorly understood. This thesis addresses the issue by providing a link between protective efficacy against lethal challenge and tissue tropism. Here, AAVs carrying an immunogenic transgene were developed, with the goal to identify those that can protect against lethal challenge of avian flu or Ebola virus in mice, and those that had poor protective efficacy. It was observed that the protective efficacy afforded by an AAV was serotype specific. The protective efficacy and immune responses were compared to the biodistribution and cellular targets of each AAV. Overall, AAVs sharing broad tropism in biodistribution studies had a tendency to protect mice against lethal challenge than those AAVs not found systemically. As well, those AAVs eliciting protective efficacy against lethal challenge were able to transduce antigen-presenting cells including dendritic and B cells. The link between tissue tropism and host immune responses has been poorly understood and this thesis contributes to the AAV field by highlighting the significance of the cellular targets of AAV and this relationship to protective efficacy. |
