Summary - Gene Transfer Properties and Structural Modeling of Human Stem Cell-Derived AAV
The ability of adeno-associated virus (AAV) to establish latency without helper virus coinfection has made AAV useful as a gene therapy vector. In addition, AAV is able to maintain transgene expression in the absence of toxicity in vivo. AAV virus serotypes are abundant and novel genomes from primate tissues continue to be discovered. This has led to the creation of a variety of AAV vectors with wide tissue tropisms. Human bone marrow has been identified as an abundant source of AAV, leading to hypotheses that AAV isolates are present in human CD34+ HSCs (Hematopoietic Stem Cells). Assuming AAV presence in HSCs, AAV capsids might have tropism for CD34+ cells.
Natural AAV variants have now been found in CD34+ human peripheral blood stem cells. CD34+ derived AAV variants possess novel viral capsids unlike other AAV serotypes. AAVHSC vectors transduced long term in …show more content…
Tests were performed using high molecular weight genomic DNA from purified cytokine primed human CD34+ PBSCs from 71 healthy stem cell donors. Approximately 70% of the donors tested positive for endogenous AAV sequences. Evidence indicates that endogenous AAV can be found frequently in CD34+ PBSCs. Furthermore, natural AAV infection of CD34+ cells is not rare. After amplifying full-length capsid genes from 2 PBSC samples (PB0130 and PB021), 18 novel AAV capsids were found sharing significant homology with AAV9 (Clade F), differing only in one to four amino acids. Testing the gene transfer capacities of the aforementioned AAVHSCs involves packaging the AAVHSC capsids with recombinant self-complementary and single stranded AAV2 genomes. Rep function was accomplished using a hybrid AAV2 rep gene. The function of the hybrid rep gene matched that of the true AAV rep