470. New Insights into rAAV Integration Mechanisms by Targeted Enrichment Sequencing

Comprehensive analysis of deep sequencing data originating from the newly introduced Targeted Enrichment Sequencing (TES) indicates so far undescribed recombinations within the Inverted Terminal Repeats of recombinant Adeno-Associated Viruses (rAAVs). For the detection of vector integration sites into the host genome we routinely apply LAM-PCR. However, TES, in which we enrich for genomic regions that include vector sequences, has major advantages over LAM-PCR, as it neither depends on the existence of a vector-specific primer binding site (often lost during rAAV integration) nor on a restriction site in the vicinity of the vector insertion site. Furthermore, regions that are captured together with the vector allow for relative quantification of vector copies per genome. As the entire vector can be sequenced by TES, mutations within the vector and transgene can be detected. In summary, we here provide new and so far unpublished information about rAAV integration patterns and show how we optimized TES to become an important complementary tool to primer-based approaches (like LAM-PCR) for mapping of vector/viral integration sites.