557. Impact of the Integrity of the ITRs on the Production of rAAV Vectors

The Adeno-Associated Virusu0027s (AAV) Inverted Terminal Repeats (ITRs) are key features of the AAV. ITRs are implied in the replication, encapsidation of the AAV genome, along with its integration in the host genome and its excision. These sequences are the only AAV DNA sequences conserved in the recombinant AAV as they allow its replication, encapsidation and long-term maintenance in the host non-dividing target cells. The ITRs are highly GC rich and structured due to the presence of repetitive palindromic sequences.During its replication, the AAV is able to reconstitute incomplete or imperfect ITR sequences. Thus it is often found that rAAV genomes cloned into the backbones of the DNA plasmids used for production, have imperfect ITRs sequences which are shortened or contain mutations.In this work, we study the impact of those imperfect ITRs and their impact on the levels of encapsidated rAAV genomes and cellular/baculovirus contaminating DNA sequences, in the baculovirus/Sf9 cells production system.