Efficient generation and amplification of high-capacity adeno-associated virus/adenovirus hybrid vectors.
Effective gene therapy is dependent on safe gene delivery vehicles that can achieve efficient transduction and sustained transgene expression. We are developing a hybrid viral vector system that combines in a single particle the large cloning capacity and efficient cell cycle-independent nuclear gene delivery of adenovirus (Ad) vectors with the long-term transgene expression and lack of viral genes of adeno-associated virus (AAV) vectors. The strategy being pursued relies on coupling the AAV DNA replication mechanism to the Ad encapsidation process through packaging of AAV-dependent replicative intermediates provided with Ad packaging elements into Ad capsids. The generation of these high-capacity AAV/Ad hybrid vectors takes place in Ad early region 1 (E1)-expressing cells and requires an Ad vector with E1 deleted to complement in trans both AAV helper functions and Ad structural proteins. The dependence on a replicating helper Ad vector leads to the contamination of AAV/Ad hybrid vector preparations with a large excess of helper Ad particles. This renders the further propagation and ultimate use of these gene delivery vehicles very difficult. Here, we show that Cre/loxP-mediated genetic selection against the packaging of helper Ad DNA can reduce helper Ad vector contamination by 99.98% without compromising hybrid vector rescue. This allowed amplification of high-capacity AAV/Ad hybrid vectors to high titers in a single round of propagation.
D000256:Adenoviridae / Q000235:genetics*; D017498:Adenovirus E1 Proteins / Q000235:genetics; D002461:Cell Line, Transformed; D000229:Dependovirus / Q000235:genetics*; D005822:Genetic Vectors / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D011995:Recombination, Genetic
D017498:Adenovirus E1 Proteins