Background: Rational design of AAV capsids is a simple method for enhancing AAV transduction efficiency.AAV-DJ is a highly recombinogenic hybrid vector created from DNA shuffling of eight AAV serotypes,which mediates efficient gene expression both in vitro and in vivo.AAV2 and AAV8 are the closest parental vectors of AAV-DJ and it has been reported that mutations on the 137/251/503 ubiquitination or phosphorylation sites of the AAV2 or AAV8 capsid lead to dramatic enhancement of gene delivery.