Figure 1.

Overview of the ABCA4 dual transgene system. The genetic elements of a typical AAV transgene are split across two transgenes, named 5′ and 3′. The 5′ transgene contains the promoter and 5′ fragment of ABCA4 coding sequence, whereas the 3′ transgene carries a 3′ fragment of ABCA4 coding sequence plus a WPRE and bovine growth hormone polyA signal. Once inside the same host cell nucleus, the two transgenes align and recombine via a region of homology shared between the transgenes (grey). ABCA4, ATP-binding cassette transporter protein family member 4; GRK1 = human rhodopsin kinase promoter; In, intron; pA, polyA signal; WPRE, Woodchuck hepatitis virus post-transcriptional regulatory element.