AAV with ALB(1.9) promoter driven iCre

This AAV expresses iCre driven by a liver ALB(1.9) promoter.

The ALB(1.9) is a synthetic promoter of ~1.9 Kb. It is based on the human Albumin promoter as well as several other regulatory elements. This synthetic promoter gives an extremely high level of long-term, liver-specific transgene expression that is 100-100 fold greater than that of the CMV promoter. For short-term (1-2 weeks post-injection into mouse liver), ALB(1.9) gives comparable expression relative to that of the CMV promoter. However, the expression level of the CMV promoter decreases 100-1000 fold from its peak level within 10-20 weeks of DNA administration whereas the ALB(1.9) promoter sustains its initial high level of expression for over 1 year. Compared to the regular ALB promoter, which is also commonly used for liver-specific transgene expression, the expression level from ALB(1.9) is about 10-100 fold greater.

Cre is a recombinase from the P1 bacteriophage. This enzyme carries out site-specific recombination between two DNA recognition sites (LoxP sites) through a topoisomerase I-like mechanism. The Cre recombinase here has been codon-optimized leading to a higher level of Cre protein expression (iCre). The 34base pair (bp) loxP recognition site, ATAACTTCGTATA ATGTATGC TATACGAAGTTAT, consists of two 13 bp palindromic sequence which flank an 8 bp spacer region. The products of Cre-mediated recombination at loxP sites are dependent upon the location and relative orientation of the loxP sites. For example, two separate DNA species both containing loxP sites can undergo fusion as the result of Cre-mediated recombination. DNA sequences found between two loxP sites on the same DNA molecule are said to be floxed. In this case, the products of Cre-mediated recombination depend upon the orientation of the loxP sites: DNA found between two loxP sites oriented in the same direction will be excised as a circular loop of DNA, whereas DNA between two loxP sites that are oriented oppositely will be inverted. Besides LoxP sites, other Lox sites have been designed and tested, such as Lox272 and LoxN etc. These Lox elements have been widely used for genetic studies