Highly Significant Antiviral Activity of HIV-1 LTR-Specific Tre-Recombinase in Humanized Mice
Figure 5
Assay of potential Tre-related off-target effects.
(A) Nucleotide sequences of genomic sites and their locations in the human genome (in brackets). Sequences are aligned to the Tre recognition site loxLTR. Nucleotides that differ from loxLTR are shown in red. (B) Representation of the recombination assay in E. coli. and in HeLa cells, respectively. The evolution vector pEVO-Tre-target contains two directly repeated recombinase target sites (loxLTR) or the sequences GS1, GS2, GS3, GS4, GS5, GS6, and GS7. In E. coli, Tre is expressed from the PBAD promoter upon induction with L-arabinose. The vector also contains the regulatory gene araC, and a chloramphenicol resistance marker (Cmr). Recombination at the target sites leads to deletion of the 700 bp intervening region. Locations of the PCR primer binding sites (F, R) for detection of recombination are indicated. (C) Agarose gel showing the activity of Tre on loxLTR and the lack thereof for the seven genomic sites GS1 to GS7 (lanes 3–9). Upper panel: Recombination assayed in E. Coli. BsrG I/Xba I restriction digest results in a 4.9 kb fragment for non-recombined plasmid (two triangles) and a 4.2 kb fragment for recombined product (one triangle). Recombination tests on loxLTR served as negative and positive control (lanes 1 and 2). −, non-induced; +, induced with 1 mg/ml L-arabinose; M, DNA marker lane. Lower panel: Recombination assayed in HeLa cells. PCR using primers F and R that anneal to the vector DNA results in a 0.4 kb product when recombination occurs, while the non-recombined template results in a 1.1 kb PCR product. −, cotransfection with pIRESneo (i.e. no Tre expression); +, cotransfection with pIRESneo-Tre [18].