Cloning, sequencing and characterization of lentiviral-mediated expression of rhesus macaque (Macaca mulatta) interleukin-2 receptor alpha cDNA

Anti-CD25 Targeted Killing of Bicistronically Transduced Cells: A Novel Safety Mechanism Against Retroviral Genotoxicity

Gene therapy for Fabry disease, a deficiency in alpha-galactosidase A (alpha-gal A) activity, has the potential to provide a cure for the disorder with a single treatment. Despite modifications to existing vectors, concerns have arisen regarding the risk of genotoxicity associated with the use of retroviruses. To address safety concerns, we propose that expression of a cell surface protein, human CD25 (huCD25) in a bicistronic format, with any therapeutic gene such as alpha-gal A can provide a target that can be used to kill transduced cells selectively should transformative events occur. We show that an anti-CD25 antibody and immunotoxin can specifically target and eliminate transduced leukemia cells expressing CD25. In a murine leukemia model, antibody treatment reduced tumor burden 32-fold and increased survival compared with untreated mice. Furthermore, after a bone marrow transplant of therapeutically transduced cells into Fabry mice, antibody treatment reduced the number of retrovirally transduced huCD25-expressing cells in the peripheral blood. A systemic loss of transduced cells with functional consequences was also evident in the liver and spleen. This proof-of-principle study demonstrates that a targeted antibody can reduce tumor burden and selectively clear bicistronically transduced hematopoietic cells that express a target antigen, thus acting as a built-in safety mechanism.

Functional expression of mouse relaxin and mouse relaxin-3 in the lung from an Ebola virus glycoprotein-pseudotyped lentivirus via tracheal delivery

The peptide hormone relaxin is a known modulator of connective tissue and the extracellular matrix by virtue of its ability to regulate matrix metalloproteinases (MMPs). Relaxin knockout mice exhibit age-related pulmonary fibrosis, and delivery of recombinant human H2 relaxin ameliorates fibrotic-like conditions in the mouse lung. We investigated whether lentiviral vectors (LVs) engineering the expression of murine relaxins could induce MMP activity in the mouse lung. Mouse relaxin and mouse relaxin-3 peptides engineered by recombinant LVs were biologically active as shown by stimulation of cAMP from both THP-1 and 293T cells stably expressing relaxin receptor LGR7 and by up-regulation of MMP-2 activity from primary C57BL/6 lung cell cultures. To provide the virions with enhanced tropism for the lung, LVs were pseudotyped with the Zaire strain of the Ebola virus glycoprotein (EboZ GP) and delivered by endotracheal intubation. LVs engineering luciferase pseudotyped with EboZ GP, but not with vesicular stomatitis virus glycoprotein resulted in successful LV transduction and transgene expression in C57BL/6 mouse lung by as early as d 4. Mice treated via tracheal delivery with EboZ GP pseudotyped LVs that engineered expression of mouse relaxins exhibited increased MMP-2 and MMP-9 activity in lung tissue up until the end of our study at d 21. Taken together, this study provides proof-of- principle that relaxin gene expression targeted to the mouse lungs can result in enhanced MMP activity offering potential for alleviating disease conditions characterized by dysregulation of extracellular matrix protein accumulation.