title: Hybrid HIV/MSCV LTR enhances transgene expression of lentiviral vectors in human CD34(+) hematopoietic cells.
abstract: HIV-based lentiviral vectors can transduce nondividing cells, an important advantage over murine leukemia virus (MLV)-based vectors when transducing slowly dividing hematopoietic stem cells. However, we find that in human CD34(+) hematopoietic cells, the HIV-based vectors with an internal cytomegalovirus (CMV) promoter express transgenes 100- to 1,000-fold less than the MLV-based retroviral vector murine stem cell virus (MSCV). To increase the expression of the integrated lentivirus, we replaced CMV promoter with that of the Rous sarcoma virus or MSCV and obtained a modest augmentation in expression. A more dramatic effect was seen when the CMV enhancer/promoter was removed and the HIV long-terminal repeat (LTR) was replaced by a novel HIV/MSCV hybrid LTR. This vector retains the ability to transduce nondividing cells but now expresses its transgene (enhanced green fluorescent protein) 10- to 100-fold greater than the original HIV-based vector. When compared under identical conditions, the HIV vector with the hybrid LTR transduced a higher percentage of CD34(+) cells than the MSCV-based retroviral vector (19.4% versus 2.4%). The number of transduced cells and level of transgene expression remain constant over 5-8 weeks as determined by long-term culture-initiating cells, fluoresence-activated cell sorting, and nonobese diabetic/severe combined immunodeficiency repopulation assay.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia 19104, USA. jkchoi@mail.med.upenn.edu
authors.forename: J K
authors.initials: JK
authors.lastname: Choi
authors.forename: N
authors.initials: N
authors.lastname: Hoang
authors.forename: A M
authors.initials: AM
authors.lastname: Vilardi
authors.forename: P
authors.initials: P
authors.lastname: Conrad
authors.forename: S G
authors.initials: SG
authors.lastname: Emerson
authors.forename: A M
authors.initials: AM
authors.lastname: Gewirtz
mesh_terms: D000818:Animals; D018952:Antigens, CD34 / Q000096:biosynthesis*; D001358:Avian Sarcoma Viruses / Q000235:genetics; D001854:Bone Marrow Cells / Q000166:cytology; D002460:Cell Line; D002469:Cell Separation; D002478:Cells, Cultured; D005312:Fetal Blood / Q000166:cytology; D005434:Flow Cytometry; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins; D006678:HIV / Q000235:genetics*; D016325:HIV Long Terminal Repeat / Q000235:genetics; D006367:HeLa Cells; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D006801:Humans; D020014:K562 Cells; D016086:Lentivirus / Q000235:genetics*; D009052:Leukemia Virus, Murine / Q000235:genetics*; D008164:Luminescent Proteins / Q000378:metabolism; D051379:Mice; D016513:Mice, SCID; D008957:Models, Genetic; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013997:Time Factors; D019076:Transgenes
chemical_list: D018952:Antigens, CD34; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins