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    Characterization of intravitreally delivered capsid mutant AAV2-Cre vector to induce tissue-specific mutations in murine retinal ganglion cells
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    Inefficient gene transfer has limited the success of gene therapy in the hematopoietic system. Here we develop a novel chimeric adenovirus (Ad) vector containing Ad serotype 11 fiber-modified capsids and E1/E3 deleted viral genomes (Ad5/11) or genomes devoid of all viral genes (DeltaAd5/11). The capsid-modified vectors transduced human hematopoietic cells more efficiently than the unmodified Ad5-based vector. The absence of viral genes from the DeltaAd5/11 vector allowed for transduction without the associated toxicity seen with the first-generation E1/E3 deleted vector. Chimeric vectors were used for transient expression of the ecotropic retrovirus receptor (ecoR) in Mo7e cells (a CD34-positive, c-Kit-positive, growth-factor-dependent human cell line) as a model for human hematopoietic progenitor cells. Expression of ecoR conferred susceptibility to subsequent retroviral transduction. The DeltaAd5/11 vector used to express ecoR allowed for expansion of retrovirally transduced cells, whereas transduction with the first-generation Ad5/11 vector resulted in cytotoxicity and, over time, loss of cells expressing the retrovirus-vector-derived transgene.
    Transduction (biophysics)
    HEK 293 cells
    Citations (61)
    To compare the transduction efficiencies of adenoviral vector, adeno-associated viral vector, baculoviral vector, and plasmid vector in human bone-marrow-derived mesenchymal stem cells (hBMSCs).The hBMSCs were cultured in vitro and transducted with the adenoviral vector, adeno-associated viral vector, baculoviral vector, and plasmid vector. The expression of target protein was observed by inverted fluorescent microscopy and flow cytometry.Inverted fluorescent microscopy showed that some of the hBMSCs after transduction expressed the green fluorescent protein (GFP) and the hBMSCs transducted with baculoviral vector expressed more GFP than those of other three vectors. Flow cytometry showed that the transduction efficiencies and mean fluorescence intensities of the adenoviral vector, adeno-associated viral vector, and plasmid vector were 42%, 37%, and 22% and 158, 115, and 77, respectively, which were significantly lower than those of baculoviral vector (70%, P < 0.01; 212, P < 0.05; respectively).Compared with the adenoviral vector, adeno-associated viral vector, and plasmid vector, the baculoviral vector has higher transduction efficiency in hBMSCs and therefore may be a more suitable gene vector for research in human gene therapy.
    Transduction (biophysics)
    Adeno-associated virus
    Citations (0)
    To facilitate clinical applications of retroviral-mediated human gene transfer, retroviral vectors must be of high titer and free of detectable replication-competent retroviruses. The purpose of this study was to optimize methods of retroviral vector production and transduction. Studies were conducted using 22 retroviral vector producer cell lines. Inactivation of retroviral vectors was greater at 37 degrees C than at 32 degrees C. A 5- to 15-fold increase of vectors was produced at 32 degrees C compared to 37 degrees C; the vector increase at 34 degrees C was intermediate. For example, PA317/G1Na.40 grew to a titer of 1.8 x 10(7) cfu/ml at 32 degrees C, compared to 5.0 x 10(5) cfu/ml at 37 degrees C. The production of retroviral vectors was scalable achieving similar results in flasks, roller bottles, or a CellCube Bioreactor. Retroviral vectors were concentrated 15-24 times with vector recovery ranging from 91 to 96% in a Pellicon tangential flow filtration system. Retroviral supernatants were successfully lyophilized. The combination of glucose or sorbitol with gelatin resulted in recovery rates of 64-83%. In studies on transduction by retroviral vectors, centrifugation of vector supernatants onto target cells significantly increased transduction efficiency as measured by vector titration for G418 resistance, fluorescence-activated cell sorting (FACS), and polymerase chain reaction (PCR) analyses. The combination of the above methods has significantly increased the growth and transduction by this vector system.
    Transduction (biophysics)
    Citations (382)
    Abstract Background Genetically modified keratinocytes generate transplantable self‐renewing epithelia suitable for delivery of therapeutic polypeptides. However, the variety of viral vectors and experimental conditions currently used make fragmented or contradictory the information on the transduction efficiency of the human primary keratinocytes. To compare the suitability of the most currently used viral vectors for efficient gene transfer to human keratinocytes, we have performed a comparative study using a panel of recombinant constructs. Methods For each vector, the transduction efficiency and the persistence of the transgene expression were quantified by fluorescence microscopy and flow cytometry analysis of the infected cells. Results We show that: (1) canine and human adenoviral vectors achieve a highly efficient but transient transduction of both primary and immortalized keratinocytes; (2) the adenovirus‐associated virus (AAV) vectors transduce immortalized keratinocytes, albeit with a short‐lived gene expression (<4 days), but fail to infect primary keratinocytes; and (3) under appropriate conditions, the oncoretroviral and lentiviral vectors can permanently transduce up to 100% of primary keratinocytes, but the highly clonogenic keratinocytes are more efficiently targeted by lentiviral vectors. Conclusions Therefore, AAV vectors are unsuitable to transduce primary keratinocytes, while human and canine adenoviral vectors appears to be appropriate to achieve short‐term delivery of therapeutic products. Recombinant retroviruses provide sustained expression of the transgene, but the lentiviral vectors are the most suitable for ex vivo gene therapy because of their ability to transduce clonogenic primary keratinocytes. Copyright © 2005 John Wiley & Sons, Ltd.
    Transduction (biophysics)
    Clonogenic assay
    HEK 293 cells
    Ex vivo
    Citations (28)
    B lymphocytes are attractive targets for gene therapy of genetic diseases associated with B-cell dysfunction and for immunotherapy. Transduction of B lymphocytes was evaluated using green fluorescent protein (GFP)-encoding onco-retroviral and HIV-derived lentiviral vectors which were pseudotyped with ecotropic, amphotropic or vesicular stomatitis virus (VSV-G) envelopes. Transduction of mouse B lymphocytes activated with lipopolysaccharides (LPS) or by cross-linking CD40 in conjunction with interleukin-4 (IL-4) was significantly more efficient (p < 0.003) with ecotropic (11%) than with VSV-G pseudotyped onco-retroviral vectors (1%). Using high-titer cell-free ecotropic viral supernatant or by coculture with ecotropic onco-retroviral vector-producing cells, transduction efficiency increased significantly (p < 0.001) to approximately 50%, whereas transduction efficiency by coculture with VSV-G pseudotyped vector-producing cells remained low (< 2%). Similarly, transduction of mouse B lymphocytes was significantly more efficient (twofold, p < 0.01) with the ecotropic (7%) than with the VSV-G pseudotyped lentiviral vectors although gene transfer efficiency remained low because of dose-limiting toxicity of the concentrated vector preparations on the LPS-activated murine B cells. Consistent with murine B-cell transduction, human B cells activated with CD40L and IL-4 were also found to be relatively refractory to VSV-G pseudotyped onco-retroviral vectors (< 1%). However, higher transduction efficiencies could be achieved in activated primary human B lymphocytes using VSV-G pseudotyped lentiviral vectors instead (5%-6%). Contrary to the significant increase in mouse B-cell transduction efficiency with ecotropic vectors, the use of amphotropic onco-retroviral or lentiviral vectors did not increase transduction efficiency in primary human B cells. The present study shows that the transduction efficiency of onco-retroviral and lentiviral vectors in human and mouse B lymphocytes is pseudotype-dependent and challenges the widely held assumption that VSV-G pseudotyping facilitates gene transfer into all cell types.
    Transduction (biophysics)
    Citations (50)
    Retroviral vectors derived from murine leukemia retrovirus (MuLV) have been widely used for efficient gene transfer to achieve long-term expression of a chosen therapeutic gene in mammLian cells (). Disadvantages of this vector are the instability and low viral titers generated from packaging cells, low efficiency of gene transfer into human cells, especially in vivo, and the requirement for dividing cells. Some authors have attempted to increase the transduction efficiency by using strategies like low-speed centrifugation of viral supernatant with cells, multiple viral exposures (), or increasing viral titers by ultracentrifugation (); they were able to produce an average transduction efficiency of 10–60%. However, all such improvements in transduction efficiency require additional procedures, which are practically inefficient.
    Transduction (biophysics)
    Gene transfer
    Citations (1)
    Application of viral vectors in gene delivery is attracting widespread attention but is hampered by the absence of control over transduction, which may lead to non-selective transduction with adverse side effects. To overcome some of these limitations, we proposed an unnatural amino acid aided caging-uncaging strategy for controlling the transduction capability of a viral vector. In this proof-of-principle study, we first expanded the genetic code of the lentiviral vector to incorporate an azido-containing unnatural amino acid (Nϵ-2-azidoethyloxycarbonyl-l-lysine, NAEK) site specifically within a lentiviral envelope protein. Screening of the resultant vectors indicated that NAEK incorporation at Y77 and Y116 was capable of inactivating viral transduction upon click conjugation with a photo-cleavable chemical molecule (T1). Exposure of the chimeric viral vector (Y77-T1) to UVA light subsequently removed the photo-caging group and restored the transduction capability of lentiviral vector both in vitro and in vivo. Our results indicate that the use of the photo-uncage activation procedure can reverse deactivated lentiviral vectors and thus enable regulation of viral transduction in a switchable manner. The methods presented here may be a general approach for generating various switchable vectors that respond to different stimulations and adapt to different viral vectors.
    Transduction (biophysics)
    Citations (12)