Spatially restricted long‐term transgene expression in the developing skin used for studying the interaction of epidermal development and sensory innervation

Aims: We aim to define parameters affecting the safety and long-term transgene expression of attenuated HSV-1 vectors and optimize the expression cassettes to achieve robust and sustained expression in CNS. Background: Engineered, attenuated Herpes simplex virus (HSV) vectors are promising vehicles for gene delivery to the peripheral and central nervous systems. The virus latent promoter (LAP) is commonly used to drive exogenous gene expression; however, parameters affecting the safety and long-term transgene expression of attenuated HSV-1 vectors have not been fully understood. Objective: This study aimed to construct attenuated HSV-1 vectors using the CRISPR-Cas9 system and examine the influence of transgene cassette construction and insertion site on transgene expression and vector safety. Method: In this study, we used a CRISPR-Cas9 system to accurately and efficiently edit attenuated HSV-1 strain 1716, and constructed two series of recombinant virus LMR and LMRx with different sets of gene cassettes insertion in Exon1(LAP2) and 2.0 kb intron downstream of LAP, respectively. The transgene expression and viral gene transcriptional kinetics were compared in in-vitro cell lines. The reporter gene expression and safety profiles of each vector were further evaluated in the mouse hippocampus gene transduction model. Result: The in-vitro cell line analysis indicated that the insertion of a gene expression cassette would disrupt virus gene transcription. Mouse hippocampus transducing analysis suggested that complete expression cassette insertion at 2.0 kb intron could achieve robust and longtime gene expression than the other constructs. Recombinants with gene expression cassettes lacked Poly (A), which induced significant neuronal inflammation due to persistent viral antigen expression and microglia activation. Conclusion: Our results indicated that the integrity of LAT transcripts was not necessary for the establishment of long-term latent expression. Exogenous strong promoters (like cBh promoter) could remain active during latency when placed in Exon1 or 2.0 Kb Intron of LAT locus, although their transcriptional activity declined with time. Consistent with previous research, the foreign gene expression would last much longer when the gene cassette was located downstream of Exon1, which suggested a role of LAP2 in maintaining promoter activity during latency. Besides, over-transcription of the downstream part of LAT may induce continuous activation of the attenuated vectors, suggesting an important role of LAT in maintaining viral reactivation potential.

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Long-term multilineage expression in peripheral blood from a Moloney murine leukemia virus vector after serial transplantation of transduced bone marrow cells

Blood ◽

10.1182/blood.v95.3.829.003k18_829_836 ◽

2000 ◽

Vol 95 (3) ◽

pp. 829-836 ◽

Cited By ~ 8

Author(s):

Timothy W. Austin ◽

Suzan Salimi ◽

Gabor Veres ◽

Franck Morel ◽

Heini Ilves ◽

...

Keyword(s):

Bone Marrow ◽

Peripheral Blood ◽

Blood Cells ◽

Transgene Expression ◽

Bone Marrow Cells ◽

Leukemia Virus ◽

Moloney Murine Leukemia Virus ◽

Marrow Cells

Using a mouse bone marrow transplantation model, the authors evaluated a Moloney murine leukemia virus (MMLV)-based vector encoding 2 anti-human immunodeficiency virus genes for long-term expression in blood cells. The vector also encoded the human nerve growth factor receptor (NGFR) to serve as a cell-surface marker for in vivo tracking of transduced cells. NGFR+ cells were detected in blood leukocytes of all mice (n=16; range 16%-45%) 4 to 5 weeks after transplantation and were repeatedly detected in blood erythrocytes, platelets, monocytes, granulocytes, T cells, and B cells of all mice for up to 8 months. Transgene expression in individual mice was not blocked in the various cell lineages of the peripheral blood and spleen, in several stages of T-cell maturation in the thymus, or in the Lin−/loSca-1+ and c-kit+Sca-1+ subsets of bone marrow cells highly enriched for long-term multilineage-reconstituting activity. Serial transplantation of purified NGFR+c-kit+Sca-1+bone marrow cells resulted in the reconstitution of multilineage hematopoiesis by donor type NGFR+ cells in all engrafted mice. The authors concluded that MMLV-based vectors were capable of efficient and sustained transgene expression in multiple lineages of peripheral blood cells and hematopoietic organs and in hematopoietic stem cell (HSC) populations. Differentiation of engrafting HSC to peripheral blood cells is not necessarily associated with dramatic suppression of retroviral gene expression. In light of earlier studies showing that vector elements other than the long-terminal repeat enhancer, promoter, and primer binding site can have an impact on long-term transgene expression, these findings accentuate the importance of empirically testing retroviral vectors to determine lasting in vivo expression.

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249. High Levels of Protein Expression in the Liver Could Be Detrimental for Long-Term Transgene Expression

Molecular Therapy ◽

10.1016/s1525-0016(16)39652-6 ◽

2008 ◽

Vol 16 ◽

pp. S94

Keyword(s):

Protein Expression ◽

Transgene Expression

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1036. Effective Long-Term Transgene Expression by Self-Complementary Adeno-Associated Virus Serotypes to Human Mesenchymal Stem Cells Derived from Both Bone-Marrow and Umbilical-Cord Blood

Molecular Therapy ◽

10.1016/s1525-0016(16)45242-1 ◽

2007 ◽

Vol 15 ◽

pp. S395-S396

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Mesenchymal Stem Cells ◽

Cord Blood ◽

Umbilical Cord ◽

Umbilical Cord Blood ◽

Transgene Expression ◽

Human Mesenchymal Stem Cells ◽

Adeno Associated Virus

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Lack of Repeat Transduction by Recombinant Adeno-Associated Virus Type 5/5 Vectors in the Mouse Airway

Journal of Virology ◽

10.1128/jvi.01010-07 ◽

2007 ◽

Vol 81 (22) ◽

pp. 12360-12367 ◽

Cited By ~ 21

Author(s):

Stephanie G. Sumner-Jones ◽

Deborah R. Gill ◽

Stephen C. Hyde

Keyword(s):

Transgene Expression ◽

Lung Diseases ◽

Repeated Administration ◽

Transduction Efficiency ◽

Viral Gene ◽

Rapid Rise ◽

Adeno Associated Virus ◽

Subsequent Failure

ABSTRACT While recombinant adeno-associated virus (rAAV) vectors promote long-term transgene expression in the lungs and other organs, the goal of correcting chronic inherited lung diseases such as cystic fibrosis with this type of viral gene transfer vector is limited by the requirement of achieving stable potent transgene expression, potentially requiring vector readministration. Here we evaluated the abilities of rAAV type 5/5 (rAAV5/5) vectors based on the genome and capsid of AAV5 to efficiently transduce the lungs and nasal epithelium of mice after repeated administration. Transduction efficiency as judged by reporter gene expression was markedly reduced on a second rAAV5/5 administration and effectively abolished on a third. Varying the period between administrations from 8 to 36 weeks did not allow efficient repeated administration. A rapid rise in anti-AAV5 antibodies was noted after rAAV5/5 vector administration that was sustained for the entire period of investigation (in some cases exceeding 9 months). Furthermore, this antibody response and subsequent failure to repeatedly administer the vector were not rescued by the in vivo expression of CTLA4Ig from an rAAV5/5 vector. These results suggest that without the development of an effective and clinically acceptable immunosuppression strategy, treatments for chronic diseases that require repeated administration of rAAV5/5 vectors will be unsuccessful.

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