Engineered packaging cell line for the enhanced production of baboon-enveloped retroviral vectors

The baboon endogenous retrovirus (BaEV) glycoprotein is superior to the commonly used vesicular stomatitis virus glycoprotein (VSVg) for retroviral gene transfer into resting hematopoietic stem cells and lymphocyte populations. The derivative BaEVRLess (lacking the R domain) produces higher viral ti...

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Main Authors: Denise Klatt, Lucia Sereni, Boya Liu, Pietro Genovese, Axel Schambach, Els Verhoeyen, David A. Williams, Christian Brendel
Format: Article
Language:English
Published: Elsevier 2024-12-01
Series:Molecular Therapy: Nucleic Acids
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Online Access:http://www.sciencedirect.com/science/article/pii/S2162253124002762
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author Denise Klatt
Lucia Sereni
Boya Liu
Pietro Genovese
Axel Schambach
Els Verhoeyen
David A. Williams
Christian Brendel
author_facet Denise Klatt
Lucia Sereni
Boya Liu
Pietro Genovese
Axel Schambach
Els Verhoeyen
David A. Williams
Christian Brendel
author_sort Denise Klatt
collection DOAJ
description The baboon endogenous retrovirus (BaEV) glycoprotein is superior to the commonly used vesicular stomatitis virus glycoprotein (VSVg) for retroviral gene transfer into resting hematopoietic stem cells and lymphocyte populations. The derivative BaEVRLess (lacking the R domain) produces higher viral titers compared with wild-type BaEV, but vector production is impaired by syncytia formation and cell death of the HEK293T cells due to the high fusogenic activity of the glycoprotein. This lowers viral titers, leads to increased batch-to-batch variability, and impedes the establishment of stable packaging cell lines essential for the economical production of viral supernatants. Here, we show that knockout of the entry receptor ASCT2 in HEK293T producer cells eliminates syncytia formation, resulting in a 2-fold increase in viral titers, reduced toxicity of viral supernatants, and enables the generation of stable packaging cell lines. In successive steps, we stably integrated BaEVRLess and α-retroviral a.Gag/Pol expression cassettes and isolated clones supporting titers up to 108 to 109 infectious particles/mL, a 10-fold increase in concentrated viral titers. The additional overexpression of CD47 and knockout of β2-microglobulin in the packaging cell line are tailored for future use in in vivo gene therapy applications by reducing non-specific uptake by macrophages and the immunogenicity of viral particles.
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spelling doaj-art-8e2e01e0ba9340b482b868e06259719f2025-08-20T02:27:42ZengElsevierMolecular Therapy: Nucleic Acids2162-25312024-12-0135410238910.1016/j.omtn.2024.102389Engineered packaging cell line for the enhanced production of baboon-enveloped retroviral vectorsDenise Klatt0Lucia Sereni1Boya Liu2Pietro Genovese3Axel Schambach4Els Verhoeyen5David A. Williams6Christian Brendel7Gene Therapy Program, Dana Farber/Boston Children’s Cancer and Blood Disorders Center, Harvard Medical School, Boston, MA 02115, USA; Division of Hematology/Oncology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USAGene Therapy Program, Dana Farber/Boston Children’s Cancer and Blood Disorders Center, Harvard Medical School, Boston, MA 02115, USA; Division of Hematology/Oncology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USADivision of Hematology/Oncology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USAGene Therapy Program, Dana Farber/Boston Children’s Cancer and Blood Disorders Center, Harvard Medical School, Boston, MA 02115, USA; Division of Hematology/Oncology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USADivision of Hematology/Oncology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA; Institute of Experimental Hematology, Hannover Medical School, 30625 Hannover, GermanyCentre International de Recherche en Infectiologie (CIRI), Université Lyon, Université Claude Bernard Lyon 1, INSERM, U1111, CNRS, UMR 5308, Ecole Normale Supérieure de Lyon, 69007 Lyon, France; Université Côte d'Azur, INSERM U1065, Centre Méditerranéen de Médecine Moléculaire, 06200 Nice, FranceGene Therapy Program, Dana Farber/Boston Children’s Cancer and Blood Disorders Center, Harvard Medical School, Boston, MA 02115, USA; Division of Hematology/Oncology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USAGene Therapy Program, Dana Farber/Boston Children’s Cancer and Blood Disorders Center, Harvard Medical School, Boston, MA 02115, USA; Division of Hematology/Oncology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA; Corresponding author: Christian Brendel, Gene Therapy Program, Dana Farber/Boston Children’s Cancer and Blood Disorders Center, Harvard Medical School, Boston, MA 02115, USA.The baboon endogenous retrovirus (BaEV) glycoprotein is superior to the commonly used vesicular stomatitis virus glycoprotein (VSVg) for retroviral gene transfer into resting hematopoietic stem cells and lymphocyte populations. The derivative BaEVRLess (lacking the R domain) produces higher viral titers compared with wild-type BaEV, but vector production is impaired by syncytia formation and cell death of the HEK293T cells due to the high fusogenic activity of the glycoprotein. This lowers viral titers, leads to increased batch-to-batch variability, and impedes the establishment of stable packaging cell lines essential for the economical production of viral supernatants. Here, we show that knockout of the entry receptor ASCT2 in HEK293T producer cells eliminates syncytia formation, resulting in a 2-fold increase in viral titers, reduced toxicity of viral supernatants, and enables the generation of stable packaging cell lines. In successive steps, we stably integrated BaEVRLess and α-retroviral a.Gag/Pol expression cassettes and isolated clones supporting titers up to 108 to 109 infectious particles/mL, a 10-fold increase in concentrated viral titers. The additional overexpression of CD47 and knockout of β2-microglobulin in the packaging cell line are tailored for future use in in vivo gene therapy applications by reducing non-specific uptake by macrophages and the immunogenicity of viral particles.http://www.sciencedirect.com/science/article/pii/S2162253124002762MT: Delivery Strategiespackaging cell lineBaEVRLess envelopeASCT2 knockoutα-retroviral vectorsCD47 overexpression
spellingShingle Denise Klatt
Lucia Sereni
Boya Liu
Pietro Genovese
Axel Schambach
Els Verhoeyen
David A. Williams
Christian Brendel
Engineered packaging cell line for the enhanced production of baboon-enveloped retroviral vectors
Molecular Therapy: Nucleic Acids
MT: Delivery Strategies
packaging cell line
BaEVRLess envelope
ASCT2 knockout
α-retroviral vectors
CD47 overexpression
title Engineered packaging cell line for the enhanced production of baboon-enveloped retroviral vectors
title_full Engineered packaging cell line for the enhanced production of baboon-enveloped retroviral vectors
title_fullStr Engineered packaging cell line for the enhanced production of baboon-enveloped retroviral vectors
title_full_unstemmed Engineered packaging cell line for the enhanced production of baboon-enveloped retroviral vectors
title_short Engineered packaging cell line for the enhanced production of baboon-enveloped retroviral vectors
title_sort engineered packaging cell line for the enhanced production of baboon enveloped retroviral vectors
topic MT: Delivery Strategies
packaging cell line
BaEVRLess envelope
ASCT2 knockout
α-retroviral vectors
CD47 overexpression
url http://www.sciencedirect.com/science/article/pii/S2162253124002762
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