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In vitro characterization of engineered red blood cells as viral traps against HIV-1 and SARS-CoV-2

Hoffmann, Magnus A. G. and Kieffer, Collin and Bjorkman, Pamela J. (2021) In vitro characterization of engineered red blood cells as viral traps against HIV-1 and SARS-CoV-2. Molecular Therapy - Methods and Clinical Development, 21 . pp. 161-170. ISSN 2329-0501. PMCID PMC7944778. doi:10.1016/j.omtm.2021.03.003.

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Engineered red blood cells (RBCs) expressing viral receptors could be used therapeutically as viral traps, as RBCs lack nuclei and other organelles required for viral replication. However, expression of viral receptors on RBCs is difficult to achieve since mature erythrocytes lack the cellular machinery to synthesize proteins. Herein, we show that the combination of a powerful erythroid-specific expression system and transgene codon optimization yields high expression levels of the HIV-1 receptors CD4 and CCR5, as well as a CD4-glycophorin A (CD4-GpA) fusion protein in erythroid progenitor cells, which efficiently differentiated into enucleated RBCs. HIV-1 efficiently entered RBCs that co-expressed CD4 and CCR5, but viral entry was not required for neutralization, as CD4 or CD4-GpA expression in the absence of CCR5 was sufficient to potently neutralize HIV-1 and prevent infection of CD4+ T cells in vitro due to the formation of high-avidity interactions with trimeric HIV-1 Env spikes on virions. To facilitate continuous large-scale production of RBC viral traps, we generated erythroblast cell lines stably expressing CD4-GpA or ACE2-GpA fusion proteins, which produced potent RBC viral traps against HIV-1 and SARS-CoV-2. Our in vitro results suggest that this approach warrants further investigation as a potential treatment against acute and chronic viral infections.

Item Type:Article
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URLURL TypeDescription CentralArticle Paper
Hoffmann, Magnus A. G.0000-0003-4923-9568
Kieffer, Collin0000-0001-9051-3819
Bjorkman, Pamela J.0000-0002-2277-3990
Additional Information:© 2021 The Author(s). This is an open access article under the CC BY license ( Received 31 December 2020, Accepted 6 March 2021, Available online 10 March 2021. We thank N.J. Huang, N. Pishesha, and H.F. Lodish for helpful discussion, advice, and reagents; P.N.P. Gnanapragasam and L.M. Kakutani for producing SARS-CoV-2 pseudovirus and setting up the SARS-CoV-2 pseudovirus neutralization assay in our laboratory; G.L. Chadwick, R. Galimidi, and A. Moradian (formerly Caltech Proteome Exploration Laboratory) for helpful discussions and reagents; G. Spigolon for guidance with light microscopy performed at the Beckman Institute Biological Imaging Facility; Z. Romero-Garcia and D.B. Kohn for the pCCL-AS3-FB plasmid; J. Voetteler and W.I. Sundquist for the CCF2-AM reagent; J.D. Bloom for 293T-ACE2 cells and plasmids for generating SARS-CoV-2 pseudovirus; and the NIH AIDS Reagent Program for reagents. BEL-A2 cell lines were created by Professor Jan Frayne, Professor David Anstee and Dr Kongtana Trakarnsanga with funding from the Wellcome Trust (grant numbers 087430/Z/08 and 102610), NHS Blood and Transplant and Department of Health (England) and were kindly provided by J. Frayne. This work was supported by the Bill and Melinda Gates Foundation grant OPP1202246, the DeLogi Trust (facilitated by Caltech), and by a generous gift from Kairos Ventures (facilitated by Caltech). Author contributions: M.A.G.H. and P.J.B. designed the research, M.A.G.H. and C.K. performed the research, M.A.G.H. and P.J.B. analyzed data, and M.A.G.H. and P.J.B. wrote the manuscript. The authors declare no competing interests.
Funding AgencyGrant Number
Wellcome Trust087430/Z/08
Wellcome Trust102610
Bill and Melinda Gates FoundationOPP1202246
Caltech De Logi FundUNSPECIFIED
Kairos VenturesUNSPECIFIED
Subject Keywords:Engineered red blood cells; anti-viral therapeutics; HIV-1; SARS-CoV-2
PubMed Central ID:PMC7944778
Record Number:CaltechAUTHORS:20201222-101000542
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Official Citation:Magnus A.G. Hoffmann, Collin Kieffer, Pamela J. Bjorkman, In vitro characterization of engineered red blood cells as viral traps against HIV-1 and SARS-CoV-2, Molecular Therapy - Methods & Clinical Development, Volume 21, 2021, Pages 161-170, ISSN 2329-0501, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107253
Deposited By: Tony Diaz
Deposited On:22 Dec 2020 19:38
Last Modified:28 Sep 2021 21:17

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