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Van Es LJC, Possee RD, King LA. Characterisation of extracellular vesicles in baculovirus infection of Spodoptera frugiperda cells. JOURNAL OF EXTRACELLULAR BIOLOGY 2024; 3:e163. [PMID: 38947876 PMCID: PMC11212295 DOI: 10.1002/jex2.163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 05/24/2024] [Accepted: 06/05/2024] [Indexed: 07/02/2024]
Abstract
Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is an enveloped DNA virus of the Baculoviridae family. This baculovirus is widely exploited for the biological control of insect pest species and as an expression platform to produce recombinant proteins in insect cells. Extracellular vesicles (EVs) are secreted by all cells and are involved in key roles in many biological processes through their cargo consisting of proteins, RNA or DNA. In viral infections, EVs have been found to transfer both viral and cellular cargo that can elicit either a pro- or antiviral response in recipient cells. Here, small EVs (sEVs) released by Spodoptera frugiperda (Sf) insect cells were characterised for the first time. Using S. frugiperda (SfC1B5) cells stably expressing the baculovirus gp64, the viral envelope protein GP64 was shown to be incorporated into sEVs. Sf9 cells were also transfected with a bacmid AcMNPV genome lacking p6.9 (AcΔP6.9) to prevent budded virus production. The protein content of sEVs from both mock- and AcΔP6.9-transfected cells were analysed by mass spectrometry. In addition to GP64, viral proteins Ac-F, ME-53 and viral ubiquitin were identified, as well as many host proteins including TSG101-which may be useful as a protein marker for sEVs.
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Affiliation(s)
- Lex J. C. Van Es
- Department of Biological and Medical SciencesOxford Brookes UniversityOxfordUK
- Oxford Expression Technologies LtdOxfordUK
| | | | - Linda A. King
- Department of Biological and Medical SciencesOxford Brookes UniversityOxfordUK
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Ma H, Kennard A, Mattson N, Khan AS. Characterization of Sf9 cell clones with differential susceptibilities to Sf-rhabdovirus X +3.7 and Sf-rhabdovirus X - replication. Virology 2024; 594:110038. [PMID: 38471199 DOI: 10.1016/j.virol.2024.110038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2023] [Revised: 02/16/2024] [Accepted: 02/22/2024] [Indexed: 03/14/2024]
Abstract
Our laboratory previously discovered a novel rhabdovirus in the Spodoptera frugiperda Sf9 insect cell line that was designated as Sf-rhabdovirus. Using limiting dilution, this cell line was found to be a mixed population of cells infected by Sf-rhabdovirus variants containing either the full length X accessory gene with a 3.7 kb internal duplication (designated as Sf-rhabdovirus X+3.7) or lacking the duplication and part of the X gene (designated as Sf-rhabdovirus X-), and cells that were negative for Sf-rhabdovirus. In this paper, we found that the Sf-rhabdovirus negative cell clones had sub-populations with different susceptibilities to the replication of Sf-rhabdovirus X+3.7 and X- variants: cell clone Sf9-13F12 was more sensitive to replication by both virus variants compared to Sf9-3003; moreover, Sf9-3003 showed more resistance to X+3.7 replication than to X- replication. RNA-Seq analysis indicated significant differentially expressed genes in the Sf9-13F12 and Sf9-3003 cell clones further supporting that distinct sub-populations of virus-negative cells co-exist in the parent Sf9 cell line.
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Affiliation(s)
- Hailun Ma
- Division of Viral Products, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, 20993, USA
| | - Andrea Kennard
- Division of Viral Products, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, 20993, USA
| | - Nicholas Mattson
- Division of Viral Products, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, 20993, USA
| | - Arifa S Khan
- Division of Viral Products, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, 20993, USA.
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Ma H, Bosma TJ, Khan AS. Long-Read High-Throughput Sequencing (HTS) Revealed That the Sf-Rhabdovirus X + Genome Contains a 3.7 kb Internal Duplication. Viruses 2023; 15:1998. [PMID: 37896775 PMCID: PMC10612052 DOI: 10.3390/v15101998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 09/19/2023] [Accepted: 09/20/2023] [Indexed: 10/29/2023] Open
Abstract
We previously reported a novel rhabdovirus produced from the Spodoptera frugiperda Sf9 cell line, designated as Sf-rhabdovirus X+ since it contained a unique accessory gene X. The Sf-rhabdovirus X+ genome sequence was generated using Sanger sequencing and short-read high-throughput sequencing (HTS). In this study, we have used long-read HTS technologies, PacBio's single-molecule real-time sequencing and Oxford's Nanopore RNA direct sequencing, to analyze the parent Sf9 cell line transcriptome and the virus RNA produced from an X+ cell clone, respectively. A unique 3.7 kb duplication was identified in the L gene between nucleotide position 8523 and 8524, preceded by a GA dinucleotide insertion. This duplication contained a partial G gene, the complete X gene, and a partial L gene, which extended from nucleotide positions 4767-8523 in the X+ virus. Thus, the X+ genome length is 17,361 nucleotides, and we have re-designated the virus as Sf-rhabdovirus X+3.7. The 3.7 kb duplication was found in all Sf9 cell clones producing the X+ variant virus. Furthermore, the Sf-rhabdovirus X+3.7 genome was stable at passage 30, which was the highest passage tested. These results highlight the importance of combining short-read and long-read technologies for accurately sequencing virus genomes using HTS.
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Affiliation(s)
| | | | - Arifa S. Khan
- Division of Viral Products, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA; (H.M.); (T.J.B.)
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Arya SK, Goodman CL, Stanley D, Palli SR. A database of crop pest cell lines. In Vitro Cell Dev Biol Anim 2022; 58:719-757. [PMID: 35994130 DOI: 10.1007/s11626-022-00710-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 07/13/2022] [Indexed: 11/27/2022]
Abstract
We have developed an online database describing the known cell lines from Coleoptera, Diptera, Hemiptera, Hymenoptera, and Lepidoptera that were developed from agricultural pests. Cell line information has been primarily obtained from previous compilations of insect cell lines. We conducted in-depth Internet literature searches and drew on Internet sources such as the Cellosaurus database (https://web.expasy.org/cellosaurus/), and inventories from cell line depositories. Here, we report on a new database of insect cell lines, which covers 719 cell lines from 86 species. We have not included cell lines developed from Drosophila because they are already known from published databases, such as https://dgrc.bio.indiana.edu/cells/Catalog. We provide the designation, tissue and species of origin, cell line developer, unique characteristics, its use in various applications, publications, and patents, and, when known, insect virus susceptibility. This information has been assembled and organized into a searchable database available at the link https://entomology.ca.uky.edu/aginsectcellsdatabase which will be updated on an ongoing basis.
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Affiliation(s)
- Surjeet Kumar Arya
- Department of Entomology, College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY, 40546, USA
| | - Cynthia L Goodman
- Biological Control of Insects Research Laboratory, United States Department of Agriculture, Agricultural Research Service, Columbia, Missouri, 65203, USA
| | - David Stanley
- Biological Control of Insects Research Laboratory, United States Department of Agriculture, Agricultural Research Service, Columbia, Missouri, 65203, USA
| | - Subba Reddy Palli
- Department of Entomology, College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY, 40546, USA.
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Parry R, de Malmanche H, Asgari S. Persistent Spodoptera frugiperda rhabdovirus infection in Sf9 cells is not restricted by Wolbachia wMelPop-CLA and wAlbB strains and is targeted by the RNAi machinery. Virology 2021; 563:82-87. [PMID: 34492433 DOI: 10.1016/j.virol.2021.08.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 08/13/2021] [Accepted: 08/31/2021] [Indexed: 11/28/2022]
Abstract
The endosymbiotic bacterium Wolbachia pipientis confers RNA virus refractoriness in Drosophila and Aedes mosquitoes. Questions remain about the Wolbachia-virus restriction phenotype and how extensive this phenomenon may be within other arthropods. Here, we generated two Spodoptera frugiperda cell lines stably transinfected with two strains of Wolbachia, wAlbB and wMelPop-CLA. Despite the high density of Wolbachia in stably infected Sf9 cells, RT-PCR indicated the presence of the negative-sense RNA virus Spodoptera frugiperda rhabdovirus (SfRV) in Wolbachia-infected and uninfected cell lines. No differences in the replication of SfRV between Sf9 and Wolbachia-infected cells was found. RNA-Seq analysis of the parental Sf9 cells supported SfRV's presence in these cells with abundant 20 nt virus-derived small RNAs indicating active replication of SfRV in these cells. Overall, this study supports a growing body of evidence that Wolbachia does not restrict negative-sense RNA viruses and generates an in vitro model to examine Lepidoptera-Wolbachia virus interactions.
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Affiliation(s)
- Rhys Parry
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
| | - Henry de Malmanche
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia
| | - Sassan Asgari
- Australian Infectious Disease Research Centre, School of Biological Sciences, The University of Queensland, Brisbane, QLD, Australia.
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Ye C, Jiang S, Gong M, Min Q, Fan M, Gao J, Meng Y. Expressional Localization and Functionally Identifying an RNA Editing Enzyme BmADARa of the Silkworm Bombyx mori. INSECTS 2020; 11:insects11080523. [PMID: 32806497 PMCID: PMC7469206 DOI: 10.3390/insects11080523] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 08/04/2020] [Accepted: 08/07/2020] [Indexed: 11/16/2022]
Abstract
The most common type of RNA editing in metazoans is the deamination of adenosine into inosine (A-to-I) catalyzed by the adenosine deaminase acting on the RNA (ADAR) family of proteins. The deletion or dysfunction of ADAR enzymes in higher eukaryotes can affect the efficiency of substrate editing and cause neurological disorders. However, the information concerning A-to-I RNA editing and ADAR members in the silkworm, Bombyx mori (BmADAR), is limited. In this study, a first molecular comprehensive cloning and sequence analysis of BmADAR transcripts was presented. A complete open reading frame (ORF) (BmADARa) was obtained using RT-PCR and RACE and its expression pattern, subcellular localization and A-to-I RNA-editing function on the silkworm synaptotagmin I (BmSyt I) were investigated. Subcellular localization analysis observed that BmADARa was mainly localized in the nucleus. To further study the A-to-I RNA-editing function of BmADARa, BmSyt I-pIZ-EGFP was constructed and co-transfected with BmADARa-pIZ-EGFP into BmN cells. The result demonstrates that BmADARa can functionally edit the specific site of BmSyt I. Taken together, this study not only provides insight into the function of the first ADAR enzyme in B. mori, but also lays foundations for further exploration of the functional domain of BmADARa and its editing substrates and target sites.
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Affiliation(s)
- Chongjun Ye
- School of Life Sciences, Anhui Agricultural University, 130 West Changjiang Road, Hefei 230036, China; (C.Y.); (S.J.); (Q.M.); (M.F.)
- Institute of Sericulture, Anhui Academy of Agricultural Sciences, 15 Huoshan Road, Hefei 230061, China
| | - Song Jiang
- School of Life Sciences, Anhui Agricultural University, 130 West Changjiang Road, Hefei 230036, China; (C.Y.); (S.J.); (Q.M.); (M.F.)
- Anhui International Joint Research and Development Center of Sericulture Resources Utilization, Hefei 230036, China
| | - Meixia Gong
- Guangxi Zhuang Autonomous Region Research Academy of Sericultural Science, 10 Xiajun Road, Nanning 530007, China;
| | - Qin Min
- School of Life Sciences, Anhui Agricultural University, 130 West Changjiang Road, Hefei 230036, China; (C.Y.); (S.J.); (Q.M.); (M.F.)
| | - Manli Fan
- School of Life Sciences, Anhui Agricultural University, 130 West Changjiang Road, Hefei 230036, China; (C.Y.); (S.J.); (Q.M.); (M.F.)
| | - Junshan Gao
- School of Life Sciences, Anhui Agricultural University, 130 West Changjiang Road, Hefei 230036, China; (C.Y.); (S.J.); (Q.M.); (M.F.)
- Anhui International Joint Research and Development Center of Sericulture Resources Utilization, Hefei 230036, China
- Correspondence: (J.G.); (Y.M.); Tel.: +86-551-65786967 (Y.M.)
| | - Yan Meng
- School of Life Sciences, Anhui Agricultural University, 130 West Changjiang Road, Hefei 230036, China; (C.Y.); (S.J.); (Q.M.); (M.F.)
- Anhui International Joint Research and Development Center of Sericulture Resources Utilization, Hefei 230036, China
- Correspondence: (J.G.); (Y.M.); Tel.: +86-551-65786967 (Y.M.)
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Ma H, Nandakumar S, Bae EH, Chin PJ, Khan AS. The Spodoptera frugiperda Sf9 cell line is a heterogeneous population of rhabdovirus-infected and virus-negative cells: Isolation and characterization of cell clones containing rhabdovirus X-gene variants and virus-negative cell clones. Virology 2019; 536:125-133. [PMID: 31494355 DOI: 10.1016/j.virol.2019.08.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 07/31/2019] [Accepted: 08/01/2019] [Indexed: 11/28/2022]
Abstract
The Sf9 cell line is broadly used for manufacturing baculovirus-expressed viral vaccines. We previously reported the presence of a novel, rhabdovirus in the Sf9 cell line, which contained a unique X gene (Sf-rhabdovirus; designated as X+ in this paper). These results were extended by other reports describing an Sf-rhabdovirus variant in Sf9 cells, which lacked 320 nucleotides encompassing the X-gene and adjacent intergenic region (designated as X- in this paper), and the development of an Sf-rhabdovirus negative cell line. Here, we report that the Sf9 cell line is a mixed-cell population, based upon isolation of cell clones with distinct phenotypes: Sf-rhabdovirus-negative, X+, and X-. We also show that Sf-rhabdovirus X+ and X- variants replicate independently in Sf-rhabdovirus-negative cells. These results shed light on the detection of different rhabdovirus variants by different laboratories using Sf9-derived cell clones and confirm that both X+ and X- viruses are infectious in rhabdovirus-negative Sf9 cells.
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Affiliation(s)
- Hailun Ma
- Division of Viral Products, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, 20993, USA
| | - Subhiksha Nandakumar
- Division of Viral Products, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, 20993, USA
| | - Eunhae H Bae
- Division of Viral Products, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, 20993, USA
| | - Pei-Ju Chin
- Division of Viral Products, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, 20993, USA
| | - Arifa S Khan
- Division of Viral Products, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, 20993, USA.
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Host Range and Population Survey of Spodoptera frugiperda Rhabdovirus. J Virol 2019; 93:JVI.02028-18. [PMID: 30626676 DOI: 10.1128/jvi.02028-18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 12/18/2018] [Indexed: 11/20/2022] Open
Abstract
The Sf9 and Sf21 cell lines derived from ovarian tissues of the wide-host-range phytophagous lepidopteran Spodoptera frugiperda are widely used for research and commercial-scale production of recombinant proteins. These cell lines are chronically infected with a rhabdovirus (Sf-RV) that does not cause any overt cytopathic effects. We demonstrate that wild populations of S. frugiperda in the eastern United States and Caribbean are infected with genetically diverse strains of Sf-RV and that this virus is also capable of infecting cells of Spodoptera exigua, Heliothis subflexa, and Bombyx mori Feeding studies demonstrated the ability of S. frugiperda larvae to deposit Sf-RV onto human-consumed vegetables during feeding. Although no evidence for replication in two species of plant cells was detected, subcellular localization studies demonstrated that the Sf-RV nucleocapsid was targeted to plasmodesmata, while two forms of the accessory protein were differentiated on the basis of their ability to localize to nuclei. Collectively, the results from this study suggest that environmental exposure of humans to Sf-RV is likely to be commonplace and frequent, but its inability to replicate in plant or human cells suggests that there is no substantial risk to human health.IMPORTANCE Insect-derived cell lines are widely used commercially for the production of vaccines and protein-based pharmaceuticals. After decades of safe and beneficial use, it was a surprise to the biotechnology industry to discover an endemic rhabdovirus in Sf9 cells. This discovery was made possible only by the substantial advancements in DNA sequencing technologies. Given the public health concerns associated with many rhabdovirus species, several initiatives were undertaken to establish that Spodoptera frugiperda rhabdovirus (Sf-RV) does not pose a threat to humans. Such actions include the generation of cell lines that have been cleared of Sf-RV. Given that Sf9 is derived from a moth whose larvae feed on human-edible foods, we explored the prevalence of Sf-RV in its wild and lab-grown populations, as well as its ability to be deposited on food items during feeding. Collectively, our data suggest that there is no overt risk from exposure to Sf-RV.
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Geisler C, Jarvis DL. Adventitious viruses in insect cell lines used for recombinant protein expression. Protein Expr Purif 2017; 144:25-32. [PMID: 29133148 DOI: 10.1016/j.pep.2017.11.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 11/08/2017] [Indexed: 11/16/2022]
Abstract
Insect cells are widely used for recombinant protein expression, typically as hosts for recombinant baculovirus vectors, but also for plasmid-mediated transient transfection or stable genetic transformation. Insect cells are used to express proteins for research, as well as to manufacture biologicals for human and veterinary medicine. Recently, several insect cell lines used for recombinant protein expression were found to be persistently infected with adventitious viruses. This has raised questions about how these infections might affect research performed using those cell lines. Furthermore, these findings raised serious concerns about the safety of biologicals produced using those cell lines. In response, new insect cell lines lacking adventitious viruses have been isolated for use as improved research tools and safer biological manufacturing platforms. Here, we review the scientific and patent literature on adventitious viruses found in insect cell lines, affected cell lines, and new virus-free cell lines.
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Affiliation(s)
| | - Donald L Jarvis
- GlycoBac LLC, 1938 Harney Street, Laramie, WY 82072, USA; University of Wyoming, Department of Molecular Biology, 1000 E. University Avenue, Laramie, WY 82071, USA
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Maghodia AB, Jarvis DL. Infectivity of Sf-rhabdovirus variants in insect and mammalian cell lines. Virology 2017; 512:234-245. [PMID: 29024851 DOI: 10.1016/j.virol.2017.09.025] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 09/27/2017] [Accepted: 09/30/2017] [Indexed: 12/31/2022]
Abstract
Sf-rhabdovirus was only recently identified as an adventitious agent of Spodoptera frugiperda (Sf) cell lines used as hosts for baculovirus vectors. As such, we still know little about its genetic variation, infectivity, and the potential impact of variation on the Sf-rhabdovirus-host interaction. Here, we characterized Sf-rhabdoviruses from two widely used Sf cell lines to confirm and extend information on Sf-rhabdovirus variation. We then used our novel Sf-rhabdovirus-negative (Sf-RVN) Sf cell line to assess the infectivity of variants with and without a 320bp X/L deletion and found both established productive persistent infections in Sf-RVN cells. We also assessed their infectivity using heterologous insect and mammalian cell lines and found neither established productive persistent infections in these cells. These results are the first to directly demonstrate Sf-rhabdoviruses are infectious for Sf cells, irrespective of the X/L deletion. They also confirm and extend previous results indicating Sf-rhabdoviruses have a narrow host range.
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Affiliation(s)
| | - Donald L Jarvis
- GlycoBac, LLC, Laramie, WY 82072, USA; Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA.
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