1
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Sari Y, Sousa Rosa S, Jeffries J, Marques MPC. Comprehensive evaluation of T7 promoter for enhanced yield and quality in mRNA production. Sci Rep 2024; 14:9655. [PMID: 38671016 PMCID: PMC11053036 DOI: 10.1038/s41598-024-59978-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 04/17/2024] [Indexed: 04/28/2024] Open
Abstract
The manufacturing of mRNA vaccines relies on cell-free based systems that are easily scalable and flexible compared with the traditional vaccine manufacturing processes. Typically, standard processes yield 2 to 5 g L-1 of mRNA, with recent process optimisations increasing yields to 12 g L-1. However, increasing yields can lead to an increase in the production of unwanted by-products, namely dsRNA. It is therefore imperative to reduce dsRNA to residual levels in order to avoid intensive purification steps, enabling cost-effective manufacturing processes. In this work, we exploit sequence modifications downstream of the T7 RNA polymerase promoter to increase mRNA yields whilst simultaneously minimising dsRNA. In particular, transcription performance was optimised by modifying the sequence downstream of the T7 promoter with additional AT-rich sequences. We have identified variants that were able to produce higher amounts of mRNA (up to 14 g L-1) in 45 min of reaction. These variants exhibited up to a 30% reduction in dsRNA byproduct levels compared to a wildtype T7 promoter, and have similar EGFP protein expression. The results show that optimising the non-coding regions can have an impact on mRNA production yields and quality, reducing overall manufacturing costs.
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Affiliation(s)
- Yustika Sari
- Department of Biochemical Engineering, University College London, Gordon Street, London, WC1E 6BT, UK
| | - Sara Sousa Rosa
- Department of Biochemical Engineering, University College London, Gordon Street, London, WC1E 6BT, UK
- Department of Bioengineering, iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
- Associate Laboratory i4HB-Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Jack Jeffries
- Department of Biochemical Engineering, University College London, Gordon Street, London, WC1E 6BT, UK
| | - Marco P C Marques
- Department of Biochemical Engineering, University College London, Gordon Street, London, WC1E 6BT, UK.
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2
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Deich C, Cash B, Sato W, Sharon J, Aufdembrink L, Gaut NJ, Heili J, Stokes K, Engelhart AE, Adamala KP. T7Max transcription system. J Biol Eng 2023; 17:4. [PMID: 36691081 PMCID: PMC9872363 DOI: 10.1186/s13036-023-00323-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Accepted: 01/04/2023] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Efficient cell-free protein expression from linear DNA templates has remained a challenge primarily due to template degradation. In addition, the yields of transcription in cell-free systems lag behind transcriptional efficiency of live cells. Most commonly used in vitro translation systems utilize T7 RNA polymerase, which is also the enzyme included in many commercial kits. RESULTS Here we present characterization of a variant of T7 RNA polymerase promoter that acts to significantly increase the yields of gene expression within in vitro systems. We have demonstrated that T7Max increases the yield of translation in many types of commonly used in vitro protein expression systems. We also demonstrated increased protein expression yields from linear templates, allowing the use of T7Max driven expression from linear templates. CONCLUSIONS The modified promoter, termed T7Max, recruits standard T7 RNA polymerase, so no protein engineering is needed to take advantage of this method. This technique could be used with any T7 RNA polymerase- based in vitro protein expression system.
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Affiliation(s)
- Christopher Deich
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN, USA
| | - Brock Cash
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN, USA
| | - Wakana Sato
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN, USA
| | - Judee Sharon
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN, USA
| | - Lauren Aufdembrink
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN, USA
| | - Nathaniel J Gaut
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN, USA
| | - Joseph Heili
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN, USA
| | - Kaitlin Stokes
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN, USA
| | - Aaron E Engelhart
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN, USA.
| | - Katarzyna P Adamala
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN, USA.
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3
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Selection of green fluorescent proteins by in vitro compartmentalization using microbead-display libraries. Biochem Eng J 2022. [DOI: 10.1016/j.bej.2022.108627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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4
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Qin W, Li L, Yang F, Wang S, Yang GY. High-throughput iSpinach fluorescent aptamer-based real-time monitoring of in vitro transcription. BIORESOUR BIOPROCESS 2022; 9:112. [PMID: 38647769 PMCID: PMC10991154 DOI: 10.1186/s40643-022-00598-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 09/30/2022] [Indexed: 11/10/2022] Open
Abstract
In vitro transcription (IVT) is an essential technique for RNA synthesis. Methods for the accurate and rapid screening of IVT conditions will facilitate RNA polymerase engineering, promoter optimization, and screening for new transcription inhibitor drugs. However, traditional polyacrylamide gel electrophoresis (PAGE) and high-performance liquid chromatography methods are labor intensive, time consuming and not compatible with real-time analysis. Here, we developed an inexpensive, high-throughput, and real-time detection method for the monitoring of in vitro RNA synthesis called iSpinach aptamer-based monitoring of Transcription Activity in Real-time (STAR). STAR has a detection speed at least 100 times faster than conventional PAGE method and provides comparable results in the analysis of in vitro RNA synthesis reactions. It also can be used as an easy and quantitative method to detect the catalytic activity of T7 RNA polymerase. To further demonstrate the utility of STAR, it was applied to optimize the initially transcribed region of the green fluorescent protein gene and the 3T4T variants demonstrated significantly enhanced transcription output, with at least 1.7-fold and 2.8-fold greater output than the wild-type DNA template and common transcription template, respectively. STAR may provide a valuable tool for many biotechnical applications related to the transcription process, which may pave the way for the development of better RNA-related enzymes and new drugs.
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Affiliation(s)
- Weitong Qin
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Liang Li
- Hzymes Biotechnology Co. Ltd, Hubei, 430010, China
| | - Fan Yang
- Hzymes Biotechnology Co. Ltd, Hubei, 430010, China
| | - Siyuan Wang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Guang-Yu Yang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.
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5
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Santos SP, Garcés LFS, Silva FS, Santiago LF, Pinheiro CS, Alcantara-Neves NM, Pacheco LG. Engineering an optimized expression operating unit for improved recombinant protein production in Escherichia coli. Protein Expr Purif 2022; 199:106150. [DOI: 10.1016/j.pep.2022.106150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 07/26/2022] [Accepted: 07/27/2022] [Indexed: 10/31/2022]
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6
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GAN R, Cabezas MD, Pan M, Zhang H, Hu G, Clark LG, Jewett MC, Nicol R. High-Throughput Regulatory Part Prototyping and Analysis by Cell-Free Protein Synthesis and Droplet Microfluidics. ACS Synth Biol 2022; 11:2108-2120. [PMID: 35549070 DOI: 10.1021/acssynbio.2c00050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Engineering regulatory parts for improved performance in genetic programs has played a pivotal role in the development of the synthetic biology cell programming toolbox. Here, we report the development of a novel high-throughput platform for regulatory part prototyping and analysis that leverages the advantages of engineered DNA libraries, cell-free protein synthesis (CFPS), high-throughput emulsion droplet microfluidics, standard flow sorting adapted to screen droplet reactions, and next-generation sequencing (NGS). With this integrated platform, we screened the activity of millions of genetic parts within hours, followed by NGS retrieval of the improved designs. This in vitro platform is particularly valuable for engineering regulatory parts of nonmodel organisms, where in vivo high-throughput screening methods are not readily available. The platform can be extended to multipart screening of complete genetic programs to optimize yield and stability.
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Affiliation(s)
- Rui GAN
- Broad Institute of MIT and Harvard, Cambridge, 415 Main Street, Cambridge, Massachusetts 02142, United States
| | - Maria D. Cabezas
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3120, United States
| | - Ming Pan
- Broad Institute of MIT and Harvard, Cambridge, 415 Main Street, Cambridge, Massachusetts 02142, United States
| | - Huaibin Zhang
- Broad Institute of MIT and Harvard, Cambridge, 415 Main Street, Cambridge, Massachusetts 02142, United States
| | - Gang Hu
- Broad Institute of MIT and Harvard, Cambridge, 415 Main Street, Cambridge, Massachusetts 02142, United States
| | - Lauren G. Clark
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3120, United States
| | - Michael C. Jewett
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3120, United States
- Interdisciplinary Biological Sciences Program, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3120, United States
- Chemistry of Life Processes Institute, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3120, United States
- Center for Synthetic Biology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3120, United States
| | - Robert Nicol
- Broad Institute of MIT and Harvard, Cambridge, 415 Main Street, Cambridge, Massachusetts 02142, United States
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Lindenburg L, Huovinen T, van de Wiel K, Herger M, Snaith MR, Hollfelder F. Split & mix assembly of DNA libraries for ultrahigh throughput on-bead screening of functional proteins. Nucleic Acids Res 2020; 48:e63. [PMID: 32383757 PMCID: PMC7293038 DOI: 10.1093/nar/gkaa270] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 04/02/2020] [Accepted: 04/21/2020] [Indexed: 12/13/2022] Open
Abstract
Site-saturation libraries reduce protein screening effort in directed evolution campaigns by focusing on a limited number of rationally chosen residues. However, uneven library synthesis efficiency leads to amino acid bias, remedied at high cost by expensive custom synthesis of oligonucleotides, or through use of proprietary library synthesis platforms. To address these shortcomings, we have devised a method where DNA libraries are constructed on the surface of microbeads by ligating dsDNA fragments onto growing, surface-immobilised DNA, in iterative split-and-mix cycles. This method-termed SpliMLiB for Split-and-Mix Library on Beads-was applied towards the directed evolution of an anti-IgE Affibody (ZIgE), generating a 160,000-membered, 4-site, saturation library on the surface of 8 million monoclonal beads. Deep sequencing confirmed excellent library balance (5.1% ± 0.77 per amino acid) and coverage (99.3%). As SpliMLiB beads are monoclonal, they were amenable to direct functional screening in water-in-oil emulsion droplets with cell-free expression. A FACS-based sorting of the library beads allowed recovery of hits improved in Kd over wild-type ZIgE by up to 3.5-fold, while a consensus mutant of the best hits provided a 10-fold improvement. With SpliMLiB, directed evolution workflows are accelerated by integrating high-quality DNA library generation with an ultra-high throughput protein screening platform.
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Affiliation(s)
- Laurens Lindenburg
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Rd, Cambridge CB2 1GA, UK
| | - Tuomas Huovinen
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Rd, Cambridge CB2 1GA, UK
| | - Kayleigh van de Wiel
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Rd, Cambridge CB2 1GA, UK
| | - Michael Herger
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Rd, Cambridge CB2 1GA, UK
- AstraZeneca Medimmune Cambridge, Antibody Discovery and Protein Engineering, Cambridge, UK
| | - Michael R Snaith
- AstraZeneca Medimmune Cambridge, Antibody Discovery and Protein Engineering, Cambridge, UK
| | - Florian Hollfelder
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Rd, Cambridge CB2 1GA, UK
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8
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König L, Szczesny S, Brixius-Anderko S, Bernhardt R, Hannemann F. Mixed-culture fermentation for enhanced C21-hydroxylation of glucocorticoids. J Biotechnol 2020; 314-315:14-24. [DOI: 10.1016/j.jbiotec.2020.03.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 03/10/2020] [Accepted: 03/24/2020] [Indexed: 12/20/2022]
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9
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Terai T, Koike T, Nemoto N. Photocrosslinking of cDNA Display Molecules with Their Target Proteins as a New Strategy for Peptide Selection. Molecules 2020; 25:molecules25061472. [PMID: 32214008 PMCID: PMC7146492 DOI: 10.3390/molecules25061472] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 03/19/2020] [Accepted: 03/23/2020] [Indexed: 12/29/2022] Open
Abstract
Binding peptides for given target molecules are often selected in vitro during drug discovery and chemical biology research. Among several display technologies for this purpose, complementary DNA (cDNA) display (a covalent complex of a peptide and its encoding cDNA linked via a specially designed puromycin-conjugated DNA) is unique in terms of library size, chemical stability, and flexibility of modification. However, selection of cDNA display libraries often suffers from false positives derived from non-specific binding. Although rigorous washing is a straightforward solution, this also leads to the loss of specific binders with moderate affinity because the interaction is non-covalent. To address this issue, herein, we propose a method to covalently link cDNA display molecules with their target proteins using light irradiation. We designed a new puromycin DNA linker that contains a photocrosslinking nucleic acid and prepared cDNA display molecules using the linker. Target proteins were also labeled with a short single-stranded DNA that should transiently hybridize with the linker. Upon ultraviolet (UV) light irradiation, cDNA display molecules encoding correct peptide aptamers made stable crosslinked products with the target proteins in solution, while display molecules encoding control peptides did not. Although further optimization and improvement is necessary, the results pave the way for efficient selection of peptide aptamers in multimolecular crowding biosystems.
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Affiliation(s)
- Takuya Terai
- Correspondence: (T.T.); or (N.N); Tel.: +81-48-858-3534 (T.T.); +81-48-858-3531 (N.N.)
| | | | - Naoto Nemoto
- Correspondence: (T.T.); or (N.N); Tel.: +81-48-858-3534 (T.T.); +81-48-858-3531 (N.N.)
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10
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Abstract
Cell-free systems (CFS) have recently evolved into key platforms for synthetic biology applications. Many synthetic biology tools have traditionally relied on cell-based systems, and while their adoption has shown great progress, the constraints inherent to the use of cellular hosts have limited their reach and scope. Cell-free systems, which can be thought of as programmable liquids, have removed many of these complexities and have brought about exciting opportunities for rational design and manipulation of biological systems. Here we review how these simple and accessible enzymatic systems are poised to accelerate the rate of advancement in synthetic biology and, more broadly, biotechnology.
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Affiliation(s)
- Aidan Tinafar
- Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College St., Toronto, ON, M5S 3M2, Canada
| | - Katariina Jaenes
- Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College St., Toronto, ON, M5S 3M2, Canada
| | - Keith Pardee
- Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College St., Toronto, ON, M5S 3M2, Canada.
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11
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Konczal J, Bower J, Gray CH. Re-introducing non-optimal synonymous codons into codon-optimized constructs enhances soluble recovery of recombinant proteins from Escherichia coli. PLoS One 2019; 14:e0215892. [PMID: 31013332 PMCID: PMC6478350 DOI: 10.1371/journal.pone.0215892] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 04/10/2019] [Indexed: 12/14/2022] Open
Abstract
Gene synthesis services have largely superseded traditional PCR methods for the generation of cDNAs destined for bacterial expression vectors. This, in turn, has increased the application of codon-optimized cDNAs where codons rarely used by Escherchia coli are replaced with common synonymous codons to accelerate translation of the target. A markedly accelerated rate of expression often results in a significant uplift in the levels of target protein but a substantial proportion of the enhanced yield can partition to the insoluble fraction rendering a significant portion of the gains unavailable for native purification. We have assessed several expression attenuation strategies for their utility in the manipulation of the soluble fraction towards higher levels of soluble target recovery from codon optimized systems. Using a set of human small GTPases as a case study, we compare the degeneration of the T7 promoter sequence, the use of alternative translational start codons and the manipulation of synonymous codon usage. Degeneration of both the T7 promoter and the translational start codon merely depressed overall expression and did not increase the percentage of product recovered in native purification of the soluble fraction. However, the selective introduction of rare non-optimal codons back into the codon-optimized sequence resulted in significantly elevated recovery of soluble targets. We propose that slowing the rate of extension during translation using a small number of rare codons allows more time for the co-translational folding of the nascent polypeptide. This increases the proportion of the target recovered in the soluble fraction by immobilized metal affinity chromatography (IMAC). Thus, a "de-optimization" of codon-optimized cDNAs, to attenuate or pause the translation process, may prove a useful strategy for improved recombinant protein production.
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Affiliation(s)
- Jennifer Konczal
- Drug Discovery Program, CRUK Beatson Institute, Glasgow, United Kingdom
| | - Justin Bower
- Drug Discovery Program, CRUK Beatson Institute, Glasgow, United Kingdom
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12
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Promoter RNA sequencing (PRSeq) for the massive and quantitative promoter analysis in vitro. Sci Rep 2019; 9:3118. [PMID: 30816266 PMCID: PMC6395800 DOI: 10.1038/s41598-019-39892-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 02/01/2019] [Indexed: 11/08/2022] Open
Abstract
Analysis of promoter strength and specificity is important for understanding and engineering gene regulation. Here, we report an in vitro promoter analysis method that can achieve both massiveness and quantitativeness. In this approach, a pool of single-stranded DNA with a partially randomized promoter sequence to be analyzed is chemically synthesized. Through enzymatic reactions, the randomized sequence will be copied to the downstream region, resulting in a template DNA pool that carries its own promoter information on its transcribed region. After in vitro transcription of the DNA pool with an RNA polymerase of interest, the sequences of the resulting transcripts will be analyzed. Since the promoter strength linearly correlates to the copy number of transcript, the strength of each promoter sequence can be evaluated. A model experiment of T7 promoter variants demonstrated the quantitativeness of the method, and the method was applied for the analysis of the promoter of cyanophage Syn5 RNA polymerase. This method provides a powerful approach for analyzing the complexity of promoter specificity and discrimination for highly abundant and often redundant alternative sigma factors such as the extracellular function (ECF) sigma factors.
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13
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Koma D, Kishida T, Yamanaka H, Moriyoshi K, Nagamori E, Ohmoto T. Escherichia coli chromosome-based T7-dependent constitutive overexpression system and its application to generating a phenylalanine producing strain. J Biosci Bioeng 2018; 126:586-595. [DOI: 10.1016/j.jbiosc.2018.05.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 05/18/2018] [Accepted: 05/21/2018] [Indexed: 11/16/2022]
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14
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Contreras-Llano LE, Tan C. High-throughput screening of biomolecules using cell-free gene expression systems. Synth Biol (Oxf) 2018; 3:ysy012. [PMID: 32995520 PMCID: PMC7445777 DOI: 10.1093/synbio/ysy012] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 05/31/2018] [Accepted: 06/25/2018] [Indexed: 01/13/2023] Open
Abstract
The incorporation of cell-free transcription and translation systems into high-throughput screening applications enables the in situ and on-demand expression of peptides and proteins. Coupled with modern microfluidic technology, the cell-free methods allow the screening, directed evolution and selection of desired biomolecules in minimal volumes within a short timescale. Cell-free high-throughput screening applications are classified broadly into in vitro display and on-chip technologies. In this review, we outline the development of cell-free high-throughput screening methods. We further discuss operating principles and representative applications of each screening method. The cell-free high-throughput screening methods may be advanced by the future development of new cell-free systems, miniaturization approaches, and automation technologies.
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Affiliation(s)
| | - Cheemeng Tan
- Department of Biomedical Engineering, University of California Davis, Davis, CA, USA
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15
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Wei Y, Mohsin A, Hong Q, Guo M, Fang H. Enhanced production of biosynthesized lycopene via heterogenous MVA pathway based on chromosomal multiple position integration strategy plus plasmid systems in Escherichia coli. BIORESOURCE TECHNOLOGY 2018; 250:382-389. [PMID: 29195149 DOI: 10.1016/j.biortech.2017.11.035] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Revised: 11/09/2017] [Accepted: 11/10/2017] [Indexed: 05/27/2023]
Abstract
The multiple plasmid system, mostly relied, for heterogeneous gene expression, results in genetic instability and low mean productivity. To address this, an integration method was employed for investigating expression of heterogenous pathway in E. coli cells; where mevalonate upper pathway was found efficiently expressed. Subsequently, to improve lycopene production, chromosomal multiple position integration strategy was used to strengthen mevalonate upper pathway. Meanwhile, the plasmid system was employed for mevalonate lower pathway and lycopene pathway expression to finally generate the mutant D711 strain. Comparatively, highest level of 68.5 mg/L lycopene was produced by D711 outperforming its maximum average productivity of 2.85 mg/L/h with over 2-folds enhancement. In addition, lycopene level was almost 224 mg/L after optimization of induction time, which was 3.3-fold higher than standard control condition. Finally, expression Performance Parameter was developed for scoring mutants and evaluating these two strategies, indicating chromosomal multiple position integration strategy as more efficient approach.
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Affiliation(s)
- Yanlong Wei
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, PR China
| | - Ali Mohsin
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, PR China
| | - Qi Hong
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, PR China
| | - Meijin Guo
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, PR China.
| | - Hongqing Fang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, PR China; Institute of Health Sciences, Anhui University, 111 Jiulong Road, Economic and Technology Development Zone, Hefei, Anhui 230601, PR China; Institute of Biotechnology, Academy of Military Medical Sciences, 20 Dongda Street, Beijing 100071, PR China
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16
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Yoo SJ, Kwon T, Lyoo YS. Challenges of influenza A viruses in humans and animals and current animal vaccines as an effective control measure. Clin Exp Vaccine Res 2018; 7:1-15. [PMID: 29399575 PMCID: PMC5795040 DOI: 10.7774/cevr.2018.7.1.1] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Revised: 12/07/2017] [Accepted: 12/12/2017] [Indexed: 11/28/2022] Open
Abstract
Influenza A viruses (IAVs) are genetically diverse and variable pathogens that share various hosts including human, swine, and domestic poultry. Interspecies and intercontinental viral spreads make the ecology of IAV more complex. Beside endemic IAV infections, human has been exposed to pandemic and zoonotic threats from avian and swine influenza viruses. Animal health also has been threatened by high pathogenic avian influenza viruses (in domestic poultry) and reverse zoonosis (in swine). Considering its dynamic interplay between species, prevention and control against IAV should be conducted effectively in both humans and animal sectors. Vaccination is one of the most efficient tools against IAV. Numerous vaccines against animal IAVs have been developed by a variety of vaccine technologies and some of them are currently commercially available. We summarize several challenges in control of IAVs faced by human and animals and discuss IAV vaccines for animal use with those application in susceptible populations.
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Affiliation(s)
- Sung J. Yoo
- College of Veterinary Medicine, Konkuk University, Seoul, Korea
| | - Taeyong Kwon
- College of Veterinary Medicine, Konkuk University, Seoul, Korea
| | - Young S. Lyoo
- College of Veterinary Medicine, Konkuk University, Seoul, Korea
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17
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Malone ML, Cavett VJ, Paegel BM. Chemoselective Coupling Preserves the Substrate Integrity of Surface-Immobilized Oligonucleotides for Emulsion PCR-Based Gene Library Construction. ACS COMBINATORIAL SCIENCE 2017; 19:9-14. [PMID: 28064476 DOI: 10.1021/acscombsci.6b00146] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Combinatorial bead libraries figure prominently in next-generation sequencing and are also important tools for in vitro evolution. The most common methodology for generating such bead libraries, emulsion PCR (emPCR), enzymatically extends bead-immobilized oligonucleotide PCR primers in emulsion droplets containing a single progenitor library member. Primers are almost always immobilized on beads via noncovalent biotin-streptavidin binding. Here, we describe covalent bead functionalization with primers (∼106 primers/2.8-μm-diameter bead) via either azide-alkyne click chemistry or Michael addition. The primers are viable polymerase substrates (4-7% bead-immobilized enzymatic extension product yield from one thermal cycle). Carbodiimide-activated carboxylic acid beads only react with oligonucleotides under conditions that promote nonspecific interactions (low salt, low pH, no detergent), comparably immobilizing primers on beads, but yielding no detectable enzymatic extension product. Click-functionalized beads perform satisfactorily in emPCR of a site-saturation mutagenesis library, generating monoclonal templated beads (104-105 copies/bead, 1.4-kb amplicons). This simpler, chemical approach to primer immobilization may spur more economical library preparation for high-throughput sequencing and enable more complex surface elaboration for in vitro evolution.
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Affiliation(s)
- Marie L. Malone
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Valerie J. Cavett
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Brian M. Paegel
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, Florida 33458, United States
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18
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A mix-and-read drop-based in vitro two-hybrid method for screening high-affinity peptide binders. Sci Rep 2016; 6:22575. [PMID: 26940078 PMCID: PMC4778045 DOI: 10.1038/srep22575] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 02/17/2016] [Indexed: 11/08/2022] Open
Abstract
Drop-based microfluidics have recently become a novel tool by providing a stable linkage between phenotype and genotype for high throughput screening. However, use of drop-based microfluidics for screening high-affinity peptide binders has not been demonstrated due to the lack of a sensitive functional assay that can detect single DNA molecules in drops. To address this sensitivity issue, we introduced in vitro two-hybrid system (IVT2H) into microfluidic drops and developed a streamlined mix-and-read drop-IVT2H method to screen a random DNA library. Drop-IVT2H was based on the correlation between the binding affinity of two interacting protein domains and transcriptional activation of a fluorescent reporter. A DNA library encoding potential peptide binders was encapsulated with IVT2H such that single DNA molecules were distributed in individual drops. We validated drop-IVT2H by screening a three-random-residue library derived from a high-affinity MDM2 inhibitor PMI. The current drop-IVT2H platform is ideally suited for affinity screening of small-to-medium-sized libraries (10(3)-10(6)). It can obtain hits within a single day while consuming minimal amounts of reagents. Drop-IVT2H simplifies and accelerates the drop-based microfluidics workflow for screening random DNA libraries, and represents a novel alternative method for protein engineering and in vitro directed protein evolution.
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19
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Gianella P, Snapp EL, Levy M. An in vitro compartmentalization-based method for the selection of bond-forming enzymes from large libraries. Biotechnol Bioeng 2016; 113:1647-57. [PMID: 26806853 DOI: 10.1002/bit.25939] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 01/10/2016] [Accepted: 01/19/2016] [Indexed: 11/09/2022]
Abstract
We have developed a generalized in vitro compartmentalization-based bead display selection strategy that allows for the identification of enzymes that can perform ligation reactions. Although a number of methods have been developed to evolve such enzymes, many of them are limited in library size (10(6) -10(7) ), do not select for enzymes using a scheme that allows for multiple turnover, or only work on enzymes specific to nucleic acids. This approach is amenable to screening libraries of up to 10(12) protein variants by allowing beads to be overloaded with up to 10(4) unique mutants. Using this approach we isolated a variant of sortase A from Staphylococcus aureus that shows a 114-fold enhancement in kcat /KM in the absence of calcium compared to the wild-type and improved resistance to the inhibitory effects of cell lysates. Unlike the wild-type protein, the newly selected variant shows intracellular activity in the cytoplasm of eukaryotic cells where it may prove useful for intracellular labeling or synthetic biological applications. Biotechnol. Bioeng. 2016;113: 1647-1657. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Paul Gianella
- Department of Biochemistry, Albert Einstein College of Medicine, 1301 Morris Park Ave, Bronx, New York, 10461
| | - Erik L Snapp
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York
| | - Matthew Levy
- Department of Biochemistry, Albert Einstein College of Medicine, 1301 Morris Park Ave, Bronx, New York, 10461. .,Price Center for Genetics and Translational Medicine, 1301 Morris Park Ave, Bronx, New York, 10461.
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20
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Tools and Principles for Microbial Gene Circuit Engineering. J Mol Biol 2016; 428:862-88. [DOI: 10.1016/j.jmb.2015.10.004] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 10/05/2015] [Accepted: 10/06/2015] [Indexed: 12/26/2022]
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21
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Catherine C, Lee SW, Ju JW, Kim HC, Shin HI, Kim YJ, Kim DM. Cell-Free Expression and In Situ Immobilization of Parasite Proteins from Clonorchis sinensis for Rapid Identification of Antigenic Candidates. PLoS One 2015; 10:e0143597. [PMID: 26599101 PMCID: PMC4657965 DOI: 10.1371/journal.pone.0143597] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Accepted: 11/06/2015] [Indexed: 01/05/2023] Open
Abstract
Progress towards genetic sequencing of human parasites has provided the groundwork for a post-genomic approach to develop novel antigens for the diagnosis and treatment of parasite infections. To fully utilize the genomic data, however, high-throughput methodologies are required for functional analysis of the proteins encoded in the genomic sequences. In this study, we investigated cell-free expression and in situ immobilization of parasite proteins as a novel platform for the discovery of antigenic proteins. PCR-amplified parasite DNA was immobilized on microbeads that were also functionalized to capture synthesized proteins. When the microbeads were incubated in a reaction mixture for cell-free synthesis, proteins expressed from the microbead-immobilized DNA were instantly immobilized on the same microbeads, providing a physical linkage between the genetic information and encoded proteins. This approach of in situ expression and isolation enables streamlined recovery and analysis of cell-free synthesized proteins and also allows facile identification of the genes coding antigenic proteins through direct PCR of the microbead-bound DNA.
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Affiliation(s)
- Christy Catherine
- Department of Fine Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon 305–764, Korea
| | - Seung-Won Lee
- Department of Fine Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon 305–764, Korea
| | - Jung Won Ju
- Division of Malaria and Parasitic Diseases, National Institute of Health, Osong 361–951, Korea
| | - Ho-Cheol Kim
- Department of Fine Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon 305–764, Korea
| | - Hyun-Il Shin
- Division of Malaria and Parasitic Diseases, National Institute of Health, Osong 361–951, Korea
| | - Yu Jung Kim
- Division of Malaria and Parasitic Diseases, National Institute of Health, Osong 361–951, Korea
| | - Dong-Myung Kim
- Department of Fine Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon 305–764, Korea
- * E-mail:
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22
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Dodevski I, Markou GC, Sarkar CA. Conceptual and methodological advances in cell-free directed evolution. Curr Opin Struct Biol 2015; 33:1-7. [PMID: 26093059 DOI: 10.1016/j.sbi.2015.04.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 04/14/2015] [Accepted: 04/30/2015] [Indexed: 12/13/2022]
Abstract
Although cell-free directed evolution methods have been used to engineer proteins for nearly two decades, selections on more complex phenotypes have largely remained in the domain of cell-based engineering approaches. Here, we review recent conceptual advances that now enable in vitro display of multimeric proteins, integral membrane proteins, and proteins with an expanded amino acid repertoire. Additionally, we discuss methodological improvements that have enhanced the accessibility, efficiency, and robustness of cell-free approaches. Coupling these advances with the in vitro advantages of creating exceptionally large libraries and precisely controlling all experimental conditions, cell-free directed evolution is poised to contribute significantly to our understanding and engineering of more complex protein phenotypes.
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Affiliation(s)
- Igor Dodevski
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - George C Markou
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Casim A Sarkar
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA; Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
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23
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Rahn J, Hoffmann D, Harder TC, Beer M. Vaccines against influenza A viruses in poultry and swine: Status and future developments. Vaccine 2015; 33:2414-24. [PMID: 25835575 DOI: 10.1016/j.vaccine.2015.03.052] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 03/01/2015] [Accepted: 03/18/2015] [Indexed: 12/29/2022]
Abstract
Influenza A viruses are important pathogens with a very broad host spectrum including domestic poultry and swine. For preventing clinical disease and controlling the spread, vaccination is one of the most efficient tools. Classical influenza vaccines for domestic poultry and swine are conventional inactivated preparations. However, a very broad range of novel vaccine types ranging from (i) nucleic acid-based vaccines, (ii) replicon particles, (iii) subunits and virus-like particles, (iv) vectored vaccines, or (v) live-attenuated vaccines has been described, and some of them are now also used in the field. The different novel approaches for vaccines against avian and swine influenza virus infections are reviewed, and additional features like universal vaccines, novel application approaches and the "differentiating infected from vaccinated animals" (DIVA)-strategy are summarized.
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Affiliation(s)
- J Rahn
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Suedufer 10, 17493 Greifswald-Insel Riems, Germany
| | - D Hoffmann
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Suedufer 10, 17493 Greifswald-Insel Riems, Germany
| | - T C Harder
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Suedufer 10, 17493 Greifswald-Insel Riems, Germany
| | - M Beer
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Suedufer 10, 17493 Greifswald-Insel Riems, Germany.
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24
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Jajesniak P, Seng Wong T. From genetic circuits to industrial-scale biomanufacturing: bacterial promoters as a cornerstone of biotechnology. AIMS BIOENGINEERING 2015. [DOI: 10.3934/bioeng.2015.3.277] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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25
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Lane MD, Seelig B. Advances in the directed evolution of proteins. Curr Opin Chem Biol 2014; 22:129-36. [PMID: 25309990 DOI: 10.1016/j.cbpa.2014.09.013] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 09/13/2014] [Indexed: 12/21/2022]
Abstract
Natural evolution has produced a great diversity of proteins that can be harnessed for numerous applications in biotechnology and pharmaceutical science. Commonly, specific applications require proteins to be tailored by protein engineering. Directed evolution is a type of protein engineering that yields proteins with the desired properties under well-defined conditions and in a practical time frame. While directed evolution has been employed for decades, recent creative developments enable the generation of proteins with previously inaccessible properties. Novel selection strategies, faster techniques, the inclusion of unnatural amino acids or modifications, and the symbiosis of rational design approaches and directed evolution continue to advance protein engineering.
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Affiliation(s)
- Michael D Lane
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA; BioTechnology Institute, University of Minnesota, St. Paul, MN, USA
| | - Burckhard Seelig
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA; BioTechnology Institute, University of Minnesota, St. Paul, MN, USA.
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26
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Smith MT, Wilding KM, Hunt JM, Bennett AM, Bundy BC. The emerging age of cell-free synthetic biology. FEBS Lett 2014; 588:2755-61. [PMID: 24931378 DOI: 10.1016/j.febslet.2014.05.062] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 05/29/2014] [Accepted: 05/30/2014] [Indexed: 01/16/2023]
Abstract
The engineering of and mastery over biological parts has catalyzed the emergence of synthetic biology. This field has grown exponentially in the past decade. As increasingly more applications of synthetic biology are pursued, more challenges are encountered, such as delivering genetic material into cells and optimizing genetic circuits in vivo. An in vitro or cell-free approach to synthetic biology simplifies and avoids many of the pitfalls of in vivo synthetic biology. In this review, we describe some of the innate features that make cell-free systems compelling platforms for synthetic biology and discuss emerging improvements of cell-free technologies. We also select and highlight recent and emerging applications of cell-free synthetic biology.
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Affiliation(s)
- Mark Thomas Smith
- Department of Chemical Engineering, Brigham Young University, Provo, UT, USA
| | - Kristen M Wilding
- Department of Chemical Engineering, Brigham Young University, Provo, UT, USA
| | - Jeremy M Hunt
- Department of Chemical Engineering, Brigham Young University, Provo, UT, USA
| | - Anthony M Bennett
- Department of Chemical Engineering, Brigham Young University, Provo, UT, USA
| | - Bradley C Bundy
- Department of Chemical Engineering, Brigham Young University, Provo, UT, USA.
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27
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Huang LC, Pan X, Yang H, Wan LKD, Stewart-Jones G, Dorrell L, Ogg G. Linking genotype to phenotype on beads: high throughput selection of peptides with biological function. Sci Rep 2013; 3:3030. [PMID: 24149829 PMCID: PMC3805977 DOI: 10.1038/srep03030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 10/08/2013] [Indexed: 11/16/2022] Open
Abstract
Although peptides are well recognised biological molecules in vivo, their selection from libraries is challenging because of relative low affinity whilst in linear conformation. We hypothesized that multiplexed peptides and DNA on the surface of beads would provide a platform for enhanced avidity and the selection of relevant peptides from a library (ORBIT bead display). Using human immunodeficiency virus (HIV-1) gp120 as a target, we identify peptides that inhibit HIV-1 replication in vitro through blocking of protein:protein interaction with the co-receptor CCR5. The bead display approach has many potential applications for probing biological systems and for drug lead development.
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Affiliation(s)
- Li-Chieh Huang
- 1] MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, NIHR Biomedical Research Centre, University of Oxford, UK [2]
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28
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Diamante L, Gatti-Lafranconi P, Schaerli Y, Hollfelder F. In vitro affinity screening of protein and peptide binders by megavalent bead surface display. Protein Eng Des Sel 2013; 26:713-24. [PMID: 23980186 PMCID: PMC3785251 DOI: 10.1093/protein/gzt039] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 06/30/2013] [Accepted: 07/02/2013] [Indexed: 11/12/2022] Open
Abstract
The advent of protein display systems has provided access to tailor-made protein binders by directed evolution. We introduce a new in vitro display system, bead surface display (BeSD), in which a gene is mounted on a bead via strong non-covalent (streptavidin/biotin) interactions and the corresponding protein is displayed via a covalent thioether bond on the DNA. In contrast to previous monovalent or low-copy bead display systems, multiple copies of the DNA and the protein or peptide of interest are displayed in defined quantities (up to 10(6) of each), so that flow cytometry can be used to obtain a measure of binding affinity. The utility of the BeSD in directed evolution is validated by library selections of randomized peptide sequences for binding to the anti-hemagglutinin (HA) antibody that proceed with enrichments in excess of 10(3) and lead to the isolation of high-affinity HA-tags within one round of flow cytometric screening. On-bead K(d) measurements suggest that the selected tags have affinities in the low nanomolar range. In contrast to other display systems (such as ribosome, mRNA and phage display) that are limited to affinity panning selections, BeSD possesses the ability to screen and rank binders by their affinity in vitro, a feature that hitherto has been exclusive to in vivo multivalent cell display systems (such as yeast display).
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Affiliation(s)
| | | | | | - Florian Hollfelder
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, CB2 1GA Cambridge, UK
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29
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Kramps T, Probst J. Messenger RNA-based vaccines: progress, challenges, applications. WILEY INTERDISCIPLINARY REVIEWS-RNA 2013; 4:737-49. [PMID: 23893949 DOI: 10.1002/wrna.1189] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 06/27/2013] [Accepted: 06/27/2013] [Indexed: 12/21/2022]
Abstract
Twenty years after the demonstration that messenger RNA (mRNA) was expressed and immunogenic upon direct injection in mice, the first successful proof-of-concept of specific protection against viral infection in small and large animals was reported. These data indicate wider applicability to infectious disease and should encourage continued translation of mRNA-based prophylactic vaccines into human clinical trials. At the conceptual level, mRNA-based vaccines-more than other genetic vectors-combine the simplicity, safety, and focused immunogenicity of subunit vaccines with favorable immunological properties of live viral vaccines: (1) mRNA vaccines are molecularly defined and carry no excess information. In the environment and upon physical contact, RNA is rapidly degraded by ubiquitous RNases and cannot persist. These characteristics also guarantee tight control over their immunogenic profile (including avoidance of vector-specific immune responses that could interfere with repeated administration), pharmacokinetics, and dosing. (2) mRNA vaccines are synthetically produced by an enzymatic process, just requiring information about the nucleic acid sequence of the desired antigen. This greatly reduces general complications associated with biological vaccine production, such as handling of infectious agents, genetic variability, environmental risks, or restrictions to vaccine distribution. (3) RNA can be tailored to provide potent adjuvant stimuli to the innate immune system by direct activation of RNA-specific receptors; this may reduce the need for additional adjuvants. The formation of native antigen in situ affords great versatility, including intracellular localization, membrane association, posttranslational modification, supra-molecular assembly, or targeted structural optimization of delivered antigen. Messenger RNA vaccines induce balanced immune responses including B cells, helper T cells, and cytotoxic T lymphocytes, rendering them an extremely adaptable platform. This article surveys the design, mode of action, and capabilities of state-of-the-art mRNA vaccines, focusing on the paradigm of influenza prophylaxis.
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