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Yang W, Dai J, Liu J, Guo M, Liu X, Hu S, Gu M, Hu J, Hu Z, Gao R, Liu K, Chen Y, Liu X, Wang X. Intranasal Immunization with a Recombinant Avian Paramyxovirus Serotypes 2 Vector-Based Vaccine Induces Protection against H9N2 Avian Influenza in Chicken. Viruses 2022; 14:v14050918. [PMID: 35632659 PMCID: PMC9144924 DOI: 10.3390/v14050918] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 04/27/2022] [Accepted: 04/27/2022] [Indexed: 12/16/2022] Open
Abstract
Commercial inactivated vaccines against H9N2 avian influenza (AI) have been developed in China since 1990s and show excellent immunogenicity with strong HI antibodies. However, currently approved vaccines cannot meet the clinical demand for a live-vectored vaccine. Newcastle disease virus (NDV) vectored vaccines have shown effective protection in chickens against H9N2 virus. However, preexisting NDV antibodies may affect protective efficacy of the vaccine in the field. Here, we explored avian paramyxovirus serotype 2 (APMV-2) as a vector for developing an H9N2 vaccine via intranasal delivery. APMV-2 belongs to the same genus as NDV, distantly related to NDV in the phylogenetic tree, based on the sequences of Fusion (F) and hemagglutinin-neuraminidase (HN) gene, and has low cross-reactivity with anti-NDV antisera. We incorporated hemagglutinin (HA) of H9N2 into the junction of P and M gene in the APMV-2 genome by being flanked with the gene start, gene end, and UTR of each gene of APMV-2-T4 to generate seven recombinant APMV-2 viruses rAPMV-2/HAs, rAPMV-2-NPUTR-HA, rAPMV-2-PUTR-HA, rAPMV-2-FUTR-HA, rAPMV-2-HNUTR-HA, rAPMV-2-LUTR-HA, and rAPMV-2-MUTR-HA, expressing HA. The rAPMV-2/HAs displayed similar pathogenicity compared with the parental APMV-2-T4 virus and expressed HA protein in infected CEF cells. The NP-UTR facilitated the expression and secretion of HA protein in cells infected with rAPMV-2-NPUTR-HA. Animal studies demonstrated that immunization with rAPMV-2-NPUTR-HA elicited effective H9N2-specific antibody (6.14 ± 1.2 log2) responses and conferred complete immune protection to prevent viral shedding in the oropharyngeal and cloacal swabs from chickens challenged with H9N2 virus. This study suggests that our recombinant APMV-2 virus is safe and immunogenic and can be a useful tool in the combat of H9N2 outbreaks in chicken.
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Affiliation(s)
- Wenhao Yang
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou 225000, China; (W.Y.); (J.D.); (J.L.); (M.G.); (X.L.); (S.H.); (M.G.); (J.H.); (R.G.); (Y.C.)
| | - Jing Dai
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou 225000, China; (W.Y.); (J.D.); (J.L.); (M.G.); (X.L.); (S.H.); (M.G.); (J.H.); (R.G.); (Y.C.)
| | - Jingjing Liu
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou 225000, China; (W.Y.); (J.D.); (J.L.); (M.G.); (X.L.); (S.H.); (M.G.); (J.H.); (R.G.); (Y.C.)
| | - Mengjiao Guo
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou 225000, China; (W.Y.); (J.D.); (J.L.); (M.G.); (X.L.); (S.H.); (M.G.); (J.H.); (R.G.); (Y.C.)
| | - Xiaowen Liu
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou 225000, China; (W.Y.); (J.D.); (J.L.); (M.G.); (X.L.); (S.H.); (M.G.); (J.H.); (R.G.); (Y.C.)
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou 225000, China; (Z.H.); (K.L.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225000, China
| | - Shunlin Hu
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou 225000, China; (W.Y.); (J.D.); (J.L.); (M.G.); (X.L.); (S.H.); (M.G.); (J.H.); (R.G.); (Y.C.)
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou 225000, China; (Z.H.); (K.L.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225000, China
| | - Min Gu
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou 225000, China; (W.Y.); (J.D.); (J.L.); (M.G.); (X.L.); (S.H.); (M.G.); (J.H.); (R.G.); (Y.C.)
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou 225000, China; (Z.H.); (K.L.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225000, China
| | - Jiao Hu
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou 225000, China; (W.Y.); (J.D.); (J.L.); (M.G.); (X.L.); (S.H.); (M.G.); (J.H.); (R.G.); (Y.C.)
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou 225000, China; (Z.H.); (K.L.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225000, China
| | - Zenglei Hu
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou 225000, China; (Z.H.); (K.L.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225000, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou 225000, China
| | - Ruyi Gao
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou 225000, China; (W.Y.); (J.D.); (J.L.); (M.G.); (X.L.); (S.H.); (M.G.); (J.H.); (R.G.); (Y.C.)
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou 225000, China; (Z.H.); (K.L.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225000, China
| | - Kaituo Liu
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou 225000, China; (Z.H.); (K.L.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225000, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou 225000, China
| | - Yu Chen
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou 225000, China; (W.Y.); (J.D.); (J.L.); (M.G.); (X.L.); (S.H.); (M.G.); (J.H.); (R.G.); (Y.C.)
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou 225000, China; (Z.H.); (K.L.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225000, China
| | - Xiufan Liu
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou 225000, China; (W.Y.); (J.D.); (J.L.); (M.G.); (X.L.); (S.H.); (M.G.); (J.H.); (R.G.); (Y.C.)
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou 225000, China; (Z.H.); (K.L.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225000, China
- Correspondence: (X.L.); (X.W.)
| | - Xiaoquan Wang
- Animal Infectious Disease Laboratory, School of Veterinary Medicine, Yangzhou University, Yangzhou 225000, China; (W.Y.); (J.D.); (J.L.); (M.G.); (X.L.); (S.H.); (M.G.); (J.H.); (R.G.); (Y.C.)
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou 225000, China; (Z.H.); (K.L.)
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225000, China
- Correspondence: (X.L.); (X.W.)
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Nanopore sequencing approach for variation detection of a live attenuated Newcastle disease virus vaccine. Biotechniques 2022; 72:201-206. [PMID: 35311385 DOI: 10.2144/btn-2022-0014] [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: 11/23/2022] Open
Abstract
Live attenuated Newcastle disease virus (NDV) vaccines have been used widely to protect chickens against Newcastle disease. However, the vaccine issues caused by genome mutations can seriously affect poultry health. In this study, the authors demonstrate the use of nanopore sequencing technology for rapid genome determination and variation analysis from a live attenuated NDV vaccine. NDV-specific reads were detected immediately after sequencing, and 24× genome coverage was obtained within 10 min. Variation analysis revealed 19 variant sites across the vaccine genome compared to the NDV clone 30 reference sequence . The sequencing and data analysis workflow employed enables all basic molecular biology laboratories to perform detailed genome sequencing in live attenuated vaccine, providing an effective means of quality control for vaccine production.
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Cole AW, Tran SD, Ellington AD. Heat adaptation of phage T7 under an extended genetic code. Virus Evol 2021; 7:veab100. [PMID: 35299785 PMCID: PMC8923235 DOI: 10.1093/ve/veab100] [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: 03/24/2021] [Revised: 10/13/2021] [Accepted: 11/30/2021] [Indexed: 11/13/2022] Open
Abstract
Abstract
While bacteriophages have previously been used as a model system to understand thermal adaptation, most adapted genomes observed to date contain very few modifications and cover a limited temperature range. Here, we set out to investigate genome adaptation to thermal stress by adapting six populations of T7 bacteriophage virions to increasingly stringent heat challenges. Further, we provided three of the phage populations’ access to a new genetic code in which Amber codons could be read as selenocysteine, potentially allowing the formation of more stable selenide-containing bonds. Phage virions responded to the thermal challenges with a greater than 10°C increase in heat tolerance and fixed highly reproducible patterns of non-synonymous substitutions and genome deletions. Most fixed mutations mapped to either the tail complex or to the three internal virion proteins that form a pore across the E. coli cell membrane during DNA injection. However, few global changes in Amber codon usage were observed, with only one natural Amber codon being lost. These results reinforce a model in which adaptation to thermal stress proceeds via the cumulative fixation of a small set of highly adaptive substitutions and that adaptation to new genetic codes proceeds only slowly, even with the possibility of potential phenotypic advantages.
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Affiliation(s)
- Austin W Cole
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas, 2500 Speedway Ave., MBB 3.424, Austin, TX 78712, USA
| | - Steven D Tran
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas, 2500 Speedway Ave., MBB 3.424, Austin, TX 78712, USA
| | - Andrew D Ellington
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas, 2500 Speedway Ave., MBB 3.424, Austin, TX 78712, USA
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Scalable live-attenuated SARS-CoV-2 vaccine candidate demonstrates preclinical safety and efficacy. Proc Natl Acad Sci U S A 2021; 118:2102775118. [PMID: 34193524 PMCID: PMC8307828 DOI: 10.1073/pnas.2102775118] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
This work demonstrates the feasibility of rationally designing and synthesizing vaccine candidates for testing in response to an emerging disease in real world conditions. Furthermore, using a live attenuated codon-pair–deoptimized virus approach ensures that all components of the host immune system will be engaged, and potential effects from the vector sequences from hybrid live viruses are avoided. Evidence from other codon-deoptimized viruses suggests that COVI-VAC will be resistant to reversion and loss of potency due to antigenic drift. The ease of large-scale virus growth under permissive conditions coupled with the potential for single-dose intranasal administration make COVI-VAC an appealing candidate for clinical testing for possible use in mass immunization programs. Successfully combating the COVID-19 pandemic depends on mass vaccination with suitable vaccines to achieve herd immunity. Here, we describe COVI-VAC, the only live attenuated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine currently in clinical development. COVI-VAC was developed by recoding a segment of the viral spike protein with synonymous suboptimal codon pairs (codon-pair deoptimization), thereby introducing 283 silent (point) mutations. In addition, the furin cleavage site within the spike protein was deleted from the viral genome for added safety of the vaccine strain. Except for the furin cleavage site deletion, the COVI-VAC and parental SARS-CoV-2 amino acid sequences are identical, ensuring that all viral proteins can engage with the host immune system of vaccine recipients. COVI-VAC was temperature sensitive in vitro yet grew robustly (>107 plaque forming units/mL) at the permissive temperature. Tissue viral loads were consistently lower, lung pathology milder, and weight loss reduced in Syrian golden hamsters (Mesocricetus auratus) vaccinated intranasally with COVI-VAC compared to those inoculated with wild-type (WT) virus. COVI-VAC inoculation generated spike IgG antibody levels and plaque reduction neutralization titers similar to those in hamsters inoculated with WT virus. Upon challenge with WT virus, COVI-VAC vaccination reduced lung challenge viral titers, resulted in undetectable virus in the brain, and protected hamsters from almost all SARS-CoV-2–associated weight loss. Highly attenuated COVI-VAC is protective at a single intranasal dose in a relevant in vivo model. This, coupled with its large-scale manufacturing potential, supports its potential use in mass vaccination programs.
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5
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Pereira-Gómez M, Carrau L, Fajardo Á, Moreno P, Moratorio G. Altering Compositional Properties of Viral Genomes to Design Live-Attenuated Vaccines. Front Microbiol 2021; 12:676582. [PMID: 34276608 PMCID: PMC8278477 DOI: 10.3389/fmicb.2021.676582] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 06/01/2021] [Indexed: 12/11/2022] Open
Abstract
Live-attenuated vaccines have been historically used to successfully prevent numerous diseases caused by a broad variety of RNA viruses due to their ability to elicit strong and perdurable immune-protective responses. In recent years, various strategies have been explored to achieve viral attenuation by rational genetic design rather than using classic and empirical approaches, based on successive passages in cell culture. A deeper understanding of evolutionary implications of distinct viral genomic compositional aspects, as well as substantial advances in synthetic biology technologies, have provided a framework to achieve new viral attenuation strategies. Herein, we will discuss different approaches that are currently applied to modify compositional features of viruses in order to develop novel live-attenuated vaccines.
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Affiliation(s)
- Marianoel Pereira-Gómez
- Laboratorio de Virología Molecular, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
- Laboratorio de Evolución Experimental de Virus, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Lucía Carrau
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Álvaro Fajardo
- Laboratorio de Virología Molecular, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
- Laboratorio de Evolución Experimental de Virus, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Pilar Moreno
- Laboratorio de Virología Molecular, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
- Laboratorio de Evolución Experimental de Virus, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Gonzalo Moratorio
- Laboratorio de Virología Molecular, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
- Laboratorio de Evolución Experimental de Virus, Institut Pasteur de Montevideo, Montevideo, Uruguay
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6
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Bailey SF, Alonso Morales LA, Kassen R. Effects of synonymous mutations beyond codon bias: The evidence for adaptive synonymous substitutions from microbial evolution experiments. Genome Biol Evol 2021; 13:6300525. [PMID: 34132772 PMCID: PMC8410137 DOI: 10.1093/gbe/evab141] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/10/2021] [Indexed: 12/22/2022] Open
Abstract
Synonymous mutations are often assumed to be neutral with respect to fitness because they do not alter the encoded amino acid and so cannot be 'seen' by natural selection. Yet a growing body of evidence suggests that synonymous mutations can have fitness effects that drive adaptive evolution through their impacts on gene expression and protein folding. Here, we review what microbial experiments have taught us about the contribution of synonymous mutations to adaptation. A survey of site-directed mutagenesis experiments reveals the distributions of fitness effects for nonsynonymous and synonymous mutations are more similar, especially for beneficial mutations, than expected if all synonymous mutations were neutral, suggesting they should drive adaptive evolution more often than is typically observed. A review of experimental evolution studies where synonymous mutations have contributed to adaptation shows they can impact fitness through a range of mechanisms including the creation of illicit RNA polymerase binding sites impacting transcription and changes to mRNA folding stability that modulate translation. We suggest that clonal interference in evolving microbial populations may be the reason synonymous mutations play a smaller role in adaptive evolution than expected based on their observed fitness effects. We finish by discussing the impacts of falsely assuming synonymous mutations are neutral and discuss directions for future work exploring the role of synonymous mutations in adaptive evolution.
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Affiliation(s)
- Susan F Bailey
- Department of Biology, Clarkson University, Potsdam, NY 13699, USA
| | | | - Rees Kassen
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada
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7
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Łobocka M, Dąbrowska K, Górski A. Engineered Bacteriophage Therapeutics: Rationale, Challenges and Future. BioDrugs 2021; 35:255-280. [PMID: 33881767 PMCID: PMC8084836 DOI: 10.1007/s40259-021-00480-z] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/29/2021] [Indexed: 12/20/2022]
Abstract
The current problems with increasing bacterial resistance to antibacterial therapies, resulting in a growing frequency of incurable bacterial infections, necessitates the acceleration of studies on antibacterials of a new generation that could offer an alternative to antibiotics or support their action. Bacteriophages (phages) can kill antibiotic-sensitive as well as antibiotic-resistant bacteria, and thus are a major subject of such studies. Their efficacy in curing bacterial infections has been demonstrated in in vivo experiments and in the clinic. Unlike antibiotics, phages have a narrow range of specificity, which makes them safe for commensal microbiota. However, targeting even only the most clinically relevant strains of pathogenic bacteria requires large collections of well characterized phages, whose specificity would cover all such strains. The environment is a rich source of diverse phages, but due to their complex relationships with bacteria and safety concerns, only some naturally occurring phages can be considered for therapeutic applications. Still, their number and diversity make a detailed characterization of all potentially promising phages virtually impossible. Moreover, no single phage combines all the features required of an ideal therapeutic agent. Additionally, the rapid acquisition of phage resistance by bacteria may make phages already approved for therapy ineffective and turn the search for environmental phages of better efficacy and new specificity into an endless race. An alternative strategy for acquiring phages with desired properties in a short time with minimal cost regarding their acquisition, characterization, and approval for therapy could be based on targeted genome modifications of phage isolates with known properties. The first example demonstrating the potential of this strategy in curing bacterial diseases resistant to traditional therapy is the recent successful treatment of a progressing disseminated Mycobacterium abscessus infection in a teenage patient with the use of an engineered phage. In this review, we briefly present current methods of phage genetic engineering, highlighting their advantages and disadvantages, and provide examples of genetically engineered phages with a modified host range, improved safety or antibacterial activity, and proven therapeutic efficacy. We also summarize novel uses of engineered phages not only for killing pathogenic bacteria, but also for in situ modification of human microbiota to attenuate symptoms of certain bacterial diseases and metabolic, immune, or mental disorders.
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Affiliation(s)
- Małgorzata Łobocka
- Institute of Biochemistry and Biophysics of the Polish Academy of Sciences, Warsaw, Poland
| | - Krystyna Dąbrowska
- Institute of Immunology and Experimental Therapy of the Polish Academy of Sciences, Wrocław, Poland
| | - Andrzej Górski
- Institute of Immunology and Experimental Therapy of the Polish Academy of Sciences, Wrocław, Poland
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8
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Rescue of codon-pair deoptimized respiratory syncytial virus by the emergence of genomes with very large internal deletions that complemented replication. Proc Natl Acad Sci U S A 2021; 118:2020969118. [PMID: 33753491 DOI: 10.1073/pnas.2020969118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recoding viral genomes by introducing numerous synonymous but suboptimal codon pairs-called codon-pair deoptimization (CPD)-provides new types of live-attenuated vaccine candidates. The large number of nucleotide changes resulting from CPD should provide genetic stability to the attenuating phenotype, but this has not been rigorously tested. Human respiratory syncytial virus in which the G and F surface glycoprotein ORFs were CPD (called Min B) was temperature-sensitive and highly restricted in vitro. When subjected to selective pressure by serial passage at increasing temperatures, Min B substantially regained expression of F and replication fitness. Whole-genome deep sequencing showed many point mutations scattered across the genome, including one combination of six linked point mutations. However, their reintroduction into Min B provided minimal rescue. Further analysis revealed viral genomes bearing very large internal deletions (LD genomes) that accumulated after only a few passages. The deletions relocated the CPD F gene to the first or second promoter-proximal gene position. LD genomes amplified de novo in Min B-infected cells were encapsidated, expressed high levels of F, and complemented Min B replication in trans This study provides insight on a variation of the adaptability of a debilitated negative-strand RNA virus, namely the generation of defective minihelper viruses to overcome its restriction. This is in contrast to the common "defective interfering particles" that interfere with the replication of the virus from which they originated. To our knowledge, defective genomes that promote rather than inhibit replication have not been reported before in RNA viruses.
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9
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Thompson JD, Ripp R, Mayer C, Poch O, Michel CJ. Potential role of the X circular code in the regulation of gene expression. Biosystems 2021; 203:104368. [PMID: 33567309 DOI: 10.1016/j.biosystems.2021.104368] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 01/18/2021] [Accepted: 01/20/2021] [Indexed: 02/06/2023]
Abstract
The X circular code is a set of 20 trinucleotides (codons) that has been identified in the protein-coding genes of most organisms (bacteria, archaea, eukaryotes, plasmids, viruses). It has been shown previously that the X circular code has the important mathematical property of being an error-correcting code. Thus, motifs of the X circular code, i.e. a series of codons belonging to X and called X motifs, allow identification and maintenance of the reading frame in genes. X motifs are significantly enriched in protein-coding genes, but have also been identified in many transfer RNA (tRNA) genes and in important functional regions of the ribosomal RNA (rRNA), notably in the peptidyl transferase center and the decoding center. Here, we investigate the potential role of X motifs as functional elements of protein-coding genes. First, we identify the codons of the X circular code which are frequent or rare in each domain of life (archaea, bacteria, eukaryota) and show that, for the amino acids with the highest codon bias, the preferred codon is often an X codon. We also observe a correlation between the 20 X codons and the optimal codons/dicodons that have been shown to influence translation efficiency. Then, we examined recently published experimental results concerning gene expression levels in diverse organisms. The approach used is the analysis of X motifs according to their density ds(X), i.e. the number of X motifs per kilobase in a gene sequence s. Surprisingly, this simple parameter identifies several unexpected relations between the X circular code and gene expression. For example, the X motifs are significantly enriched in the minimal gene set belonging to the three domains of life, and in codon-optimized genes. Furthermore, the density of X motifs generally correlates with experimental measures of translation efficiency and mRNA stability. Taken together, these results lead us to propose that the X motifs may represent a genetic signal contributing to the maintenance of the correct reading frame and the optimization and regulation of gene expression.
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Affiliation(s)
- Julie D Thompson
- Department of Computer Science, ICube, CNRS, University of Strasbourg, Strasbourg, France.
| | - Raymond Ripp
- Department of Computer Science, ICube, CNRS, University of Strasbourg, Strasbourg, France.
| | - Claudine Mayer
- Department of Computer Science, ICube, CNRS, University of Strasbourg, Strasbourg, France; Unité de Microbiologie Structurale, Institut Pasteur, CNRS, 75724, Paris Cedex 15, France; Université Paris Diderot, Sorbonne Paris Cité, 75724, Paris Cedex 15, France.
| | - Olivier Poch
- Department of Computer Science, ICube, CNRS, University of Strasbourg, Strasbourg, France.
| | - Christian J Michel
- Department of Computer Science, ICube, CNRS, University of Strasbourg, Strasbourg, France.
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10
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Van Leuven JT, Ederer MM, Burleigh K, Scott L, Hughes RA, Codrea V, Ellington AD, Wichman HA, Miller CR. ΦX174 Attenuation by Whole-Genome Codon Deoptimization. Genome Biol Evol 2020; 13:5921183. [PMID: 33045052 PMCID: PMC7881332 DOI: 10.1093/gbe/evaa214] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/07/2020] [Indexed: 12/11/2022] Open
Abstract
Natural selection acting on synonymous mutations in protein-coding genes influences genome composition and evolution. In viruses, introducing synonymous mutations in genes encoding structural proteins can drastically reduce viral growth, providing a means to generate potent, live-attenuated vaccine candidates. However, an improved understanding of what compositional features are under selection and how combinations of synonymous mutations affect viral growth is needed to predictably attenuate viruses and make them resistant to reversion. We systematically recoded all nonoverlapping genes of the bacteriophage ΦX174 with codons rarely used in its Escherichia coli host. The fitness of recombinant viruses decreases as additional deoptimizing mutations are made to the genome, although not always linearly, and not consistently across genes. Combining deoptimizing mutations may reduce viral fitness more or less than expected from the effect size of the constituent mutations and we point out difficulties in untangling correlated compositional features. We test our model by optimizing the same genes and find that the relationship between codon usage and fitness does not hold for optimization, suggesting that wild-type ΦX174 is at a fitness optimum. This work highlights the need to better understand how selection acts on patterns of synonymous codon usage across the genome and provides a convenient system to investigate the genetic determinants of virulence.
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Affiliation(s)
- James T Van Leuven
- Department of Biological Science, University of Idaho.,Institute for Modeling Collaboration and Innovation, University of Idaho
| | | | - Katelyn Burleigh
- Department of Biological Science, University of Idaho.,Present address: Seattle Children's Research Institute, Seattle, WA
| | - LuAnn Scott
- Department of Biological Science, University of Idaho
| | - Randall A Hughes
- Applied Research Laboratories, University of Texas, Austin.,Present address: Biotechnology Branch, CCDC US Army Research Laboratory, Adelphi, MD
| | - Vlad Codrea
- Institute for Cellular and Molecular Biology, University of Texas, Austin
| | - Andrew D Ellington
- Applied Research Laboratories, University of Texas, Austin.,Institute for Cellular and Molecular Biology, University of Texas, Austin
| | - Holly A Wichman
- Department of Biological Science, University of Idaho.,Institute for Modeling Collaboration and Innovation, University of Idaho
| | - Craig R Miller
- Department of Biological Science, University of Idaho.,Institute for Modeling Collaboration and Innovation, University of Idaho
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11
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Ge Z, Li X, Cao X, Wang R, Hu W, Gen L, Han S, Shang Y, Liu Y, Zhou JH. Viral adaption of staphylococcal phage: A genome-based analysis of the selective preference based on codon usage Bias. Genomics 2020; 112:4657-4665. [PMID: 32818632 DOI: 10.1016/j.ygeno.2020.08.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 07/19/2020] [Accepted: 08/11/2020] [Indexed: 12/09/2022]
Abstract
Given the high therapeutic value of the staphylococcal phage, the genome co-evolution of the phage and the host has gained great attention. Though the genome-wide AT richness in staphylococcal phages has been well-studied with nucleotide usage bias, here we proved that host factor, lifestyle and taxonomy are also important factors in understanding the phage nucleotide usages bias using information entropy formula. Such correlation is especially prominent when it comes to the synonymous codon usages of staphylococcal phages, despite the overall scattered codon usage pattern represented by principal component analysis. This strong relationship is explained by nucleotide skew which testified that the usage biases of nucleotide at different codon positions are acting on synonymous codons. Therefore, our study reveals a hidden relationship of genome evolution with host limitation and phagic phenotype, providing new insight into phage genome evolution at genetic level.
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Affiliation(s)
- Zhiyi Ge
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, Gansu, PR China
| | - Xuerui Li
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, Gansu, PR China
| | - Xiaoan Cao
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, Gansu, PR China
| | - Rui Wang
- Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, United States of America
| | - Wen Hu
- Gansu Police Vocational College, Lanzhou 730046, Gansu, PR China
| | - Ling Gen
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, Gansu, PR China
| | - Shengyi Han
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, Gansu, PR China; The College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, Gansu Province, PR China
| | - Youjun Shang
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, Gansu, PR China
| | - Yongsheng Liu
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, Gansu, PR China
| | - Jian-Hua Zhou
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, Gansu, PR China.
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12
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Isaev A, Drobiazko A, Sierro N, Gordeeva J, Yosef I, Qimron U, Ivanov NV, Severinov K. Phage T7 DNA mimic protein Ocr is a potent inhibitor of BREX defence. Nucleic Acids Res 2020; 48:5397-5406. [PMID: 32338761 PMCID: PMC7261183 DOI: 10.1093/nar/gkaa290] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 04/08/2020] [Accepted: 04/16/2020] [Indexed: 11/12/2022] Open
Abstract
BREX (for BacteRiophage EXclusion) is a superfamily of common bacterial and archaeal defence systems active against diverse bacteriophages. While the mechanism of BREX defence is currently unknown, self versus non-self differentiation requires methylation of specific asymmetric sites in host DNA by BrxX (PglX) methyltransferase. Here, we report that T7 bacteriophage Ocr, a DNA mimic protein that protects the phage from the defensive action of type I restriction-modification systems, is also active against BREX. In contrast to the wild-type phage, which is resistant to BREX defence, T7 lacking Ocr is strongly inhibited by BREX, and its ability to overcome the defence could be complemented by Ocr provided in trans. We further show that Ocr physically associates with BrxX methyltransferase. Although BREX+ cells overproducing Ocr have partially methylated BREX sites, their viability is unaffected. The result suggests that, similar to its action against type I R-M systems, Ocr associates with as yet unidentified BREX system complexes containing BrxX and neutralizes their ability to both methylate and exclude incoming phage DNA.
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Affiliation(s)
- Artem Isaev
- Skolkovo Institute of Science and Technology, Moscow 143028, Russia
| | - Alena Drobiazko
- Skolkovo Institute of Science and Technology, Moscow 143028, Russia
| | - Nicolas Sierro
- Philip Morris International R&D, Philip Morris Products S.A., Neuchatel 2000, Switzerland
| | - Julia Gordeeva
- Skolkovo Institute of Science and Technology, Moscow 143028, Russia
| | - Ido Yosef
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Udi Qimron
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Nikolai V Ivanov
- Philip Morris International R&D, Philip Morris Products S.A., Neuchatel 2000, Switzerland
| | - Konstantin Severinov
- Skolkovo Institute of Science and Technology, Moscow 143028, Russia
- Waksman Institute of Microbiology, Piscataway, NJ 08854, USA
- Institute of Gene Biology, Russian Academy of Sciences, Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov str., 119334 Moscow, Russia
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13
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Jack BR, Boutz DR, Paff ML, Smith BL, Wilke CO. Transcript degradation and codon usage regulate gene expression in a lytic phage. Virus Evol 2019; 5:vez055. [PMID: 31908847 PMCID: PMC6938266 DOI: 10.1093/ve/vez055] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Many viral genomes are small, containing only single- or double-digit numbers of genes and relatively few regulatory elements. Yet viruses successfully execute complex regulatory programs as they take over their host cells. Here, we propose that some viruses regulate gene expression via a carefully balanced interplay between transcription, translation, and transcript degradation. As our model system, we employ bacteriophage T7, whose genome of approximately sixty genes is well annotated and for which there is a long history of computational models of gene regulation. We expand upon prior modeling work by implementing a stochastic gene expression simulator that tracks individual transcripts, polymerases, ribosomes, and ribonucleases participating in the transcription, translation, and transcript-degradation processes occurring during a T7 infection. By combining this detailed mechanistic modeling of a phage infection with high-throughput gene expression measurements of several strains of bacteriophage T7, evolved and engineered, we can show that both the dynamic interplay between transcription and transcript degradation, and between these two processes and translation, appear to be critical components of T7 gene regulation. Our results point to targeted degradation as a generic gene regulation strategy that may have evolved in many other viruses. Further, our results suggest that detailed mechanistic modeling may uncover the biological mechanisms at work in both evolved and engineered virus variants.
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Affiliation(s)
- Benjamin R Jack
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, USA
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, USA
| | - Daniel R Boutz
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, USA
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, USA
| | - Matthew L Paff
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, USA
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, USA
| | - Bartram L Smith
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, USA
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, USA
| | - Claus O Wilke
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, USA
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, USA
- Corresponding author: E-mail:
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14
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Le Nouën C, Collins PL, Buchholz UJ. Attenuation of Human Respiratory Viruses by Synonymous Genome Recoding. Front Immunol 2019; 10:1250. [PMID: 31231383 PMCID: PMC6558635 DOI: 10.3389/fimmu.2019.01250] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 05/16/2019] [Indexed: 01/01/2023] Open
Abstract
Using computer algorithms and commercial DNA synthesis, one or more ORFs of a microbial pathogen such as a virus can be recoded and deoptimized by several strategies that may involve the introduction of up to thousands of nucleotide (nt) changes without affecting amino acid (aa) coding. The synonymous recoding strategies that have been applied to RNA viruses include: deoptimization of codon or codon-pair usage, which may reduce protein expression among other effects; increased content of immunomodulatory CpG and UpA RNA, which increase immune responses and thereby restrict viral replication; and substitution of serine and leucine codons with synonymous codons for which single-nt substitutions can yield nonsense codons, thus limiting evolutionary potential. This can reduce pathogen fitness and create potential live-attenuated vaccines that may have improved properties. The combined approach of genome recoding, synthetic biology, and reverse genetics offers several advantages for the generation of attenuated RNA viruses. First, synonymous recoding involves many mutations, which should reduce the rate and magnitude of de-attenuation. Second, increasing the amount of recoding can provide increased attenuation. Third, because there are no changes at the aa level, all of the relevant epitopes should be expressed. Fourth, attenuation frequently does not compromise immunogenicity, suggesting that the recoded viruses have increased immunogenicity per infectious particle. Synonymous deoptimization approaches have been applied to two important human viral pathogens, namely respiratory syncytial virus (RSV) and influenza A virus (IAV). This manuscript will briefly review the use of these different methods of synonymous recoding to generate attenuated RSV and IAV strains. It also will review the characterization of these vaccine candidates in vitro and in animal models, and describe several surprising findings with respect to phenotypic and genetic instability of some of these candidates.
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Affiliation(s)
- Cyril Le Nouën
- RNA Viruses Section, LID, NIAID, NIH, Bethesda, MD, United States
| | - Peter L Collins
- RNA Viruses Section, LID, NIAID, NIH, Bethesda, MD, United States
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15
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Abstract
Heterologously expressed genes require adaptation to the host organism to ensure adequate levels of protein synthesis, which is typically approached by replacing codons by the target organism’s preferred codons. In view of frequently encountered suboptimal outcomes we introduce the codon-specific elongation model (COSEM) as an alternative concept. COSEM simulates ribosome dynamics during mRNA translation and informs about protein synthesis rates per mRNA in an organism- and context-dependent way. Protein synthesis rates from COSEM are integrated with further relevant covariates such as translation accuracy into a protein expression score that we use for codon optimization. The scoring algorithm further enables fine-tuning of protein expression including deoptimization and is implemented in the software OCTOPOS. The protein expression score produces competitive predictions on proteomic data from prokaryotic, eukaryotic, and human expression systems. In addition, we optimized and tested heterologous expression of manA and ova genes in Salmonella enterica serovar Typhimurium. Superiority over standard methodology was demonstrated by a threefold increase in protein yield compared to wildtype and commercially optimized sequences.
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16
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Abstract
Live viral vaccines rely on attenuated viruses that can successfully infect their host but have reduced fitness or virulence. Such attenuated viruses were originally developed through trial and error, typically by adaptation of the wild-type virus to novel conditions. That method was haphazard, with no way of controlling the degree of attenuation or the number of attenuating mutations or preventing evolutionary reversion. Synthetic biology now enables rational design and engineering of viral attenuation, but rational design must be informed by biological principles to achieve stable, quantitative attenuation. This work shows that in a model system for viral attenuation, bacteriophage T7, attenuation can be obtained from rational design principles, and multiple different attenuation approaches can be combined for enhanced overall effect. Attenuated viruses have numerous applications, in particular in the context of live viral vaccines. However, purposefully designing attenuated viruses remains challenging, in particular if the attenuation is meant to be resistant to rapid evolutionary recovery. Here we develop and analyze a new attenuation method, promoter ablation, using an established viral model, bacteriophage T7. Ablation of promoters of the two most highly expressed T7 proteins (scaffold and capsid) led to major reductions in transcript abundance of the affected genes, with the effect of the double knockout approximately additive of the effects of single knockouts. Fitness reduction was moderate and also approximately additive; fitness recovery on extended adaptation was partial and did not restore the promoters. The fitness effect of promoter knockouts combined with a previously tested codon deoptimization of the capsid gene was less than additive, as anticipated from their competing mechanisms of action. In one design, the engineering created an unintended consequence that led to further attenuation, the effect of which was studied and understood in hindsight. Overall, the mechanisms and effects of genome engineering on attenuation behaved in a predictable manner. Therefore, this work suggests that the rational design of viral attenuation methods is becoming feasible. IMPORTANCE Live viral vaccines rely on attenuated viruses that can successfully infect their host but have reduced fitness or virulence. Such attenuated viruses were originally developed through trial and error, typically by adaptation of the wild-type virus to novel conditions. That method was haphazard, with no way of controlling the degree of attenuation or the number of attenuating mutations or preventing evolutionary reversion. Synthetic biology now enables rational design and engineering of viral attenuation, but rational design must be informed by biological principles to achieve stable, quantitative attenuation. This work shows that in a model system for viral attenuation, bacteriophage T7, attenuation can be obtained from rational design principles, and multiple different attenuation approaches can be combined for enhanced overall effect.
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17
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Kula A, Saelens J, Cox J, Schubert AM, Travisano M, Putonti C. The Evolution of Molecular Compatibility between Bacteriophage ΦX174 and its Host. Sci Rep 2018; 8:8350. [PMID: 29844443 PMCID: PMC5974221 DOI: 10.1038/s41598-018-25914-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 05/01/2018] [Indexed: 12/05/2022] Open
Abstract
Viruses rely upon their hosts for biosynthesis of viral RNA, DNA and protein. This dependency frequently engenders strong selection for virus genome compatibility with potential hosts, appropriate gene regulation and expression necessary for a successful infection. While bioinformatic studies have shown strong correlations between codon usage in viral and host genomes, the selective factors by which this compatibility evolves remain a matter of conjecture. Engineered to include codons with a lesser usage and/or tRNA abundance within the host, three different attenuated strains of the bacterial virus ФX174 were created and propagated via serial transfers. Molecular sequence data indicate that biosynthetic compatibility was recovered rapidly. Extensive computational simulations were performed to assess the role of mutational biases as well as selection for translational efficiency in the engineered phage. Using bacteriophage as a model system, we can begin to unravel the evolutionary processes shaping codon compatibility between viruses and their host.
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Affiliation(s)
- Alexander Kula
- Department of Biology, Loyola University Chicago, Chicago, IL, USA.,Department of Biology, University of Miami, Coral Gables, FL, USA
| | - Joseph Saelens
- Bioinformatics Program, Loyola University Chicago, Chicago, IL, USA.,Department of Molecular Genetics and Microbiology, Duke University, Durham, NC, USA
| | - Jennifer Cox
- Department of Biology, Loyola University Chicago, Chicago, IL, USA
| | - Alyxandria M Schubert
- Bioinformatics Program, Loyola University Chicago, Chicago, IL, USA.,Division of Bacterial, Parasitic, and Allergenic Products, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, USA
| | - Michael Travisano
- Department of Ecology, Evolution and Behavior, University of Minnesota, Saint Paul, MN, USA.,BioTechnology Institute, University of Minnesota, Saint Paul, MN, USA
| | - Catherine Putonti
- Department of Biology, Loyola University Chicago, Chicago, IL, USA. .,Bioinformatics Program, Loyola University Chicago, Chicago, IL, USA. .,Department of Computer Science, Loyola University Chicago, Chicago, IL, USA.
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18
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Abstract
Background Synthetic virology is an important multidisciplinary scientific field, with emerging applications in biotechnology and medicine, aiming at developing methods to generate and engineer synthetic viruses. In particular, many of the RNA viruses, including among others the Dengue and Zika, are widespread pathogens of significant importance to human health. The ability to design and synthesize such viruses may contribute to exploring novel approaches for developing vaccines and virus based therapies. Results Here we develop a full multidisciplinary pipeline for generation and analysis of synthetic RNA viruses and specifically apply it to Dengue virus serotype 2 (DENV-2). The major steps of the pipeline include comparative genomics of endogenous and synthetic viral strains. Specifically, we show that although the synthetic DENV-2 viruses were found to have lower nucleotide variability, their phenotype, as reflected in the study of the AG129 mouse model morbidity, RNA levels, and neutralization antibodies, is similar or even more pathogenic in comparison to the wildtype master strain. Additionally, the highly variable positions, identified in the analyzed DENV-2 population, were found to overlap with less conserved homologous positions in Zika virus and other Dengue serotypes. These results may suggest that synthetic DENV-2 could enhance virulence if the correct sequence is selected. Conclusions The approach reported in this study can be used to generate and analyze synthetic RNA viruses both on genotypic and on phenotypic level. It could be applied for understanding the functionality and the fitness effects of any set of mutations in viral RNA and for editing RNA viruses for various target applications. Electronic supplementary material The online version of this article (10.1186/s12859-018-2132-3) contains supplementary material, which is available to authorized users.
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19
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Garry DJ, Ellington AD, Molineux IJ, Bull JJ. Viral attenuation by engineered protein fragmentation. Virus Evol 2018; 4:vey017. [PMID: 29942657 PMCID: PMC6009699 DOI: 10.1093/ve/vey017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
A possible but untested method of viral attenuation is protein fragmentation, engineering wild-type proteins as two or more peptides that self-assemble after translation. Here, the bacteriophage T7 was engineered to encode its essential RNA polymerase as two peptides. Initial fitness was profoundly suppressed. Subjecting the engineered virus to over 100 generations of adaptation by serial transfer resulted in a large fitness increase, still remaining below that of evolved wild-type. The fitness increase was accompanied by three substitutions in the fragmented peptides as well as six mutations in other parts of the genome, but the fragmentation was retained. This study thereby demonstrates the feasibility of using gene fragmentation as a possibly permanent method of attenuation, but the initial fitness of the engineered genome may be a poor measure of its fitness on extended adaptation.
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Affiliation(s)
- Daniel J Garry
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, TX 78712, USA
| | - Andrew D Ellington
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, TX 78712, USA
| | - Ian J Molineux
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas, Austin, TX 78712, USA
| | - James J Bull
- Department of Integrative Biology, Institute for Cellular and Molecular Biology, University of Texas, Austin, TX 78712, USA
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20
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Mioduser O, Goz E, Tuller T. Significant differences in terms of codon usage bias between bacteriophage early and late genes: a comparative genomics analysis. BMC Genomics 2017; 18:866. [PMID: 29132309 PMCID: PMC5683454 DOI: 10.1186/s12864-017-4248-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 10/31/2017] [Indexed: 11/13/2022] Open
Abstract
Background Viruses undergo extensive evolutionary selection for efficient replication which effects, among others, their codon distribution. In the current study, we aimed at understanding the way evolution shapes the codon distribution in early vs. late viral genes in terms of their expression during different stages in the viral replication cycle. To this end we analyzed 14 bacteriophages and 11 human viruses with available information about the expression phases of their genes. Results We demonstrated evidence of selection for distinct composition of synonymous codons in early and late viral genes in 50% of the analyzed bacteriophages. Among others, this phenomenon may be related to the time specific adaptation of the viral genes to the translation efficiency factors involved at different bacteriophage developmental stages. Specifically, we showed that the differences in codon composition in different temporal gene groups cannot be explained only by phylogenetic proximities between the analyzed bacteriophages, and can be partially explained by differences in the adaptation to the host tRNA pool, nucleotide bias, GC content and more. In contrast, no difference in temporal regulation of synonymous codon usage was observed in human viruses, possibly because of a stronger selection pressure due to a larger effective population size in bacteriophages and their bacterial hosts. Conclusions The codon distribution in large fractions of bacteriophage genomes tend to be different in early and late genes. This phenomenon seems to be related to various aspects of the viral life cycle, and to various intracellular processes. We believe that the reported results should contribute towards better understanding of viral evolution and may promote the development of relevant procedures in synthetic virology. Electronic supplementary material The online version of this article (10.1186/s12864-017-4248-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Oriah Mioduser
- Department of Biomedical Engineering, Tel-Aviv University, Ramat Aviv, Israel
| | - Eli Goz
- Department of Biomedical Engineering, Tel-Aviv University, Ramat Aviv, Israel.,SynVaccineLtd. Ramat Hachayal, Tel Aviv, Israel
| | - Tamir Tuller
- Department of Biomedical Engineering, Tel-Aviv University, Ramat Aviv, Israel. .,SynVaccineLtd. Ramat Hachayal, Tel Aviv, Israel. .,Sagol School of Neuroscience, Tel-Aviv University, Ramat Aviv, Israel.
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21
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Bull JJ, Smithson MW, Nuismer SL. Transmissible Viral Vaccines. Trends Microbiol 2017; 26:6-15. [PMID: 29033339 PMCID: PMC5777272 DOI: 10.1016/j.tim.2017.09.007] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 08/15/2017] [Accepted: 09/22/2017] [Indexed: 12/28/2022]
Abstract
Genetic engineering now enables the design of live viral vaccines that are potentially transmissible. Some designs merely modify a single viral genome to improve on the age-old method of attenuation whereas other designs create chimeras of viral genomes. Transmission has the benefit of increasing herd immunity above that achieved by direct vaccination alone but also increases the opportunity for vaccine evolution, which typically undermines vaccine utility. Different designs have different epidemiological consequences but also experience different evolution. Approaches that integrate vaccine engineering with an understanding of evolution and epidemiology will reap the greatest benefit from vaccine transmission.
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Affiliation(s)
- James J Bull
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, 78712 USA.
| | - Mark W Smithson
- School of Biological Sciences, Washington State University, Pullman, WA, 99164-4236, USA
| | - Scott L Nuismer
- Department of Biological Sciences, Department of Mathematics, University of Idaho, Moscow, ID, 83844, USA.
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22
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Abstract
Evolution in the form of selective breeding has long been harnessed as a useful tool by humans. However, rapid evolution can also be a danger to our health and a stumbling block for biotechnology. Unwanted evolution can underlie the emergence of drug and pesticide resistance, cancer, and weeds. It makes live vaccines and engineered cells inherently unreliable and unpredictable, and therefore potentially unsafe. Yet, there are strategies that have been and can possibly be used to stop or slow many types of evolution. We review and classify existing population genetics-inspired methods for arresting evolution. Then, we discuss how genome editing techniques enable a radically new set of approaches to limit evolution.
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23
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Abstract
A general means of viral attenuation involves the extensive recoding of synonymous codons in the viral genome. The mechanistic underpinnings of this approach remain unclear, however. Using quantitative proteomics and RNA sequencing, we explore the molecular basis of attenuation in a strain of bacteriophage T7 whose major capsid gene was engineered to carry 182 suboptimal codons. We do not detect transcriptional effects from recoding. Proteomic observations reveal that translation is halved for the recoded major capsid gene, and a more modest reduction applies to several coexpressed downstream genes. We observe no changes in protein abundances of other coexpressed genes that are encoded upstream. Viral burst size, like capsid protein abundance, is also decreased by half. Together, these observations suggest that, in this virus, reduced translation of an essential polycistronic transcript and diminished virion assembly form the molecular basis of attenuation.
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24
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Genetic stability of genome-scale deoptimized RNA virus vaccine candidates under selective pressure. Proc Natl Acad Sci U S A 2017; 114:E386-E395. [PMID: 28049853 DOI: 10.1073/pnas.1619242114] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Recoding viral genomes by numerous synonymous but suboptimal substitutions provides live attenuated vaccine candidates. These vaccine candidates should have a low risk of deattenuation because of the many changes involved. However, their genetic stability under selective pressure is largely unknown. We evaluated phenotypic reversion of deoptimized human respiratory syncytial virus (RSV) vaccine candidates in the context of strong selective pressure. Codon pair deoptimized (CPD) versions of RSV were attenuated and temperature-sensitive. During serial passage at progressively increasing temperature, a CPD RSV containing 2,692 synonymous mutations in 9 of 11 ORFs did not lose temperature sensitivity, remained genetically stable, and was restricted at temperatures of 34 °C/35 °C and above. However, a CPD RSV containing 1,378 synonymous mutations solely in the polymerase L ORF quickly lost substantial attenuation. Comprehensive sequence analysis of virus populations identified many different potentially deattenuating mutations in the L ORF as well as, surprisingly, many appearing in other ORFs. Phenotypic analysis revealed that either of two competing mutations in the virus transcription antitermination factor M2-1, outside of the CPD area, substantially reversed defective transcription of the CPD L gene and substantially restored virus fitness in vitro and in case of one of these two mutations, also in vivo. Paradoxically, the introduction into Min L of one mutation each in the M2-1, N, P, and L proteins resulted in a virus with increased attenuation in vivo but increased immunogenicity. Thus, in addition to providing insights on the adaptability of genome-scale deoptimized RNA viruses, stability studies can yield improved synthetic RNA virus vaccine candidates.
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25
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Benureau Y, Colin P, Staropoli I, Gonzalez N, Garcia-Perez J, Alcami J, Arenzana-Seisdedos F, Lagane B. Guidelines for cloning, expression, purification and functional characterization of primary HIV-1 envelope glycoproteins. J Virol Methods 2016; 236:184-195. [PMID: 27451265 DOI: 10.1016/j.jviromet.2016.07.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 07/13/2016] [Accepted: 07/19/2016] [Indexed: 12/14/2022]
Abstract
The trimeric HIV-1 envelope (Env) glycoproteins gp120 and gp41 mediate virus entry into target cells by engaging CD4 and the coreceptors CCR5 or CXCR4 at the cell surface and driving membrane fusion. Receptor/gp120 interactions regulate the virus life cycle, HIV infection transmission and pathogenesis. Env is also the target of neutralizing antibodies. Efforts have thus been made to produce soluble HIV-1 glycoproteins to develop vaccines and study the role and mechanisms of HIV/receptor interactions. However, production and purification of Env glycoproteins and their functional assessment has to cope with multiple obstacles. These include difficulties in amplifying and cloning env sequences and setting up receptor binding assays that are suitable for studies on large collections of glycoproteins, flexible enough to adapt to Env and receptor structural heterogeneities, and allow recapitulating the receptor binding properties of virion-associated Env trimers. Here we identify these difficulties and present protocols to produce primary gp120 and determination of their binding properties to receptors. The receptor binding assays confirmed that the produced glycoproteins are competent for binding CD4 and undergo proper CD4-induced conformational changes required for interaction with CCR5. These assays may help elucidate the role of gp120/receptor interactions in the pathophysiology of HIV infection and develop HIV-1 entry inhibitors.
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Affiliation(s)
- Yann Benureau
- INSERM U1108, Institut Pasteur, 75015 Paris, France; Viral Pathogenesis Unit, Department of Virology, Institut Pasteur, 75015 Paris, France.
| | - Philippe Colin
- INSERM U1108, Institut Pasteur, 75015 Paris, France; Viral Pathogenesis Unit, Department of Virology, Institut Pasteur, 75015 Paris, France.
| | - Isabelle Staropoli
- INSERM U1108, Institut Pasteur, 75015 Paris, France; Viral Pathogenesis Unit, Department of Virology, Institut Pasteur, 75015 Paris, France.
| | - Nuria Gonzalez
- AIDS Immunopathogenesis Unit, Instituto de Salud Carlos III, 28220, Majadahonda, Madrid, Spain.
| | - Javier Garcia-Perez
- AIDS Immunopathogenesis Unit, Instituto de Salud Carlos III, 28220, Majadahonda, Madrid, Spain.
| | - Jose Alcami
- AIDS Immunopathogenesis Unit, Instituto de Salud Carlos III, 28220, Majadahonda, Madrid, Spain.
| | - Fernando Arenzana-Seisdedos
- INSERM U1108, Institut Pasteur, 75015 Paris, France; Viral Pathogenesis Unit, Department of Virology, Institut Pasteur, 75015 Paris, France.
| | - Bernard Lagane
- INSERM U1108, Institut Pasteur, 75015 Paris, France; Viral Pathogenesis Unit, Department of Virology, Institut Pasteur, 75015 Paris, France.
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Brandis G, Hughes D. The Selective Advantage of Synonymous Codon Usage Bias in Salmonella. PLoS Genet 2016; 12:e1005926. [PMID: 26963725 PMCID: PMC4786093 DOI: 10.1371/journal.pgen.1005926] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 02/18/2016] [Indexed: 11/18/2022] Open
Abstract
The genetic code in mRNA is redundant, with 61 sense codons translated into 20 different amino acids. Individual amino acids are encoded by up to six different codons but within codon families some are used more frequently than others. This phenomenon is referred to as synonymous codon usage bias. The genomes of free-living unicellular organisms such as bacteria have an extreme codon usage bias and the degree of bias differs between genes within the same genome. The strong positive correlation between codon usage bias and gene expression levels in many microorganisms is attributed to selection for translational efficiency. However, this putative selective advantage has never been measured in bacteria and theoretical estimates vary widely. By systematically exchanging optimal codons for synonymous codons in the tuf genes we quantified the selective advantage of biased codon usage in highly expressed genes to be in the range 0.2-4.2 x 10-4 per codon per generation. These data quantify for the first time the potential for selection on synonymous codon choice to drive genome-wide sequence evolution in bacteria, and in particular to optimize the sequences of highly expressed genes. This quantification may have predictive applications in the design of synthetic genes and for heterologous gene expression in biotechnology.
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Affiliation(s)
- Gerrit Brandis
- Department of Medical Biochemistry and Microbiology, Uppsala University, Biomedical Center, Uppsala, Sweden
| | - Diarmaid Hughes
- Department of Medical Biochemistry and Microbiology, Uppsala University, Biomedical Center, Uppsala, Sweden
- * E-mail:
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Agashe D, Sane M, Phalnikar K, Diwan GD, Habibullah A, Martinez-Gomez NC, Sahasrabuddhe V, Polachek W, Wang J, Chubiz LM, Marx CJ. Large-Effect Beneficial Synonymous Mutations Mediate Rapid and Parallel Adaptation in a Bacterium. Mol Biol Evol 2016; 33:1542-53. [PMID: 26908584 PMCID: PMC4868122 DOI: 10.1093/molbev/msw035] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Contrary to previous understanding, recent evidence indicates that synonymous codon changes may sometimes face strong selection. However, it remains difficult to generalize the nature, strength, and mechanism(s) of such selection. Previously, we showed that synonymous variants of a key enzyme-coding gene (fae) of Methylobacterium extorquens AM1 decreased enzyme production and reduced fitness dramatically. We now show that during laboratory evolution, these variants rapidly regained fitness via parallel yet variant-specific, highly beneficial point mutations in the N-terminal region of fae. These mutations (including four synonymous mutations) had weak but consistently positive impacts on transcript levels, enzyme production, or enzyme activity. However, none of the proposed mechanisms (including internal ribosome pause sites or mRNA structure) predicted the fitness impact of evolved or additional, engineered point mutations. This study shows that synonymous mutations can be fixed through strong positive selection, but the mechanism for their benefit varies depending on the local sequence context.
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Affiliation(s)
- Deepa Agashe
- National Center for Biological Sciences, Tata Institute of Fundamental Research, GKVK, Bangalore, India Department of Organismic and Evolutionary Biology, Harvard University
| | - Mrudula Sane
- National Center for Biological Sciences, Tata Institute of Fundamental Research, GKVK, Bangalore, India
| | - Kruttika Phalnikar
- National Center for Biological Sciences, Tata Institute of Fundamental Research, GKVK, Bangalore, India
| | - Gaurav D Diwan
- National Center for Biological Sciences, Tata Institute of Fundamental Research, GKVK, Bangalore, India SASTRA University, Thanjavur, India
| | - Alefiyah Habibullah
- National Center for Biological Sciences, Tata Institute of Fundamental Research, GKVK, Bangalore, India
| | | | - Vinaya Sahasrabuddhe
- National Center for Biological Sciences, Tata Institute of Fundamental Research, GKVK, Bangalore, India
| | - William Polachek
- Department of Organismic and Evolutionary Biology, Harvard University
| | - Jue Wang
- Department of Organismic and Evolutionary Biology, Harvard University Systems Biology Graduate Program, Harvard University
| | - Lon M Chubiz
- Department of Organismic and Evolutionary Biology, Harvard University
| | - Christopher J Marx
- Department of Organismic and Evolutionary Biology, Harvard University Faculty of Arts and Sciences Center for Systems Biology, Harvard University Department of Biological Sciences, University of Idaho Institute for Bioinformatics and Evolutionary Studies, University of Idaho
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Abstract
Synonymous mutations do not change the sequence of the polypeptide but they may still influence fitness. We investigated in Salmonella enterica how four synonymous mutations in the rpsT gene (encoding ribosomal protein S20) reduce fitness (i.e., growth rate) and the mechanisms by which this cost can be genetically compensated. The reduced growth rates of the synonymous mutants were correlated with reduced levels of the rpsT transcript and S20 protein. In an adaptive evolution experiment, these fitness impairments could be compensated by mutations that either caused up-regulation of S20 through increased gene dosage (due to duplications), increased transcription of the rpsT gene (due to an rpoD mutation or mutations in rpsT), or increased translation from the rpsT transcript (due to rpsT mutations). We suggest that the reduced levels of S20 in the synonymous mutants result in production of a defective subpopulation of 30S subunits lacking S20 that reduce protein synthesis and bacterial growth and that the compensatory mutations restore S20 levels and the number of functional ribosomes. Our results demonstrate how specific synonymous mutations can cause substantial fitness reductions and that many different types of intra- and extragenic compensatory mutations can efficiently restore fitness. Furthermore, this study highlights that also synonymous sites can be under strong selection, which may have implications for the use of dN/dS ratios as signature for selection.
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Affiliation(s)
- Anna Knöppel
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Joakim Näsvall
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Dan I Andersson
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
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Jorge DMDM, Mills RE, Lauring AS. CodonShuffle: a tool for generating and analyzing synonymously mutated sequences. Virus Evol 2015; 1:vev012. [PMID: 27774284 PMCID: PMC5014483 DOI: 10.1093/ve/vev012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Because synonymous mutations do not change the amino acid sequence of a protein, they are generally considered to be selectively neutral. Empiric data suggest, however, that a significant fraction of viral mutational fitness effects may be attributable to synonymous mutation. Bias in synonymous codon usage in viruses may result from selection for translational efficiency, mutational bias, base pairing requirements in RNA structures, or even selection against specific dinucleotides by innate immune effectors. Experimental analyses of codon usage and genome evolution have been facilitated by advances in synthetic biology, which now make it feasible to generate viral genomes that contain large numbers of synonymous mutations. The generally pleiotropic effects of synonymous mutation on viral fitness have, at times, made it difficult to define the mechanistic basis for the observed attenuation of these heavily mutated viruses. We have addressed this problem by developing a bioinformatic tool for the generation and analysis of viral sequences with large-scale synonymous mutation. A variety of permutation strategies are applied to shuffle codons within an open reading frame. After measuring the dinucleotide frequency, codon usage, codon pair bias, and free energy of RNA folding for each permuted genome, we used z-score normalization and a least squares regression model to quantify their overall distance from the starting sequence. Using this approach, the user can easily identify a large number of synonymously mutated sequences with varying similarity to a wild-type genome across a range of nucleic-acid-based determinants of viral fitness. We believe that this tool will be useful in designing genomes for subsequent experimental studies of the fitness impacts of synonymous mutation.
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Affiliation(s)
- Daniel Macedo de Melo Jorge
- Division of Infectious Diseases, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Ryan E Mills
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48109, USA,; Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA and
| | - Adam S Lauring
- Division of Infectious Diseases, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA,; Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI 48109, USA
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Abstract
How biological systems such as proteins achieve robustness to ubiquitous perturbations is a fundamental biological question. Such perturbations include errors that introduce phenotypic mutations into nascent proteins during the translation of mRNA. These errors are remarkably frequent. They are also costly, because they reduce protein stability and help create toxic misfolded proteins. Adaptive evolution might reduce these costs of protein mistranslation by two principal mechanisms. The first increases the accuracy of translation via synonymous "high fidelity" codons at especially sensitive sites. The second increases the robustness of proteins to phenotypic errors via amino acids that increase protein stability. To study how these mechanisms are exploited by populations evolving in the laboratory, we evolved the antibiotic resistance gene TEM-1 in Escherichia coli hosts with either normal or high rates of mistranslation. We analyzed TEM-1 populations that evolved under relaxed and stringent selection for antibiotic resistance by single molecule real-time sequencing. Under relaxed selection, mistranslating populations reduce mistranslation costs by reducing TEM-1 expression. Under stringent selection, they efficiently purge destabilizing amino acid changes. More importantly, they accumulate stabilizing amino acid changes rather than synonymous changes that increase translational accuracy. In the large populations we study, and on short evolutionary timescales, the path of least resistance in TEM-1 evolution consists of reducing the consequences of translation errors rather than the errors themselves.
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Tubiana L, Božič AL, Micheletti C, Podgornik R. Synonymous mutations reduce genome compactness in icosahedral ssRNA viruses. Biophys J 2015; 108:194-202. [PMID: 25564866 DOI: 10.1016/j.bpj.2014.10.070] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 09/29/2014] [Accepted: 10/08/2014] [Indexed: 12/15/2022] Open
Abstract
Recent studies have shown that single-stranded (ss) viral RNAs fold into more compact structures than random RNA sequences with similar chemical composition and identical length. Based on this comparison, it has been suggested that wild-type viral RNA may have evolved to be atypically compact so as to aid its encapsidation and assist the viral assembly process. To further explore the compactness selection hypothesis, we systematically compare the predicted sizes of >100 wild-type viral sequences with those of their mutants, which are evolved in silico and subject to a number of known evolutionary constraints. In particular, we enforce mutation synonynimity, preserve the codon-bias, and leave untranslated regions intact. It is found that progressive accumulation of these restricted mutations still suffices to completely erase the characteristic compactness imprint of the viral RNA genomes, making them in this respect physically indistinguishable from randomly shuffled RNAs. This shows that maintaining the physical compactness of the genome is indeed a primary factor among ssRNA viruses' evolutionary constraints, contributing also to the evidence that synonymous mutations in viral ssRNA genomes are not strictly neutral.
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Affiliation(s)
- Luca Tubiana
- Department of Theoretical Physics, Jožef Stefan Institute, Ljubljana, Slovenia.
| | - Anže Lošdorfer Božič
- Department of Theoretical Physics, Jožef Stefan Institute, Ljubljana, Slovenia; Max Planck Institute for Biology of Ageing, Cologne, Germany
| | | | - Rudolf Podgornik
- Department of Theoretical Physics, Jožef Stefan Institute, Ljubljana, Slovenia; Department of Physics, Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana, Slovenia; Department of Physics, University of Massachusetts, Amherst, Massachusetts
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33
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Codon Usage Influences the Local Rate of Translation Elongation to Regulate Co-translational Protein Folding. Mol Cell 2015; 59:744-54. [PMID: 26321254 DOI: 10.1016/j.molcel.2015.07.018] [Citation(s) in RCA: 360] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 04/08/2015] [Accepted: 07/20/2015] [Indexed: 12/20/2022]
Abstract
Codon usage bias is a universal feature of eukaryotic and prokaryotic genomes and has been proposed to regulate translation efficiency, accuracy, and protein folding based on the assumption that codon usage affects translation dynamics. The roles of codon usage in translation, however, are not clear and have been challenged by recent ribosome profiling studies. Here we used a Neurospora cell-free translation system to directly monitor the velocity of mRNA translation. We demonstrated that the preferred codons enhance the rate of translation elongation, whereas non-optimal codons slow elongation. Codon usage also controls ribosome traffic on mRNA. These conclusions were supported by ribosome profiling results in vitro and in vivo with template mRNAs designed to increase the signal-to-noise ratio. Finally, we demonstrate that codon usage regulates protein function by affecting co-translational protein folding. These results resolve a long-standing fundamental question and suggest the existence of a codon usage code for protein folding.
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de Fabritus L, Nougairède A, Aubry F, Gould EA, de Lamballerie X. Attenuation of tick-borne encephalitis virus using large-scale random codon re-encoding. PLoS Pathog 2015; 11:e1004738. [PMID: 25734338 PMCID: PMC4348424 DOI: 10.1371/journal.ppat.1004738] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 02/09/2015] [Indexed: 12/20/2022] Open
Abstract
Large-scale codon re-encoding (i.e. introduction of a large number of synonymous mutations) is a novel method of generating attenuated viruses. Here, it was applied to the pathogenic flavivirus, tick-borne encephalitis virus (TBEV) which causes febrile illness and encephalitis in humans in forested regions of Europe and Asia. Using an infectious clone of the Oshima 5–10 strain ("wild-type virus"), a cassette of 1.4kb located in the NS5 coding region, was modified by randomly introducing 273 synonymous mutations ("re-encoded virus"). Whilst the in cellulo replicative fitness of the re-encoded virus was only slightly reduced, the re-encoded virus displayed an attenuated phenotype in a laboratory mouse model of non-lethal encephalitis. Following intra-peritoneal inoculation of either 2.105 or 2.106 TCID50 of virus, the frequency of viraemia, neurovirulence (measured using weight loss and appearance of symptoms) and neuroinvasiveness (detection of virus in the brain) were significantly decreased when compared with the wild-type virus. Mice infected by wild-type or re-encoded viruses produced comparable amounts of neutralising antibodies and results of challenge experiments demonstrated that mice previously infected with the re-encoded virus were protected against subsequent infection by the wild-type virus. This constitutes evidence that a mammalian species can be protected against infection by a virulent wild-type positive-stranded RNA virus following immunisation with a derived randomly re-encoded strain. Our results demonstrate that random codon re-encoding is potentially a simple and effective method of generating live-attenuated vaccine candidates against pathogenic flaviviruses. The arbovirus Tick-borne encephalitis virus (TBEV; genus Flavivirus) is transmitted by ticks of the Ixodes genus. TBEV causes febrile illness and encephalitis in humans in forested regions of Europe and Asia. The incidence of TBE is increasing across Central and Eastern European countries despite the availability of several licensed inactivated vaccines and appropriate vaccination programmes. Large-scale codon re-encoding, a recently developed attenuation method that modifies viral RNA nucleotide composition of large coding regions without alteration of the encoded proteins, has been successfully applied to a variety of RNA viruses. In contrast with previous empirical methods of generating live attenuated vaccines, large-scale codon re-encoding facilitates rapid generation of vaccine candidates using reverse genetics methods, by direct control of the attenuation phenotype. Additional benefits include reduced costs and induction of long-term immunity. Here, we have applied the large-scale codon re-encoding method to the TBEV to demonstrate the principle of developing a live attenuated virus vaccine which protects mice against subsequent infection with the wild type virulent virus. This study therefore illustrates that codon re-encoding is potentially an easily derived and effective method of producing live attenuated vaccine candidates against positive-stranded RNA viruses.
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Affiliation(s)
- Lauriane de Fabritus
- Aix Marseille Université, IRD French Institute of Research for Development, EHESP French School of Public Health, EPV UMR_D 190 “Emergence des Pathologies Virales”, Marseille, France
- * E-mail:
| | - Antoine Nougairède
- Aix Marseille Université, IRD French Institute of Research for Development, EHESP French School of Public Health, EPV UMR_D 190 “Emergence des Pathologies Virales”, Marseille, France
- Institut Hospitalo-Universitaire Méditerranée Infection, Marseille, France
| | - Fabien Aubry
- Aix Marseille Université, IRD French Institute of Research for Development, EHESP French School of Public Health, EPV UMR_D 190 “Emergence des Pathologies Virales”, Marseille, France
| | - Ernest A Gould
- Aix Marseille Université, IRD French Institute of Research for Development, EHESP French School of Public Health, EPV UMR_D 190 “Emergence des Pathologies Virales”, Marseille, France
| | - Xavier de Lamballerie
- Aix Marseille Université, IRD French Institute of Research for Development, EHESP French School of Public Health, EPV UMR_D 190 “Emergence des Pathologies Virales”, Marseille, France
- Institut Hospitalo-Universitaire Méditerranée Infection, Marseille, France
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Abstract
Attenuated, live viral vaccines have been extraordinarily successful in protecting against many diseases. The main drawbacks in their development and use have been reliance on an unpredictable method of attenuation and the potential for evolutionary reversion to high virulence. Methods of genetic engineering now provide many safer alternatives to live vaccines, so if live vaccines are to compete with these alternatives in the future, they must either have superior immunogenicity or they must be able to overcome these former disadvantages. Several live vaccine designs that were historically inaccessible are now feasible because of advances in genome synthesis. Some of those methods are addressed here, with an emphasis on whether they enable predictable levels of attenuation and whether they are stable against evolutionary reversion. These new designs overcome many of the former drawbacks and position live vaccines to be competitive with alternatives. Not only do new methods appear to retard evolutionary reversion enough to prevent vaccine-derived epidemics, but it may even be possible to permanently attenuate live vaccines that are transmissible but cannot evolve to higher virulence under prolonged adaptation.
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Affiliation(s)
- J J Bull
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA; Center for Computational Biology and Bioinformatics, The University of Texas at Austin, Austin, TX 78712, USA
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36
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Abstract
Live, attenuated viruses provide many of the most effective vaccines. For the better part of a century, the standard method of attenuation has been viral growth in novel environments, whereby the virus adapts to the new environment but incurs a reduced ability to grow in the original host. The downsides of this approach were that it produced haphazard results, and even when it achieved sufficient attenuation for vaccine production, the attenuated virus was prone to evolve back to high virulence. Using bacteriophage T7, we apply a synthetic biology approach for creating attenuated genomes and specifically study their evolutionary stability. Three different genome rearrangements are used, and although some initial fitness recovery occurs, all exhibit greatly impaired abilities to recover wild-type fitness over a hundred or more generations. Different degrees of stable attenuation appear to be attainable by different rearrangements. Efforts to predict fitness recovery using the extensive background of T7 genetics and biochemistry were only sometimes successful. The use of genome rearrangement thus offers a practical mechanism of evolutionary stable viral attenuation, with some progress toward prediction.
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Abstract
The high mutation rates of poliovirus and other RNA viruses promote viral diversity by rapid sampling of mutations. In this issue, Lauring et al. (2012) report that underlying synonymous codon variation in virus populations can have a considerable impact on adaptive potential with implications for viral fitness and virulence.
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Affiliation(s)
- Nels C Elde
- Department of Human Genetics, University of Utah, School of Medicine, Salt Lake City, UT 84112, USA.
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38
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Abstract
RNA viruses face dynamic environments and are masters at adaptation. During their short 'lifespans', they must surmount multiple physical, anatomical and immunological challenges. Central to their adaptative capacity is the enormous genetic diversity that characterizes RNA virus populations. Although genetic diversity increases the rate of adaptive evolution, low replication fidelity can present a risk because excess mutations can lead to population extinction. In this Review, we discuss the strategies used by RNA viruses to deal with the increased mutational load and consider how this mutational robustness might influence viral evolution and pathogenesis.
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Nougairede A, De Fabritus L, Aubry F, Gould EA, Holmes EC, de Lamballerie X. Random codon re-encoding induces stable reduction of replicative fitness of Chikungunya virus in primate and mosquito cells. PLoS Pathog 2013; 9:e1003172. [PMID: 23436995 PMCID: PMC3578757 DOI: 10.1371/journal.ppat.1003172] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 12/18/2012] [Indexed: 11/22/2022] Open
Abstract
Large-scale codon re-encoding represents a powerful method of attenuating viruses to generate safe and cost-effective vaccines. In contrast to specific approaches of codon re-encoding which modify genome-scale properties, we evaluated the effects of random codon re-encoding on the re-emerging human pathogen Chikungunya virus (CHIKV), and assessed the stability of the resultant viruses during serial in cellulo passage. Using different combinations of three 1.4 kb randomly re-encoded regions located throughout the CHIKV genome six codon re-encoded viruses were obtained. Introducing a large number of slightly deleterious synonymous mutations reduced the replicative fitness of CHIKV in both primate and arthropod cells, demonstrating the impact of synonymous mutations on fitness. Decrease of replicative fitness correlated with the extent of re-encoding, an observation that may assist in the modulation of viral attenuation. The wild-type and two re-encoded viruses were passaged 50 times either in primate or insect cells, or in each cell line alternately. These viruses were analyzed using detailed fitness assays, complete genome sequences and the analysis of intra-population genetic diversity. The response to codon re-encoding and adaptation to culture conditions occurred simultaneously, resulting in significant replicative fitness increases for both re-encoded and wild type viruses. Importantly, however, the most re-encoded virus failed to recover its replicative fitness. Evolution of these viruses in response to codon re-encoding was largely characterized by the emergence of both synonymous and non-synonymous mutations, sometimes located in genomic regions other than those involving re-encoding, and multiple convergent and compensatory mutations. However, there was a striking absence of codon reversion (<0.4%). Finally, multiple mutations were rapidly fixed in primate cells, whereas mosquito cells acted as a brake on evolution. In conclusion, random codon re-encoding provides important information on the evolution and genetic stability of CHIKV viruses and could be exploited to develop a safe, live attenuated CHIKV vaccine. Emerging arthropod-borne viruses (arboviruses) are a major cause of human and animal morbidity and mortality. Climatic and anthropological activities are responsible for the dispersal of arbovirus transmission vectors into new territories. Chikungunya virus (CHIKV) is an important example of a re-emerging pathogen for which no licensed vaccine exists. One of the vectors of CHIKV, the mosquito Aedes albopictus, has dispersed into new temperate regions resulting in outbreaks where they had not been previously observed. Here, we demonstrate that random codon re-encoding, a method that modifies the nucleic acid composition of large coding regions without modifying the encoded proteins, can significantly decrease the replicative fitness of CHIKV. This powerful method of attenuating viruses has several potential advantages for vaccine development, including the possibility to modulate precisely the degree of replicative fitness loss and to generate safe, live-attenuated vaccines that confer long-term protection, in a cost effective manner. Our studies also demonstrate that these re-encoded viruses exhibit a stable phenotype, and that the response to codon re-encoding was largely compensatory in nature, with little reversion of mutations. Finally, we provide further evidence that many synonymous sites in RNA viruses are not neutral and clearly impact viral fitness.
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Affiliation(s)
- Antoine Nougairede
- Aix Marseille Univ, IRD French Institute of Research for Development, EHESP French School of Public Health, UMR_D 190 Emergence des Pathologies Virales, Marseille, France.
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Cardinale DJ, DeRosa K, Duffy S. Base composition and translational selection are insufficient to explain codon usage bias in plant viruses. Viruses 2013; 5:162-81. [PMID: 23322170 PMCID: PMC3564115 DOI: 10.3390/v5010162] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 01/09/2013] [Accepted: 01/11/2013] [Indexed: 02/06/2023] Open
Abstract
Viral codon usage bias may be the product of a number of synergistic or antagonistic factors, including genomic nucleotide composition, translational selection, genomic architecture, and mutational or repair biases. Most studies of viral codon bias evaluate only the relative importance of genomic base composition and translational selection, ignoring other possible factors. We analyzed the codon preferences of ssRNA (luteoviruses and potyviruses) and ssDNA (geminiviruses) plant viruses that infect translationally distinct monocot and dicot hosts. We found that neither genomic base composition nor translational selection satisfactorily explains their codon usage biases. Furthermore, we observed a strong relationship between the codon preferences of viruses in the same family or genus, regardless of host or genomic nucleotide content. Our results suggest that analyzing codon bias as either due to base composition or translational selection is a false dichotomy that obscures the role of other factors. Constraints such as genomic architecture and secondary structure can and do influence codon usage in plant viruses, and likely in viruses of other hosts.
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Affiliation(s)
- Daniel J Cardinale
- Department of Ecology, Evolution, and Natural Resources, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA.
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Goñi N, Iriarte A, Comas V, Soñora M, Moreno P, Moratorio G, Musto H, Cristina J. Pandemic influenza A virus codon usage revisited: biases, adaptation and implications for vaccine strain development. Virol J 2012; 9:263. [PMID: 23134595 PMCID: PMC3543350 DOI: 10.1186/1743-422x-9-263] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Accepted: 11/02/2012] [Indexed: 11/20/2022] Open
Abstract
Background Influenza A virus (IAV) is a member of the family Orthomyxoviridae and contains eight segments of a single-stranded RNA genome with negative polarity. The first influenza pandemic of this century was declared in April of 2009, with the emergence of a novel H1N1 IAV strain (H1N1pdm) in Mexico and USA. Understanding the extent and causes of biases in codon usage is essential to the understanding of viral evolution. A comprehensive study to investigate the effect of selection pressure imposed by the human host on the codon usage of an emerging, pandemic IAV strain and the trends in viral codon usage involved over the pandemic time period is much needed. Results We performed a comprehensive codon usage analysis of 310 IAV strains from the pandemic of 2009. Highly biased codon usage for Ala, Arg, Pro, Thr and Ser were found. Codon usage is strongly influenced by underlying biases in base composition. When correspondence analysis (COA) on relative synonymous codon usage (RSCU) is applied, the distribution of IAV ORFs in the plane defined by the first two major dimensional factors showed that different strains are located at different places, suggesting that IAV codon usage also reflects an evolutionary process. Conclusions A general association between codon usage bias, base composition and poor adaptation of the virus to the respective host tRNA pool, suggests that mutational pressure is the main force shaping H1N1 pdm IAV codon usage. A dynamic process is observed in the variation of codon usage of the strains enrolled in these studies. These results suggest a balance of mutational bias and natural selection, which allow the virus to explore and re-adapt its codon usage to different environments. Recoding of IAV taking into account codon bias, base composition and adaptation to host tRNA may provide important clues to develop new and appropriate vaccines.
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Affiliation(s)
- Natalia Goñi
- Laboratorio de Virología Molecular, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Iguá 4225, Montevideo, 11400, Uruguay
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42
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Sawyer SL, Elde NC. A cross-species view on viruses. Curr Opin Virol 2012; 2:561-8. [PMID: 22835485 DOI: 10.1016/j.coviro.2012.07.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 07/08/2012] [Accepted: 07/09/2012] [Indexed: 10/28/2022]
Abstract
We describe the creative ways that virologists are leveraging experimental cross-species infections to study the interactions between viruses and hosts. While viruses are usually well adapted to their hosts, cross-species approaches involve pairing viruses with species that they do not naturally infect. These cross-species infections pit viruses against animals, cell lines, or even single genes from foreign species. We highlight examples where cross-species infections have yielded insights into mechanisms of host innate immunity, viral countermeasures, and the evolutionary interplay between viruses and hosts.
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Affiliation(s)
- Sara L Sawyer
- Section of Molecular Genetics and Microbiology, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, USA.
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