1
|
Castellano LA, McNamara RJ, Pallarés HM, Gamarnik AV, Alvarez DE, Bazzini AA. Dengue virus preferentially uses human and mosquito non-optimal codons. Mol Syst Biol 2024:10.1038/s44320-024-00052-7. [PMID: 39039212 DOI: 10.1038/s44320-024-00052-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 06/25/2024] [Accepted: 06/26/2024] [Indexed: 07/24/2024] Open
Abstract
Codon optimality refers to the effect that codon composition has on messenger RNA (mRNA) stability and translation level and implies that synonymous codons are not silent from a regulatory point of view. Here, we investigated the adaptation of virus genomes to the host optimality code using mosquito-borne dengue virus (DENV) as a model. We demonstrated that codon optimality exists in mosquito cells and showed that DENV preferentially uses nonoptimal (destabilizing) codons and avoids codons that are defined as optimal (stabilizing) in either human or mosquito cells. Human genes enriched in the codons preferentially and frequently used by DENV are upregulated during infection, and so is the tRNA decoding the nonoptimal and DENV preferentially used codon for arginine. We found that adaptation during single-host passaging in human or mosquito cells results in the selection of synonymous mutations towards DENV's preferred nonoptimal codons that increase virus fitness. Finally, our analyses revealed that hundreds of viruses preferentially use nonoptimal codons, with those infecting a single host displaying an even stronger bias, suggesting that host-pathogen interaction shapes virus-synonymous codon choice.
Collapse
Affiliation(s)
- Luciana A Castellano
- Stowers Institute for Medical Research, 1000 E 50th Street, Kansas City, MO, 64110, USA
| | - Ryan J McNamara
- Stowers Institute for Medical Research, 1000 E 50th Street, Kansas City, MO, 64110, USA
| | - Horacio M Pallarés
- Stowers Institute for Medical Research, 1000 E 50th Street, Kansas City, MO, 64110, USA
- Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires IIBBA-CONICET, Ciudad Autónoma de Buenos Aires, Argentina
| | - Andrea V Gamarnik
- Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas de Buenos Aires IIBBA-CONICET, Ciudad Autónoma de Buenos Aires, Argentina
| | - Diego E Alvarez
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín-CONICET, San Martín B1650, Argentina
| | - Ariel A Bazzini
- Stowers Institute for Medical Research, 1000 E 50th Street, Kansas City, MO, 64110, USA.
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS, 66160, USA.
| |
Collapse
|
2
|
Abstract
The debate over whether viruses are living organisms tends to be paradigmatically determined. The metabolic paradigm denies that they are, while new research evidences the opposite. The purpose of this paper is to deliver a generic model for viral contexts that explains why viruses are alive. It will take a systems biology approach, with a qualitative part (using metacybernetics) to provide deeper explanations of viral contexts, and a quantitative part (using Fisher Information deriving from the variational principle of Extreme Physical Information) which is in principle able to take measurements and predict outcomes. The modelling process provides an extended view of the epigenetic processes of viruses. The generic systems biology model will depict viruses as autonomous entities with metaphysical processes of autopoietic self-organisation and adaptation, enabling them to maintain their physical viability and hence, within their populations, mutate and evolve. The autopoietic epigenetic processes are shown to describe their capability to change, and these are both qualitatively and quantitatively explored, the latter providing an approach to make measurements of physical phenomena under uncertainty. Viruses maintain their fitness when they are able to maintain their stability, and this is indicated by information flow efficacy. A brief case study is presented on the COVID-19 virus from the perspective that it is a living system, and this includes outcome predictions given Fisher Information conditions for known contexts.
Collapse
|
3
|
Pavesi A. Prediction of two novel overlapping ORFs in the genome of SARS-CoV-2. Virology 2021; 562:149-157. [PMID: 34339929 PMCID: PMC8317007 DOI: 10.1016/j.virol.2021.07.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 07/21/2021] [Accepted: 07/21/2021] [Indexed: 10/25/2022]
Abstract
Six candidate overlapping genes have been detected in SARS-CoV-2, yet current methods struggle to detect overlapping genes that recently originated. However, such genes might encode proteins beneficial to the virus, and provide a model system to understand gene birth. To complement existing detection methods, I first demonstrated that selection pressure to avoid stop codons in alternative reading frames is a driving force in the origin and retention of overlapping genes. I then built a detection method, CodScr, based on this selection pressure. Finally, I combined CodScr with methods that detect other properties of overlapping genes, such as a biased nucleotide and amino acid composition. I detected two novel ORFs (ORF-Sh and ORF-Mh), overlapping the spike and membrane genes respectively, which are under selection pressure and may be beneficial to SARS-CoV-2. ORF-Sh and ORF-Mh are present, as ORF uninterrupted by stop codons, in 100% and 95% of the SARS-CoV-2 genomes, respectively.
Collapse
Affiliation(s)
- Angelo Pavesi
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area Delle Scienze 23/A, I-43124, Parma, Italy.
| |
Collapse
|
4
|
Pintó RM, Bosch A. The codon usage code for co-translational folding of viral capsids. Genome Biol Evol 2021; 13:6259148. [PMID: 33914886 PMCID: PMC8410136 DOI: 10.1093/gbe/evab089] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/22/2021] [Indexed: 12/25/2022] Open
Abstract
Codon bias is common to all organisms and is the result of mutation, drift, and selection. Selection for the efficiency and accuracy of translation is well recognized as a factor shaping the codon usage. In contrast, fewer studies report the control of the rate of translation as an additional selective pressure influencing the codon usage of an organism. Experimental molecular evolution using RNA virus populations is a powerful tool for the identification of mechanisms underlying the codon bias. Indeed, the role of deoptimized codons on the cotranslational folding has been proven in the capsids of two fecal-orally transmitted picornaviruses, poliovirus, and the hepatitis A virus, emphasizing the role of the frequency of codons in determining the phenotype. However, most studies on virus codon usage rely only on computational analyses, and experimental studies should be encouraged to clearly define the role of selection on codon evolution.
Collapse
Affiliation(s)
- Rosa M Pintó
- Enteric Virus Laboratory, Section of Microbiology, Virology and Biotechnology, Department of Genetics, Microbiology and Statistics, School of Biology, and Institute of Nutrition and Safety, University of Barcelona, Barcelona, Spain
| | - Albert Bosch
- Enteric Virus Laboratory, Section of Microbiology, Virology and Biotechnology, Department of Genetics, Microbiology and Statistics, School of Biology, and Institute of Nutrition and Safety, University of Barcelona, Barcelona, Spain
| |
Collapse
|
5
|
Plant EP, Manukyan H, Laassri M, Ye Z. Insights from the comparison of genomic variants from two influenza B viruses grown in the presence of human antibodies in cell culture. PLoS One 2020; 15:e0239015. [PMID: 32925936 PMCID: PMC7489522 DOI: 10.1371/journal.pone.0239015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 08/27/2020] [Indexed: 12/25/2022] Open
Abstract
Understanding the extent and limitation of viral genome evolution can provide insight about potential drug and vaccine targets. Influenza B Viruses (IBVs) infect humans in a seasonal manner and causes significant morbidity and mortality. IBVs are negative-sense single-stranded RNA viruses with a segmented genome and can be divided into two antigenically distinct lineages. The two lineages have been circulating and further evolving for almost four decades. The immune response to IBV infection can lead to antibodies that target the strain causing the infection. Some antibodies are cross-reactive and are able to bind strains from both lineages but, because of antigenic drift and immunodominance, both lineages continue to evolve and challenge human health. Here we investigate changes in the genomes of an IBVs from each lineage after passage in tissue culture in the presence of human sera containing polyclonal antibodies directed toward antigenically and temporally distinct viruses. Our previous analysis of the fourth segment, which encodes the major surface protein HA, revealed a pattern of change in which signature sequences from one lineage mutated to the signature sequences of the other lineage. Here we analyze genes from the other genomic segments and observe that most of the quasispecies’ heterogeneity occurs at the same loci in each lineage. The nature of the variants at these loci are investigated and possible reasons for this pattern are discussed. This work expands our understanding of the extent and limitations of genomic change in IBV.
Collapse
Affiliation(s)
- Ewan P. Plant
- Office of Vaccine Research and Review, US Food and Drug Administration, Silver Spring, Maryland, United States of America
- * E-mail:
| | - Hasmik Manukyan
- Office of Vaccine Research and Review, US Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Majid Laassri
- Office of Vaccine Research and Review, US Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Zhiping Ye
- Office of Vaccine Research and Review, US Food and Drug Administration, Silver Spring, Maryland, United States of America
| |
Collapse
|
6
|
Luo M, Terrell JR, Mcmanus SA. Nucleocapsid Structure of Negative Strand RNA Virus. Viruses 2020; 12:E835. [PMID: 32751700 PMCID: PMC7472042 DOI: 10.3390/v12080835] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 07/23/2020] [Accepted: 07/27/2020] [Indexed: 12/14/2022] Open
Abstract
Negative strand RNA viruses (NSVs) include many important human pathogens, such as influenza virus, Ebola virus, and rabies virus. One of the unique characteristics that NSVs share is the assembly of the nucleocapsid and its role in viral RNA synthesis. In NSVs, the single strand RNA genome is encapsidated in the linear nucleocapsid throughout the viral replication cycle. Subunits of the nucleocapsid protein are parallelly aligned along the RNA genome that is sandwiched between two domains composed of conserved helix motifs. The viral RNA-dependent-RNA polymerase (vRdRp) must recognize the protein-RNA complex of the nucleocapsid and unveil the protected genomic RNA in order to initiate viral RNA synthesis. In addition, vRdRp must continuously translocate along the protein-RNA complex during elongation in viral RNA synthesis. This unique mechanism of viral RNA synthesis suggests that the nucleocapsid may play a regulatory role during NSV replication.
Collapse
Affiliation(s)
- Ming Luo
- Department of Chemistry, Georgia State University, Atlanta, GA 30302, USA; (J.R.T.); (S.A.M.)
| | | | | |
Collapse
|
7
|
Kandeel M, Ibrahim A, Fayez M, Al-Nazawi M. From SARS and MERS CoVs to SARS-CoV-2: Moving toward more biased codon usage in viral structural and nonstructural genes. J Med Virol 2020; 92:660-666. [PMID: 32159237 PMCID: PMC7228358 DOI: 10.1002/jmv.25754] [Citation(s) in RCA: 124] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 03/09/2020] [Indexed: 12/11/2022]
Abstract
Background Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is an emerging disease with fatal outcomes. In this study, a fundamental knowledge gap question is to be resolved by evaluating the differences in biological and pathogenic aspects of SARS‐CoV‐2 and the changes in SARS‐CoV‐2 in comparison with the two prior major COV epidemics, SARS and Middle East respiratory syndrome (MERS) coronaviruses. Methods The genome composition, nucleotide analysis, codon usage indices, relative synonymous codons usage, and effective number of codons (ENc) were analyzed in the four structural genes; Spike (S), Envelope (E), membrane (M), and Nucleocapsid (N) genes, and two of the most important nonstructural genes comprising RNA‐dependent RNA polymerase and main protease (Mpro) of SARS‐CoV‐2, Beta‐CoV from pangolins, bat SARS, MERS, and SARS CoVs. Results SARS‐CoV‐2 prefers pyrimidine rich codons to purines. Most high‐frequency codons were ending with A or T, while the low frequency and rare codons were ending with G or C. SARS‐CoV‐2 structural proteins showed 5 to 20 lower ENc values, compared with SARS, bat SARS, and MERS CoVs. This implies higher codon bias and higher gene expression efficiency of SARS‐CoV‐2 structural proteins. SARS‐CoV‐2 encoded the highest number of over‐biased and negatively biased codons. Pangolin Beta‐CoV showed little differences with SARS‐CoV‐2 ENc values, compared with SARS, bat SARS, and MERS CoV. Conclusion Extreme bias and lower ENc values of SARS‐CoV‐2, especially in Spike, Envelope, and Mpro genes, are suggestive for higher gene expression efficiency, compared with SARS, bat SARS, and MERS CoVs.
Collapse
Affiliation(s)
- Mahmoud Kandeel
- Department of Biomedical Sciences, College of Veterinary Medicine, King Faisal University, Al-hofuf, Egypt.,Department of Pharmacology, Faculty of Veterinary Medicine, Kafrelshikh University, Kafrelshikh, Egypt
| | - Abdelazim Ibrahim
- Department of Pathology, College of Veterinary Medicine, King Faisal University, Al-hofuf, Saudi Arabia.,Department of Pathology, Faculty of Veterinary Medicine, Suez Canal University, Ismailia, Egypt
| | - Mahmoud Fayez
- Al Ahsa Veterinary Diagnostic Laboratory, Ministry of Agriculture, Al-Ahsa, Kingdom of Saudi Arabia.,Veterinary Serum and Vaccine Institute, Cairo, Egypt
| | - Mohammed Al-Nazawi
- Department of Biomedical Sciences, College of Veterinary Medicine, King Faisal University, Al-hofuf, Egypt
| |
Collapse
|
8
|
Plant EP, Manukyan H, Sanchez JL, Laassri M, Ye Z. Immune Pressure on Polymorphous Influenza B Populations Results in Diverse Hemagglutinin Escape Mutants and Lineage Switching. Vaccines (Basel) 2020; 8:vaccines8010125. [PMID: 32168968 PMCID: PMC7157493 DOI: 10.3390/vaccines8010125] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 02/27/2020] [Accepted: 03/06/2020] [Indexed: 02/06/2023] Open
Abstract
Mutations arise in the genomes of progeny viruses during infection. Mutations that occur in epitopes targeted by host antibodies allow the progeny virus to escape the host adaptive, B-cell mediated antibody immune response. Major epitopes have been identified in influenza B virus (IBV) hemagglutinin (HA) protein. However, IBV strains maintain a seasonal presence in the human population and changes in IBV genomes in response to immune pressure are not well characterized. There are two lineages of IBV that have circulated in the human population since the 1980s, B-Victoria and B-Yamagata. It is hypothesized that early exposure to one influenza subtype leads to immunodominance. Subsequent seasonal vaccination or exposure to new subtypes may modify subsequent immune responses, which, in turn, results in selection of escape mutations in the viral genome. Here we show that while some mutations do occur in known epitopes suggesting antibody escape, many mutations occur in other parts of the HA protein. Analysis of mutations outside of the known epitopes revealed that these mutations occurred at the same amino acid position in viruses from each of the two IBV lineages. Interestingly, where the amino acid sequence differed between viruses from each lineage, reciprocal amino acid changes were observed. That is, the virus from the Yamagata lineage become more like the Victoria lineage virus and vice versa. Our results suggest that some IBV HA sequences are constrained to specific amino acid codons when viruses are cultured in the presence of antibodies. Some changes to the known antigenic regions may also be restricted in a lineage-dependent manner. Questions remain regarding the mechanisms underlying these results. The presence of amino acid residues that are constrained within the HA may provide a new target for universal vaccines for IBV.
Collapse
Affiliation(s)
- Ewan P. Plant
- Division of Viral Products, Center for Biologics Evaluation and Research, US Food and Drug Administration, Silver Spring, MD 20993, USA; (H.M.); (M.L.); (Z.Y.)
- Correspondence: ; Tel.: +1-240-402-7319
| | - Hasmik Manukyan
- Division of Viral Products, Center for Biologics Evaluation and Research, US Food and Drug Administration, Silver Spring, MD 20993, USA; (H.M.); (M.L.); (Z.Y.)
| | - Jose L. Sanchez
- Armed Forces Health Surveillance Branch, Public Health Division, Assistant Director for Combat Support (AD-CS), Defense Health Agency, Silver Spring, MD 20904, USA;
| | - Majid Laassri
- Division of Viral Products, Center for Biologics Evaluation and Research, US Food and Drug Administration, Silver Spring, MD 20993, USA; (H.M.); (M.L.); (Z.Y.)
| | - Zhiping Ye
- Division of Viral Products, Center for Biologics Evaluation and Research, US Food and Drug Administration, Silver Spring, MD 20993, USA; (H.M.); (M.L.); (Z.Y.)
| |
Collapse
|
9
|
Xue M, Zhao BS, Zhang Z, Lu M, Harder O, Chen P, Lu Z, Li A, Ma Y, Xu Y, Liang X, Zhou J, Niewiesk S, Peeples ME, He C, Li J. Viral N 6-methyladenosine upregulates replication and pathogenesis of human respiratory syncytial virus. Nat Commun 2019; 10:4595. [PMID: 31597913 PMCID: PMC6785563 DOI: 10.1038/s41467-019-12504-y] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 09/11/2019] [Indexed: 12/02/2022] Open
Abstract
N6-methyladenosine (m6A) is the most prevalent internal modification of mRNAs in most eukaryotes. Here we show that RNAs of human respiratory syncytial virus (RSV) are modified by m6A within discreet regions and that these modifications enhance viral replication and pathogenesis. Knockdown of m6A methyltransferases decreases RSV replication and gene expression whereas knockdown of m6A demethylases has the opposite effect. The G gene transcript contains the most m6A modifications. Recombinant RSV variants expressing G transcripts that lack particular clusters of m6A display reduced replication in A549 cells, primary well differentiated human airway epithelial cultures, and respiratory tracts of cotton rats. One of the m6A-deficient variants is highly attenuated yet retains high immunogenicity in cotton rats. Collectively, our results demonstrate that viral m6A methylation upregulates RSV replication and pathogenesis and identify viral m6A methylation as a target for rational design of live attenuated vaccine candidates for RSV and perhaps other pneumoviruses.
Collapse
Affiliation(s)
- Miaoge Xue
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, 43210, USA
| | - Boxuan Simen Zhao
- Department of Chemistry, Department of Biochemistry and Molecular Biology, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, 60637, USA
| | - Zijie Zhang
- Department of Chemistry, Department of Biochemistry and Molecular Biology, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, 60637, USA
| | - Mijia Lu
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, 43210, USA
| | - Olivia Harder
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, 43210, USA
| | - Phylip Chen
- Center for Vaccines and Immunity, The Research Institute at Nationwide Children's Hospital, Columbus, OH, 43205, USA
| | - Zhike Lu
- Department of Chemistry, Department of Biochemistry and Molecular Biology, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, 60637, USA
| | - Anzhong Li
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, 43210, USA
| | - Yuanmei Ma
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, 43210, USA
| | - Yunsheng Xu
- Institute of Translational Medicine, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325015, Zhejiang, P.R. China
| | - Xueya Liang
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, 43210, USA
| | - Jiyong Zhou
- College of Animal Sciences, Zhejiang University, Hangzhou, 310058, Zhejiang, P. R. China
| | - Stefan Niewiesk
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, 43210, USA
| | - Mark E Peeples
- Center for Vaccines and Immunity, The Research Institute at Nationwide Children's Hospital, Columbus, OH, 43205, USA
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH, 43210, USA
| | - Chuan He
- Department of Chemistry, Department of Biochemistry and Molecular Biology, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, 60637, USA
- Howard Hughes Medical Institute, The University of Chicago, Chicago, IL, 60637, USA
| | - Jianrong Li
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, 43210, USA.
| |
Collapse
|
10
|
Sexton NR, Ebel GD. Effects of Arbovirus Multi-Host Life Cycles on Dinucleotide and Codon Usage Patterns. Viruses 2019; 11:v11070643. [PMID: 31336898 PMCID: PMC6669465 DOI: 10.3390/v11070643] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 07/09/2019] [Accepted: 07/11/2019] [Indexed: 12/12/2022] Open
Abstract
Arthropod-borne viruses (arboviruses) of vertebrates including dengue, zika, chikungunya, Rift Valley fever, and blue tongue viruses cause extensive morbidity and mortality in humans, agricultural animals, and wildlife across the globe. As obligate intercellular pathogens, arboviruses must be well adapted to the cellular and molecular environment of both their arthropod (invertebrate) and vertebrate hosts, which are vastly different due to hundreds of millions of years of separate evolution. Here we discuss the comparative pressures on arbovirus RNA genomes as a result of a dual host life cycle, focusing on pressures that do not alter amino acids. We summarize what is currently known about arboviral genetic composition, such as dinucleotide and codon usage, and how cyclical infection of vertebrate and invertebrate hosts results in different genetic profiles compared with single-host viruses. To serve as a comparison, we compile what is known about arthropod tRNA, dinucleotide, and codon usages and compare this with vertebrates. Additionally, we discuss the potential roles of genetic robustness in arboviral evolution and how it may vary from other viruses. Overall, both arthropod and vertebrate hosts influence the resulting genetic composition of arboviruses, but a great deal remains to be investigated.
Collapse
Affiliation(s)
- Nicole R Sexton
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Gregory D Ebel
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
| |
Collapse
|
11
|
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.
Collapse
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
| | | |
Collapse
|