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In Silico Serotyping Based on Whole-Genome Sequencing Improves the Accuracy of Shigella Identification. Appl Environ Microbiol 2019; 85:AEM.00165-19. [PMID: 30709819 DOI: 10.1128/aem.00165-19] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 01/25/2019] [Indexed: 12/21/2022] Open
Abstract
Bacteria of the genus Shigella, consisting of 4 species and >50 serotypes, cause shigellosis, a foodborne disease of significant morbidity, mortality, and economic loss worldwide. Classical Shigella identification based on selective media and serology is tedious, time-consuming, expensive, and not always accurate. A molecular diagnostic assay does not distinguish Shigella at the species level or from enteroinvasive Escherichia coli (EIEC). We inspected genomic sequences from 221 Shigella isolates and observed low concordance rates between conventional designation and molecular serotyping: 86.4% and 80.5% at the species and serotype levels, respectively. Serotype determinants for 6 additional serotypes were identified. Examination of differentiation gene markers commonly perceived as characteristic hallmarks in Shigella showed high variability among different serotypes. Using this information, we developed ShigaTyper, an automated workflow that utilizes limited computational resources to accurately and rapidly determine 59 Shigella serotypes using Illumina paired-end whole-genome sequencing (WGS) reads. Shigella serotype determinants and species-specific diagnostic markers were first identified through read alignment to an in-house curated reference sequence database. Relying on sequence hits that passed a threshold level of coverage and accuracy, serotype could be unambiguously predicted within 1 min for an average-size WGS sample of ∼500 MB. Validation with WGS data from 380 isolates showed an accuracy rate of 98.2%. This pipeline is the first step toward building a comprehensive WGS-based analysis pipeline of Shigella spp. in a field laboratory setting, where speed is essential and resources need to be more cost-effectively dedicated.IMPORTANCE Shigella causes diarrheal disease with serious public health implications. However, conventional Shigella identification methods are laborious and time-consuming and can be erroneous due to the high similarity between Shigella and enteroinvasive Escherichia coli (EIEC) and cross-reactivity between serotyping antisera. Further, serotype interpretation is complicated for inexperienced users. To develop an easier method with higher accuracy based on whole-genome sequencing (WGS) for Shigella serotyping, we systematically examined genomic information of Shigella isolates from 53 serotypes to define rules for differentiation and serotyping. We created ShigaTyper, an automated pipeline that accurately and rapidly excludes non-Shigella isolates and identifies 59 Shigella serotypes using Illumina paired-end WGS reads. A serotype can be unambiguously predicted at a data processing speed of 538 MB/min with 98.2% accuracy from a regular laptop. Once it is installed, training in bioinformatics analysis and Shigella genetics is not required. This pipeline is particularly useful to general microbiologists in field laboratories.
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The HC, Thanh DP, Holt KE, Thomson NR, Baker S. The genomic signatures of Shigella evolution, adaptation and geographical spread. Nat Rev Microbiol 2016; 14:235-50. [PMID: 26923111 DOI: 10.1038/nrmicro.2016.10] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Shigella spp. are some of the key pathogens responsible for the global burden of diarrhoeal disease. These facultative intracellular bacteria belong to the family Enterobacteriaceae, together with other intestinal pathogens, such as Escherichia coli and Salmonella spp. The genus Shigella comprises four different species, each consisting of several serogroups, all of which show phenotypic similarity, including invasive pathogenicity. DNA sequencing suggests that this similarity results from the convergent evolution of different Shigella spp. founders. Here, we review the evolutionary relationships between Shigella spp. and E . coli, and we highlight how the genomic plasticity of these bacteria and their acquisition of a distinctive virulence plasmid have enabled the development of such highly specialized pathogens. Furthermore, we discuss the insights that genotyping and whole-genome sequencing have provided into the phylogenetics and intercontinental spread of Shigella spp.
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Affiliation(s)
- Hao Chung The
- The Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, 764 Vo Van Kiet, Quan 5, Ho Chi Minh City, Vietnam
| | - Duy Pham Thanh
- The Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, 764 Vo Van Kiet, Quan 5, Ho Chi Minh City, Vietnam
| | - Kathryn E Holt
- Centre for Systems Genomics, University of Melbourne.,Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria 3052, Australia
| | - Nicholas R Thomson
- Bacterial Genomics, The Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK.,Centre for Tropical Medicine and Global Health, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford OX3 7FZ, UK
| | - Stephen Baker
- The Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, 764 Vo Van Kiet, Quan 5, Ho Chi Minh City, Vietnam.,Centre for Tropical Medicine and Global Health, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford OX3 7FZ, UK.,Department of Pathogen and Molecular Biology, The London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT, UK
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Sun Q, Lan R, Wang Y, Wang J, Wang Y, Li P, Du P, Xu J. Isolation and genomic characterization of SfI, a serotype-converting bacteriophage of Shigella flexneri. BMC Microbiol 2013; 13:39. [PMID: 23414301 PMCID: PMC3636060 DOI: 10.1186/1471-2180-13-39] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 01/31/2013] [Indexed: 11/10/2022] Open
Abstract
Background All Shigella flexneri serotypes except serotype 6 share a common O-antigen tetrasaccharide backbone and nearly all variations between serotypes are due to glucosyl and/or O-acetyl modifications of the common O unit mediated by glycosyltransferases encoded by serotype-converting bacteriophages. Several S. flexneri serotype-converting phages including SfV, SfX, Sf6 and SfII have been isolated and characterized. However, S. flexneri serotype-converting phage SfI which encodes a type I modification of serotype 1 (1a, 1b, 1c and 1d) had not yet been characterized. Results The SfI phage was induced and purified from a S. flexneri serotype 1a clinical strain 019. Electron microscopy showed that the SfI phage has a hexagonal head and a long contractile tail, characteristic of the members of Myoviridae family. SfI can convert serotype Y to serotype 1a and serotype X to serotype 1d, but cannot convert 10 other S. flexneri serotypes (1a, 1b, 2a, 2b, 3a, 3b, 4a, 4b, 5a, Xv) tested, suggesting that SfI has a narrow host range. Similar to other S. flexneri serotype-converting phages, SfI integrates into the tRNA-thrW gene adjacent to proA of the host chromosome when lysogenized. The complete sequence of the SfI genome was 38,389 bp, encoding 66 open reading frames and two tRNA genes. Phage SfI shares significant homology with S. flexneri phage SfV, Escherichia coli prophage e14 and lambda, and is classified into the lambdoid phage family. SfI was found to use a cos mechanism for DNA packaging similar to that of phage SfV. Conclusions SfI contains features of lambdoid phages and is closely related to S. flexneri phage SfV, E. coli prophage e14 and lambda. The characterization of SfI enhances our understanding of serotype conversion of S. flexneri.
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Pham TT, Jacobs-Sera D, Pedulla ML, Hendrix RW, Hatfull GF. Comparative genomic analysis of mycobacteriophage Tweety: evolutionary insights and construction of compatible site-specific integration vectors for mycobacteria. MICROBIOLOGY-SGM 2007; 153:2711-2723. [PMID: 17660435 PMCID: PMC2884959 DOI: 10.1099/mic.0.2007/008904-0] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Mycobacteriophage Tweety is a newly isolated phage of Mycobacterium smegmatis. It has a viral morphology with an isometric head and a long flexible tail, and forms turbid plaques from which stable lysogens can be isolated. The Tweety genome is 58 692 bp in length, contains 109 protein-coding genes, and shows significant but interrupted nucleotide sequence similarity with the previously described mycobacteriophages Llij, PMC and Che8. However, overall the genome possesses mosaic architecture, with gene products being related to other mycobacteriophages such as Che9d, Omega and Corndog. A gene encoding an integrase of the tyrosine-recombinase family is located close to the centre of the genome, and a putative attP site has been identified within a short intergenic region immediately upstream of int. This Tweety attP–int cassette was used to construct a new set of integration-proficient plasmid vectors that efficiently transform both fast- and slow-growing mycobacteria through plasmid integration at a chromosomal locus containing a tRNALys gene. These vectors are maintained well in the absence of selection and are completely compatible with integration vectors derived from mycobacteriophage L5, enabling the simple construction of complex recombinants with genes integrated simultaneously at different chromosomal positions.
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Affiliation(s)
- Thuy T. Pham
- Department of Biological Sciences and Pittsburgh Bacteriophage Institute, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Deborah Jacobs-Sera
- Department of Biological Sciences and Pittsburgh Bacteriophage Institute, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Marisa L. Pedulla
- Department of Biology, Montana Tech, University of Montana, Butte, MT 59701, USA
| | - Roger W. Hendrix
- Department of Biological Sciences and Pittsburgh Bacteriophage Institute, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Graham F. Hatfull
- Department of Biological Sciences and Pittsburgh Bacteriophage Institute, University of Pittsburgh, Pittsburgh, PA 15260, USA
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Kaluzny K, Abeyrathne PD, Lam JS. Coexistence of two distinct versions of O-antigen polymerase, Wzy-alpha and Wzy-beta, in Pseudomonas aeruginosa serogroup O2 and their contributions to cell surface diversity. J Bacteriol 2007; 189:4141-52. [PMID: 17384183 PMCID: PMC1913395 DOI: 10.1128/jb.00237-07] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Assembly of B-band lipopolysaccharide (LPS) in Pseudomonas aeruginosa follows a Wzy-dependent pathway, requiring the O-antigen polymerase Wzy and other proteins. The peptide sequences of the wzy(alpha) product from strains of serotypes O2, O5, and O16 are identical, but the O units in O5 are alpha-glycosidically linked, while those in O2 and O16 are beta-linked. We hypothesized that a derivative of the D3 bacteriophage wzy(beta) is present in the chromosomes of O2 and O16 and that this gene is responsible for the beta-linkage. By a combination of PCR and primer walking, wzy(beta) genes of both serotypes have been amplified and cloned. They are identical but share only 87.42% sequence identity with their xenolog in D3. A chromosomal knockout mutant of O16 wzy(beta) was made, and it produces semirough LPS devoid of B-band O antigen. The cloned wzy(beta) is capable of complementing the O16 wzy(beta) mutant, as well as cross-complementing a wzy(alpha) knockout mutant. However, in the latter case, the restored O antigen was beta-linked. Using reverse transcription-PCR, we showed that wzy(alpha) was transcribed in O2 and O16 strains and was functional, since both of these genes could complement the wzy(alpha) mutant of O5. With the coexistence of wzy(alpha) and wzy(beta) in O2 and O16 and the B-band O polysaccharides in these being beta-linked, we hypothesized that iap, an inhibitor of the alpha-polymerase gene, must be present in these serotypes. Indeed, through PCR, TOPO-cloning, and nucleotide-sequencing results, we verified the presence of iap in both O2 and O16 serotypes.
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Affiliation(s)
- Katarina Kaluzny
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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Jennison AV, Roberts F, Verma NK. Construction of a multivalent vaccine strain ofShigella flexneriand evaluation of serotype-specific immunity. ACTA ACUST UNITED AC 2006; 46:444-51. [PMID: 16553820 DOI: 10.1111/j.1574-695x.2006.00062.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Shigella flexneri causes more fatalities by shigellosis than any other Shigella species. There are 13 different serotypes of S. flexneri and their distribution varies between endemic geographical regions. The immune response against S. flexneri is serotype-specific, so current immunization strategies have required the administration of multiple vaccine strains to provide protection against multiple serotypes. In this study, we report the construction of a multivalent S. flexneri vaccine strain, SFL1425, expressing the O-antigen structure specific for serotypes 2a and 5a. This combination of type antigens has not previously been reported for S. flexneri. The multivalent vaccine strain, SFL1425 was able to induce a specific immune response against both serotypes 2a and 5a in a mouse pulmonary model.
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MESH Headings
- Animals
- Antibodies, Bacterial/blood
- Blotting, Southern
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- Dysentery, Bacillary/immunology
- Dysentery, Bacillary/microbiology
- Dysentery, Bacillary/prevention & control
- Enzyme-Linked Immunosorbent Assay
- Female
- Mice
- Mice, Inbred BALB C
- O Antigens/genetics
- O Antigens/immunology
- Polymerase Chain Reaction
- Shigella Vaccines/genetics
- Shigella Vaccines/immunology
- Shigella Vaccines/pharmacology
- Shigella flexneri/genetics
- Shigella flexneri/immunology
- Species Specificity
- Vaccines, Attenuated/genetics
- Vaccines, Attenuated/immunology
- Vaccines, Attenuated/pharmacology
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Affiliation(s)
- Amy V Jennison
- School of Biochemistry and Molecular Biology, Faculty of Science, The Australian National University, Canberra, Australia
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Allison GE, Angeles D, Tran-Dinh N, Verma NK. Complete genomic sequence of SfV, a serotype-converting temperate bacteriophage of Shigella flexneri. J Bacteriol 2002; 184:1974-87. [PMID: 11889106 PMCID: PMC134923 DOI: 10.1128/jb.184.7.1974-1987.2002] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2001] [Accepted: 01/08/2002] [Indexed: 11/20/2022] Open
Abstract
Bacteriophage SfV is a temperate serotype-converting phage of Shigella flexneri. SfV encodes the factors involved in type V O-antigen modification, and the serotype conversion and integration-excision modules of the phage have been isolated and characterized. We now report on the complete sequence of the SfV genome (37,074 bp). A total of 53 open reading frames were predicted from the nucleotide sequence, and analysis of the corresponding proteins was used to construct a functional map. The general organization of the genes in the SfV genome is similar to that of bacteriophage lambda, and numerous features of the sequence are described. The superinfection immunity system of SfV includes a lambda-like repression system and a P4-like transcription termination mechanism. Sequence analysis also suggests that SfV encodes multiple DNA methylases, and experiments confirmed that orf-41 encodes a Dam methylase. Studies conducted to determine if the phage-encoded methylase confers host DNA methylation showed that the two S. flexneri strains analyzed encode their own Dam methylase. Restriction mapping and sequence analysis revealed that the phage genome has cos sites at the termini. The tail assembly and structural genes of SfV show homology to those of phage Mu and Mu-like prophages in the genome of Escherichia coli O157:H7 and Haemophilus influenzae. Significant homology (30% of the genome in total) between sections of the early, regulatory, and structural regions of the SfV genome and the e14 and KpLE1 prophages in the E. coli K-12 genome were noted, suggesting that these three phages have common evolutionary origins.
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Affiliation(s)
- Gwen E Allison
- School of Biochemistry and Molecular Biology, Faculty of Science, The Australian National University, Canberra ACT 0200, Australia
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