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Panda S, Swain SK, Sahu BP, Sarangi R. Insights into genome plasticity and gene regulation in Orientia tsutsugamushi through genome-wide mining of microsatellite markers. 3 Biotech 2023; 13:366. [PMID: 37840877 PMCID: PMC10575825 DOI: 10.1007/s13205-023-03795-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 09/25/2023] [Indexed: 10/17/2023] Open
Abstract
Microsatellite markers are being used for molecular identification and characterization as well as estimation of evolution patterns due to their highly polymorphic nature. The repeats hold 40% of the entire genome of Orientia tsutsugamushi (OT), but not yet been characterized. Thus, we investigated the genome-wide presence of microsatellites within nine complete genomes of OT and analyzed their distribution pattern, composition, and complexity. The in-silico study revealed that the genome of OT enriched with microsatellites having a total of 126,187 SSRs and 10,374 cSSRs throughout the genome, of which 70% and 30% are represented within the coding and non-coding regions, respectively. The relative density (RD) and relative abundance (RA) of SSRs were 42-44.43/kb and 6.25-6.59/kb, while for cSSRs this value ranged from 7.06 to 8.1/kb and 0.50 to 0.55/kb, respectively. However, RA and RD were weakly correlated with genome size and incidence of microsatellites. The mononucleotide repeats (54.55%) were prevalent over di- (33.22%), tri- (11.88%), tetra- (0.27%), penta- (0.02%), hexanucleotide (0.04%) repeats, with poly (A/T) richness over poly (G/C). The motif composition of cSSRs revealed that maximum cSSRs were made up of two microsatellites having unique duplication patterns such as AT-x-AT and CG-x-CG. To our knowledge, this is the first study of microsatellites in the OT genome, where characterization of such variations in repeat sequences would be important in deciphering the origin, rate of mutation, and role of repeat sequences in the genome. More numbers of microsatellites represented within the coding region provide an insight into the genome plasticity that may interfere with gene regulation to mitigate host-pathogen interaction and evolution of the species.
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Affiliation(s)
- Subhasmita Panda
- Department of Pediatrics, IMS and SUM Hospital, Siksha ‘O’ Anusandhan (Deemed to be University), K8, Kalinga Nagar, Bhubaneswar, Odisha 751003 India
| | - Subrat Kumar Swain
- Medical Research Laboratory, IMS and SUM Hospital, Siksha ‘O’ Anusandhan (Deemed to be University), K8, Kalinga Nagar, Bhubaneswar, Odisha 751003 India
| | - Basanta Pravas Sahu
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Rachita Sarangi
- Department of Pediatrics, IMS and SUM Hospital, Siksha “O” Anusandhan (Deemed to be University), K8, Kalinga Nagar, Bhubaneswar, Odisha 751003 India
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2
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Nahar N, Tram G, Jen FEC, Phillips ZN, Weinert L, Bossé J, Jabbari J, Gouil Q, Du MM, Ritchie M, Bowden R, Langford P, Tucker A, Jennings M, Turni C, Blackall P, Atack J. Actinobacillus pleuropneumoniae encodes multiple phase-variable DNA methyltransferases that control distinct phasevarions. Nucleic Acids Res 2023; 51:3240-3260. [PMID: 36840716 PMCID: PMC10123105 DOI: 10.1093/nar/gkad091] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 01/31/2023] [Accepted: 02/03/2023] [Indexed: 02/26/2023] Open
Abstract
Actinobacillus pleuropneumoniae is the cause of porcine pleuropneumonia, a severe respiratory tract infection that is responsible for major economic losses to the swine industry. Many host-adapted bacterial pathogens encode systems known as phasevarions (phase-variable regulons). Phasevarions result from variable expression of cytoplasmic DNA methyltransferases. Variable expression results in genome-wide methylation differences within a bacterial population, leading to altered expression of multiple genes via epigenetic mechanisms. Our examination of a diverse population of A. pleuropneumoniae strains determined that Type I and Type III DNA methyltransferases with the hallmarks of phase variation were present in this species. We demonstrate that phase variation is occurring in these methyltransferases, and show associations between particular Type III methyltransferase alleles and serovar. Using Pacific BioSciences Single-Molecule, Real-Time (SMRT) sequencing and Oxford Nanopore sequencing, we demonstrate the presence of the first ever characterised phase-variable, cytosine-specific Type III DNA methyltransferase. Phase variation of distinct Type III DNA methyltransferase in A. pleuropneumoniae results in the regulation of distinct phasevarions, and in multiple phenotypic differences relevant to pathobiology. Our characterisation of these newly described phasevarions in A. pleuropneumoniae will aid in the selection of stably expressed antigens, and direct and inform development of a rationally designed subunit vaccine against this major veterinary pathogen.
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Affiliation(s)
- Nusrat Nahar
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
| | - Greg Tram
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
| | - Freda E-C Jen
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
| | - Zachary N Phillips
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
| | - Lucy A Weinert
- Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, UK
| | - Janine T Bossé
- Section of Paediatric Infectious Disease, Imperial College London, St Mary's Campus, London W2 1PG, UK
| | - Jafar S Jabbari
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville 3010, Australia
| | - Quentin Gouil
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville 3010, Australia
| | - Mei R M Du
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Matthew E Ritchie
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville 3010, Australia
| | - Rory Bowden
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville 3010, Australia
| | - Paul R Langford
- Section of Paediatric Infectious Disease, Imperial College London, St Mary's Campus, London W2 1PG, UK
| | - Alexander W Tucker
- Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, UK
| | - Michael P Jennings
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
| | - Conny Turni
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Patrick J Blackall
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - John M Atack
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
- School of Environment and Science, Griffith University, Gold Coast, Queensland 4222, Australia
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3
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Topaz N, Tsang R, Deghmane AE, Claus H, Lâm TT, Litt D, Bajanca-Lavado MP, Pérez-Vázquez M, Vestrheim D, Giufrè M, Van Der Ende A, Gaillot O, Kuch A, McElligott M, Taha MK, Wang X. Phylogenetic Structure and Comparative Genomics of Multi-National Invasive Haemophilus influenzae Serotype a Isolates. Front Microbiol 2022; 13:856884. [PMID: 35401483 PMCID: PMC8988223 DOI: 10.3389/fmicb.2022.856884] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 02/24/2022] [Indexed: 11/13/2022] Open
Abstract
Recent reports have indicated a rise of invasive disease caused by Haemophilus influenzae serotype a (Hia) in North America and some European countries. The whole-genome sequences for a total of 410 invasive Hia isolates were obtained from 12 countries spanning the years of 1998 to 2019 and underwent phylogenetic and comparative genomic analysis in order to characterize the major strains causing disease and the genetic variation present among factors contributing to virulence and antimicrobial resistance. Among 410 isolate sequences received, 408 passed our quality control and underwent genomic analysis. Phylogenetic analysis revealed that the Hia isolates formed four genetically distinct clades: clade 1 (n = 336), clade 2 (n = 13), clade 3 (n = 3) and clade 4 (n = 56). A low diversity subclade 1.1 was found in clade 1 and contained almost exclusively North American isolates. The predominant sequence types in the Hia collection were ST-56 (n = 125), ST-23 (n = 98) and ST-576 (n = 51), which belonged to clade 1, and ST-62 (n = 54), which belonged to clade 4. Clades 1 and 4 contained predominantly North American isolates, and clades 2 and 3 predominantly contained European isolates. Evidence of the presence of capsule duplication was detected in clade 1 and 2 isolates. Seven of the virulence genes involved in endotoxin biosynthesis were absent from all Hia isolates. In general, the presence of known factors contributing to β-lactam antibiotic resistance was low among Hia isolates. Further tests for virulence and antibiotic susceptibility would be required to determine the impact of these variations among the isolates.
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Affiliation(s)
- Nadav Topaz
- Meningitis and Vaccine Preventable Diseases Branch, Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, United States
| | - Raymond Tsang
- Vaccine Preventable Bacterial Diseases, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Ala-Eddine Deghmane
- Centre National de Référence des Méningocoques, Institut Pasteur, Paris, France
| | - Heike Claus
- Institute for Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
| | - Thiên-Trí Lâm
- Institute for Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
| | - David Litt
- Respiratory and Vaccine Preventable Bacterial Reference Unit, Public Health England, London, United Kingdom
| | - Maria Paula Bajanca-Lavado
- Haemophilus Influenzae Reference Laboratory, Department of Infectious Disease, National Institute of Health, Lisbon, Portugal
| | - María Pérez-Vázquez
- Laboratorio de Referencia e Investigación en Resistencia a Antibióticos e Infecciones Relacionadas con la Asistencia Sanitaria, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain
| | - Didrik Vestrheim
- Norwegian Institute of Public Health, Division of Infection Control and Environmental Health, Oslo, Norway
| | - Maria Giufrè
- Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Arie Van Der Ende
- Department of Medical Microbiology and Infection Prevention and the Netherlands Reference Laboratory for Bacterial Meningitis, University of Amsterdam, Amsterdam, Netherlands
| | - Olivier Gaillot
- Service de Bactériologie-Hygiène, CHU Lille, Lille, France
- CNRS, INSERM, U1019-UMR 8204, Center for Infection and Immunity, CHU Lille, Lille, France
| | - Alicja Kuch
- Department of Epidemiology and Clinical Microbiology, National Medicines Institute, Warsaw, Poland
| | - Martha McElligott
- Irish Meningitis and Sepsis Reference Laboratory, Children’s Health Ireland at Temple Street, Dublin, Ireland
| | - Muhamed-Kheir Taha
- Centre National de Référence des Méningocoques, Institut Pasteur, Paris, France
| | - Xin Wang
- Meningitis and Vaccine Preventable Diseases Branch, Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, United States
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Phase Variation in HMW1A Controls a Phenotypic Switch in Haemophilus influenzae Associated with Pathoadaptation during Persistent Infection. mBio 2021; 12:e0078921. [PMID: 34154422 PMCID: PMC8262952 DOI: 10.1128/mbio.00789-21] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Genetic variants arising from within-patient evolution shed light on bacterial adaptation during chronic infection. Contingency loci generate high levels of genetic variation in bacterial genomes, enabling adaptation to the stringent selective pressures exerted by the host. A significant gap in our understanding of phase-variable contingency loci is the extent of their contribution to natural infections. The human-adapted pathogen nontypeable Haemophilus influenzae (NTHi) causes persistent infections, which contribute to underlying disease progression. The phase-variable high-molecular-weight (HMW) adhesins located on the NTHi surface mediate adherence to respiratory epithelial cells and, depending on the allelic variant, can also confer high epithelial invasiveness or hyperinvasion. In this study, we characterize the dynamics of HMW-mediated hyperinvasion in living cells and identify a specific HMW binding domain shared by hyperinvasive NTHi isolates of distinct pathological origins. Moreover, we observed that HMW expression decreased over time by using a longitudinal set of persistent NTHi strains collected from chronic obstructive pulmonary disease (COPD) patients, resulting from increased numbers of simple-sequence repeats (SSRs) downstream of the functional P2hmw1A promoter, which is the one primarily driving HMW expression. Notably, the increased SSR numbers at the hmw1 promoter region also control a phenotypic switch toward lower bacterial intracellular invasion and higher biofilm formation, likely conferring adaptive advantages during chronic airway infection by NTHi. Overall, we reveal novel molecular mechanisms of NTHi pathoadaptation based on within-patient lifestyle switching controlled by phase variation.
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Isaev AB, Musharova OS, Severinov KV. Microbial Arsenal of Antiviral Defenses - Part I. BIOCHEMISTRY (MOSCOW) 2021; 86:319-337. [PMID: 33838632 DOI: 10.1134/s0006297921030081] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Bacteriophages or phages are viruses that infect bacterial cells (for the scope of this review we will also consider viruses that infect Archaea). Constant threat of phage infection is a major force that shapes evolution of the microbial genomes. To withstand infection, bacteria had evolved numerous strategies to avoid recognition by phages or to directly interfere with phage propagation inside the cell. Classical molecular biology and genetic engineering have been deeply intertwined with the study of phages and host defenses. Nowadays, owing to the rise of phage therapy, broad application of CRISPR-Cas technologies, and development of bioinformatics approaches that facilitate discovery of new systems, phage biology experiences a revival. This review describes variety of strategies employed by microbes to counter phage infection, with a focus on novel systems discovered in recent years. First chapter covers defense associated with cell surface, role of small molecules, and innate immunity systems relying on DNA modification.
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Affiliation(s)
- Artem B Isaev
- Skolkovo Institute of Science and Technology, Moscow, 143028, Russia.
| | - Olga S Musharova
- Skolkovo Institute of Science and Technology, Moscow, 143028, Russia. .,Institute of Molecular Genetics, Moscow, 119334, Russia
| | - Konstantin V Severinov
- Skolkovo Institute of Science and Technology, Moscow, 143028, Russia. .,Waksman Institute of Microbiology, Piscataway, NJ 08854, USA
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6
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Structures and stability of simple DNA repeats from bacteria. Biochem J 2020; 477:325-339. [PMID: 31967649 PMCID: PMC7015867 DOI: 10.1042/bcj20190703] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 12/20/2019] [Accepted: 01/03/2020] [Indexed: 01/12/2023]
Abstract
DNA is a fundamentally important molecule for all cellular organisms due to its biological role as the store of hereditary, genetic information. On the one hand, genomic DNA is very stable, both in chemical and biological contexts, and this assists its genetic functions. On the other hand, it is also a dynamic molecule, and constant changes in its structure and sequence drive many biological processes, including adaptation and evolution of organisms. DNA genomes contain significant amounts of repetitive sequences, which have divergent functions in the complex processes that involve DNA, including replication, recombination, repair, and transcription. Through their involvement in these processes, repetitive DNA sequences influence the genetic instability and evolution of DNA molecules and they are located non-randomly in all genomes. Mechanisms that influence such genetic instability have been studied in many organisms, including within human genomes where they are linked to various human diseases. Here, we review our understanding of short, simple DNA repeats across a diverse range of bacteria, comparing the prevalence of repetitive DNA sequences in different genomes. We describe the range of DNA structures that have been observed in such repeats, focusing on their propensity to form local, non-B-DNA structures. Finally, we discuss the biological significance of such unusual DNA structures and relate this to studies where the impacts of DNA metabolism on genetic stability are linked to human diseases. Overall, we show that simple DNA repeats in bacteria serve as excellent and tractable experimental models for biochemical studies of their cellular functions and influences.
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7
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Moraxella catarrhalis phase-variable loci show differences in expression during conditions relevant to disease. PLoS One 2020; 15:e0234306. [PMID: 32555615 PMCID: PMC7302503 DOI: 10.1371/journal.pone.0234306] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Accepted: 05/22/2020] [Indexed: 11/29/2022] Open
Abstract
Moraxella catarrhalis is a human-adapted, opportunistic bacterial pathogen of the respiratory mucosa. Although asymptomatic colonization of the nasopharynx is common, M. catarrhalis can ascend into the middle ear, where it is a prevalent causative agent of otitis media in children, or enter the lower respiratory tract, where it is associated with acute exacerbations of chronic obstructive pulmonary disease in adults. Phase variation is the high frequency, random, reversible switching of gene expression that allows bacteria to adapt to different host microenvironments and evade host defences, and is most commonly mediated by simple DNA sequence repeats. Bioinformatic analysis of five closed M. catarrhalis genomes identified 17 unique simple DNA sequence repeat tracts that were variable between strains, indicating the potential to mediate phase variable expression of the associated genes. Assays designed to assess simple sequence repeat variation under conditions mimicking host infection demonstrated that phase variation of uspA1 (ubiquitous surface protein A1) from high to low expression occurs over 72 hours of biofilm passage, while phase variation of uspA2 (ubiquitous surface protein A2) to high expression variants occurs during repeated exposure to human serum, as measured by mRNA levels. We also identify and confirm the variable expression of two novel phase variable genes encoding a Type III DNA methyltransferase (modO), and a conserved hypothetical permease (MC25239_RS00020). These data reveal the repertoire of phase variable genes mediated by simple sequence repeats in M. catarrhalis and demonstrate that modulation of expression under conditions mimicking human infection is attributed to changes in simple sequence repeat length.
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Santos-Cortez RLP, Bhutta MF, Earl JP, Hafrén L, Jennings M, Mell JC, Pichichero ME, Ryan AF, Tateossian H, Ehrlich GD. Panel 3: Genomics, precision medicine and targeted therapies. Int J Pediatr Otorhinolaryngol 2020; 130 Suppl 1:109835. [PMID: 32007292 PMCID: PMC7155947 DOI: 10.1016/j.ijporl.2019.109835] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
OBJECTIVE To review the most recent advances in human and bacterial genomics as applied to pathogenesis and clinical management of otitis media. DATA SOURCES PubMed articles published since the last meeting in June 2015 up to June 2019. REVIEW METHODS A panel of experts in human and bacterial genomics of otitis media was formed. Each panel member reviewed the literature in their respective fields and wrote draft reviews. The reviews were shared with all panel members, and a merged draft was created. The panel met at the 20th International Symposium on Recent Advances in Otitis Media in June 2019, discussed the review and refined the content. A final draft was made, circulated, and approved by the panel members. CONCLUSION Trans-disciplinary approaches applying pan-omic technologies to identify human susceptibility to otitis media and to understand microbial population dynamics, patho-adaptation and virulence mechanisms are crucial to the development of novel, personalized therapeutics and prevention strategies for otitis media. IMPLICATIONS FOR PRACTICE In the future otitis media prevention strategies may be augmented by mucosal immunization, combination vaccines targeting multiple pathogens, and modulation of the middle ear microbiome. Both treatment and vaccination may be tailored to an individual's otitis media phenotype as defined by molecular profiles obtained by using rapidly developing techniques in microbial and host genomics.
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Affiliation(s)
- Regie Lyn P. Santos-Cortez
- Department of Otolaryngology, School of Medicine, University of Colorado Anschutz Medical Campus, 12700 E. 19 Ave., Aurora, CO 80045, USA
| | - Mahmood F. Bhutta
- Department of ENT, Royal Sussex County Hospital, Eastern Road, Brighton BN2 5BE, UK
| | - Joshua P. Earl
- Center for Genomic Sciences, Institute for Molecular Medicine and Infectious Disease; Department of Microbiology and Immunology; Drexel University College of Medicine, 245 N. 15 St., Philadelphia, PA 19102, USA
| | - Lena Hafrén
- Department of Otorhinolaryngology, Head & Neck Surgery, University of Helsinki and Helsinki University Hospital, Helsinki, Tukholmankatu 8A, 00290 Helsinki, Finland
| | - Michael Jennings
- Institute for Glycomics, Gold Coast campus, Griffith University, QLD 4222, Australia
| | - Joshua C. Mell
- Center for Genomic Sciences, Institute for Molecular Medicine and Infectious Disease; Department of Microbiology and Immunology; Drexel University College of Medicine, 245 N. 15 St., Philadelphia, PA 19102, USA
| | - Michael E. Pichichero
- Center for Infectious Diseases and Immunology, Rochester General Hospital Research Institute, 1425 Portland Ave., Rochester, NY 14621, USA
| | - Allen F. Ryan
- Department of Surgery/Otolaryngology, University of California San Diego, 9500 Gilman Dr., La Jolla, CA 92093, USA
| | - Hilda Tateossian
- Mammalian Genetics Unit, MRC Harwell Institute, Harwell, Oxford, Didcot OX11 0RD, UK
| | - Garth D. Ehrlich
- Center for Genomic Sciences, Institute for Molecular Medicine and Infectious Disease; Department of Microbiology and Immunology; Drexel University College of Medicine, 245 N. 15 St., Philadelphia, PA 19102, USA
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Abstract
Nontypeable Haemophilus influenzae (NTHi) is a leading cause of respiratory tract infections worldwide and continues to be a global health burden. Adhesion and colonization of host cells are crucial steps in bacterial pathogenesis, and in many strains of NTHi, the interaction with the host is mediated by the high molecular weight adhesins HMW1A and HMW2A. These adhesins are N-glycoproteins that are modified by cytoplasmic glycosyltransferases HMW1C and HMW2C. Phase variation in the number of short sequence repeats in the promoters of hmw1A and hmw2A directly affects their expression. Here, we report the presence of similar variable repeat elements in the promoters of hmw1C and hmw2C in diverse NTHi isolates. In an ex vivo assay, we systematically altered the substrate and glycosyltransferase expression and showed that both of these factors quantitatively affected the site-specific efficiency of glycosylation on HMW-A. This represents a novel mechanism through which phase variation can generate diversity in the quantitative extent of site-specific post-translational modifications on antigenic surface proteins. Glycosylation occupancy was incomplete at many sites, variable between sites, and generally lower close to the C-terminus of HMW-A. We investigated the causes of this variability. As HMW-C glycosylates HMW-A in the cytoplasm, we tested how secretion affected glycosylation on HMW-A and showed that retaining HMW-A in the cytoplasm indeed increased glycosylation occupancy across the full length of the protein. Site-directed mutagenesis showed that HMW-C had no inherent preference for glycosylating asparagines in NxS or NxT sequons. This work provides key insights into factors contributing to the heterogenous modifications of NTHi HMW-A adhesins, expands knowledge of NTHi population diversity and pathogenic capability, and is relevant to vaccine design for NTHi and related pathogens.
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Atack JM, Guo C, Yang L, Zhou Y, Jennings MP. DNA sequence repeats identify numerous Type I restriction-modification systems that are potential epigenetic regulators controlling phase-variable regulons; phasevarions. FASEB J 2019; 34:1038-1051. [PMID: 31914596 PMCID: PMC7383803 DOI: 10.1096/fj.201901536rr] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 11/07/2019] [Accepted: 11/09/2019] [Indexed: 12/27/2022]
Abstract
Over recent years several examples of randomly switching methyltransferases, associated with Type III restriction‐modification (R‐M) systems, have been described in pathogenic bacteria. In every case examined, changes in simple DNA sequence repeats result in variable methyltransferase expression and result in global changes in gene expression, and differentiation of the bacterial cell into distinct phenotypes. These epigenetic regulatory systems are called phasevarions, phase‐variable regulons, and are widespread in bacteria, with 17.4% of Type III R‐M system containing simple DNA sequence repeats. A distinct, recombination‐driven random switching system has also been described in Streptococci in Type I R‐M systems that also regulate gene expression. Here, we interrogate the most extensive and well‐curated database of R‐M systems, REBASE, by searching for all possible simple DNA sequence repeats in the hsdRMS genes that encode Type I R‐M systems. We report that 7.9% of hsdS, 2% of hsdM, and of 4.3% of hsdR genes contain simple sequence repeats that are capable of mediating phase variation. Phase variation of both hsdM and hsdS genes will lead to differential methyltransferase expression or specificity, and thereby the potential to control phasevarions. These data suggest that in addition to well characterized phasevarions controlled by Type III mod genes, and the previously described Streptococcal Type I R‐M systems that switch via recombination, approximately 10% of all Type I R‐M systems surveyed herein have independently evolved the ability to randomly switch expression via simple DNA sequence repeats.
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Affiliation(s)
- John M Atack
- Institute for Glycomics, Griffith University, Gold Coast, QLD, Australia
| | - Chengying Guo
- College of Plant Protection, Shandong Agricultural University, Taian City, China
| | - Long Yang
- College of Plant Protection, Shandong Agricultural University, Taian City, China
| | - Yaoqi Zhou
- Institute for Glycomics, Griffith University, Gold Coast, QLD, Australia
| | - Michael P Jennings
- Institute for Glycomics, Griffith University, Gold Coast, QLD, Australia
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11
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Atack JM, Yang Y, Seib KL, Zhou Y, Jennings MP. A survey of Type III restriction-modification systems reveals numerous, novel epigenetic regulators controlling phase-variable regulons; phasevarions. Nucleic Acids Res 2019; 46:3532-3542. [PMID: 29554328 PMCID: PMC5909438 DOI: 10.1093/nar/gky192] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 03/10/2018] [Indexed: 12/21/2022] Open
Abstract
Many bacteria utilize simple DNA sequence repeats as a mechanism to randomly switch genes on and off. This process is called phase variation. Several phase-variable N6-adenine DNA-methyltransferases from Type III restriction-modification systems have been reported in bacterial pathogens. Random switching of DNA methyltransferases changes the global DNA methylation pattern, leading to changes in gene expression. These epigenetic regulatory systems are called phasevarions — phase-variable regulons. The extent of these phase-variable genes in the bacterial kingdom is unknown. Here, we interrogated a database of restriction-modification systems, REBASE, by searching for all simple DNA sequence repeats in mod genes that encode Type III N6-adenine DNA-methyltransferases. We report that 17.4% of Type III mod genes (662/3805) contain simple sequence repeats. Of these, only one-fifth have been previously identified. The newly discovered examples are widely distributed and include many examples in opportunistic pathogens as well as in environmental species. In many cases, multiple phasevarions exist in one genome, with examples of up to 4 independent phasevarions in some species. We found several new types of phase-variable mod genes, including the first example of a phase-variable methyltransferase in pathogenic Escherichia coli. Phasevarions are a common epigenetic regulation contingency strategy used by both pathogenic and non-pathogenic bacteria.
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Affiliation(s)
- John M Atack
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
| | - Yuedong Yang
- School of Data and Computer Science, Sun Yat-Sen University, Guangzhou 510006, China
| | - Kate L Seib
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
| | - Yaoqi Zhou
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
| | - Michael P Jennings
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4222, Australia
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12
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Turkington CJR, Morozov A, Clokie MRJ, Bayliss CD. Phage-Resistant Phase-Variant Sub-populations Mediate Herd Immunity Against Bacteriophage Invasion of Bacterial Meta-Populations. Front Microbiol 2019; 10:1473. [PMID: 31333609 PMCID: PMC6625227 DOI: 10.3389/fmicb.2019.01473] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Accepted: 06/13/2019] [Indexed: 01/06/2023] Open
Abstract
Hypermutable loci are widespread in bacteria as mechanisms for rapid generation of phenotypic diversity within a population that enables survival of fluctuating, often antagonistic, selection pressures. Localized hypermutation can mediate phase variation and enable survival of bacteriophage predation due to high frequency, reversible alterations in the expression of phage receptors. As phase variation can also generate population-to-population heterogeneity, we hypothesized that this phenomenon may facilitate survival of spatially-separated bacterial populations from phage invasion in a manner analogous to herd immunity to infectious diseases in human populations. The lic2A gene of Haemophilus influenzae is subject to “ON” and “OFF” switches in expression mediated by mutations in a 5′CAAT repeat tract present within the reading frame. The enzyme encoded by lic2A mediates addition of a galactose moiety of the lipopolysaccharide. This moiety is required for attachment of the HP1C1 phage such that the ON state of the lic2A gene is associated with HP1c1 susceptibility while the OFF state is resistant to infection. We developed an “oscillating prey assay” to examine phage spread through a series of sub-populations of Haemophilus influenzae whose phage receptor is in an ON or OFF state. Phage extinction was frequently observed when the proportion of phage-resistant sub-populations exceeded 34%. In silico modeling indicated that phage extinction was interdependent on phage loss during transfer between sub-populations and the frequency of resistant sub-populations. In a fixed-area oscillating prey assay, heterogeneity in phage resistance was observed to generate vast differences in phage densities across a meta-population of multiple bacterial sub-populations resulting in protective quarantining of some sub-populations from phage attack. We conclude that phase-variable hypermutable loci produce bacterial “herd immunity” with resistant intermediary-populations acting as a barricade to reduce the viral load faced by phage-susceptible sub-populations. This paradigm of meta-population protection is applicable to evolution of hypermutable loci in multiple bacteria-phage and host-pathogen interactions.
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Affiliation(s)
| | - Andrew Morozov
- Department of Mathematics, University of Leicester, Leicester, United Kingdom
| | - Martha R J Clokie
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Christopher D Bayliss
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
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Insights into the population structure and pan-genome of Haemophilus influenzae. INFECTION GENETICS AND EVOLUTION 2018; 67:126-135. [PMID: 30391557 DOI: 10.1016/j.meegid.2018.10.025] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 10/20/2018] [Accepted: 10/30/2018] [Indexed: 12/25/2022]
Abstract
The human-restricted bacterium Haemophilus influenzae is responsible for respiratory infections in both children and adults. While colonization begins in the upper airways, it can spread throughout the respiratory tract potentially leading to invasive infections. Although the spread of H. influenzae serotype b (Hib) has been prevented by vaccination, the emergence of infections by other serotypes as well as by non-typeable isolates (NTHi) have been observed, prompting the need for novel prevention strategies. Here, we aimed to study the population structure of H. influenzae and to get some insights into its pan-genome. We studied 305H. influenzae strains, enrolling 217 publicly available genomes, as well as 88 newly sequenced H. influenzae invasive strains isolated in Portugal, spanning a 24-year period. NTHi isolates presented a core-SNP-based genetic diversity about 10-fold higher than the one observed for Hib. The analysis of key factors involved in pathogenesis, such as lipooligosaccharides, hemagglutinating pili and High Molecular Weight-adhesins, suggests that NTHi shape its virulence repertoire, either by acquisition and loss of genes or by SNP-based diversification, likely towards host immune evasion and persistence. Discreet NTHi subpopulations structures are proposed based on core-genome supported with 17 candidate genetic markers identified in the accessory genome. Additionally, this study provides two bioinformatics tools for in silico rapid identification of H. influenzae serotypes and NTHi clades previously proposed, obviating laboratory-based demanding procedures. The present study constitutes an important genomic framework that could lay way for future studies on the genetic determinants underlying invasiveness and disease and population structure of H. influenzae.
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Hall JPJ, Harrison E, Brockhurst MA. Competitive species interactions constrain abiotic adaptation in a bacterial soil community. Evol Lett 2018; 2:580-589. [PMID: 30564441 PMCID: PMC6292705 DOI: 10.1002/evl3.83] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 08/29/2018] [Indexed: 01/27/2023] Open
Abstract
Studies of abiotic adaptation often consider single species in isolation, yet natural communities contain many coexisting species which could limit or promote abiotic adaptation. Here we show, using soil bacterial communities, that evolving in the presence of a competitor constrained abiotic adaptation. Specifically, Pseudomonas fluorescens evolved alone was fitter than P. fluorescens evolved alongside Pseudomonas putida, when P. putida was absent. Genome analyses indicated this was due to mutation of the acetate scavenger actP, which occurred exclusively, and almost universally, in single‐species‐evolved clones. actP disruption was associated with increased growth in soil compared with wild‐type actP, but this benefit was abolished when P. putida was present, suggesting a role for carbon scavenging transporters in species interactions, possibly through nutrient competition. Our results show that competitive species interactions can limit the evolutionary response to abiotic selection, because the fitness benefits of abiotic adaptive mutations were negated in more complex communities.
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Affiliation(s)
- James P J Hall
- Department of Animal and Plant Sciences University of Sheffield Western Bank Sheffield S10 2TN United Kingdom.,Department of Biology University of York Wentworth Way York YO10 5DD United Kingdom
| | - Ellie Harrison
- Department of Animal and Plant Sciences University of Sheffield Western Bank Sheffield S10 2TN United Kingdom
| | - Michael A Brockhurst
- Department of Animal and Plant Sciences University of Sheffield Western Bank Sheffield S10 2TN United Kingdom
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15
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Antagonistic Pleiotropy in the Bifunctional Surface Protein FadL (OmpP1) during Adaptation of Haemophilus influenzae to Chronic Lung Infection Associated with Chronic Obstructive Pulmonary Disease. mBio 2018; 9:mBio.01176-18. [PMID: 30254117 PMCID: PMC6156194 DOI: 10.1128/mbio.01176-18] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Tracking bacterial evolution during chronic infection provides insights into how host selection pressures shape bacterial genomes. The human-restricted opportunistic pathogen nontypeable Haemophilus influenzae (NTHi) infects the lower airways of patients suffering chronic obstructive pulmonary disease (COPD) and contributes to disease progression. To identify bacterial genetic variation associated with bacterial adaptation to the COPD lung, we sequenced the genomes of 92 isolates collected from the sputum of 13 COPD patients over 1 to 9 years. Individuals were colonized by distinct clonal types (CTs) over time, but the same CT was often reisolated at a later time or found in different patients. Although genomes from the same CT were nearly identical, intra-CT variation due to mutation and recombination occurred. Recurrent mutations in several genes were likely involved in COPD lung adaptation. Notably, nearly a third of CTs were polymorphic for null alleles of ompP1 (also called fadL), which encodes a bifunctional membrane protein that both binds the human carcinoembryonic antigen-related cell adhesion molecule 1 (hCEACAM1) receptor and imports long-chain fatty acids (LCFAs). Our computational studies provide plausible three-dimensional models for FadL's interaction with hCEACAM1 and LCFA binding. We show that recurrent fadL mutations are likely a case of antagonistic pleiotropy, since loss of FadL reduces NTHi's ability to infect epithelia but also increases its resistance to bactericidal LCFAs enriched within the COPD lung. Supporting this interpretation, truncated fadL alleles are common in publicly available NTHi genomes isolated from the lower airway tract but rare in others. These results shed light on molecular mechanisms of bacterial pathoadaptation and guide future research toward developing novel COPD therapeutics.IMPORTANCE Nontypeable Haemophilus influenzae is an important pathogen in patients with chronic obstructive pulmonary disease (COPD). To elucidate the bacterial pathways undergoing in vivo evolutionary adaptation, we compared bacterial genomes collected over time from 13 COPD patients and identified recurrent genetic changes arising in independent bacterial lineages colonizing different patients. Besides finding changes in phase-variable genes, we found recurrent loss-of-function mutations in the ompP1 (fadL) gene. We show that loss of OmpP1/FadL function reduces this bacterium's ability to infect cells via the hCEACAM1 epithelial receptor but also increases its resistance to bactericidal fatty acids enriched within the COPD lung, suggesting a case of antagonistic pleiotropy that restricts ΔfadL strains' niche. These results show how H. influenzae adapts to host-generated inflammatory mediators in the COPD airways.
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Changes in IgA Protease Expression Are Conferred by Changes in Genomes during Persistent Infection by Nontypeable Haemophilus influenzae in Chronic Obstructive Pulmonary Disease. Infect Immun 2018; 86:IAI.00313-18. [PMID: 29760213 DOI: 10.1128/iai.00313-18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 05/05/2018] [Indexed: 11/20/2022] Open
Abstract
Nontypeable Haemophilus influenzae (NTHi) is an exclusively human pathobiont that plays a critical role in the course and pathogenesis of chronic obstructive pulmonary disease (COPD). NTHi causes acute exacerbations of COPD and also causes persistent infection of the lower airways. NTHi expresses four IgA protease variants (A1, A2, B1, and B2) that play different roles in virulence. Expression of IgA proteases varies among NTHi strains, but little is known about the frequency and mechanisms by which NTHi modulates IgA protease expression during infection in COPD. To assess expression of IgA protease during natural infection in COPD, we studied IgA protease expression by 101 persistent strains (median duration of persistence, 161 days; range, 2 to 1,422 days) collected longitudinally from patients enrolled in a 20-year study of COPD upon initial acquisition and immediately before clearance from the host. Upon acquisition, 89 (88%) expressed IgA protease. A total of 16 of 101 (16%) strains of NTHi altered expression of IgA protease during persistence. Indels and slipped-strand mispairing of mononucleotide repeats conferred changes in expression of igaA1, igaA2, and igaB1 Strains with igaB2 underwent frequent changes in expression of IgA protease B2 during persistence, mediated by slipped-strand mispairing of a 7-nucleotide repeat, TCAAAAT, within the open reading frame of igaB2 We conclude that changes in iga gene sequences result in changes in expression of IgA proteases by NTHi during persistent infection in the respiratory tract of patients with COPD.
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17
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Pettigrew MM, Ahearn CP, Gent JF, Kong Y, Gallo MC, Munro JB, D'Mello A, Sethi S, Tettelin H, Murphy TF. Haemophilus influenzae genome evolution during persistence in the human airways in chronic obstructive pulmonary disease. Proc Natl Acad Sci U S A 2018; 115:E3256-E3265. [PMID: 29555745 PMCID: PMC5889651 DOI: 10.1073/pnas.1719654115] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nontypeable Haemophilus influenzae (NTHi) exclusively colonize and infect humans and are critical to the pathogenesis of chronic obstructive pulmonary disease (COPD). In vitro and animal models do not accurately capture the complex environments encountered by NTHi during human infection. We conducted whole-genome sequencing of 269 longitudinally collected cleared and persistent NTHi from a 15-y prospective study of adults with COPD. Genome sequences were used to elucidate the phylogeny of NTHi isolates, identify genomic changes that occur with persistence in the human airways, and evaluate the effect of selective pressure on 12 candidate vaccine antigens. Strains persisted in individuals with COPD for as long as 1,422 d. Slipped-strand mispairing, mediated by changes in simple sequence repeats in multiple genes during persistence, regulates expression of critical virulence functions, including adherence, nutrient uptake, and modification of surface molecules, and is a major mechanism for survival in the hostile environment of the human airways. A subset of strains underwent a large 400-kb inversion during persistence. NTHi does not undergo significant gene gain or loss during persistence, in contrast to other persistent respiratory tract pathogens. Amino acid sequence changes occurred in 8 of 12 candidate vaccine antigens during persistence, an observation with important implications for vaccine development. These results indicate that NTHi alters its genome during persistence by regulation of critical virulence functions primarily by slipped-strand mispairing, advancing our understanding of how a bacterial pathogen that plays a critical role in COPD adapts to survival in the human respiratory tract.
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Affiliation(s)
- Melinda M Pettigrew
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT 06510
| | - Christian P Ahearn
- Department of Microbiology and Immunology, University at Buffalo, The State University of New York, Buffalo, NY 14203
- Clinical and Translational Research Center, University at Buffalo, The State University of New York, Buffalo, NY 14203
| | - Janneane F Gent
- Department of Environmental Health Sciences, Yale School of Public Health, New Haven, CT 06510
| | - Yong Kong
- Department of Biostatistics, Yale School of Public Health, New Haven, CT 06510
- Department of Molecular Biophysics and Biochemistry, Yale School of Medicine, New Haven, CT 06510
- W.M. Keck Foundation Biotechnology Resource Laboratory, Yale School of Medicine, New Haven, CT 06510
| | - Mary C Gallo
- Department of Microbiology and Immunology, University at Buffalo, The State University of New York, Buffalo, NY 14203
- Clinical and Translational Research Center, University at Buffalo, The State University of New York, Buffalo, NY 14203
| | - James B Munro
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Adonis D'Mello
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Sanjay Sethi
- Clinical and Translational Research Center, University at Buffalo, The State University of New York, Buffalo, NY 14203
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University at Buffalo, The State University of New York, Buffalo, NY 14203
- Department of Medicine, Veterans Affairs Western New York Healthcare System, Buffalo, NY 14215
| | - Hervé Tettelin
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Timothy F Murphy
- Department of Microbiology and Immunology, University at Buffalo, The State University of New York, Buffalo, NY 14203;
- Clinical and Translational Research Center, University at Buffalo, The State University of New York, Buffalo, NY 14203
- Division of Infectious Diseases, Department of Medicine, University at Buffalo, The State University of New York, Buffalo, NY 14203
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18
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Ahearn CP, Gallo MC, Murphy TF. Insights on persistent airway infection by non-typeable Haemophilus influenzae in chronic obstructive pulmonary disease. Pathog Dis 2017; 75:3753446. [PMID: 28449098 PMCID: PMC5437125 DOI: 10.1093/femspd/ftx042] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 04/28/2017] [Indexed: 12/21/2022] Open
Abstract
Non-typeable Haemophilus influenzae (NTHi) is the most common bacterial cause of infection of the lower airways in adults with chronic obstructive pulmonary disease (COPD). Infection of the COPD airways causes acute exacerbations, resulting in substantial morbidity and mortality. NTHi has evolved multiple mechanisms to establish infection in the hostile environment of the COPD airways, allowing the pathogen to persist in the airways for months to years. Persistent infection of the COPD airways contributes to chronic airway inflammation that increases symptoms and accelerates the progressive loss of pulmonary function, which is a hallmark of the disease. Persistence mechanisms of NTHi include the expression of multiple redundant adhesins that mediate binding to host cellular and extracellular matrix components. NTHi evades host immune recognition and clearance by invading host epithelial cells, forming biofilms, altering gene expression and displaying surface antigenic variation. NTHi also binds host serum factors that confer serum resistance. Here we discuss the burden of COPD and the role of NTHi infections in the course of the disease. We provide an overview of NTHi mechanisms of persistence that allow the pathogen to establish a niche in the hostile COPD airways.
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Affiliation(s)
- Christian P. Ahearn
- Department of Microbiology and Immunology, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
- Clinical and Translational Research Center, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
| | - Mary C. Gallo
- Department of Microbiology and Immunology, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
- Clinical and Translational Research Center, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
| | - Timothy F. Murphy
- Department of Microbiology and Immunology, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
- Clinical and Translational Research Center, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
- Division of Infectious Disease, Department of Medicine, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
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A Naturally Occurring Single Nucleotide Polymorphism in a Multicopy Plasmid Produces a Reversible Increase in Antibiotic Resistance. Antimicrob Agents Chemother 2017; 61:AAC.01735-16. [PMID: 27895020 DOI: 10.1128/aac.01735-16] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 11/22/2016] [Indexed: 11/20/2022] Open
Abstract
ColE1 plasmids are small mobilizable replicons that play an important role in the spread of antibiotic resistance in Pasteurellaceae In this study, we describe how a natural single nucleotide polymorphism (SNP) near the origin of replication of the ColE1-type plasmid pB1000 found in a Pasteurella multocida clinical isolate generates two independent plasmid variants able to coexist in the same cell simultaneously. Using the Haemophilus influenzae Rd KW20 strain as a model system, we combined antibiotic susceptibility tests, quantitative PCRs, competition assays, and experimental evolution to characterize the consequences of the coexistence of the pB1000 plasmid variants. This coexistence produced an increase of the total plasmid copy number (PCN) in the host bacteria, leading to a rise in both the antibiotic resistance level and the metabolic burden produced by pB1000. Using experimental evolution, we showed that in the presence of ampicillin, the bacteria maintained both plasmid variants for 300 generations. In the absence of antibiotics, on the other hand, the bacteria are capable of reverting to the single-plasmid genotype via the loss of one of the plasmid variants. Our results revealed how a single mutation in plasmid pB1000 provides the bacterial host with a mechanism to increase the PCN and, consequently, the ampicillin resistance level. Crucially, this mechanism can be rapidly reversed to avoid the extra cost entailed by the increased PCN in the absence of antibiotics.
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20
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Brockman KL, Jurcisek JA, Atack JM, Srikhanta YN, Jennings MP, Bakaletz LO. ModA2 Phasevarion Switching in Nontypeable Haemophilus influenzae Increases the Severity of Experimental Otitis Media. J Infect Dis 2016; 214:817-24. [PMID: 27288538 DOI: 10.1093/infdis/jiw243] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 05/31/2016] [Indexed: 12/11/2022] Open
Abstract
Several human-adapted bacterial pathogens use a phasevarion (ie, a phase-variable regulon) to rapidly and reversibly regulate the expression of many genes, which include known virulence factors, yet the influence of phasevarion-mediated regulation in pathogenesis remains poorly understood. Here we examine the impact of the nontypeable Haemophilus influenzae (NTHI) ModA2 phasevarion on pathogenesis and disease severity in a chinchilla model of experimental otitis media. Chinchillas were challenged with NTHI variant populations that were either inoculated ON and remained ON, inoculated OFF and shifted ON, or inoculated OFF and remained OFF, within the middle ear. We show that populations that shift from OFF to ON within the middle ear induce significantly greater disease severity than populations that are unable to shift. These observations support the importance of phasevarion switching in NTHI pathogenesis and the necessity to considered phasevarion regulation when developing methods to treat and prevent infection.
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Affiliation(s)
- Kenneth L Brockman
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital The Ohio State University College of Medicine, Columbus, Ohio
| | - Joseph A Jurcisek
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital The Ohio State University College of Medicine, Columbus, Ohio
| | - John M Atack
- Institute for Glycomics, Griffith University, Gold Coast, Australia
| | | | | | - Lauren O Bakaletz
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital The Ohio State University College of Medicine, Columbus, Ohio
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21
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A biphasic epigenetic switch controls immunoevasion, virulence and niche adaptation in non-typeable Haemophilus influenzae. Nat Commun 2015. [PMID: 26215614 PMCID: PMC4525171 DOI: 10.1038/ncomms8828] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Non-typeable Haemophilus influenzae contains an N6-adenine DNA-methyltransferase (ModA) that is subject to phase-variable expression (random ON/OFF switching). Five modA alleles, modA2, modA4, modA5, modA9 and modA10, account for over two-thirds of clinical otitis media isolates surveyed. Here, we use single molecule, real-time (SMRT) methylome analysis to identify the DNA-recognition motifs for all five of these modA alleles. Phase variation of these alleles regulates multiple proteins including vaccine candidates, and key virulence phenotypes such as antibiotic resistance (modA2, modA5, modA10), biofilm formation (modA2) and immunoevasion (modA4). Analyses of a modA2 strain in the chinchilla model of otitis media show a clear selection for ON switching of modA2 in the middle ear. Our results indicate that a biphasic epigenetic switch can control bacterial virulence, immunoevasion and niche adaptation in an animal model system. Non-typeable Haemophilus influenzae, which causes ear and lung infections, has a DNA methyltransferase encoded by alternative alleles that are subject to random ON/OFF switching. Here, Atack et al. show that this epigenetic switch controls the expression of key proteins involved in virulence.
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22
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Atack JM, Winter LE, Jurcisek JA, Bakaletz LO, Barenkamp SJ, Jennings MP. Selection and Counterselection of Hia Expression Reveals a Key Role for Phase-Variable Expression of Hia in Infection Caused by Nontypeable Haemophilus influenzae. J Infect Dis 2015; 212:645-53. [PMID: 25712964 DOI: 10.1093/infdis/jiv103] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 02/13/2015] [Indexed: 11/12/2022] Open
Abstract
Hia is a major adhesin of nontypeable Haemophilus influenzae (NTHi) and has long been investigated as a vaccine candidate. Here we show that Hia phase variation is controlled by changes in the length of a polythymidine tract located in the hia promoter. Studies of an invasive clinical isolate (strain R2866) show that strains expressing high Hia levels are more efficiently killed by opsonophagocytosis. An opsonophagocytic assay was used to select for a subpopulation of variants that expressed a low level of Hia, which facilitated their escape from killing by anti-Hia antisera. Conversely, a subpopulation of variants expressing a high level of Hia was selected for during passaging through Chang cells. In both cases, phase variation of Hia expression corresponded directly with discrete modal changes in polythymidine tract length. In the chinchilla model of NTHi infection, we observed consistent selection for high Hia expression upon nasopharyngeal colonization, confirming the key role of phase-variable expression of Hia within a specific niche in vivo.
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Affiliation(s)
- John M Atack
- Institute for Glycomics, Griffith University, Gold Coast, Australia
| | - Linda E Winter
- Department of Pediatrics, Saint Louis University School of Medicine Pediatric Research Institute, Cardinal Glennon Children's Medical Center, Saint Louis, Missouri
| | - Joseph A Jurcisek
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital and The Ohio State University College of Medicine, Columbus
| | - Lauren O Bakaletz
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital and The Ohio State University College of Medicine, Columbus
| | - Stephen J Barenkamp
- Department of Pediatrics, Saint Louis University School of Medicine Pediatric Research Institute, Cardinal Glennon Children's Medical Center, Saint Louis, Missouri
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The Many Facets of Lipooligosaccharide as a Virulence Factor for Histophilus somni. Curr Top Microbiol Immunol 2015; 396:131-48. [PMID: 26814887 DOI: 10.1007/82_2015_5020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The lipooligosaccharide (LOS) of Histophilus somni is a multifaceted molecule that provides critical protection to the bacterium against host defenses, may act as an adhesin, and like similar molecules of gram-negative bacteria, is an endotoxin that signals through toll-like receptor 4 and NF-κB to cause inflammation. The lipid A component is responsible for the endotoxic and apoptotic activity of the LOS. The H. somni LOS lacks O-side chains typically characteristic of gram-negative bacteria that have lipopolysaccharide, but has a complex, microheterogeneous outer core. The LOS of disease isolates is capable of undergoing structural and antigenic phase variation of its outer core due to slip-strand mispairing of glycosyltransferase genes that contain repetitive sequences of DNA base pairs. Such variation enables the bacteria to evade bactericidal antibodies made to oligosaccharide antigens. In addition, the LOS can be decorated with phase-variable phosphorylcholine (ChoP), which binds to platelet-activating factor receptor on host cells, thereby aiding in colonization of the upper respiratory tract. However, ChoP is likely not expressed when the bacteria are in systemic sites because ChoP also binds to C-reactive protein, resulting in activation of host complement and promoting bactericidal activity. The structure of some LOS outer core chains is identical to oligosaccharides on host glycosphingolipids of red blood cells, other cells, and merconium (lacto-N-neotetraose, lacto-N-biose, N-acetyllactosamine, etc.). Furthermore, terminal galactose residues on LOS and elsewhere are decorated with sialic acid, which blocks antibody binding, activation of complement, phagocytosis, and intracellular killing. Therefore, antigenic mimicry of host antigens is an important defense mechanism provided by the oligosaccharide component of the LOS to avoid innate and adaptive host defense mechanisms. However, some strains of H. somni isolated from the bovine genital tract, particularly the normal bovine prepuce, are incapable of LOS phase variation, sialylation of the LOS, and expression of ChoP. At least 1 such strain has been shown to be avirulent, underscoring the importance of the LOS as a virulence factor, although this strain is deficient in other factors as well. The structure and arrangement of the inner core glycoses (heptose and 3-deoxy-D-manno-2-octulosnic acid) is remarkably similar to the inner core oligosaccharide on some strains of Neisseria spp., and mutants that contain a truncated LOS oligosaccharide are considerably more serum-sensitive than the parent strain. Therefore, the LOS is a critical component that enables H. somni to resist host defenses and cause disease.
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24
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The analysis of microsatellites and compound microsatellites in 56 complete genomes of Herpesvirales. Gene 2014; 551:103-9. [DOI: 10.1016/j.gene.2014.08.054] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Revised: 08/09/2014] [Accepted: 08/26/2014] [Indexed: 01/13/2023]
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25
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Garmendia J, Viadas C, Calatayud L, Mell JC, Martí-Lliteras P, Euba B, Llobet E, Gil C, Bengoechea JA, Redfield RJ, Liñares J. Characterization of nontypable Haemophilus influenzae isolates recovered from adult patients with underlying chronic lung disease reveals genotypic and phenotypic traits associated with persistent infection. PLoS One 2014; 9:e97020. [PMID: 24824990 PMCID: PMC4019658 DOI: 10.1371/journal.pone.0097020] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 04/14/2014] [Indexed: 01/09/2023] Open
Abstract
Nontypable Haemophilus influenzae (NTHi) has emerged as an important opportunistic pathogen causing infection in adults suffering obstructive lung diseases. Existing evidence associates chronic infection by NTHi to the progression of the chronic respiratory disease, but specific features of NTHi associated with persistence have not been comprehensively addressed. To provide clues about adaptive strategies adopted by NTHi during persistent infection, we compared sequential persistent isolates with newly acquired isolates in sputa from six patients with chronic obstructive lung disease. Pulse field gel electrophoresis (PFGE) identified three patients with consecutive persistent strains and three with new strains. Phenotypic characterisation included infection of respiratory epithelial cells, bacterial self-aggregation, biofilm formation and resistance to antimicrobial peptides (AMP). Persistent isolates differed from new strains in showing low epithelial adhesion and inability to form biofilms when grown under continuous-flow culture conditions in microfermenters. Self-aggregation clustered the strains by patient, not by persistence. Increasing resistance to AMPs was observed for each series of persistent isolates; this was not associated with lipooligosaccharide decoration with phosphorylcholine or with lipid A acylation. Variation was further analyzed for the series of three persistent isolates recovered from patient 1. These isolates displayed comparable growth rate, natural transformation frequency and murine pulmonary infection. Genome sequencing of these three isolates revealed sequential acquisition of single-nucleotide variants in the AMP permease sapC, the heme acquisition systems hgpB, hgpC, hup and hxuC, the 3-deoxy-D-manno-octulosonic acid kinase kdkA, the long-chain fatty acid transporter ompP1, and the phosphoribosylamine glycine ligase purD. Collectively, we frame a range of pathogenic traits and a repertoire of genetic variants in the context of persistent infection by NTHi.
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Affiliation(s)
- Junkal Garmendia
- Instituto de Agrobiotecnología, CSIC-Universidad Pública Navarra-Gobierno Navarra, Mutilva, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
- Laboratory Microbial Pathogenesis, Fundación Investigación Sanitaria Illes Balears, Bunyola, Spain
- * E-mail:
| | - Cristina Viadas
- Instituto de Agrobiotecnología, CSIC-Universidad Pública Navarra-Gobierno Navarra, Mutilva, Spain
| | - Laura Calatayud
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
- Microbiology Department, University Hospital Bellvitge, IDIBELL, University of Barcelona, Barcelona, Spain
| | - Joshua Chang Mell
- Department of Zoology, University British Columbia, Vancouver, British Columbia, Canada
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Pau Martí-Lliteras
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
- Laboratory Microbial Pathogenesis, Fundación Investigación Sanitaria Illes Balears, Bunyola, Spain
| | - Begoña Euba
- Instituto de Agrobiotecnología, CSIC-Universidad Pública Navarra-Gobierno Navarra, Mutilva, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
| | - Enrique Llobet
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
- Laboratory Microbial Pathogenesis, Fundación Investigación Sanitaria Illes Balears, Bunyola, Spain
| | - Carmen Gil
- Instituto de Agrobiotecnología, CSIC-Universidad Pública Navarra-Gobierno Navarra, Mutilva, Spain
| | - José Antonio Bengoechea
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
- Laboratory Microbial Pathogenesis, Fundación Investigación Sanitaria Illes Balears, Bunyola, Spain
- Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Rosemary J. Redfield
- Department of Zoology, University British Columbia, Vancouver, British Columbia, Canada
| | - Josefina Liñares
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
- Microbiology Department, University Hospital Bellvitge, IDIBELL, University of Barcelona, Barcelona, Spain
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Genomic and global approaches to unravelling how hypermutable sequences influence bacterial pathogenesis. Pathogens 2014; 3:164-84. [PMID: 25437613 PMCID: PMC4235727 DOI: 10.3390/pathogens3010164] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 01/06/2014] [Accepted: 02/13/2014] [Indexed: 12/23/2022] Open
Abstract
Rapid adaptation to fluctuations in the host milieu contributes to the host persistence and virulence of bacterial pathogens. Adaptation is frequently mediated by hypermutable sequences in bacterial pathogens. Early bacterial genomic studies identified the multiplicity and virulence-associated functions of these hypermutable sequences. Thus, simple sequence repeat tracts (SSRs) and site-specific recombination were found to control capsular type, lipopolysaccharide structure, pilin diversity and the expression of outer membrane proteins. We review how the population diversity inherent in the SSR-mediated mechanism of localised hypermutation is being unlocked by the investigation of whole genome sequences of disease isolates, analysis of clinical samples and use of model systems. A contrast is presented between the problematical nature of analysing simple sequence repeats in next generation sequencing data and in simpler, pragmatic PCR-based approaches. Specific examples are presented of the potential relevance of this localized hypermutation to meningococcal pathogenesis. This leads us to speculate on the future prospects for unravelling how hypermutable mechanisms may contribute to the transmission, spread and persistence of bacterial pathogens.
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Zhou K, Aertsen A, Michiels CW. The role of variable DNA tandem repeats in bacterial adaptation. FEMS Microbiol Rev 2013; 38:119-41. [PMID: 23927439 DOI: 10.1111/1574-6976.12036] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 07/13/2013] [Accepted: 07/26/2013] [Indexed: 01/05/2023] Open
Abstract
DNA tandem repeats (TRs), also designated as satellite DNA, are inter- or intragenic nucleotide sequences that are repeated two or more times in a head-to-tail manner. Because TR tracts are prone to strand-slippage replication and recombination events that cause the TR copy number to increase or decrease, loci containing TRs are hypermutable. An increasing number of examples illustrate that bacteria can exploit this instability of TRs to reversibly shut down or modulate the function of specific genes, allowing them to adapt to changing environments on short evolutionary time scales without an increased overall mutation rate. In this review, we discuss the prevalence and distribution of inter- and intragenic TRs in bacteria and the mechanisms of their instability. In addition, we review evidence demonstrating a role of TR variations in bacterial adaptation strategies, ranging from immune evasion and tissue tropism to the modulation of environmental stress tolerance. Nevertheless, while bioinformatic analysis reveals that most bacterial genomes contain a few up to several dozens of intra- and intergenic TRs, only a small fraction of these have been functionally studied to date.
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Affiliation(s)
- Kai Zhou
- Department of Microbial and Molecular Systems (M²S), Faculty of Bioscience Engineering, Laboratory of Food Microbiology and Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Leuven, Belgium
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Zhang BC, Zhang M, Sun BG, Fang Y, Xiao ZZ, Sun L. Complete genome sequence and transcription profiles of the rock bream iridovirus RBIV-C1. DISEASES OF AQUATIC ORGANISMS 2013; 104:203-214. [PMID: 23759558 DOI: 10.3354/dao02587] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The family Iridoviridae consists of 5 genera of double-stranded DNA viruses, including the genus Megalocytivirus, which contains species that are important fish pathogens. In a previous study, we isolated the first rock bream iridovirus from China (RBIV-C1) and identified it as a member of the genus Megalocytivirus. In this report, we determined the complete genomic sequence of RBIV-C1 and examined its in vivo expression profiles. The genome of RBIV-C1 is 112333 bp in length, with a GC content of 55% and a coding density of 92%. RBIV-C1 contains 4584 simple sequence repeats, 89.8% of which are distributed among coding regions. A total of 119 potential open reading frames (ORFs) were identified in RBIV-C1, including the 26 core iridovirus genes; 41 ORFs encode proteins that are predicted to be associated with essential biological functions. RBIV-C1 exhibits the highest degree of sequence conservation and colinear arrangement of genes with orange-spotted grouper iridovirus (OSGIV) and rock bream iridovirus (RBIV). The pairwise nucleotide identities are 99.49% between RBIV-C1 and OSGIV and 98.69% between RBIV-C1 and RBIV. Compared to OSGIV, RBIV-C1 contains 11 insertions, 13 deletions, and 103 single nucleotide mutations. Whole-genome transcription analysis showed that following experimental infection of rock bream with RBIV-C1, all but 1 of the 119 ORFs were expressed at different time points and clustered into 3 hierarchical groups based on their expression patterns. These results provide new insights into the genetic nature and gene expression features of megalocytiviruses.
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Affiliation(s)
- Bao-Cun Zhang
- Institute of Oceanology, Chinese Academy of Sciences, Qingdao, People's Republic of China
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Clark SE, Eichelberger KR, Weiser JN. Evasion of killing by human antibody and complement through multiple variations in the surface oligosaccharide of Haemophilus influenzae. Mol Microbiol 2013; 88:603-18. [PMID: 23577840 DOI: 10.1111/mmi.12214] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/20/2013] [Indexed: 11/29/2022]
Abstract
The lipopolysaccharide (LPS) of H. influenzae is highly variable. Much of the structural diversity is derived from phase variation, or high frequency on-off switching, of molecules attached during LPS biosynthesis. In this study, we examined the dynamics of LPS phase variation following exposure to human serum as a source of antibody and complement in multiple H. influenzae isolates. We show that lic2A, lgtC and lex2A switch from phase-off to phase-on following serial passage in human serum. These genes, which control attachment of a galα1-4gal di-galactoside structure (lic2A and lgtC phase-on) or an alternative glucose extension (lex2A phase-on) from the same hexose moiety, reduce binding of bactericidal antibody to conserved inner core LPS structures. The effects of the di-galactoside and alternative glucose extension were also examined in the context of the additional LPS phase variable structures phosphorylcholine (ChoP) and sialic acid. We found that di-galactoside, the alternative glucose extension, ChoP, and sialic acid each contribute independently to bacterial survival in the presence of human complement, and have an additive effect in combination. We propose that LPS phase variable extensions serve to shield conserved inner core structures from recognition by host immune components encountered during infection.
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Affiliation(s)
- Sarah E Clark
- Department of Microbiology, University of Pennsylvania, Philadelphia, PA, USA
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Haemophilus parainfluenzae has a limited core lipopolysaccharide repertoire with no phase variation. Glycoconj J 2012; 30:561-76. [PMID: 23093380 DOI: 10.1007/s10719-012-9455-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2012] [Revised: 10/14/2012] [Accepted: 10/15/2012] [Indexed: 10/27/2022]
Abstract
Cell surface lipopolysaccharide (LPS) is a well characterized virulence determinant for the human pathogen Haemophilus influenzae, so an investigation of LPS in the less pathogenic Haemophilus parainfluenzae could yield important insights. Using a panel of 18 commensal H. parainfluenzae isolates we demonstrate that the set of genes for inner core LPS biosynthesis largely resembles that of H. influenzae, with an additional heptosyltransferase I gene similar to waaC from Pasteurella multocida. Inner core LPS structure is therefore likely to be largely conserved across the two Haemophilus species. Outer core LPS biosynthetic genes are much less prevalent in H. parainfluenzae, although homologues of the H. influenzae LPS genes lpsB, non-phase variable lic2A and lgtC, and losA1, losB1 and lic2C are found in certain isolates. Immunoblotting using antibodies directed against selected LPS epitopes was consistent with these data. We found no evidence for tetranucleotide repeat-mediated phase variation in H. parainfluenzae. Phosphocholine, a phase variable H. influenzae LPS epitope that has been implicated in disease, was absent in H. parainfluenzae LPS as were the respective (lic1) biosynthetic genes. The introduction of the lic1 genes into H. parainfluenzae led to the phase variable incorporation of phosphocholine into its LPS. Differences in LPS structure between Haemophilus species could affect interactions at the bacterial-host interface and therefore the pathogenic potential of these bacteria.
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Chen M, Tan Z, Zeng G, Zeng Z. Differential distribution of compound microsatellites in various Human Immunodeficiency Virus Type 1 complete genomes. INFECTION GENETICS AND EVOLUTION 2012; 12:1452-7. [DOI: 10.1016/j.meegid.2012.05.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 05/04/2012] [Accepted: 05/12/2012] [Indexed: 12/21/2022]
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Strouts FR, Power P, Croucher NJ, Corton N, van Tonder A, Quail MA, Langford PR, Hudson MJ, Parkhill J, Kroll JS, Bentley SD. Lineage-specific virulence determinants of Haemophilus influenzae biogroup aegyptius. Emerg Infect Dis 2012; 18:449-57. [PMID: 22377449 PMCID: PMC3309571 DOI: 10.3201/eid1803.110728] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Novel adhesions, including trimeric autotransporters, might contribute to virulence. An emergent clone of Haemophilus influenzae biogroup aegyptius (Hae) is responsible for outbreaks of Brazilian purpuric fever (BPF). First recorded in Brazil in 1984, the so-called BPF clone of Hae caused a fulminant disease that started with conjunctivitis but developed into septicemic shock; mortality rates were as high as 70%. To identify virulence determinants, we conducted a pan-genomic analysis. Sequencing of the genomes of the BPF clone strain F3031 and a noninvasive conjunctivitis strain, F3047, and comparison of these sequences with 5 other complete H. influenzae genomes showed that >77% of the F3031 genome is shared among all H. influenzae strains. Delineation of the Hae accessory genome enabled characterization of 163 predicted protein-coding genes; identified differences in established autotransporter adhesins; and revealed a suite of novel adhesins unique to Hae, including novel trimeric autotransporter adhesins and 4 new fimbrial operons. These novel adhesins might play a critical role in host–pathogen interactions.
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Affiliation(s)
- Fiona R Strouts
- Imperial College London, Medicine, St Mary’s Hospital campus, Norfolk Place, London W2 1PG, UK
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Phosphorylcholine allows for evasion of bactericidal antibody by Haemophilus influenzae. PLoS Pathog 2012; 8:e1002521. [PMID: 22396641 PMCID: PMC3291618 DOI: 10.1371/journal.ppat.1002521] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Accepted: 12/20/2011] [Indexed: 11/19/2022] Open
Abstract
The human pathogen Haemophilus influenzae has the ability to quickly adapt to different host environments through phase variation of multiple structures on its lipooligosaccharide (LPS), including phosphorylcholine (ChoP). During colonization with H. influenzae, there is a selection for ChoP+ phase variants. In a murine model of nasopharyngeal colonization, this selection is lost in the absence of adaptive immunity. Based on previous data highlighting the importance of natural antibody in limiting H. influenzae colonization, the effect of ChoP expression on antibody binding and its bactericidal activity was investigated. Flow cytometric analysis revealed that ChoP+ phase variants had decreased binding of antibody to LPS epitopes compared to ChoP- phase variants. This difference in antibody binding correlated with increased survival of ChoP+ phase variants in the presence of antibody-dependent, complement-mediated killing. ChoP+ phase variants were also more resistant to trypsin digestion, suggesting a general effect on the physical properties of the outer membrane. Moreover, ChoP-mediated protection against antibody binding correlated with increased resilience of outer membrane integrity. Collectively, these data suggest that ChoP expression provides a selective advantage during colonization through ChoP-mediated effects on the accessibility of bactericidal antibody to the cell surface.
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Schott T, Kondadi PK, Hänninen ML, Rossi M. Comparative genomics of Helicobacter pylori and the human-derived Helicobacter bizzozeronii CIII-1 strain reveal the molecular basis of the zoonotic nature of non-pylori gastric Helicobacter infections in humans. BMC Genomics 2011; 12:534. [PMID: 22039924 PMCID: PMC3234257 DOI: 10.1186/1471-2164-12-534] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Accepted: 10/31/2011] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND The canine Gram-negative Helicobacter bizzozeronii is one of seven species in Helicobacter heilmannii sensu lato that are detected in 0.17-2.3% of the gastric biopsies of human patients with gastric symptoms. At the present, H. bizzozeronii is the only non-pylori gastric Helicobacter sp. cultivated from human patients and is therefore a good alternative model of human gastric Helicobacter disease. We recently sequenced the genome of the H. bizzozeronii human strain CIII-1, isolated in 2008 from a 47-year old Finnish woman suffering from severe dyspeptic symptoms. In this study, we performed a detailed comparative genome analysis with H. pylori, providing new insights into non-pylori Helicobacter infections and the mechanisms of transmission between the primary animal host and humans. RESULTS H. bizzozeronii possesses all the genes necessary for its specialised life in the stomach. However, H. bizzozeronii differs from H. pylori by having a wider metabolic flexibility in terms of its energy sources and electron transport chain. Moreover, H. bizzozeronii harbours a higher number of methyl-accepting chemotaxis proteins, allowing it to respond to a wider spectrum of environmental signals. In this study, H. bizzozeronii has been shown to have high level of genome plasticity. We were able to identify a total of 43 contingency genes, 5 insertion sequences (ISs), 22 mini-IS elements, 1 genomic island and a putative prophage. Although H. bizzozeronii lacks homologues of some of the major H. pylori virulence genes, other candidate virulence factors are present. In particular, we identified a polysaccharide lyase (HBZC1_15820) as a potential new virulence factor of H. bizzozeronii. CONCLUSIONS The comparative genome analysis performed in this study increased the knowledge of the biology of gastric Helicobacter species. In particular, we propose the hypothesis that the high metabolic versatility and the ability to react to a range of environmental signals, factors which differentiate H. bizzozeronii as well as H. felis and H. suis from H. pylori, are the molecular basis of the of the zoonotic nature of H. heilmannii sensu lato infection in humans.
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Affiliation(s)
- Thomas Schott
- Department of Food Hygiene and Environmental Health (DFHEH), Faculty of Veterinary Medicine, University of Helsinki, P.O. Box 66, FI-00014 University of Helsinki, Finland
| | - Pradeep K Kondadi
- Department of Food Hygiene and Environmental Health (DFHEH), Faculty of Veterinary Medicine, University of Helsinki, P.O. Box 66, FI-00014 University of Helsinki, Finland
| | - Marja-Liisa Hänninen
- Department of Food Hygiene and Environmental Health (DFHEH), Faculty of Veterinary Medicine, University of Helsinki, P.O. Box 66, FI-00014 University of Helsinki, Finland
| | - Mirko Rossi
- Department of Food Hygiene and Environmental Health (DFHEH), Faculty of Veterinary Medicine, University of Helsinki, P.O. Box 66, FI-00014 University of Helsinki, Finland
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Chen M, Tan Z, Zeng G. Microsatellite is an important component of complete Hepatitis C virus genomes. INFECTION GENETICS AND EVOLUTION 2011; 11:1646-54. [DOI: 10.1016/j.meegid.2011.06.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Revised: 06/02/2011] [Accepted: 06/16/2011] [Indexed: 12/15/2022]
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Martí-Lliteras P, López-Gómez A, Mauro S, Hood DW, Viadas C, Calatayud L, Morey P, Servin A, Liñares J, Oliver A, Bengoechea JA, Garmendia J. Nontypable Haemophilus influenzae displays a prevalent surface structure molecular pattern in clinical isolates. PLoS One 2011; 6:e21133. [PMID: 21698169 PMCID: PMC3116884 DOI: 10.1371/journal.pone.0021133] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Accepted: 05/20/2011] [Indexed: 11/22/2022] Open
Abstract
Non-typable Haemophilus influenzae (NTHi) is a Gram negative pathogen that causes acute respiratory infections and is associated with the progression of chronic respiratory diseases. Previous studies have established the existence of a remarkable genetic variability among NTHi strains. In this study we show that, in spite of a high level of genetic heterogeneity, NTHi clinical isolates display a prevalent molecular feature, which could confer fitness during infectious processes. A total of 111 non-isogenic NTHi strains from an identical number of patients, isolated in two distinct geographical locations in the same period of time, were used to analyse nine genes encoding bacterial surface molecules, and revealed the existence of one highly prevalent molecular pattern (lgtF+, lic2A+, lic1D+, lic3A+, lic3B+, siaA−, lic2C+, ompP5+, oapA+) displayed by 94.6% of isolates. Such a genetic profile was associated with a higher bacterial resistance to serum mediated killing and enhanced adherence to human respiratory epithelial cells.
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Affiliation(s)
- Pau Martí-Lliteras
- Programa de Infección e Inmunidad, Fundación Caubet-CIMERA, Bunyola, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias-CIBERES, Vitoria, Spain
| | - Antonio López-Gómez
- Programa de Infección e Inmunidad, Fundación Caubet-CIMERA, Bunyola, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias-CIBERES, Vitoria, Spain
| | - Silvia Mauro
- Programa de Infección e Inmunidad, Fundación Caubet-CIMERA, Bunyola, Spain
| | - Derek W. Hood
- Molecular Infectious Diseases Group, Department of Paediatrics, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Headington, Oxford, United Kingdom
| | - Cristina Viadas
- Programa de Infección e Inmunidad, Fundación Caubet-CIMERA, Bunyola, Spain
| | - Laura Calatayud
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias-CIBERES, Vitoria, Spain
- Servicio de Microbiología, Hospital Universitario Bellvitge, Barcelona, Spain
- Instituto de Investigación Biomédica de Bellvitge (IDIBELL), Barcelona, Spain
- Universidad de Barcelona, Barcelona, Spain
| | - Pau Morey
- Programa de Infección e Inmunidad, Fundación Caubet-CIMERA, Bunyola, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias-CIBERES, Vitoria, Spain
| | - Alain Servin
- INSERM, UMR 756, Signalisation and Physiopathology of Epithelial cells, Paris, France
| | - Josefina Liñares
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias-CIBERES, Vitoria, Spain
- Servicio de Microbiología, Hospital Universitario Bellvitge, Barcelona, Spain
- Instituto de Investigación Biomédica de Bellvitge (IDIBELL), Barcelona, Spain
- Universidad de Barcelona, Barcelona, Spain
| | - Antonio Oliver
- Servicio de Microbiología, Hospital Universitario Son Espases, Palma Mallorca, Spain
| | - José Antonio Bengoechea
- Programa de Infección e Inmunidad, Fundación Caubet-CIMERA, Bunyola, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias-CIBERES, Vitoria, Spain
- Consejo Superior de Investigaciones Científicas-CSIC, Madrid, Spain
| | - Junkal Garmendia
- Programa de Infección e Inmunidad, Fundación Caubet-CIMERA, Bunyola, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias-CIBERES, Vitoria, Spain
- Instituto de Agrobiotecnología, CSIC-Universidad Pública de Navarra-Gobierno de Navarra, Mutilva, Spain
- * E-mail:
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Phase variation: how to create and coordinate population diversity. Curr Opin Microbiol 2011; 14:205-11. [DOI: 10.1016/j.mib.2011.01.002] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 01/06/2011] [Accepted: 01/07/2011] [Indexed: 12/26/2022]
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38
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Morey P, Cano V, Martí-Lliteras P, López-Gómez A, Regueiro V, Saus C, Bengoechea JA, Garmendia J. Evidence for a non-replicative intracellular stage of nontypable Haemophilus influenzae in epithelial cells. MICROBIOLOGY-SGM 2010; 157:234-250. [PMID: 20929955 DOI: 10.1099/mic.0.040451-0] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Nontypable Haemophilus influenzae (NTHi) is a Gram-negative, non-capsulated human bacterial pathogen, a major cause of a repertoire of respiratory infections, and intimately associated with persistent lung bacterial colonization in patients suffering from chronic obstructive pulmonary disease (COPD). Despite its medical relevance, relatively little is known about its mechanisms of pathogenicity. In this study, we found that NTHi invades the airway epithelium by a distinct mechanism, requiring microtubule assembly, lipid rafts integrity, and activation of phosphatidylinositol 3-kinase (PI3K) signalling. We found that the majority of intracellular bacteria are located inside an acidic subcellular compartment, in a metabolically active and non-proliferative state. This NTHi-containing vacuole (NTHi-CV) is endowed with late endosome features, co-localizing with LysoTracker, lamp-1, lamp-2, CD63 and Rab7. The NTHi-CV does not acquire Golgi- or autophagy-related markers. These observations were extended to immortalized and primary human airway epithelial cells. By using NTHi clinical isolates expressing different amounts of phosphocholine (PCho), a major modification of NTHi lipooligosaccharide, on their surfaces, and an isogenic lic1BC mutant strain lacking PCho, we showed that PCho is not responsible for NTHi intracellular location. In sum, this study indicates that NTHi can survive inside airway epithelial cells.
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Affiliation(s)
- Pau Morey
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Bunyola, Spain.,Programa de Infección e Inmunidad, Fundación Caubet-CIMERA, recinto Hospital Joan March, carretera Sóller, km 12, 07110, Bunyola, Spain
| | - Victoria Cano
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Bunyola, Spain.,Programa de Infección e Inmunidad, Fundación Caubet-CIMERA, recinto Hospital Joan March, carretera Sóller, km 12, 07110, Bunyola, Spain
| | - Pau Martí-Lliteras
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Bunyola, Spain.,Programa de Infección e Inmunidad, Fundación Caubet-CIMERA, recinto Hospital Joan March, carretera Sóller, km 12, 07110, Bunyola, Spain
| | - Antonio López-Gómez
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Bunyola, Spain.,Programa de Infección e Inmunidad, Fundación Caubet-CIMERA, recinto Hospital Joan March, carretera Sóller, km 12, 07110, Bunyola, Spain
| | - Verónica Regueiro
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Bunyola, Spain.,Programa de Infección e Inmunidad, Fundación Caubet-CIMERA, recinto Hospital Joan March, carretera Sóller, km 12, 07110, Bunyola, Spain
| | - Carles Saus
- Servicio de Anatomía Patológica, Hospital Universitario Son Dureta, Palma Mallorca, Spain
| | - José Antonio Bengoechea
- Área Microbiología, Facultad de Biología, Universitat Illes Balears, carretera Valldemossa, km 7.5, 07122, Palma Mallorca, Spain.,Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Bunyola, Spain.,Programa de Infección e Inmunidad, Fundación Caubet-CIMERA, recinto Hospital Joan March, carretera Sóller, km 12, 07110, Bunyola, Spain
| | - Junkal Garmendia
- Programa de Infección e Inmunidad, Fundación Caubet-CIMERA, recinto Hospital Joan March, carretera Sóller, km 12, 07110, Bunyola, Spain.,Instituto Agrobiotecnología (UPNA-CSIC), Campus Arrosadía s/n, 31192 Mutilva Baja, Navarra, Spain.,Área Microbiología, Facultad de Biología, Universitat Illes Balears, carretera Valldemossa, km 7.5, 07122, Palma Mallorca, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Bunyola, Spain
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Metruccio MME, Pigozzi E, Roncarati D, Berlanda Scorza F, Norais N, Hill SA, Scarlato V, Delany I. A novel phase variation mechanism in the meningococcus driven by a ligand-responsive repressor and differential spacing of distal promoter elements. PLoS Pathog 2009; 5:e1000710. [PMID: 20041170 PMCID: PMC2791445 DOI: 10.1371/journal.ppat.1000710] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Accepted: 11/25/2009] [Indexed: 01/14/2023] Open
Abstract
Phase variable expression, mediated by high frequency reversible changes in the length of simple sequence repeats, facilitates adaptation of bacterial populations to changing environments and is frequently important in bacterial virulence. Here we elucidate a novel phase variable mechanism for NadA, an adhesin and invasin of Neisseria meningitidis. The NadR repressor protein binds to operators flanking the phase variable tract and contributes to the differential expression levels of phase variant promoters with different numbers of repeats likely due to different spacing between operators. We show that IHF binds between these operators, and may permit looping of the promoter, allowing interaction of NadR at operators located distally or overlapping the promoter. The 4-hydroxyphenylacetic acid, a metabolite of aromatic amino acid catabolism that is secreted in saliva, induces NadA expression by inhibiting the DNA binding activity of the repressor. When induced, only minor differences are evident between NadR-independent transcription levels of promoter phase variants and are likely due to differential RNA polymerase contacts leading to altered promoter activity. Our results suggest that NadA expression is under both stochastic and tight environmental-sensing regulatory control, both mediated by the NadR repressor, and may be induced during colonization of the oropharynx where it plays a major role in the successful adhesion and invasion of the mucosa. Hence, simple sequence repeats in promoter regions may be a strategy used by host-adapted bacterial pathogens to randomly switch between expression states that may nonetheless still be induced by appropriate niche-specific signals. Diversification strategies, through genetic switches that randomly turn genes on and off, occur in many pathogenic bacterial populations and confer adaptive advantages to new environments and evasion of host immune responses. This is often mediated by spontaneous changes in the length of short DNA sequence repeats located in protein-coding regions or upstream regulatory regions, leading to deactivation or alteration of the associated genes. In this study we describe how a repeat sequence, distally upstream of the promoter region, alters the expression of an important adhesin of N. meningitidis. We identify the major mediator of this control, a negative regulator NadR, which binds to sequences flanking the variable repeat. Changes in the spacing between these sequences affect the ability of NadR to shut down expression from the promoter. We also identify a relevant metabolite that can block NadR activity and therefore act as a signal to induce adhesin expression. This finding sheds new light on the role of DNA-repeats identified in intergenic regions for which no role could be hypothesised, and may be a model mechanism used by bacterial pathogens for fine-tuning diversity within the host. Elucidating these mechanisms can aid in our understanding and prevention of disease.
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Affiliation(s)
| | - Eva Pigozzi
- Novartis Vaccines and Diagnostics, Siena, Italy
| | | | | | | | - Stuart A. Hill
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, United States of America
| | - Vincenzo Scarlato
- Novartis Vaccines and Diagnostics, Siena, Italy
- Department of Biology, University of Bologna, Bologna, Italy
| | - Isabel Delany
- Novartis Vaccines and Diagnostics, Siena, Italy
- * E-mail:
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