1
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Polycarpo CR, Walter-Nuno AB, Azevedo-Reis L, Paiva-Silva GO. The vector-symbiont affair: a relationship as (im)perfect as it can be. CURRENT OPINION IN INSECT SCIENCE 2024; 63:101203. [PMID: 38705385 DOI: 10.1016/j.cois.2024.101203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 04/24/2024] [Accepted: 04/25/2024] [Indexed: 05/07/2024]
Abstract
Vector-borne diseases are globally prevalent and represent a major socioeconomic problem worldwide. Blood-sucking arthropods transmit most pathogenic agents that cause these human infections. The pathogens transmission to their vertebrate hosts depends on how efficiently they infect their vector, which is particularly impacted by the microbiota residing in the intestinal lumen, as well as its cells or internal organs such as ovaries. The balance between costs and benefits provided by these interactions ultimately determines the outcome of the relationship. Here, we will explore aspects concerning the nature of microbe-vector interactions, including the adaptive traits required for their establishment, the varied outcomes of symbiotic interactions, as well as the factors influencing the transition of these relationships across a continuum from parasitism to mutualism.
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Affiliation(s)
- Carla R Polycarpo
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular (INCT-EM), Rio de Janeiro 21941-902, Brazil
| | - Ana B Walter-Nuno
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular (INCT-EM), Rio de Janeiro 21941-902, Brazil
| | - Leonan Azevedo-Reis
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular (INCT-EM), Rio de Janeiro 21941-902, Brazil
| | - Gabriela O Paiva-Silva
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular (INCT-EM), Rio de Janeiro 21941-902, Brazil.
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2
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Hoang KL, Read TD, King KC. Incomplete immunity in a natural animal-microbiota interaction selects for higher pathogen virulence. Curr Biol 2024; 34:1357-1363.e3. [PMID: 38430909 PMCID: PMC10962313 DOI: 10.1016/j.cub.2024.02.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 12/18/2023] [Accepted: 02/07/2024] [Indexed: 03/05/2024]
Abstract
Incomplete immunity in recovered hosts is predicted to favor more virulent pathogens upon re-infection in the population.1 The microbiota colonizing animals can generate a similarly long-lasting, partial immune response, allowing for infection but dampened disease severity.2 We tracked the evolutionary trajectories of a widespread pathogen (Pseudomonas aeruginosa), experimentally passaged through populations of nematodes immune-primed by a natural microbiota member (P. berkeleyensis). This bacterium can induce genes regulated by a mitogen-activated protein kinase (MAPK) signaling pathway effective at conferring protection against pathogen-induced death despite infection.3 Across host populations, this incomplete immunity selected for pathogens more than twice as likely to kill as those evolved in non-primed (i.e., naive) or immune-compromised (mutants with a knockout of the MAPK ortholog) control populations. Despite the higher virulence, pathogen molecular evolution in immune-primed hosts was slow and constrained. In comparison, evolving pathogens in immune-compromised hosts were characterized by substantial genomic differentiation and attenuated virulence. These findings directly attribute the incomplete host immunity induced from microbiota as a significant force shaping the virulence and evolutionary dynamics of novel infectious diseases.
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Affiliation(s)
- Kim L Hoang
- Department of Biology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK; Division of Infectious Diseases, Emory University School of Medicine, 1760 Haygood Drive, Atlanta, GA 30322, USA.
| | - Timothy D Read
- Division of Infectious Diseases, Emory University School of Medicine, 1760 Haygood Drive, Atlanta, GA 30322, USA
| | - Kayla C King
- Department of Biology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK; Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, BC V6T 1Z4, Canada; Department of Microbiology & Immunology, University of British Columbia, 1365 - 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada.
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3
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Ruhluel D, Fisher L, Barton TE, Leighton H, Kumar S, Amores Morillo P, O’Brien S, Fothergill JL, Neill DR. Secondary messenger signalling influences Pseudomonas aeruginosa adaptation to sinus and lung environments. THE ISME JOURNAL 2024; 18:wrae065. [PMID: 38647527 PMCID: PMC11102083 DOI: 10.1093/ismejo/wrae065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Revised: 03/08/2024] [Accepted: 04/18/2024] [Indexed: 04/25/2024]
Abstract
Pseudomonas aeruginosa is a cause of chronic respiratory tract infections in people with cystic fibrosis (CF), non-CF bronchiectasis, and chronic obstructive pulmonary disease. Prolonged infection allows the accumulation of mutations and horizontal gene transfer, increasing the likelihood of adaptive phenotypic traits. Adaptation is proposed to arise first in bacterial populations colonizing upper airway environments. Here, we model this process using an experimental evolution approach. Pseudomonas aeruginosa PAO1, which is not airway adapted, was serially passaged, separately, in media chemically reflective of upper or lower airway environments. To explore whether the CF environment selects for unique traits, we separately passaged PAO1 in airway-mimicking media with or without CF-specific factors. Our findings demonstrated that all airway environments-sinus and lungs, under CF and non-CF conditions-selected for loss of twitching motility, increased resistance to multiple antibiotic classes, and a hyper-biofilm phenotype. These traits conferred increased airway colonization potential in an in vivo model. CF-like conditions exerted stronger selective pressures, leading to emergence of more pronounced phenotypes. Loss of twitching was associated with mutations in type IV pili genes. Type IV pili mediate surface attachment, twitching, and induction of cAMP signalling. We additionally identified multiple evolutionary routes to increased biofilm formation involving regulation of cyclic-di-GMP signalling. These included the loss of function mutations in bifA and dipA phosphodiesterase genes and activating mutations in the siaA phosphatase. These data highlight that airway environments select for traits associated with sessile lifestyles and suggest upper airway niches support emergence of phenotypes that promote establishment of lung infection.
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Affiliation(s)
- Dilem Ruhluel
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Ronald Ross Building, 8 West Derby Street, Liverpool, United Kingdom
| | - Lewis Fisher
- Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, United Kingdom
| | - Thomas E Barton
- Division of Molecular Microbiology, University of Dundee, Dow Street, Dundee, United Kingdom
| | - Hollie Leighton
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Ronald Ross Building, 8 West Derby Street, Liverpool, United Kingdom
| | - Sumit Kumar
- Division of Molecular Microbiology, University of Dundee, Dow Street, Dundee, United Kingdom
| | - Paula Amores Morillo
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Ronald Ross Building, 8 West Derby Street, Liverpool, United Kingdom
| | - Siobhan O’Brien
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College, Dublin, 2, Ireland
| | - Joanne L Fothergill
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Ronald Ross Building, 8 West Derby Street, Liverpool, United Kingdom
| | - Daniel R Neill
- Division of Molecular Microbiology, University of Dundee, Dow Street, Dundee, United Kingdom
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4
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Gordon JL, Oliva Chavez AS, Martinez D, Vachiery N, Meyer DF. Possible biased virulence attenuation in the Senegal strain of Ehrlichia ruminantium by ntrX gene conversion from an inverted segmental duplication. PLoS One 2023; 18:e0266234. [PMID: 36800354 PMCID: PMC9937504 DOI: 10.1371/journal.pone.0266234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 03/16/2022] [Indexed: 02/18/2023] Open
Abstract
Ehrlichia ruminantium is a tick-borne intracellular pathogen of ruminants that causes heartwater, a disease present in Sub-saharan Africa, islands in the Indian Ocean and the Caribbean, inducing significant economic losses. At present, three avirulent strains of E. ruminantium (Gardel, Welgevonden and Senegal isolates) have been produced by a process of serial passaging in mammalian cells in vitro, but unfortunately their use as vaccines do not offer a large range of protection against other strains, possibly due to the genetic diversity present within the species. So far no genetic basis for virulence attenuation has been identified in any E. ruminantium strain that could offer targets to facilitate vaccine production. Virulence attenuated Senegal strains have been produced twice independently, and require many fewer passages to attenuate than the other strains. We compared the genomes of a virulent and attenuated Senegal strain and identified a likely attenuator gene, ntrX, a global transcription regulator and member of a two-component system that is linked to environmental sensing. This gene has an inverted partial duplicate close to the parental gene that shows evidence of gene conversion in different E. ruminantium strains. The pseudogenisation of the gene in the avirulent Senegal strain occurred by gene conversion from the duplicate to the parent, transferring a 4 bp deletion which is unique to the Senegal strain partial duplicate amongst the wild isolates. We confirmed that the ntrX gene is not expressed in the avirulent Senegal strain by RT-PCR. The inverted duplicate structure combined with the 4 bp deletion in the Senegal strain can explain both the attenuation and the faster speed of attenuation in the Senegal strain relative to other strains of E. ruminantium. Our results identify nrtX as a promising target for the generation of attenuated strains of E. ruminantium by random or directed mutagenesis that could be used for vaccine production.
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Affiliation(s)
- Jonathan L. Gordon
- CIRAD, UMR ASTRE, Petit-Bourg, Guadeloupe, France
- ASTRE, CIRAD, INRAe, Univ Montpellier, Montpellier, France
| | - Adela S. Oliva Chavez
- CIRAD, UMR ASTRE, Petit-Bourg, Guadeloupe, France
- ASTRE, CIRAD, INRAe, Univ Montpellier, Montpellier, France
| | | | | | - Damien F. Meyer
- CIRAD, UMR ASTRE, Petit-Bourg, Guadeloupe, France
- ASTRE, CIRAD, INRAe, Univ Montpellier, Montpellier, France
- * E-mail:
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5
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Jayakumar P, Figueiredo ART, Kümmerli R. Evolution of Quorum Sensing in Pseudomonas aeruginosa Can Occur via Loss of Function and Regulon Modulation. mSystems 2022; 7:e0035422. [PMID: 36190124 PMCID: PMC9600717 DOI: 10.1128/msystems.00354-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 09/12/2022] [Indexed: 12/24/2022] Open
Abstract
Pseudomonas aeruginosa populations evolving in cystic fibrosis lungs, animal hosts, natural environments and in vitro undergo extensive genetic adaption and diversification. A common mutational target is the quorum sensing (QS) system, a three-unit regulatory system that controls the expression of virulence factors and secreted public goods. Three evolutionary scenarios have been advocated to explain selection for QS mutants: (i) disuse of the regulon, (ii) cheating through the exploitation of public goods, or (ii) modulation of the QS regulon. Here, we examine these scenarios by studying a set of 61 QS mutants from an experimental evolution study. We observed nonsynonymous mutations in all three QS systems: Las, Rhl, and Pseudomonas Quinolone Signal (PQS). The majority of the Las mutants had large deletions of the Las regulon, resulting in loss of QS function and the inability to produce QS-regulated traits, thus supporting the first or second scenarios. Conversely, phenotypic and gene expression analyses of Rhl mutants support network modulation (third scenario), as these mutants overexpressed the Las and Rhl receptors and showed an altered QS-regulated trait production profile. PQS mutants also showed patterns of regulon modulation leading to strain diversification and phenotypic tradeoffs, where the upregulation of certain QS traits is associated with the downregulation of others. Overall, our results indicate that mutations in the different QS systems lead to diverging effects on the QS trait profile in P. aeruginosa populations. These mutations might not only affect the plasticity and diversity of evolved populations but could also impact bacterial fitness and virulence in infections. IMPORTANCE Pseudomonas aeruginosa uses quorum sensing (QS), a three-unit multilayered network, to coordinate expression of traits required for growth and virulence in the context of infections. Despite its importance for bacterial fitness, the QS regulon appears to be a common mutational target during long-term adaptation of P. aeruginosa in the host, natural environments, and experimental evolutions. This raises questions of why such an important regulatory system is under selection and how mutations change the profile of QS-regulated traits. Here, we examine a set of 61 experimentally evolved QS mutants to address these questions. We found that mutations involving the master regulator, LasR, resulted in an almost complete breakdown of QS, while mutations in RhlR and PqsR resulted in modulations of the regulon, where both the regulon structure and the QS-regulated trait profile changed. Our work reveals that natural selection drives diversification in QS activity patterns in evolving populations.
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Affiliation(s)
- Priyanikha Jayakumar
- Department of Quantitative Biomedicine, University of Zurich, Zurich, Switzerland
| | - Alexandre R. T. Figueiredo
- Department of Quantitative Biomedicine, University of Zurich, Zurich, Switzerland
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Rolf Kümmerli
- Department of Quantitative Biomedicine, University of Zurich, Zurich, Switzerland
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6
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Hoque MM, Noorian P, Espinoza-Vergara G, Manuneedhi Cholan P, Kim M, Rahman MH, Labbate M, Rice SA, Pernice M, Oehlers SH, McDougald D. Adaptation to an amoeba host drives selection of virulence-associated traits in Vibrio cholerae. THE ISME JOURNAL 2022; 16:856-867. [PMID: 34654895 PMCID: PMC8857207 DOI: 10.1038/s41396-021-01134-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 09/20/2021] [Accepted: 09/29/2021] [Indexed: 12/02/2022]
Abstract
Predation by heterotrophic protists drives the emergence of adaptive traits in bacteria, and often these traits lead to altered interactions with hosts and persistence in the environment. Here we studied adaptation of the cholera pathogen, Vibrio cholerae during long-term co-incubation with the protist host, Acanthamoeba castellanii. We determined phenotypic and genotypic changes associated with long-term intra-amoebal host adaptation and how this impacts pathogen survival and fitness. We showed that adaptation to the amoeba host leads to temporal changes in multiple phenotypic traits in V. cholerae that facilitate increased survival and competitive fitness in amoeba. Genome sequencing and mutational analysis revealed that these altered lifestyles were linked to non-synonymous mutations in conserved regions of the flagellar transcriptional regulator, flrA. Additionally, the mutations resulted in enhanced colonisation in zebrafish, establishing a link between adaptation of V. cholerae to amoeba predation and enhanced environmental persistence. Our results show that pressure imposed by amoeba on V. cholerae selects for flrA mutations that serves as a key driver for adaptation. Importantly, this study provides evidence that adaptive traits that evolve in pathogens in response to environmental predatory pressure impact the colonisation of eukaryotic organisms by these pathogens.
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Affiliation(s)
- M. Mozammel Hoque
- grid.117476.20000 0004 1936 7611The iThree Institute, University of Technology Sydney, Sydney, NSW Australia
| | - Parisa Noorian
- grid.117476.20000 0004 1936 7611The iThree Institute, University of Technology Sydney, Sydney, NSW Australia
| | - Gustavo Espinoza-Vergara
- grid.117476.20000 0004 1936 7611The iThree Institute, University of Technology Sydney, Sydney, NSW Australia
| | - Pradeep Manuneedhi Cholan
- grid.1013.30000 0004 1936 834XTuberculosis Research Program at the Centenary Institute, The University of Sydney, Camperdown, NSW Australia ,grid.1013.30000 0004 1936 834XFaculty of Medicine and Health & Marie Bashir Institute, The University of Sydney, Camperdown, NSW Australia
| | - Mikael Kim
- grid.117476.20000 0004 1936 7611Climate Change Cluster, University of Technology Sydney, Sydney, NSW Australia
| | - Md Hafizur Rahman
- grid.117476.20000 0004 1936 7611School of Life Sciences, Faculty of Science, University of Technology Sydney, Sydney, NSW Australia
| | - Maurizio Labbate
- grid.117476.20000 0004 1936 7611School of Life Sciences, Faculty of Science, University of Technology Sydney, Sydney, NSW Australia
| | - Scott A. Rice
- grid.117476.20000 0004 1936 7611The iThree Institute, University of Technology Sydney, Sydney, NSW Australia ,grid.59025.3b0000 0001 2224 0361Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
| | - Mathieu Pernice
- grid.117476.20000 0004 1936 7611Climate Change Cluster, University of Technology Sydney, Sydney, NSW Australia
| | - Stefan H. Oehlers
- grid.1013.30000 0004 1936 834XTuberculosis Research Program at the Centenary Institute, The University of Sydney, Camperdown, NSW Australia ,grid.1013.30000 0004 1936 834XFaculty of Medicine and Health & Marie Bashir Institute, The University of Sydney, Camperdown, NSW Australia
| | - Diane McDougald
- grid.117476.20000 0004 1936 7611The iThree Institute, University of Technology Sydney, Sydney, NSW Australia ,grid.59025.3b0000 0001 2224 0361Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
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7
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Abstract
In the opportunistic pathogenic bacterium Pseudomonas aeruginosa acyl-homoserine lactone quorum sensing (QS) can activate expression of dozens to hundreds of genes depending on the strain under investigation. Many QS-activated genes code for extracellular products. P. aeruginosa has become a model for studies of cell-cell communication and coordination of cooperative activities, which result from production of extracellular products. We hypothesized that strain variation in the size of the QS regulon might reflect the environmental history of an isolate. We tested the hypothesis by performing long-term growth experiments with the well-studied strain PAO1, which has a relatively large QS regulon, under conditions where only limited QS-controlled functions are required. We grew P. aeruginosa for about 1000 generations in a condition where expression of QS-activated genes was required, and emergence of QS mutants was constrained and compared the QS regulons of populations after 35 generations to those after about 1000 generations in two independent lineages by using quorum quenching and RNA-seq technology. In one lineage the number of QS-activated genes identified was reduced by over 60% and in the other by about 30% in 1000-generation populations compared to 35-generation populations. Our results provide insight about the variations in the number of QS-activated genes reported for different P. aeruginosa environmental and clinical isolates and, about how environmental conditions might influence social evolution. IMPORTANCE Pseudomonas aeruginosa uses quorum sensing (QS) to activate expression of dozens of genes (the QS regulon). Because there is strain-to-strain variation in the size and content of the QS regulon, we asked how the regulon might evolve during long-term P. aeruginosa growth when cells require some but not all the functions activated by QS. We demonstrate that the P. aeruginosa QS-regulon can undergo a reductive adaptation in response to continuous QS-dependent growth. Our results provide insights into why there is strain-to-strain variability in the size and content of the P. aeruginosa QS regulon.
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8
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Rafaluk-Mohr C, Gerth M, Sealey JE, Ekroth AKE, Aboobaker AA, Kloock A, King KC. Microbial protection favors parasite tolerance and alters host-parasite coevolutionary dynamics. Curr Biol 2022; 32:1593-1598.e3. [PMID: 35148861 PMCID: PMC9355892 DOI: 10.1016/j.cub.2022.01.063] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 10/14/2021] [Accepted: 01/21/2022] [Indexed: 12/05/2022]
Abstract
Coevolution between hosts and parasites is a major driver of rapid evolutionary change1 and diversification.2,3 However, direct antagonistic interactions between hosts and parasites could be disrupted4 when host microbiota form a line of defense, a phenomenon widespread across animal and plant species.5,6 By suppressing parasite infection, protective microbiota could reduce the need for host-based defenses and favor host support for microbiota colonization,6 raising the possibility that the microbiota can alter host-parasite coevolutionary patterns and processes.7 Here, using an experimental evolution approach, we co-passaged populations of nematode host (Caenorhabditis elegans) and parasites (Staphylococcus aureus) when hosts were colonized (or not) by protective bacteria (Enterococcus faecalis). We found that microbial protection during coevolution resulted in the evolution of host mortality tolerance—higher survival following parasite infection—and in parasites adapting to microbial defenses. Compared to unprotected host-parasite coevolution, the protected treatment was associated with reduced dominance of fluctuating selection dynamics in host populations. No differences in host recombination rate or genetic diversity were detected. Genomic divergence was observed between parasite populations coevolved in protected and unprotected hosts. These findings indicate that protective host microbiota can determine the evolution of host defense strategies and shape host-parasite coevolutionary dynamics. Microbial protection resulted in the evolution of host mortality tolerance Parasites adapted to counter microbial defenses within hosts Protective microbes reduced fluctuating selection dynamics Microbial protection did not impact host genetic diversity or recombination rates
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Affiliation(s)
| | - Michael Gerth
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Headington, Oxford OX3 0BP, UK
| | - Jordan E Sealey
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK
| | - Alice K E Ekroth
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK
| | - Aziz A Aboobaker
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK
| | - Anke Kloock
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK
| | - Kayla C King
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK.
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9
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Adaptation to an amoeba host leads to Pseudomonas aeruginosa isolates with attenuated virulence. Appl Environ Microbiol 2022; 88:e0232221. [PMID: 35020451 PMCID: PMC8904051 DOI: 10.1128/aem.02322-21] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The opportunistic pathogen Pseudomonas aeruginosa is ubiquitous in the environment, and in humans, it is capable of causing acute or chronic infections. In the natural environment, predation by bacterivorous protozoa represents a primary threat to bacteria. Here, we determined the impact of long-term exposure of P. aeruginosa to predation pressure. P. aeruginosa persisted when coincubated with the bacterivorous Acanthamoeba castellanii for extended periods and produced genetic and phenotypic variants. Sequencing of late-stage amoeba-adapted P. aeruginosa isolates demonstrated single nucleotide polymorphisms within genes that encode known virulence factors, and this correlated with a reduction in expression of virulence traits. Virulence for the nematode Caenorhabditis elegans was attenuated in late-stage amoeba-adapted P. aeruginosa compared to early-stage amoeba-adapted and nonadapted counterparts. Further, late-stage amoeba-adapted P. aeruginosa showed increased competitive fitness and enhanced survival in amoebae as well as in macrophage and neutrophils. Interestingly, our findings indicate that the selection imposed by amoebae resulted in P. aeruginosa isolates with reduced virulence and enhanced fitness, similar to those recovered from chronic cystic fibrosis infections. Thus, predation by protozoa and long-term colonization of the human host may represent similar environments that select for similar losses of gene function. IMPORTANCEPseudomonas aeruginosa is an opportunistic pathogen that causes both acute infections in plants and animals, including humans, and chronic infections in immunocompromised and cystic fibrosis patients. This bacterium is commonly found in soils and water, where bacteria are constantly under threat of being consumed by bacterial predators, e.g., protozoa. To escape being killed, bacteria have evolved a suite of mechanisms that protect them from being consumed or digested. Here, we examined the effect of long-term predation on the genotypes and phenotypes expressed by P. aeruginosa. We show that long-term coincubation with protozoa gave rise to mutations that resulted in P. aeruginosa becoming less pathogenic. This is particularly interesting as similar mutations arise in bacteria associated with chronic infections. Importantly, the genetic and phenotypic traits possessed by late-stage amoeba-adapted P. aeruginosa are similar to those observed in isolates obtained from chronic cystic fibrosis infections. This notable overlap in adaptation to different host types suggests similar selection pressures among host cell types as well as similar adaptation strategies.
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10
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Bansept F, Obeng N, Schulenburg H, Traulsen A. Modeling host-associating microbes under selection. THE ISME JOURNAL 2021; 15:3648-3656. [PMID: 34158630 PMCID: PMC8630024 DOI: 10.1038/s41396-021-01039-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 05/28/2021] [Accepted: 06/09/2021] [Indexed: 02/06/2023]
Abstract
The concept of fitness is often reduced to a single component, such as the replication rate in a given habitat. For species with multi-step life cycles, this can be an unjustified oversimplification, as every step of the life cycle can contribute to the overall reproductive success in a specific way. In particular, this applies to microbes that spend part of their life cycles associated to a host. In this case, there is a selection pressure not only on the replication rates, but also on the phenotypic traits associated to migrating from the external environment to the host and vice-versa (i.e., the migration rates). Here, we investigate a simple model of a microbial lineage living, replicating, migrating and competing in and between two compartments: a host and an environment. We perform a sensitivity analysis on the overall growth rate to determine the selection gradient experienced by the microbial lineage. We focus on the direction of selection at each point of the phenotypic space, defining an optimal way for the microbial lineage to increase its fitness. We show that microbes can adapt to the two-compartment life cycle through either changes in replication or migration rates, depending on the initial values of the traits, the initial distribution across the two compartments, the intensity of competition, and the time scales involved in the life cycle versus the time scale of adaptation (which determines the adequate probing time to measure fitness). Overall, our model provides a conceptual framework to study the selection on microbes experiencing a host-associated life cycle.
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Affiliation(s)
- Florence Bansept
- grid.419520.b0000 0001 2222 4708Max-Planck-Institute for Evolutionary Biology, Ploen, Germany
| | - Nancy Obeng
- grid.9764.c0000 0001 2153 9986Department of Evolutionary Ecology and Genetics, University of Kiel, Kiel, Germany
| | - Hinrich Schulenburg
- grid.419520.b0000 0001 2222 4708Max-Planck-Institute for Evolutionary Biology, Ploen, Germany ,grid.9764.c0000 0001 2153 9986Department of Evolutionary Ecology and Genetics, University of Kiel, Kiel, Germany
| | - Arne Traulsen
- grid.419520.b0000 0001 2222 4708Max-Planck-Institute for Evolutionary Biology, Ploen, Germany
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11
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Drew GC, Stevens EJ, King KC. Microbial evolution and transitions along the parasite-mutualist continuum. Nat Rev Microbiol 2021; 19:623-638. [PMID: 33875863 PMCID: PMC8054256 DOI: 10.1038/s41579-021-00550-7] [Citation(s) in RCA: 108] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/12/2021] [Indexed: 12/28/2022]
Abstract
Virtually all plants and animals, including humans, are home to symbiotic microorganisms. Symbiotic interactions can be neutral, harmful or have beneficial effects on the host organism. However, growing evidence suggests that microbial symbionts can evolve rapidly, resulting in drastic transitions along the parasite-mutualist continuum. In this Review, we integrate theoretical and empirical findings to discuss the mechanisms underpinning these evolutionary shifts, as well as the ecological drivers and why some host-microorganism interactions may be stuck at the end of the continuum. In addition to having biomedical consequences, understanding the dynamic life of microorganisms reveals how symbioses can shape an organism's biology and the entire community, particularly in a changing world.
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Affiliation(s)
| | | | - Kayla C King
- Department of Zoology, University of Oxford, Oxford, UK.
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12
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Figueiredo ART, Wagner A, Kümmerli R. Ecology drives the evolution of diverse social strategies in Pseudomonas aeruginosa. Mol Ecol 2021; 30:5214-5228. [PMID: 34390514 PMCID: PMC9291133 DOI: 10.1111/mec.16119] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 06/03/2021] [Accepted: 07/28/2021] [Indexed: 11/27/2022]
Abstract
Bacteria often cooperate by secreting molecules that can be shared as public goods between cells. Because the production of public goods is subject to cheating by mutants that exploit the good without contributing to it, there has been great interest in elucidating the evolutionary forces that maintain cooperation. However, little is known about how bacterial cooperation evolves under conditions where cheating is unlikely to be of importance. Here we use experimental evolution to follow changes in the production of a model public good, the iron‐scavenging siderophore pyoverdine, of the bacterium Pseudomonas aeruginosa. After 1200 generations of evolution in nine different environments, we observed that cheaters only reached high frequency in liquid medium with low iron availability. Conversely, when adding iron to reduce the cost of producing pyoverdine, we observed selection for pyoverdine hyperproducers. Similarly, hyperproducers also spread in populations evolved in highly viscous media, where relatedness between interacting individuals is increased. Whole‐genome sequencing of evolved clones revealed that hyperproduction is associated with mutations involving genes encoding quorum‐sensing communication systems, while cheater clones had mutations in the iron‐starvation sigma factor or in pyoverdine biosynthesis genes. Our findings demonstrate that bacterial social traits can evolve rapidly in divergent directions, with particularly strong selection for increased levels of cooperation occurring in environments where individual dispersal is reduced, as predicted by social evolution theory. Moreover, we establish a regulatory link between pyoverdine production and quorum‐sensing, showing that increased cooperation with respect to one trait (pyoverdine) can be associated with the loss (quorum‐sensing) of another social trait.
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Affiliation(s)
- Alexandre R T Figueiredo
- Department of Quantitative Biomedicine, University of Zurich, 8057, Zurich, Switzerland.,Department of Evolutionary Biology and Environmental Studies, University of Zurich, 8057, Zurich, Switzerland.,Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
| | - Andreas Wagner
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, 8057, Zurich, Switzerland.,Swiss Institute of Bioinformatics, Lausanne, Switzerland.,The Santa Fe Institute, Santa Fe, New Mexico, United States of America
| | - Rolf Kümmerli
- Department of Quantitative Biomedicine, University of Zurich, 8057, Zurich, Switzerland.,Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
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13
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Ren LY, Zhao H, Liu XL, Zong TK, Qiao M, Liu SY, Liu XY. Transcriptome Reveals Roles of Lignin-Modifying Enzymes and Abscisic Acid in the Symbiosis of Mycena and Gastrodia elata. Int J Mol Sci 2021; 22:6557. [PMID: 34207287 PMCID: PMC8235111 DOI: 10.3390/ijms22126557] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/16/2021] [Accepted: 06/16/2021] [Indexed: 01/17/2023] Open
Abstract
Gastrodia elata is a well-known medicinal and heterotrophic orchid. Its germination, limited by the impermeability of seed coat lignin and inhibition by abscisic acid (ABA), is triggered by symbiosis with fungi such as Mycena spp. However, the molecular mechanisms of lignin degradation by Mycena and ABA biosynthesis and signaling in G. elata remain unclear. In order to gain insights into these two processes, this study analyzed the transcriptomes of these organisms during their dynamic symbiosis. Among the 25 lignin-modifying enzyme genes in Mycena, two ligninolytic class II peroxidases and two laccases were significantly upregulated, most likely enabling Mycena hyphae to break through the lignin seed coats of G. elata. Genes related to reduced virulence and loss of pathogenicity in Mycena accounted for more than half of annotated genes, presumably contributing to symbiosis. After coculture, upregulated genes outnumbered downregulated genes in G. elata seeds, suggesting slightly increased biological activity, while Mycena hyphae had fewer upregulated than downregulated genes, indicating decreased biological activity. ABA biosynthesis in G. elata was reduced by the downregulated expression of 9-cis-epoxycarotenoid dioxygenase (NCED-2), and ABA signaling was blocked by the downregulated expression of a receptor protein (PYL12-like). This is the first report to describe the role of NCED-2 and PYL12-like in breaking G. elata seed dormancy by reducing the synthesis and blocking the signaling of the germination inhibitor ABA. This study provides a theoretical basis for screening germination fungi to identify effective symbionts and for reducing ABA inhibition of G. elata seed germination.
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Affiliation(s)
- Li-Ying Ren
- College of Plant Protection, Jilin Agricultural University, Changchun 130118, China;
- Engineering Research Center of Edible and Medicinal Fungi, Ministry of Education, Jilin Agricultural University, Changchun 130118, China
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; (H.Z.); (X.-L.L.)
| | - Heng Zhao
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; (H.Z.); (X.-L.L.)
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiao-Ling Liu
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; (H.Z.); (X.-L.L.)
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tong-Kai Zong
- Key Laboratory for Forest Resources Conservation and Utilization in the Southwest Mountains of China, Ministry of Education, Southwest Forestry University, Kunming 650224, China;
| | - Min Qiao
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming 650091, China
| | - Shu-Yan Liu
- College of Plant Protection, Jilin Agricultural University, Changchun 130118, China;
- Engineering Research Center of Edible and Medicinal Fungi, Ministry of Education, Jilin Agricultural University, Changchun 130118, China
| | - Xiao-Yong Liu
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; (H.Z.); (X.-L.L.)
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14
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Trivellone V, Wei W, Filippin L, Dietrich CH. Screening potential insect vectors in a museum biorepository reveals undiscovered diversity of plant pathogens in natural areas. Ecol Evol 2021; 11:6493-6503. [PMID: 34141234 PMCID: PMC8207438 DOI: 10.1002/ece3.7502] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 03/12/2021] [Accepted: 03/15/2021] [Indexed: 12/03/2022] Open
Abstract
Phytoplasmas (Mollicutes, Acholeplasmataceae), vector-borne obligate bacterial plant parasites, infect nearly 1,000 plant species and unknown numbers of insects, mainly leafhoppers (Hemiptera, Deltocephalinae), which play a key role in transmission and epidemiology. Although the plant-phytoplasma-insect association has been evolving for >300 million years, nearly all known phytoplasmas have been discovered as a result of the damage inflicted by phytoplasma diseases on crops. Few efforts have been made to study phytoplasmas occurring in noneconomically important plants in natural habitats. In this study, a subsample of leafhopper specimens preserved in a large museum biorepository was analyzed to unveil potential new associations. PCR screening for phytoplasmas performed on 227 phloem-feeding leafhoppers collected worldwide from natural habitats revealed the presence of 6 different previously unknown phytoplasma strains. This indicates that museum collections of herbivorous insects represent a rich and largely untapped resource for discovery of new plant pathogens, that natural areas worldwide harbor a diverse but largely undiscovered diversity of phytoplasmas and potential insect vectors, and that independent epidemiological cycles occur in such habitats, posing a potential threat of disease spillover into agricultural systems. Larger-scale future investigations will contribute to a better understanding of phytoplasma genetic diversity, insect host range, and insect-borne phytoplasma transmission and provide an early warning for the emergence of new phytoplasma diseases across global agroecosystems.
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Affiliation(s)
- Valeria Trivellone
- Illinois Natural History SurveyPrairie Research InstituteUniversity of IllinoisChampaignILUSA
| | - Wei Wei
- Molecular Plant Pathology LaboratoryBeltsville Agricultural Research CenterAgricultural Research ServiceUnited States Department of AgricultureBeltsvilleMDUSA
| | - Luisa Filippin
- CREA–VECouncil for Agricultural Research and EconomicsResearch Centre for Viticulture and EnologyConegliano, TrevisoItaly
| | - Christopher H. Dietrich
- Illinois Natural History SurveyPrairie Research InstituteUniversity of IllinoisChampaignILUSA
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15
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Obeng N, Bansept F, Sieber M, Traulsen A, Schulenburg H. Evolution of Microbiota-Host Associations: The Microbe's Perspective. Trends Microbiol 2021; 29:779-787. [PMID: 33674142 DOI: 10.1016/j.tim.2021.02.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 02/07/2023]
Abstract
Microbiota-host associations are ubiquitous in nature. They are often studied using a host-centered view, while microbes are assumed to have coevolved with hosts or colonize hosts as nonadapted entities. Both assumptions are often incorrect. Instead, many host-associated microbes are adapted to a biphasic life cycle in which they alternate between noncoadapted hosts and a free-living phase. Full appreciation of microbiota-host symbiosis thus needs to consider how microbes optimize fitness across this life cycle. Here, we evaluate the key stages of the biphasic life cycle and propose a new conceptual framework for microbiota-host interactions which includes an integrative measure of microbial fitness, related to the parasite fitness parameter R0, and which will help in-depth assessment of the evolution of these widespread associations.
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Affiliation(s)
- Nancy Obeng
- Department of Evolutionary Ecology and Genetics, University of Kiel, Am Botanischen Garten 1- 9, 24118 Kiel, Germany
| | - Florence Bansept
- Max-Planck-Institute for Evolutionary Biology, August-Thienemann-Str. 2, Ploen, Germany
| | - Michael Sieber
- Max-Planck-Institute for Evolutionary Biology, August-Thienemann-Str. 2, Ploen, Germany
| | - Arne Traulsen
- Max-Planck-Institute for Evolutionary Biology, August-Thienemann-Str. 2, Ploen, Germany
| | - Hinrich Schulenburg
- Department of Evolutionary Ecology and Genetics, University of Kiel, Am Botanischen Garten 1- 9, 24118 Kiel, Germany; Max-Planck-Institute for Evolutionary Biology, August-Thienemann-Str. 2, Ploen, Germany.
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16
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Kloock A, Bonsall MB, King KC. Evolution and maintenance of microbe-mediated protection under occasional pathogen infection. Ecol Evol 2020; 10:8634-8642. [PMID: 32884646 PMCID: PMC7452762 DOI: 10.1002/ece3.6555] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 06/15/2020] [Indexed: 01/03/2023] Open
Abstract
Every host is colonized by a variety of microbes, some of which can protect their hosts from pathogen infection. However, pathogen presence naturally varies over time in nature, such as in the case of seasonal epidemics. We experimentally coevolved populations of Caenorhabditis elegans worm hosts with bacteria possessing protective traits (Enterococcus faecalis), in treatments varying the infection frequency with pathogenic Staphylococcus aureus every host generation, alternating host generations, every fifth host generation, or never. We additionally investigated the effect of initial pathogen presence at the formation of the defensive symbiosis. Our results show that enhanced microbe-mediated protection evolved during host-protective microbe coevolution when faced with rare infections by a pathogen. Initial pathogen presence had no effect on the evolutionary outcome of microbe-mediated protection. We also found that protection was only effective at preventing mortality during the time of pathogen infection. Overall, our results suggest that resident microbes can be a form of transgenerational immunity against rare pathogen infection.
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Affiliation(s)
- Anke Kloock
- Department of ZoologyUniversity of OxfordOxfordUK
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17
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Holden ER, Webber MA. MarA, RamA, and SoxS as Mediators of the Stress Response: Survival at a Cost. Front Microbiol 2020. [PMID: 32431683 DOI: 10.3389/fmicb.2020.0082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
To survive and adapt to changing environments, bacteria have evolved mechanisms to express appropriate genes at appropriate times. Exposure to antimicrobials triggers a global stress response in Enterobacteriaceae, underpinned by activation of a family of transcriptional regulators, including MarA, RamA, and SoxS. These control a program of altered gene expression allowing a rapid and measured response to improve fitness in the presence of toxic drugs. Increased expression of marA, ramA, and soxS up regulates efflux activity to allow detoxification of the cell. However, this also results in trade-offs in other phenotypes, such as impaired growth rates, biofilm formation and virulence. Here, we review the current knowledge regarding the trade-offs that exist between drug survival and other phenotypes that result from induction of marA, ramA, and soxS. Additionally, we present some new findings linking expression of these regulators and biofilm formation in Enterobacteriaceae, thereby demonstrating the interconnected nature of regulatory networks within the cell and explaining how trade-offs can exist between important phenotypes. This has important implications for our understanding of how bacterial virulence and biofilms can be influenced by exposure to antimicrobials.
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Affiliation(s)
- Emma R Holden
- Quadram Institute Biosciences, Norwich, United Kingdom
| | - Mark A Webber
- Quadram Institute Biosciences, Norwich, United Kingdom.,Norwich Medical School, University of East Anglia, Norwich, United Kingdom
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18
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Holden ER, Webber MA. MarA, RamA, and SoxS as Mediators of the Stress Response: Survival at a Cost. Front Microbiol 2020; 11:828. [PMID: 32431683 PMCID: PMC7216687 DOI: 10.3389/fmicb.2020.00828] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 04/07/2020] [Indexed: 01/17/2023] Open
Abstract
To survive and adapt to changing environments, bacteria have evolved mechanisms to express appropriate genes at appropriate times. Exposure to antimicrobials triggers a global stress response in Enterobacteriaceae, underpinned by activation of a family of transcriptional regulators, including MarA, RamA, and SoxS. These control a program of altered gene expression allowing a rapid and measured response to improve fitness in the presence of toxic drugs. Increased expression of marA, ramA, and soxS up regulates efflux activity to allow detoxification of the cell. However, this also results in trade-offs in other phenotypes, such as impaired growth rates, biofilm formation and virulence. Here, we review the current knowledge regarding the trade-offs that exist between drug survival and other phenotypes that result from induction of marA, ramA, and soxS. Additionally, we present some new findings linking expression of these regulators and biofilm formation in Enterobacteriaceae, thereby demonstrating the interconnected nature of regulatory networks within the cell and explaining how trade-offs can exist between important phenotypes. This has important implications for our understanding of how bacterial virulence and biofilms can be influenced by exposure to antimicrobials.
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Affiliation(s)
- Emma R Holden
- Quadram Institute Biosciences, Norwich, United Kingdom
| | - Mark A Webber
- Quadram Institute Biosciences, Norwich, United Kingdom.,Norwich Medical School, University of East Anglia, Norwich, United Kingdom
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19
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Pearson T, Sahl JW, Hepp CM, Handady K, Hornstra H, Vazquez AJ, Settles E, Mayo M, Kaestli M, Williamson CHD, Price EP, Sarovich DS, Cook JM, Wolken SR, Bowen RA, Tuanyok A, Foster JT, Drees KP, Kidd TJ, Bell SC, Currie BJ, Keim P. Pathogen to commensal? Longitudinal within-host population dynamics, evolution, and adaptation during a chronic >16-year Burkholderia pseudomallei infection. PLoS Pathog 2020; 16:e1008298. [PMID: 32134991 PMCID: PMC7077878 DOI: 10.1371/journal.ppat.1008298] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 03/17/2020] [Accepted: 01/02/2020] [Indexed: 12/14/2022] Open
Abstract
Although acute melioidosis is the most common outcome of Burkholderia pseudomallei infection, we have documented a case, P314, where disease severity lessened with time, and the pathogen evolved towards a commensal relationship with the host. In the current study, we used whole-genome sequencing to monitor this long-term symbiotic relationship to better understand B. pseudomallei persistence in P314's sputum despite intensive initial therapeutic regimens. We collected and sequenced 118 B. pseudomallei isolates from P314's airways over a >16-year period, and also sampled the patient's home environment, recovering six closely related B. pseudomallei isolates from the household water system. Using comparative genomics, we identified 126 SNPs in the core genome of the 124 isolates or 162 SNPs/indels when the accessory genome was included. The core SNPs were used to construct a phylogenetic tree, which demonstrated a close relationship between environmental and clinical isolates and detailed within-host evolutionary patterns. The phylogeny had little homoplasy, consistent with a strictly clonal mode of genetic inheritance. Repeated sampling revealed evidence of genetic diversification, but frequent extinctions left only one successful lineage through the first four years and two lineages after that. Overall, the evolution of this population is nonadaptive and best explained by genetic drift. However, some genetic and phenotypic changes are consistent with in situ adaptation. Using a mouse model, P314 isolates caused greatly reduced morbidity and mortality compared to the environmental isolates. Additionally, potentially adaptive phenotypes emerged and included differences in the O-antigen, capsular polysaccharide, motility, and colony morphology. The >13-year co-existence of two long-lived lineages presents interesting hypotheses that can be tested in future studies to provide additional insights into selective pressures, niche differentiation, and microbial adaptation. This unusual melioidosis case presents a rare example of the evolutionary progression towards commensalism by a highly virulent pathogen within a single human host.
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Affiliation(s)
- Talima Pearson
- Pathogen & Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Jason W. Sahl
- Pathogen & Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Crystal M. Hepp
- Pathogen & Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Karthik Handady
- Pathogen & Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Heidie Hornstra
- Pathogen & Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Adam J. Vazquez
- Pathogen & Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Erik Settles
- Pathogen & Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Mark Mayo
- Global and Tropical Health Division, Menzies School of Health Research, Darwin, Northern Territory, Australia
| | - Mirjam Kaestli
- Global and Tropical Health Division, Menzies School of Health Research, Darwin, Northern Territory, Australia
| | - Charles H. D. Williamson
- Pathogen & Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Erin P. Price
- Pathogen & Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Derek S. Sarovich
- Pathogen & Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - James M. Cook
- Pathogen & Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Spenser R. Wolken
- Pathogen & Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Richard A. Bowen
- Department of Biomedical Sciences, Colorado State University, Colorado, United States of America
| | - Apichai Tuanyok
- Pathogen & Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Jeffrey T. Foster
- Pathogen & Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Kevin P. Drees
- Pathogen & Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
| | - Timothy J. Kidd
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia
| | - Scott C. Bell
- Department of Thoracic Medicine, The Prince Charles Hospital, Chermside, and QIMR Berghofer Medical Research Institute, Queensland, Australia
| | - Bart J. Currie
- Global and Tropical Health Division, Menzies School of Health Research, Darwin, Northern Territory, Australia
- Infectious Diseases Department and Northern Territory Medical Program, Royal Darwin Hospital, Darwin, Northern Territory, Australia
| | - Paul Keim
- Pathogen & Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, United States of America
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20
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Rezzoagli C, Granato ET, Kümmerli R. Harnessing bacterial interactions to manage infections: a review on the opportunistic pathogen Pseudomonas aeruginosa as a case example. J Med Microbiol 2020; 69:147-161. [PMID: 31961787 PMCID: PMC7116537 DOI: 10.1099/jmm.0.001134] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
During infections, bacterial pathogens can engage in a variety of interactions with each other, ranging from the cooperative sharing of resources to deadly warfare. This is especially relevant in opportunistic infections, where different strains and species often co-infect the same patient and interact in the host. Here, we review the relevance of these social interactions during opportunistic infections using the human pathogen Pseudomonas aeruginosa as a case example. In particular, we discuss different types of pathogen-pathogen interactions, involving both cooperation and competition, and elaborate on how they impact virulence in multi-strain and multi-species infections. We then review evolutionary dynamics within pathogen populations during chronic infections. We particuarly discuss how local adaptation through niche separation, evolutionary successions and antagonistic co-evolution between pathogens can alter virulence and the damage inflicted on the host. Finally, we outline how studying bacterial social dynamics could be used to manage infections. We show that a deeper appreciation of bacterial evolution and ecology in the clinical context is important for understanding microbial infections and can inspire novel treatment strategies.
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Affiliation(s)
- Chiara Rezzoagli
- Department of Quantitative Biomedicine, University of Zurich, Zurich, Switzerland
| | - Elisa T. Granato
- Department of Zoology, University of Oxford, Oxford, United Kingdom
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Rolf Kümmerli
- Department of Quantitative Biomedicine, University of Zurich, Zurich, Switzerland
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21
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Stress-induced adaptations in Salmonella: A ground for shaping its pathogenesis. Microbiol Res 2019; 229:126311. [DOI: 10.1016/j.micres.2019.126311] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 08/01/2019] [Accepted: 08/06/2019] [Indexed: 12/12/2022]
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22
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Pradhan D, Negi VD. Repeated in-vitro and in-vivo exposure leads to genetic alteration, adaptations, and hypervirulence in Salmonella. Microb Pathog 2019; 136:103654. [DOI: 10.1016/j.micpath.2019.103654] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 08/03/2019] [Accepted: 08/05/2019] [Indexed: 11/30/2022]
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23
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Barbosa C, Römhild R, Rosenstiel P, Schulenburg H. Evolutionary stability of collateral sensitivity to antibiotics in the model pathogen Pseudomonas aeruginosa. eLife 2019; 8:e51481. [PMID: 31658946 PMCID: PMC6881144 DOI: 10.7554/elife.51481] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 10/21/2019] [Indexed: 12/27/2022] Open
Abstract
Evolution is at the core of the impending antibiotic crisis. Sustainable therapy must thus account for the adaptive potential of pathogens. One option is to exploit evolutionary trade-offs, like collateral sensitivity, where evolved resistance to one antibiotic causes hypersensitivity to another one. To date, the evolutionary stability and thus clinical utility of this trade-off is unclear. We performed a critical experimental test on this key requirement, using evolution experiments with Pseudomonas aeruginosa, and identified three main outcomes: (i) bacteria commonly failed to counter hypersensitivity and went extinct; (ii) hypersensitivity sometimes converted into multidrug resistance; and (iii) resistance gains frequently caused re-sensitization to the previous drug, thereby maintaining the trade-off. Drug order affected the evolutionary outcome, most likely due to variation in the effect size of collateral sensitivity, epistasis among adaptive mutations, and fitness costs. Our finding of robust genetic trade-offs and drug-order effects can guide design of evolution-informed antibiotic therapy.
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Affiliation(s)
- Camilo Barbosa
- Department of Evolutionary Ecology and GeneticsUniversity of KielKielGermany
| | - Roderich Römhild
- Department of Evolutionary Ecology and GeneticsUniversity of KielKielGermany
- Max Planck Institute for Evolutionary BiologyPlönGermany
| | | | - Hinrich Schulenburg
- Department of Evolutionary Ecology and GeneticsUniversity of KielKielGermany
- Max Planck Institute for Evolutionary BiologyPlönGermany
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24
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O'Brien S, Kümmerli R, Paterson S, Winstanley C, Brockhurst MA. Transposable temperate phages promote the evolution of divergent social strategies in Pseudomonas aeruginosa populations. Proc Biol Sci 2019; 286:20191794. [PMID: 31594506 DOI: 10.1098/rspb.2019.1794] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Transposable temperate phages randomly insert into bacterial genomes, providing increased supply and altered spectra of mutations available to selection, thus opening alternative evolutionary trajectories. Transposable phages accelerate bacterial adaptation to new environments, but their effect on adaptation to the social environment is unclear. Using experimental evolution of Pseudomonas aeruginosa in iron-limited and iron-rich environments, where the cost of producing cooperative iron-chelating siderophores is high and low, respectively, we show that transposable phages promote divergence into extreme siderophore production phenotypes. Iron-limited populations with transposable phages evolved siderophore overproducing clones alongside siderophore non-producing cheats. Low siderophore production was associated with parallel mutations in pvd genes, encoding pyoverdine biosynthesis, and pqs genes, encoding quinolone signalling, while high siderophore production was associated with parallel mutations in phenazine-associated gene clusters. Notably, some of these parallel mutations were caused by phage insertional inactivation. These data suggest that transposable phages, which are widespread in microbial communities, can mediate the evolutionary divergence of social strategies.
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Affiliation(s)
- Siobhán O'Brien
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Rolf Kümmerli
- Department of Plant and Microbial Biology, University of Zürich, Switzerland
| | - Steve Paterson
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Craig Winstanley
- Institute of Infection and Global Health, University of Liverpool, Liverpool L69 7BE, UK
| | - Michael A Brockhurst
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
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25
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Remigi P, Masson-Boivin C, Rocha EP. Experimental Evolution as a Tool to Investigate Natural Processes and Molecular Functions. Trends Microbiol 2019; 27:623-634. [DOI: 10.1016/j.tim.2019.02.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 01/31/2019] [Accepted: 02/05/2019] [Indexed: 12/17/2022]
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26
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Hong Z, Bolard A, Giraud C, Prévost S, Genta‐Jouve G, Deregnaucourt C, Häussler S, Jeannot K, Li Y. Azetidine‐Containing Alkaloids Produced by a Quorum‐Sensing Regulated Nonribosomal Peptide Synthetase Pathway in
Pseudomonas aeruginosa. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201809981] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Zhilai Hong
- Unité Molécules de Communication et Adaptation des Microorganismes (MCAM)Muséum National d'Histoire Naturelle (MNHN)Centre National de la Recherche Scientifique (CNRS), CP 54 57 rue Cuvier 75005 Paris France
| | - Arnaud Bolard
- Laboratoire de BactériologieCentre National de Référence (CNR) de la Résistance aux Antibiotiques, Centre Hospitalier Régional Universitaire (CHRU) de Besançon, UMR4269 “Chrono-Environnement” Boulevard Fleming 25030 Besançon France
| | - Caroline Giraud
- U2RM Stress/VirulenceNormandy University, UNICAEN 14000 Caen France
| | - Sébastien Prévost
- Laboratoire de Synthèse Organique, UMR 7652CNRS, Ecole PolytechniqueENSTA ParisTechUniversité Paris-Saclay 828 Bd des Maréchaux 91128 Palaiseau France
| | - Grégory Genta‐Jouve
- Unité Molécules de Communication et Adaptation des Microorganismes (MCAM)Muséum National d'Histoire Naturelle (MNHN)Centre National de la Recherche Scientifique (CNRS), CP 54 57 rue Cuvier 75005 Paris France
- C-TAC, UMR 8638, CNRSFaculté de Pharmacie de ParisUniversité Paris Descartes, Sorbonne Paris Cité 4 Avenue de l'Observatoire 75006 Paris France
| | - Christiane Deregnaucourt
- Unité Molécules de Communication et Adaptation des Microorganismes (MCAM)Muséum National d'Histoire Naturelle (MNHN)Centre National de la Recherche Scientifique (CNRS), CP 54 57 rue Cuvier 75005 Paris France
| | - Susanne Häussler
- Institute for Molecular Bacteriology, TWINCORECentre for Experimental and Clinical Infection Research Hannover Germany
- Department of Molecular BacteriologyHelmholtz Centre for Infection Research Braunschweig Germany
| | - Katy Jeannot
- Laboratoire de BactériologieCentre National de Référence (CNR) de la Résistance aux Antibiotiques, Centre Hospitalier Régional Universitaire (CHRU) de Besançon, UMR4269 “Chrono-Environnement” Boulevard Fleming 25030 Besançon France
| | - Yanyan Li
- Unité Molécules de Communication et Adaptation des Microorganismes (MCAM)Muséum National d'Histoire Naturelle (MNHN)Centre National de la Recherche Scientifique (CNRS), CP 54 57 rue Cuvier 75005 Paris France
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27
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Hong Z, Bolard A, Giraud C, Prévost S, Genta-Jouve G, Deregnaucourt C, Häussler S, Jeannot K, Li Y. Azetidine-Containing Alkaloids Produced by a Quorum-Sensing Regulated Nonribosomal Peptide Synthetase Pathway in Pseudomonas aeruginosa. Angew Chem Int Ed Engl 2019; 58:3178-3182. [PMID: 30548135 DOI: 10.1002/anie.201809981] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 11/08/2018] [Indexed: 12/26/2022]
Abstract
Pseudomonas aeruginosa displays an impressive metabolic versatility, which ensures its survival in diverse environments. Reported herein is the identification of rare azetidine-containing alkaloids from P. aeruginosa PAO1, termed azetidomonamides, which are derived from a conserved, quorum-sensing regulated nonribosomal peptide synthetase (NRPS) pathway. Biosynthesis of the azetidine motif has been elucidated by gene inactivation, feeding experiments, and biochemical characterization in vitro, which involves a new S-adenosylmethionine-dependent enzyme to produce azetidine 2-carboxylic acid as an unusual building block of NRPS. The mutants of P. aeruginosa unable to produce azetidomonamides had an advantage in growth at high cell density in vitro and displayed rapid virulence in Galleria mellonella model, inferring functional roles of azetidomonamides in the host adaptation. This work opens the avenue to study the biological functions of azetidomonamides and related compounds in pathogenic and environmental bacteria.
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Affiliation(s)
- Zhilai Hong
- Unité Molécules de Communication et Adaptation des Microorganismes (MCAM), Muséum National d'Histoire Naturelle (MNHN), Centre National de la Recherche Scientifique (CNRS), CP 54, 57 rue Cuvier, 75005, Paris, France
| | - Arnaud Bolard
- Laboratoire de Bactériologie, Centre National de Référence (CNR) de la Résistance aux Antibiotiques, Centre Hospitalier Régional Universitaire (CHRU) de Besançon, UMR4269 "Chrono-Environnement", Boulevard Fleming, 25030, Besançon, France
| | - Caroline Giraud
- U2RM Stress/Virulence, Normandy University, UNICAEN, 14000, Caen, France
| | - Sébastien Prévost
- Laboratoire de Synthèse Organique, UMR 7652, CNRS, Ecole Polytechnique, ENSTA ParisTech, Université Paris-Saclay, 828 Bd des Maréchaux, 91128, Palaiseau, France
| | - Grégory Genta-Jouve
- Unité Molécules de Communication et Adaptation des Microorganismes (MCAM), Muséum National d'Histoire Naturelle (MNHN), Centre National de la Recherche Scientifique (CNRS), CP 54, 57 rue Cuvier, 75005, Paris, France.,C-TAC, UMR 8638, CNRS, Faculté de Pharmacie de Paris, Université Paris Descartes, Sorbonne Paris Cité, 4 Avenue de l'Observatoire, 75006, Paris, France
| | - Christiane Deregnaucourt
- Unité Molécules de Communication et Adaptation des Microorganismes (MCAM), Muséum National d'Histoire Naturelle (MNHN), Centre National de la Recherche Scientifique (CNRS), CP 54, 57 rue Cuvier, 75005, Paris, France
| | - Susanne Häussler
- Institute for Molecular Bacteriology, TWINCORE, Centre for Experimental and Clinical Infection Research, Hannover, Germany.,Department of Molecular Bacteriology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Katy Jeannot
- Laboratoire de Bactériologie, Centre National de Référence (CNR) de la Résistance aux Antibiotiques, Centre Hospitalier Régional Universitaire (CHRU) de Besançon, UMR4269 "Chrono-Environnement", Boulevard Fleming, 25030, Besançon, France
| | - Yanyan Li
- Unité Molécules de Communication et Adaptation des Microorganismes (MCAM), Muséum National d'Histoire Naturelle (MNHN), Centre National de la Recherche Scientifique (CNRS), CP 54, 57 rue Cuvier, 75005, Paris, France
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28
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Granato ET, Ziegenhain C, Marvig RL, Kümmerli R. Low spatial structure and selection against secreted virulence factors attenuates pathogenicity in Pseudomonas aeruginosa. ISME JOURNAL 2018; 12:2907-2918. [PMID: 30065310 DOI: 10.1038/s41396-018-0231-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 06/14/2018] [Accepted: 06/19/2018] [Indexed: 02/01/2023]
Abstract
Bacterial opportunistic pathogens are feared for their difficult-to-treat nosocomial infections and for causing morbidity in immunocompromised patients. Here, we study how such a versatile opportunist, Pseudomonas aeruginosa, adapts to conditions inside and outside its model host Caenorhabditis elegans, and use phenotypic and genotypic screens to identify the mechanistic basis of virulence evolution. We found that virulence significantly dropped in unstructured environments both in the presence and absence of the host, but remained unchanged in spatially structured environments. Reduction of virulence was either driven by a substantial decline in the production of siderophores (in treatments without hosts) or toxins and proteases (in treatments with hosts). Whole-genome sequencing of evolved clones revealed positive selection and parallel evolution across replicates, and showed an accumulation of mutations in regulator genes controlling virulence factor expression. Our study identifies the spatial structure of the non-host environment as a key driver of virulence evolution in an opportunistic pathogen.
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Affiliation(s)
- Elisa T Granato
- Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland. .,Department of Zoology, University of Oxford, Oxford, United Kingdom.
| | - Christoph Ziegenhain
- Department Biology II, Ludwig-Maximilians-University, Munich, Germany.,Department of Cell and Molecular Biology, Karolinska Institutet, Solna, Sweden
| | - Rasmus L Marvig
- Center for Genomic Medicine, Rigshospitalet, Copenhagen, Denmark
| | - Rolf Kümmerli
- Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland
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29
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Rafaluk‐Mohr C, Ashby B, Dahan DA, King KC. Mutual fitness benefits arise during coevolution in a nematode-defensive microbe model. Evol Lett 2018; 2:246-256. [PMID: 30283680 PMCID: PMC6121859 DOI: 10.1002/evl3.58] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 04/19/2018] [Indexed: 12/14/2022] Open
Abstract
Species interactions can shift along the parasitism-mutualism continuum. However, the consequences of these transitions for coevolutionary interactions remain unclear. We experimentally coevolved a novel species interaction between Caenorhabditis elegans hosts and a mildly parasitic bacterium, Enterococcus faecalis, with host-protective properties against virulent Staphylococcus aureus. Coinfections drove the evolutionary transition of the C. elegans-E. faecalis relationship toward a reciprocally beneficial interaction. As E. faecalis evolved to protect nematodes against S. aureus infection, hosts adapted by accommodating greater numbers of protective bacteria. The mutualism was strongest in pairings of contemporary coevolved populations. To generally assess the conditions under which these defensive mutualisms can arise and coevolve, we analyzed a model that showed that they are favored when mild parasites confer an intermediate level of protection. Our results reveal that coevolution can shape the transition of animal-parasite interactions toward defensive symbioses in response to coinfections.
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Affiliation(s)
| | - Ben Ashby
- Department of Mathematical SciencesUniversity of BathBathBA2 7AYUnited Kingdom
- Integrative BiologyUniversity of California BerkeleyBerkeleyCalifornia94720
| | - Dylan A. Dahan
- Department of ZoologyUniversity of OxfordOxfordOX1 3PSUnited Kingdom
- Current Address: Department of Microbiology and ImmunologyStanford University School of MedicineStanfordCalifornia94305
| | - Kayla C. King
- Department of ZoologyUniversity of OxfordOxfordOX1 3PSUnited Kingdom
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30
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Pseudomonas aeruginosa type IV minor pilins and PilY1 regulate virulence by modulating FimS-AlgR activity. PLoS Pathog 2018; 14:e1007074. [PMID: 29775484 PMCID: PMC5979040 DOI: 10.1371/journal.ppat.1007074] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 05/31/2018] [Accepted: 05/04/2018] [Indexed: 11/19/2022] Open
Abstract
Type IV pili are expressed by a wide range of prokaryotes, including the opportunistic pathogen Pseudomonas aeruginosa. These flexible fibres mediate twitching motility, biofilm maturation, surface adhesion, and virulence. The pilus is composed mainly of major pilin subunits while the low abundance minor pilins FimU-PilVWXE and the putative adhesin PilY1 prime pilus assembly and are proposed to form the pilus tip. The minor pilins and PilY1 are encoded in an operon that is positively regulated by the FimS-AlgR two-component system. Independent of pilus assembly, PilY1 was proposed to be a mechanosensory component that—in conjunction with minor pilins—triggers up-regulation of acute virulence phenotypes upon surface attachment. Here, we investigated the link between the minor pilins/PilY1 and virulence. pilW, pilX, and pilY1 mutants had reduced virulence towards Caenorhabditis elegans relative to wild type or a major pilin mutant, implying a role in pathogenicity that is independent of pilus assembly. We hypothesized that loss of specific minor pilins relieves feedback inhibition on FimS-AlgR, increasing transcription of the AlgR regulon and delaying C. elegans killing. Reporter assays confirmed that FimS-AlgR were required for increased expression of the minor pilin operon upon loss of select minor pilins. Overexpression of AlgR or its hyperactivation via a phosphomimetic mutation reduced virulence, and the virulence defects of pilW, pilX, and pilY1 mutants required FimS-AlgR expression and activation. We propose that PilY1 and the minor pilins inhibit their own expression, and that loss of these proteins leads to FimS-mediated activation of AlgR that suppresses expression of acute-phase virulence factors and delays killing. This mechanism could contribute to adaptation of P. aeruginosa in chronic lung infections, as mutations in the minor pilin operon result in the loss of piliation and increased expression of AlgR-dependent virulence factors–such as alginate–that are characteristic of such infections. Pseudomonas aeruginosa causes dangerous infections, including chronic lung infections in cystic fibrosis patients. It uses many strategies to infect its hosts, including deployment of grappling hook-like fibres called type IV pili. Among the components involved in assembly and function of the pilus are five proteins called minor pilins that—along with a larger protein called PilY1—may help the pilus attach to surfaces. In a roundworm infection model, loss of PilY1 and specific minor pilins delayed killing, while loss of other pilus components did not. We traced this effect to increased activation of the FimS-AlgR regulatory system that inhibits the expression of virulence factors used early in infection, while positively regulating chronic infection traits such as alginate production, a phenotype called mucoidy. A disruption in the appropriate timing of FimS-AlgR-dependent virulence factor expression when select minor pilins or PilY1 are missing may explain why those pilus-deficient mutants have reduced virulence compared with others whose products are not under FimS-AlgR control. Increased FimS-AlgR activity upon loss of PilY1 and specific minor pilins could help to explain the frequent co-occurrence of the non-piliated and mucoid phenotypes that are hallmarks of chronic P. aeruginosa lung infections.
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31
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Barbosa C, Trebosc V, Kemmer C, Rosenstiel P, Beardmore R, Schulenburg H, Jansen G. Alternative Evolutionary Paths to Bacterial Antibiotic Resistance Cause Distinct Collateral Effects. Mol Biol Evol 2017; 34:2229-2244. [PMID: 28541480 PMCID: PMC5850482 DOI: 10.1093/molbev/msx158] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
When bacteria evolve resistance against a particular antibiotic, they may simultaneously gain increased sensitivity against a second one. Such collateral sensitivity may be exploited to develop novel, sustainable antibiotic treatment strategies aimed at containing the current, dramatic spread of drug resistance. To date, the presence and molecular basis of collateral sensitivity has only been studied in few bacterial species and is unknown for opportunistic human pathogens such as Pseudomonas aeruginosa. In the present study, we assessed patterns of collateral effects by experimentally evolving 160 independent populations of P. aeruginosa to high levels of resistance against eight commonly used antibiotics. The bacteria evolved resistance rapidly and expressed both collateral sensitivity and cross-resistance. The pattern of such collateral effects differed to those previously reported for other bacterial species, suggesting interspecific differences in the underlying evolutionary trade-offs. Intriguingly, we also identified contrasting patterns of collateral sensitivity and cross-resistance among the replicate populations adapted to the same drug. Whole-genome sequencing of 81 independently evolved populations revealed distinct evolutionary paths of resistance to the selective drug, which determined whether bacteria became cross-resistant or collaterally sensitive towards others. Based on genomic and functional genetic analysis, we demonstrate that collateral sensitivity can result from resistance mutations in regulatory genes such as nalC or mexZ, which mediate aminoglycoside sensitivity in β-lactam-adapted populations, or the two-component regulatory system gene pmrB, which enhances penicillin sensitivity in gentamicin-resistant populations. Our findings highlight substantial variation in the evolved collateral effects among replicates, which in turn determine their potential in antibiotic therapy.
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Affiliation(s)
- Camilo Barbosa
- Evolutionary Ecology and Genetics, Zoological Institute, CAU Kiel, Kiel, Germany
| | | | | | - Philip Rosenstiel
- Institute of Clinical Molecular Biology (IKMB), CAU Kiel, Kiel, Germany
| | | | - Hinrich Schulenburg
- Evolutionary Ecology and Genetics, Zoological Institute, CAU Kiel, Kiel, Germany
| | - Gunther Jansen
- Evolutionary Ecology and Genetics, Zoological Institute, CAU Kiel, Kiel, Germany
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32
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High Levels of the Xenorhabdus nematophila Transcription Factor Lrp Promote Mutualism with the Steinernema carpocapsae Nematode Host. Appl Environ Microbiol 2017; 83:AEM.00276-17. [PMID: 28389546 DOI: 10.1128/aem.00276-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 04/04/2017] [Indexed: 11/20/2022] Open
Abstract
Xenorhabdus nematophila bacteria are mutualistic symbionts of Steinernema carpocapsae nematodes and pathogens of insects. The X. nematophila global regulator Lrp controls the expression of many genes involved in both mutualism and pathogenic activities, suggesting a role in the transition between the two host organisms. We previously reported that natural populations of X. nematophila exhibit various levels of Lrp expression and that cells expressing relatively low levels of Lrp are optimized for virulence in the insect Manduca sexta The adaptive advantage of the high-Lrp-expressing state was not established. Here we used strains engineered to express constitutively high or low levels of Lrp to test the model in which high-Lrp-expressing cells are adapted for mutualistic activities with the nematode host. We demonstrate that high-Lrp cells form more robust biofilms in laboratory media than do low-Lrp cells, which may reflect adherence to host tissues. Also, our data showed that nematodes cultivated with high-Lrp strains are more frequently colonized than are those associated with low-Lrp strains. Taken together, these data support the idea that high-Lrp cells have an advantage in tissue adherence and colonization initiation. Furthermore, our data show that high-Lrp-expressing strains better support nematode reproduction than do their low-Lrp counterparts under both in vitro and in vivo conditions. Our data indicate that heterogeneity of Lrp expression in X. nematophila populations provides diverse cell populations adapted to both pathogenic (low-Lrp) and mutualistic (high-Lrp) states.IMPORTANCE Host-associated bacteria experience fluctuating conditions during both residence within an individual host and transmission between hosts. For bacteria that engage in evolutionarily stable, long-term relationships with particular hosts, these fluctuations provide selective pressure for the emergence of adaptive regulatory mechanisms. Here we present evidence that the bacterium Xenorhabdus nematophila uses various levels of the transcription factor Lrp to optimize its association with its two animal hosts, nematodes and insects, with which it behaves as a mutualist and a pathogen, respectively. Building on our previous finding that relatively low cellular levels of Lrp are optimal for pathogenesis, we demonstrate that, conversely, high levels of Lrp promote mutualistic activities with the Steinernema carpocapsae nematode host. These data suggest that X. nematophila has evolved to utilize phenotypic variation between high- and low-Lrp-expression states to optimize its alternating behaviors as a mutualist and a pathogen.
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33
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Schulenburg H, Félix MA. The Natural Biotic Environment of Caenorhabditis elegans. Genetics 2017; 206:55-86. [PMID: 28476862 PMCID: PMC5419493 DOI: 10.1534/genetics.116.195511] [Citation(s) in RCA: 249] [Impact Index Per Article: 35.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 02/28/2017] [Indexed: 01/05/2023] Open
Abstract
Organisms evolve in response to their natural environment. Consideration of natural ecological parameters are thus of key importance for our understanding of an organism's biology. Curiously, the natural ecology of the model species Caenorhabditis elegans has long been neglected, even though this nematode has become one of the most intensively studied models in biological research. This lack of interest changed ∼10 yr ago. Since then, an increasing number of studies have focused on the nematode's natural ecology. Yet many unknowns still remain. Here, we provide an overview of the currently available information on the natural environment of C. elegans We focus on the biotic environment, which is usually less predictable and thus can create high selective constraints that are likely to have had a strong impact on C. elegans evolution. This nematode is particularly abundant in microbe-rich environments, especially rotting plant matter such as decomposing fruits and stems. In this environment, it is part of a complex interaction network, which is particularly shaped by a species-rich microbial community. These microbes can be food, part of a beneficial gut microbiome, parasites and pathogens, and possibly competitors. C. elegans is additionally confronted with predators; it interacts with vector organisms that facilitate dispersal to new habitats, and also with competitors for similar food environments, including competitors from congeneric and also the same species. Full appreciation of this nematode's biology warrants further exploration of its natural environment and subsequent integration of this information into the well-established laboratory-based research approaches.
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Affiliation(s)
- Hinrich Schulenburg
- Zoological Institute, Christian-Albrechts Universitaet zu Kiel, 24098 Kiel, Germany
| | - Marie-Anne Félix
- Institut de Biologie de l'Ecole Normale Supérieure, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, École Normale Supérieure, L'université de Recherche Paris Sciences et Lettres, 75005, France
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34
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Pankey MS, Foxall RL, Ster IM, Perry LA, Schuster BM, Donner RA, Coyle M, Cooper VS, Whistler CA. Host-selected mutations converging on a global regulator drive an adaptive leap towards symbiosis in bacteria. eLife 2017; 6:e24414. [PMID: 28447935 PMCID: PMC5466423 DOI: 10.7554/elife.24414] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 04/23/2017] [Indexed: 01/14/2023] Open
Abstract
Host immune and physical barriers protect against pathogens but also impede the establishment of essential symbiotic partnerships. To reveal mechanisms by which beneficial organisms adapt to circumvent host defenses, we experimentally evolved ecologically distinct bioluminescent Vibrio fischeri by colonization and growth within the light organs of the squid Euprymna scolopes. Serial squid passaging of bacteria produced eight distinct mutations in the binK sensor kinase gene, which conferred an exceptional selective advantage that could be demonstrated through both empirical and theoretical analysis. Squid-adaptive binK alleles promoted colonization and immune evasion that were mediated by cell-associated matrices including symbiotic polysaccharide (Syp) and cellulose. binK variation also altered quorum sensing, raising the threshold for luminescence induction. Preexisting coordinated regulation of symbiosis traits by BinK presented an efficient solution where altered BinK function was the key to unlock multiple colonization barriers. These results identify a genetic basis for microbial adaptability and underscore the importance of hosts as selective agents that shape emergent symbiont populations.
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Affiliation(s)
- M Sabrina Pankey
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States
- Northeast Center for Vibrio Disease and Ecology, College of Life Science and Agriculture, University of New Hampshire, Durham, United States
| | - Randi L Foxall
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States
- Northeast Center for Vibrio Disease and Ecology, College of Life Science and Agriculture, University of New Hampshire, Durham, United States
| | - Ian M Ster
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States
- Northeast Center for Vibrio Disease and Ecology, College of Life Science and Agriculture, University of New Hampshire, Durham, United States
- Graduate Program in Biochemistry, University of New Hampshire, Durham, United States
| | - Lauren A Perry
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States
- Graduate Program in Microbiology, University of New Hampshire, Durham, United States
| | - Brian M Schuster
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States
| | - Rachel A Donner
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States
| | - Matthew Coyle
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States
- Graduate Program in Microbiology, University of New Hampshire, Durham, United States
| | - Vaughn S Cooper
- Northeast Center for Vibrio Disease and Ecology, College of Life Science and Agriculture, University of New Hampshire, Durham, United States
| | - Cheryl A Whistler
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States
- Northeast Center for Vibrio Disease and Ecology, College of Life Science and Agriculture, University of New Hampshire, Durham, United States
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35
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Qi Q, Toll-Riera M, Heilbron K, Preston GM, MacLean RC. The genomic basis of adaptation to the fitness cost of rifampicin resistance in Pseudomonas aeruginosa. Proc Biol Sci 2016; 283:rspb.2015.2452. [PMID: 26763710 PMCID: PMC4721101 DOI: 10.1098/rspb.2015.2452] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Antibiotic resistance carries a fitness cost that must be overcome in order for resistance to persist over the long term. Compensatory mutations that recover the functional defects associated with resistance mutations have been argued to play a key role in overcoming the cost of resistance, but compensatory mutations are expected to be rare relative to generally beneficial mutations that increase fitness, irrespective of antibiotic resistance. Given this asymmetry, population genetics theory predicts that populations should adapt by compensatory mutations when the cost of resistance is large, whereas generally beneficial mutations should drive adaptation when the cost of resistance is small. We tested this prediction by determining the genomic mechanisms underpinning adaptation to antibiotic-free conditions in populations of the pathogenic bacterium Pseudomonas aeruginosa that carry costly antibiotic resistance mutations. Whole-genome sequencing revealed that populations founded by high-cost rifampicin-resistant mutants adapted via compensatory mutations in three genes of the RNA polymerase core enzyme, whereas populations founded by low-cost mutants adapted by generally beneficial mutations, predominantly in the quorum-sensing transcriptional regulator gene lasR. Even though the importance of compensatory evolution in maintaining resistance has been widely recognized, our study shows that the roles of general adaptation in maintaining resistance should not be underestimated and highlights the need to understand how selection at other sites in the genome influences the dynamics of resistance alleles in clinical settings.
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Affiliation(s)
- Qin Qi
- Department of Zoology, University of Oxford, Oxford, UK Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Macarena Toll-Riera
- Department of Zoology, University of Oxford, Oxford, UK Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Karl Heilbron
- Department of Zoology, University of Oxford, Oxford, UK
| | - Gail M Preston
- Department of Plant Sciences, University of Oxford, Oxford, UK
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36
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Tago D, Meyer DF. Economic Game Theory to Model the Attenuation of Virulence of an Obligate Intracellular Bacterium. Front Cell Infect Microbiol 2016; 6:86. [PMID: 27610355 PMCID: PMC4997789 DOI: 10.3389/fcimb.2016.00086] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 08/09/2016] [Indexed: 12/19/2022] Open
Abstract
Diseases induced by obligate intracellular pathogens have a large burden on global human and animal health. Understanding the factors involved in the virulence and fitness of these pathogens contributes to the development of control strategies against these diseases. Based on biological observations, a theoretical model using game theory is proposed to explain how obligate intracellular bacteria interact with their host. The equilibrium in such a game shows that the virulence and fitness of the bacterium is host-triggered and by changing the host's defense system to which the bacterium is confronted, an evolutionary process leads to an attenuated strain. Although, the attenuation procedure has already been conducted in practice in order to develop an attenuated vaccine (e.g., with Ehrlichia ruminantium), there was a lack of understanding of the theoretical basis behind this process. Our work provides a model to better comprehend the existence of different phenotypes and some underlying evolutionary mechanisms for the virulence of obligate intracellular bacteria.
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Affiliation(s)
- Damian Tago
- La Recherche Agronomique Pour le Développement (CIRAD), UMR Contrôle des Maladies Animales, Exotiques et Émergentes (CMAEE)Petit-Bourg, France; Institut National de la Recherche Agronomique, UMR1309 CMAEEMontpellier, France
| | - Damien F Meyer
- La Recherche Agronomique Pour le Développement (CIRAD), UMR Contrôle des Maladies Animales, Exotiques et Émergentes (CMAEE)Petit-Bourg, France; Institut National de la Recherche Agronomique, UMR1309 CMAEEMontpellier, France
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37
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Zhao X, Liu Q, Xiao K, Hu Y, Liu X, Li Y, Kong Q. Identification of the crp gene in avian Pasteurella multocida and evaluation of the effects of crp deletion on its phenotype, virulence and immunogenicity. BMC Microbiol 2016; 16:125. [PMID: 27343075 PMCID: PMC4921010 DOI: 10.1186/s12866-016-0739-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 06/09/2016] [Indexed: 12/14/2022] Open
Abstract
Background Pasteurella multocida (P. multocida) is an important veterinary pathogen that can cause severe diseases in a wide range of mammals and birds. The global regulator crp gene has been found to regulate the virulence of some bacteria, and crp mutants have been demonstrated to be effective attenuated vaccines against Salmonella enterica and Yersinia enterocolitica. Here, we first characterized the crp gene in P. multocida, and we report the effects of a crp deletion. Results The P. multocida crp mutant exhibited a similar lipopolysaccharide and outer membrane protein profile but displayed defective growth and serum complement resistance in vitro compared with the parent strain. Furthermore, crp deletion decreased virulence but did not result in full attenuation. The 50 % lethal dose (LD50) of the Δcrp mutant was 85-fold higher than that of the parent strain for intranasal infection. Transcriptome sequencing analysis showed that 92 genes were up-regulated and 94 genes were down-regulated in the absence of the crp gene. Finally, we found that intranasal immunization with the Δcrp mutant triggered both systematic and mucosal antibody responses and conferred 60 % protection against virulent P. multocida challenge in ducks. Conclusion The deletion of the crp gene has an inhibitory effect on bacterial growth and bacterial resistance to serum complement in vitro. The P. multocida crp mutant was attenuated and conferred moderate protection in ducks. This work affords a platform for analyzing the function of crp and aiding the formulation of a novel vaccine against P. multocida. Electronic supplementary material The online version of this article (doi:10.1186/s12866-016-0739-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xinxin Zhao
- Institute of Preventive Veterinary Medicine, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, 611130, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Wenjiang, Sichuan, 611130, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Wenjiang, Sichuan, 611130, China
| | - Qing Liu
- Department of Bioengineering, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Wenjiang, 611130, China.
| | - Kangpeng Xiao
- Institute of Preventive Veterinary Medicine, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, 611130, China
| | - Yunlong Hu
- Institute of Preventive Veterinary Medicine, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, 611130, China
| | - Xueyan Liu
- Institute of Preventive Veterinary Medicine, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, 611130, China
| | - Yanyan Li
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, 214122, China
| | - Qingke Kong
- Institute of Preventive Veterinary Medicine, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, 611130, China. .,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Wenjiang, Sichuan, 611130, China. .,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Wenjiang, Sichuan, 611130, China.
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Wassermann T, Meinike Jørgensen K, Ivanyshyn K, Bjarnsholt T, Khademi SMH, Jelsbak L, Høiby N, Ciofu O. The phenotypic evolution of Pseudomonas aeruginosa populations changes in the presence of subinhibitory concentrations of ciprofloxacin. MICROBIOLOGY-SGM 2016; 162:865-875. [PMID: 26953154 DOI: 10.1099/mic.0.000273] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Ciprofloxacin is a widely used antibiotic, in the class of quinolones, for treatment of Pseudomonas aeruginosa infections. The immediate response of P. aeruginosa to subinhibitory concentrations of ciprofloxacin has been investigated previously. However, the long-term phenotypic adaptation, which identifies the fitted phenotypes that have been selected during evolution with subinhibitory concentrations of ciprofloxacin, has not been studied. We chose an experimental evolution approach to investigate how exposure to subinhibitory concentrations of ciprofloxacin changes the evolution of P. aeruginosa populations compared to unexposed populations. Three replicate populations of P. aeruginosa PAO1 and its hypermutable mutant ΔmutS were cultured aerobically for approximately 940 generations by daily passages in LB medium with and without subinhibitory concentration of ciprofloxacin and aliquots of the bacterial populations were regularly sampled and kept at - 80 °C for further investigations. We investigate here phenotypic changes between the ancestor (50 colonies) and evolved populations (120 colonies/strain). Decreased protease activity and swimming motility, higher levels of quorum-sensing signal molecules and occurrence of mutator subpopulations were observed in the ciprofloxacin-exposed populations compared to the ancestor and control populations. Transcriptomic analysis showed downregulation of the type III secretion system in evolved populations compared to the ancestor population and upregulation of denitrification genes in ciprofloxacin-evolved populations. In conclusion, the presence of antibiotics at subinhibitory concentration in the environment affects bacterial evolution and further studies are needed to obtain insight into the dynamics of the phenotypes and the mechanisms involved.
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Affiliation(s)
- Tina Wassermann
- Department of Clinical Microbiology, University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Karin Meinike Jørgensen
- Department of Immunology and Microbiology, Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Karolina Ivanyshyn
- Department of Immunology and Microbiology, Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Bjarnsholt
- Department of Clinical Microbiology, University Hospital Rigshospitalet, Copenhagen, Denmark.,Department of Immunology and Microbiology, Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - S M Hossein Khademi
- Department of System Biology, Technical University of Denmark, Lyngby, Denmark
| | - Lars Jelsbak
- Department of System Biology, Technical University of Denmark, Lyngby, Denmark
| | - Niels Høiby
- Department of Clinical Microbiology, University Hospital Rigshospitalet, Copenhagen, Denmark.,Department of Immunology and Microbiology, Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Oana Ciofu
- Department of Immunology and Microbiology, Costerton Biofilm Center, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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39
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Winstanley C, O'Brien S, Brockhurst MA. Pseudomonas aeruginosa Evolutionary Adaptation and Diversification in Cystic Fibrosis Chronic Lung Infections. Trends Microbiol 2016; 24:327-337. [PMID: 26946977 PMCID: PMC4854172 DOI: 10.1016/j.tim.2016.01.008] [Citation(s) in RCA: 449] [Impact Index Per Article: 56.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 01/06/2016] [Accepted: 01/25/2016] [Indexed: 12/02/2022]
Abstract
Pseudomonas aeruginosa populations undergo a characteristic evolutionary adaptation during chronic infection of the cystic fibrosis (CF) lung, including reduced production of virulence factors, transition to a biofilm-associated lifestyle, and evolution of high-level antibiotic resistance. Populations of P. aeruginosa in chronic CF lung infections typically exhibit high phenotypic diversity, including for clinically important traits such as antibiotic resistance and toxin production, and this diversity is dynamic over time, making accurate diagnosis and treatment challenging. Population genomics studies reveal extensive genetic diversity within patients, including for transmissible strains the coexistence of highly divergent lineages acquired by patient-to-patient transmission. The inherent spatial structure and spatial heterogeneity of selection in the CF lung appears to play a key role in driving P. aeruginosa diversification. During chronic lung infections of CF patients common genetic adaptations occur in P. aeruginosa, such as conversion to mucoidy, loss of virulence factors, and resistance to antibiotics. Although pathoadaptive mutations in regulatory proteins are common, the actual regulators affected vary between populations. P. aeruginosa populations in CF lungs exhibit high levels of phenotypic diversity. Fine-scale population genomics approaches reveal that divergent sublineages can coexist, with evidence for regional isolation in the spatially structured and heterogeneous lung environment. Experimental evolution is beginning to provide insights into the selective drivers of evolution in P. aeruginosa infection, including the role of social interactions.
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Affiliation(s)
- Craig Winstanley
- Department of Clinical Infection, Microbiology and Immunology, Institute of Infection and Global Health, Ronald Ross Building, University of Liverpool, 8 West Derby Street, Liverpool, L69 7BE, UK.
| | - Siobhan O'Brien
- Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK
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Gibson AK, Stoy KS, Gelarden IA, Penley MJ, Lively CM, Morran LT. The evolution of reduced antagonism--A role for host-parasite coevolution. Evolution 2015; 69:2820-30. [PMID: 26420682 DOI: 10.1111/evo.12785] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 09/02/2015] [Accepted: 09/20/2015] [Indexed: 12/18/2022]
Abstract
Why do some host-parasite interactions become less antagonistic over evolutionary time? Vertical transmission can select for reduced antagonism. Vertical transmission also promotes coevolution between hosts and parasites. Therefore, we hypothesized that coevolution itself may underlie transitions to reduced antagonism. To test the coevolution hypothesis, we selected for reduced antagonism between the host Caenorhabditis elegans and its parasite Serratia marcescens. This parasite is horizontally transmitted, which allowed us to study coevolution independently of vertical transmission. After 20 generations, we observed a response to selection when coevolution was possible: reduced antagonism evolved in the copassaged treatment. Reduced antagonism, however, did not evolve when hosts or parasites were independently selected without coevolution. In addition, we found strong local adaptation for reduced antagonism between replicate host/parasite lines in the copassaged treatment. Taken together, these results strongly suggest that coevolution was critical to the rapid evolution of reduced antagonism.
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Affiliation(s)
- A K Gibson
- Department of Biology, Indiana University, Bloomington, Indiana, 47405.
| | - K S Stoy
- Department of Biology, Indiana University, Bloomington, Indiana, 47405
| | - I A Gelarden
- Department of Biology, Indiana University, Bloomington, Indiana, 47405
| | - M J Penley
- Department of Biology, Emory University, Atlanta, Georgia, 30322
| | - C M Lively
- Department of Biology, Indiana University, Bloomington, Indiana, 47405
| | - L T Morran
- Department of Biology, Indiana University, Bloomington, Indiana, 47405. .,Department of Biology, Emory University, Atlanta, Georgia, 30322.
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