1
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Pulkkinen K, Taskinen J. Nutrient enrichment increases virulence in an opportunistic environmental pathogen, with greater effect at low bacterial doses. FEMS Microbiol Ecol 2024; 100:fiae013. [PMID: 38305097 PMCID: PMC10959552 DOI: 10.1093/femsec/fiae013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 01/29/2024] [Accepted: 01/31/2024] [Indexed: 02/03/2024] Open
Abstract
Eutrophication of aquatic ecosystems is associated with an increased risk of pathogen infection via increased pathogen growth and host exposure via increased pathogen doses. Here, we studied the effect of nutrients on the virulence of an opportunistic bacterial pathogen of fish, Flavobacterium columnare, in challenge experiments with rainbow trout fingerlings. We hypothesized that removing all nutrients by washing the bacteria would reduce virulence as compared to unwashed bacteria, but adding nutrients to the tank water would increase the virulence of the bacterium. Nutrient addition and increase in bacterial dose increased virulence for both unwashed and washed bacteria. For unwashed bacteria, the addition of nutrients reduced the survival probability of fish challenged with low bacterial doses more than for fish challenged with higher bacterial doses, suggesting activation of bacterial virulence factors. Washing and centrifugation reduced viable bacterial counts, and the addition of washed bacteria alone did not lead to fish mortality. However, a small addition of nutrient medium, 0.05% of the total water volume, added separately to the fish container, restored the virulence of the washed bacteria. Our results show that human-induced eutrophication could trigger epidemics of aquatic pathogens at the limits of their survival and affect their ecology and evolution by altering the dynamics between strains that differ in their growth characteristics.
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Affiliation(s)
- Katja Pulkkinen
- Department of Biological and Environmental Science, P.O. Box 35 (Survontie 9), University of Jyväskylä, Jyväskylä, Finland
| | - Jouni Taskinen
- Department of Biological and Environmental Science, P.O. Box 35 (Survontie 9), University of Jyväskylä, Jyväskylä, Finland
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2
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Ketola T, Kronholm I. Experimental evolution of evolutionary potential in fluctuating environments. J Evol Biol 2023. [PMID: 37129538 DOI: 10.1111/jeb.14178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 02/02/2023] [Accepted: 03/22/2023] [Indexed: 05/03/2023]
Abstract
Variation is the raw material for evolution. Evolutionary potential is determined by the amount of genetic variation, but evolution can also alter the visibility of genetic variation to natural selection. Fluctuating environments are suggested to maintain genetic variation but they can also affect environmental variance, and thus, the visibility of genetic variation to natural selection. However, experimental studies testing these ideas are relatively scarce. In order to determine differences in evolutionary potential we quantified variance attributable to population, genotype and environment for populations of the bacterium Serratia marcescens. These populations had been experimentally evolved in constant and two fluctuating environments. We found that strains that evolved in fluctuating environments exhibited larger environmental variation suggesting that adaptation to fluctuations has decreased the visibility of genetic variation to selection.
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Affiliation(s)
- Tarmo Ketola
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - Ilkka Kronholm
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
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3
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Wang L, Zhan LJ, Wise MJ. Editorial: What does not kill you makes you stronger: Interactions between environmental stresses and microbial virulence. Front Microbiol 2023; 13:1127058. [PMID: 36699596 PMCID: PMC9869246 DOI: 10.3389/fmicb.2022.1127058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 12/28/2022] [Indexed: 01/12/2023] Open
Affiliation(s)
- Liang Wang
- Laboratory Medicine, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, Guangdong, China,Centre for Precision Health, School of Medical and Health Sciences, Edith Cowan University, Perth, WA, Australia,Liang Wang ✉
| | - Ling-Jun Zhan
- Beijing Key Laboratory for Animal Models of Emerging and Reemerging Infectious Diseases, Beijing, China,Institute of Laboratory Animal Sciences, Chinese Academy of Medical Sciences, Comparative Medicine Center, Peking Union Medical College, Beijing, China
| | - Michael J. Wise
- Department of Computer Science and Software Engineering, The University of Western Australia, Perth, WA, Australia,The Marshall Centre for Infectious Diseases Research and Training, The University of Western Australia, Perth, WA, Australia,*Correspondence: Michael J. Wise ✉
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4
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Mucin induces CRISPR-Cas defense in an opportunistic pathogen. Nat Commun 2022; 13:3653. [PMID: 35752617 PMCID: PMC9233685 DOI: 10.1038/s41467-022-31330-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 06/14/2022] [Indexed: 01/21/2023] Open
Abstract
Parasitism by bacteriophages has led to the evolution of a variety of defense mechanisms in their host bacteria. However, it is unclear what factors lead to specific defenses being deployed upon phage infection. To explore this question, we co-evolved the bacterial fish pathogen Flavobacterium columnare and its virulent phage V156 in presence and absence of a eukaryotic host signal (mucin) for sixteen weeks. The presence of mucin leads to a dramatic increase in CRISPR spacer acquisition, especially in low nutrient conditions where over 60% of colonies obtain at least one new spacer. Additionally, we show that the presence of a competitor bacterium further increases CRISPR spacer acquisition in F. columnare. These results suggest that ecological factors are important in determining defense strategies against phages, and that the phage-bacterium interactions on mucosal surfaces may select for the diversification of bacterial immune systems. It is unknown what circumstances promote particular bacterial defenses against bacterial viruses (phages). Almeida & Hoikkala et al. show that mucin, derived from mucus, greatly accelerates CRISPR-Cas defenses against phage in an opportunistic pathogen.
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5
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de Freitas Almeida GM, Hoikkala V, Ravantti J, Rantanen N, Sundberg LR. Mucin induces CRISPR-Cas defense in an opportunistic pathogen. Nat Commun 2022; 13:3653. [PMID: 35752617 DOI: 10.1101/2021.08.10.455787v1.abstract] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 06/14/2022] [Indexed: 05/27/2023] Open
Abstract
Parasitism by bacteriophages has led to the evolution of a variety of defense mechanisms in their host bacteria. However, it is unclear what factors lead to specific defenses being deployed upon phage infection. To explore this question, we co-evolved the bacterial fish pathogen Flavobacterium columnare and its virulent phage V156 in presence and absence of a eukaryotic host signal (mucin) for sixteen weeks. The presence of mucin leads to a dramatic increase in CRISPR spacer acquisition, especially in low nutrient conditions where over 60% of colonies obtain at least one new spacer. Additionally, we show that the presence of a competitor bacterium further increases CRISPR spacer acquisition in F. columnare. These results suggest that ecological factors are important in determining defense strategies against phages, and that the phage-bacterium interactions on mucosal surfaces may select for the diversification of bacterial immune systems.
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Affiliation(s)
- Gabriel Magno de Freitas Almeida
- University of Jyväskylä, Department of Biological and Environmental Science and Nanoscience Center, Jyväskylä, Finland
- Faculty of Biosciences, Fisheries and Economics, Norwegian College of Fishery Science, UiT The Arctic University of Norway, Tromsø, Norway
| | - Ville Hoikkala
- University of Jyväskylä, Department of Biological and Environmental Science and Nanoscience Center, Jyväskylä, Finland
| | - Janne Ravantti
- University of Helsinki, Molecular and Integrative Biosciences Research Programme, Helsinki, Finland
| | - Noora Rantanen
- University of Jyväskylä, Department of Biological and Environmental Science and Nanoscience Center, Jyväskylä, Finland
| | - Lotta-Riina Sundberg
- University of Jyväskylä, Department of Biological and Environmental Science and Nanoscience Center, Jyväskylä, Finland.
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6
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Survival Characteristics and Transcriptomic Analyses Reveal the Adaptive Response of the Aquatic Pathogen Non-O1/O139 Vibrio cholerae to Starvation Stress. Microbiol Spectr 2022; 10:e0193921. [PMID: 35532354 PMCID: PMC9241822 DOI: 10.1128/spectrum.01939-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Non-O1/O139 Vibrio cholerae is a pathogen of various aquatic organisms but requires major self-regulation to overcome environmental stress in the aquatic environment. However, its survival strategies under environmental stress are not well understood. The objective of this study was to describe the survival characteristics and changes in expression of stress resistance-related genes of non-O1/O139 V. cholerae after 6 months of starvation at room temperature. The results demonstrated that starved cells were still viable, exhibited shortened rods and shrinking surface, and maintained virulence to Macrobrachium rosenbergii. To investigate the changes in gene expression in non-O1/O139 V. cholerae under starvation stress, especially those involved in stress resistance, transcriptome profiles of starved and wild-type cells were determined. The differentially expressed genes (DEGs) in starved cells were identified, including 191 upregulated genes and 180 downregulated genes. Among these DEGs, the well-known stress resistance-related genes were upregulated significantly, including rpoS, rpoD, rpoN, rpoE, uspA, uspC, cspD, hslJ, etc. Gene Ontology (GO) analysis of the DEGs demonstrated that environmental adaptation-related categories, such as response to stimulus and signal transduction, were upregulated significantly in the starved cells, while cell motility was downregulated significantly. These DEGs were also enriched into 54 KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways, including biofilm formation, two-component system, quorum sensing, flagellar assembly, bacterial chemotaxis stress resistance-related pathways, etc. The potential existence of long-starved non-O1/O139 V. cholerae bacteria in the aquatic environment may raise new concerns about this devastating pathogen in aquaculture. IMPORTANCE Non-O1/O139 V. cholerae is a causal agent of vibriosis that can be subject to nutrient insufficiency and cause high rates of mortality in aquatic animals. However, its molecular mechanisms of survival in response to starvation stress have been investigated only partially. Here, we demonstrate that under starvation stress, non-O1/O139 V. cholerae can survive over the long term and cause disease by dwarfing of the cell structure, upregulation of a series of stress resistance-related genes, and downregulation of flagellum assembly-related genes. This knowledge can help the development of intervention strategies to control non-O1/O139 V. cholerae infection in aquaculture.
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Jiang Z, Zhuang Z, Mi K. Experimental Evolution Reveals Redox State Modulates Mycobacterial Pathogenicity. Front Genet 2022; 13:758304. [PMID: 35368697 PMCID: PMC8965865 DOI: 10.3389/fgene.2022.758304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 02/10/2022] [Indexed: 11/19/2022] Open
Abstract
Understanding how Mycobacterium tuberculosis has evolved into a professional pathogen is helpful in studying its pathogenesis and for designing vaccines. We investigated how the evolutionary adaptation of M. smegmatis mc251 to an important clinical stressor H2O2 allows bacteria to undergo coordinated genetic mutations, resulting in increased pathogenicity. Whole-genome sequencing identified a mutation site in the fur gene, which caused increased expression of katG. Using a Wayne dormancy model, mc251 showed a growth advantage over its parental strain mc2155 in recovering from dormancy under anaerobic conditions. Meanwhile, the high level of KatG in mc251 was accompanied by a low level of ATP, which meant that mc251 is at a low respiratory level. Additionally, the redox-related protein Rv1996 showed different phenotypes in different specific redox states in M. smegmatis mc2155 and mc251, M. bovis BCG, and M. tuberculosis mc27000. In conclusion, our study shows that the same gene presents different phenotypes under different physiological conditions. This may partly explain why M. smegmatis and M. tuberculosis have similar virulence factors and signaling transduction systems such as two-component systems and sigma factors, but due to the different redox states in the corresponding bacteria, M. smegmatis is a nonpathogen, while M. tuberculosis is a pathogen. As mc251 overcomes its shortcomings of rapid removal, it can potentially be developed as a vaccine vector.
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Affiliation(s)
- Zheng Jiang
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
| | - Zengfang Zhuang
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
| | - Kaixia Mi
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
- *Correspondence: Kaixia Mi,
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8
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Pulkkinen K, Ketola T, Laakso J, Mappes J, Sundberg L. Rich resource environment of fish farms facilitates phenotypic variation and virulence in an opportunistic fish pathogen. Evol Appl 2022; 15:417-428. [PMID: 35386393 PMCID: PMC8965373 DOI: 10.1111/eva.13355] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 01/27/2022] [Accepted: 02/01/2022] [Indexed: 12/05/2022] Open
Abstract
Phenotypic variation is suggested to facilitate the persistence of environmentally growing pathogens under environmental change. Here, we hypothesized that the intensive farming environment induces higher phenotypic variation in microbial pathogens than natural environment, because of high stochasticity for growth and stronger survival selection compared to the natural environment. We tested the hypothesis with an opportunistic fish pathogen Flavobacterium columnare isolated either from fish farms or from natural waters. We measured growth parameters of two morphotypes from all isolates in different resource concentrations and two temperatures relevant for the occurrence of disease epidemics at farms and tested their virulence using a zebrafish (Danio rerio) infection model. According to our hypothesis, isolates originating from the fish farms had higher phenotypic variation in growth between the morphotypes than the isolates from natural waters. The difference was more pronounced in higher resource concentrations and the higher temperature, suggesting that phenotypic variation is driven by the exploitation of increased outside‐host resources at farms. Phenotypic variation of virulence was not observed based on isolate origin but only based on morphotype. However, when in contact with the larger fish, the less virulent morphotype of some of the isolates also had high virulence. As the less virulent morphotype also had higher growth rate in outside‐host resources, the results suggest that both morphotypes can contribute to F. columnare epidemics at fish farms, especially with current prospects of warming temperatures. Our results suggest that higher phenotypic variation per se does not lead to higher virulence, but that environmental conditions at fish farms could select isolates with high phenotypic variation in bacterial population and hence affect evolution in F. columnare at fish farms. Our results highlight the multifaceted effects of human‐induced environmental alterations in shaping epidemiology and evolution in microbial pathogens.
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Affiliation(s)
- Katja Pulkkinen
- Department of Biological and Environmental Science University of Jyväskylä Finland
| | - Tarmo Ketola
- Department of Biological and Environmental Science University of Jyväskylä Finland
| | - Jouni Laakso
- Faculty of Biological and Environmental Sciences University of Helsinki Finland
| | - Johanna Mappes
- Department of Biological and Environmental Science University of Jyväskylä Finland
- Faculty of Biological and Environmental Sciences University of Helsinki Finland
| | - Lotta‐Riina Sundberg
- Department of Biological and Environmental Science University of Jyväskylä Finland
- Nanoscience Center University of Jyväskylä Finland
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9
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Pandey A, Mideo N, Platt TG. Virulence Evolution of Pathogens That Can Grow in Reservoir Environments. Am Nat 2022; 199:141-158. [DOI: 10.1086/717177] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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10
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Li F, Xiong XS, Yang YY, Wang JJ, Wang MM, Tang JW, Liu QH, Wang L, Gu B. Effects of NaCl Concentrations on Growth Patterns, Phenotypes Associated With Virulence, and Energy Metabolism in Escherichia coli BW25113. Front Microbiol 2021; 12:705326. [PMID: 34484145 PMCID: PMC8415458 DOI: 10.3389/fmicb.2021.705326] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 07/21/2021] [Indexed: 12/02/2022] Open
Abstract
According to the sit-and-wait hypothesis, long-term environmental survival is positively correlated with increased bacterial pathogenicity because high durability reduces the dependence of transmission on host mobility. Many indirectly transmitted bacterial pathogens, such as Mycobacterium tuberculosis and Burkhoderia pseudomallei, have high durability in the external environment and are highly virulent. It is possible that abiotic stresses may activate certain pathways or the expressions of certain genes, which might contribute to bacterial durability and virulence, synergistically. Therefore, exploring how bacterial phenotypes change in response to environmental stresses is important for understanding their potentials in host infections. In this study, we investigated the effects of different concentrations of salt (sodium chloride, NaCl), on survival ability, phenotypes associated with virulence, and energy metabolism of the lab strain Escherichia coli BW25113. In particular, we investigated how NaCl concentrations influenced growth patterns, biofilm formation, oxidative stress resistance, and motile ability. In terms of energy metabolism that is central to bacterial survival, glucose consumption, glycogen accumulation, and trehalose content were measured in order to understand their roles in dealing with the fluctuation of osmolarity. According to the results, trehalose is preferred than glycogen at high NaCl concentration. In order to dissect the molecular mechanisms of NaCl effects on trehalose metabolism, we further checked how the impairment of trehalose synthesis pathway (otsBA operon) via single-gene mutants influenced E. coli durability and virulence under salt stress. After that, we compared the transcriptomes of E. coli cultured at different NaCl concentrations, through which differentially expressed genes (DEGs) and differential pathways with statistical significance were identified, which provided molecular insights into E. coli responses to NaCl concentrations. In sum, this study explored the in vitro effects of NaCl concentrations on E. coli from a variety of aspects and aimed to facilitate our understanding of bacterial physiological changes under salt stress, which might help clarify the linkages between bacterial durability and virulence outside hosts under environmental stresses.
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Affiliation(s)
- Fen Li
- Medical Technology School of Xuzhou Medical University, Xuzhou, China
| | - Xue-Song Xiong
- Medical Technology School of Xuzhou Medical University, Xuzhou, China
| | - Ying-Ying Yang
- School of Life Sciences, Xuzhou Medical University, Xuzhou, China
| | - Jun-Jiao Wang
- Department of Bioinformatics, School of Medical Informatics and Engineering, Xuzhou Medical University, Xuzhou, China
| | - Meng-Meng Wang
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, Xuzhou, China.,Department of Pharmaceutical Analysis, School of Pharmacy, Xuzhou Medical University, Xuzhou, China
| | - Jia-Wei Tang
- Department of Bioinformatics, School of Medical Informatics and Engineering, Xuzhou Medical University, Xuzhou, China
| | - Qing-Hua Liu
- State Key Laboratory of Quality Research in Chinese Medicines, Macau University of Science and Technology, Taipa, China
| | - Liang Wang
- Department of Bioinformatics, School of Medical Informatics and Engineering, Xuzhou Medical University, Xuzhou, China.,Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Bing Gu
- Medical Technology School of Xuzhou Medical University, Xuzhou, China.,Laboratory Medicine, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
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11
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Turner WC, Kamath PL, van Heerden H, Huang YH, Barandongo ZR, Bruce SA, Kausrud K. The roles of environmental variation and parasite survival in virulence-transmission relationships. ROYAL SOCIETY OPEN SCIENCE 2021; 8:210088. [PMID: 34109041 PMCID: PMC8170194 DOI: 10.1098/rsos.210088] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Disease outbreaks are a consequence of interactions among the three components of a host-parasite system: the infectious agent, the host and the environment. While virulence and transmission are widely investigated, most studies of parasite life-history trade-offs are conducted with theoretical models or tractable experimental systems where transmission is standardized and the environment controlled. Yet, biotic and abiotic environmental factors can strongly affect disease dynamics, and ultimately, host-parasite coevolution. Here, we review research on how environmental context alters virulence-transmission relationships, focusing on the off-host portion of the parasite life cycle, and how variation in parasite survival affects the evolution of virulence and transmission. We review three inter-related 'approaches' that have dominated the study of the evolution of virulence and transmission for different host-parasite systems: (i) evolutionary trade-off theory, (ii) parasite local adaptation and (iii) parasite phylodynamics. These approaches consider the role of the environment in virulence and transmission evolution from different angles, which entail different advantages and potential biases. We suggest improvements to how to investigate virulence-transmission relationships, through conceptual and methodological developments and taking environmental context into consideration. By combining developments in life-history evolution, phylogenetics, adaptive dynamics and comparative genomics, we can improve our understanding of virulence-transmission relationships across a diversity of host-parasite systems that have eluded experimental study of parasite life history.
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Affiliation(s)
- Wendy C. Turner
- US Geological Survey, Wisconsin Cooperative Wildlife Research Unit, Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Pauline L. Kamath
- School of Food and Agriculture, University of Maine, Orono, ME 04469, USA
| | - Henriette van Heerden
- Faculty of Veterinary Science, Department of Veterinary Tropical Diseases, University of Pretoria, Onderstepoort, South Africa
| | - Yen-Hua Huang
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Zoe R. Barandongo
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Spencer A. Bruce
- Department of Biological Sciences, University at Albany, State University of New York, Albany, NY 12222, USA
| | - Kyrre Kausrud
- Section for Epidemiology, Norwegian Veterinary Institute, Ullevålsveien 68, 0454 Oslo, Norway
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12
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Donati VL, Dalsgaard I, Runtuvuori-Salmela A, Kunttu H, Jørgensen J, Castillo D, Sundberg LR, Middelboe M, Madsen L. Interactions between Rainbow Trout Eyed Eggs and Flavobacterium spp. Using a Bath Challenge Model: Preliminary Evaluation of Bacteriophages as Pathogen Control Agents. Microorganisms 2021; 9:971. [PMID: 33946270 PMCID: PMC8146780 DOI: 10.3390/microorganisms9050971] [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: 02/27/2021] [Revised: 04/10/2021] [Accepted: 04/14/2021] [Indexed: 11/17/2022] Open
Abstract
The microbial community surrounding fish eyed eggs can harbor pathogenic bacteria. In this study we focused on rainbow trout (Oncorhynchus mykiss) eyed eggs and the potential of bacteriophages against the pathogenic bacteria Flavobacterium psychrophilum and F. columnare. An infection bath method was first established, and the effects of singular phages on fish eggs was assessed (survival of eyed eggs, interaction of phages with eyed eggs). Subsequently, bacteria-challenged eyed eggs were exposed to phages to evaluate their effects in controlling the bacterial population. Culture-based methods were used to enumerate the number of bacteria and/or phages associated with eyed eggs and in the surrounding environment. The results of the study showed that, with our infection model, it was possible to re-isolate F. psychrophilum associated with eyed eggs after the infection procedure, without affecting the survival of the eggs in the short term. However, this was not possible for F. columnare, as this bacterium grows at higher temperatures than the ones recommended for incubation of rainbow trout eyed eggs. Bacteriophages do not appear to negatively affect the survival of rainbow trout eyed eggs and they do not seem to strongly adhere to the surface of eyed eggs either. Finally, the results demonstrated a strong potential for short term (24 h) phage control of F. psychrophilum. However, further studies are needed to explore if phage control can be maintained for a longer period and to further elucidate the mechanisms of interactions between Flavobacteria and their phages in association with fish eggs.
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Affiliation(s)
- Valentina L. Donati
- Unit for Fish and Shellfish Diseases, National Institute of Aquatic Resources, Technical University of Denmark, 2800 Kongens Lyngby, Denmark; (I.D.); (L.M.)
| | - Inger Dalsgaard
- Unit for Fish and Shellfish Diseases, National Institute of Aquatic Resources, Technical University of Denmark, 2800 Kongens Lyngby, Denmark; (I.D.); (L.M.)
| | - Anniina Runtuvuori-Salmela
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä, Finland; (A.R.-S.); (H.K.); (L.-R.S.)
| | - Heidi Kunttu
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä, Finland; (A.R.-S.); (H.K.); (L.-R.S.)
| | - Johanna Jørgensen
- Marine Biological Section, Department of Biology, University of Copenhagen, 3000 Helsingør, Denmark; (J.J.); (D.C.); (M.M.)
| | - Daniel Castillo
- Marine Biological Section, Department of Biology, University of Copenhagen, 3000 Helsingør, Denmark; (J.J.); (D.C.); (M.M.)
| | - Lotta-Riina Sundberg
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä, Finland; (A.R.-S.); (H.K.); (L.-R.S.)
| | - Mathias Middelboe
- Marine Biological Section, Department of Biology, University of Copenhagen, 3000 Helsingør, Denmark; (J.J.); (D.C.); (M.M.)
| | - Lone Madsen
- Unit for Fish and Shellfish Diseases, National Institute of Aquatic Resources, Technical University of Denmark, 2800 Kongens Lyngby, Denmark; (I.D.); (L.M.)
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13
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Laanto E, Mäkelä K, Hoikkala V, Ravantti JJ, Sundberg LR. Adapting a Phage to Combat Phage Resistance. Antibiotics (Basel) 2020; 9:E291. [PMID: 32486059 PMCID: PMC7345892 DOI: 10.3390/antibiotics9060291] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 05/27/2020] [Accepted: 05/27/2020] [Indexed: 01/24/2023] Open
Abstract
Phage therapy is becoming a widely recognized alternative for fighting pathogenic bacteria due to increasing antibiotic resistance problems. However, one of the common concerns related to the use of phages is the evolution of bacterial resistance against the phages, putatively disabling the treatment. Experimental adaptation of the phage (phage training) to infect a resistant host has been used to combat this problem. Yet, there is very little information on the trade-offs of phage infectivity and host range. Here we co-cultured a myophage FCV-1 with its host, the fish pathogen Flavobacterium columnare, in lake water and monitored the interaction for a one-month period. Phage resistance was detected within one day of co-culture in the majority of the bacterial isolates (16 out of the 18 co-evolved clones). The primary phage resistance mechanism suggests defense via surface modifications, as the phage numbers rose in the first two days of the experiment and remained stable thereafter. However, one bacterial isolate had acquired a spacer in its CRISPR (Clustered Regularly Interspaced Short Palindromic Repeat)-Cas locus, indicating that also CRISPR-Cas defense was employed in the phage-host interactions. After a week of co-culture, a phage isolate was obtained that was able to infect 18 out of the 32 otherwise resistant clones isolated during the experiment. Phage genome sequencing revealed several mutations in two open reading frames (ORFs) likely to be involved in the regained infectivity of the evolved phage. Their location in the genome suggests that they encode tail genes. Characterization of this evolved phage, however, showed a direct cost for the ability to infect several otherwise resistant clones-adsorption was significantly lower than in the ancestral phage. This work describes a method for adapting the phage to overcome phage resistance in a fish pathogenic system.
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Affiliation(s)
- Elina Laanto
- Faculty of Biological and Environmental Sciences, Molecular and Integrative Biosciences Research Programme, University of Helsinki, 00014 Helsinki, Finland;
- Department of Biological and Environmental Science, Nanoscience Center, University of Jyvaskyla, 40014 Jyvaskyla, Finland; (K.M.); (V.H.); (L.R.S.)
| | - Kati Mäkelä
- Department of Biological and Environmental Science, Nanoscience Center, University of Jyvaskyla, 40014 Jyvaskyla, Finland; (K.M.); (V.H.); (L.R.S.)
| | - Ville Hoikkala
- Department of Biological and Environmental Science, Nanoscience Center, University of Jyvaskyla, 40014 Jyvaskyla, Finland; (K.M.); (V.H.); (L.R.S.)
| | - Janne J. Ravantti
- Faculty of Biological and Environmental Sciences, Molecular and Integrative Biosciences Research Programme, University of Helsinki, 00014 Helsinki, Finland;
| | - Lotta-Riina Sundberg
- Department of Biological and Environmental Science, Nanoscience Center, University of Jyvaskyla, 40014 Jyvaskyla, Finland; (K.M.); (V.H.); (L.R.S.)
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14
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Pulkkinen K, Pekkala N, Ashrafi R, Hämäläinen DM, Nkembeng AN, Lipponen A, Hiltunen T, Valkonen JK, Taskinen J. Effect of resource availability on evolution of virulence and competition in an environmentally transmitted pathogen. FEMS Microbiol Ecol 2019; 94:4962392. [PMID: 29659817 DOI: 10.1093/femsec/fiy060] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 04/04/2018] [Indexed: 01/21/2023] Open
Abstract
Understanding ecological and epidemiological factors driving pathogen evolution in contemporary time scales is a major challenge in modern health management. Pathogens that replicate outside the hosts are subject to selection imposed by ambient environmental conditions. Increased nutrient levels could increase pathogen virulence by pre-adapting for efficient use of resources upon contact to a nutrient rich host or by favouring transmission of fast-growing virulent strains. We measured changes in virulence and competition in Flavobacterium columnare, a bacterial pathogen of freshwater fish, under high and low nutrient levels. To test competition between strains in genotype mixtures, we developed a quantitative real-time PCR assay. We found that a virulent strain maintained its virulence and outcompeted less virulent strains independent of the nutrient level and resource renewal rate while a less virulent strain further lost virulence in chemostats under low nutrient level and over long-term serial culture under high nutrient level. Our results suggest that increased outside-host nutrient levels might maintain virulence in less virulent strains and increase their contribution to epidemics in aquaculture. The results highlight a need to further explore the role of resource in the outside-host environment in maintaining strain diversity and driving evolution of virulence among environmentally growing pathogens.
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Affiliation(s)
- Katja Pulkkinen
- Department of Biological and Environmental Science, P. O. Box 35, (Survontie 9), University of Jyväskylä, Jyväskylä, Finland
| | - Nina Pekkala
- Department of Biological and Environmental Science, P. O. Box 35, (Survontie 9), University of Jyväskylä, Jyväskylä, Finland
| | - Roghaieh Ashrafi
- Department of Biological and Environmental Science, P. O. Box 35, (Survontie 9), University of Jyväskylä, Jyväskylä, Finland.,Centre of Excellence in Biological Interactions, P. O. Box 35, (Survontie 9), University of Jyväskylä, Jyväskylä,Finland
| | - Dorrit M Hämäläinen
- Department of Biological and Environmental Science, P. O. Box 35, (Survontie 9), University of Jyväskylä, Jyväskylä, Finland
| | - Aloysius N Nkembeng
- Department of Biological and Environmental Science, P. O. Box 35, (Survontie 9), University of Jyväskylä, Jyväskylä, Finland
| | - Anssi Lipponen
- A. I. Virtanen Institute for Molecular Sciences, P. O. Box 1627, (Neulaniementie 2), University of Eastern Finland, Kuopio, Finland
| | - Teppo Hiltunen
- Department of Microbiology, P. O. Box 56, (Viikinkaari 9), University of Helsinki, Helsinki, Finland
| | - Janne K Valkonen
- Department of Biological and Environmental Science, P. O. Box 35, (Survontie 9), University of Jyväskylä, Jyväskylä, Finland.,Centre of Excellence in Biological Interactions, P. O. Box 35, (Survontie 9), University of Jyväskylä, Jyväskylä,Finland
| | - Jouni Taskinen
- Department of Biological and Environmental Science, P. O. Box 35, (Survontie 9), University of Jyväskylä, Jyväskylä, Finland
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15
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Ashrafi R, Bruneaux M, Sundberg L, Pulkkinen K, Valkonen J, Ketola T. Broad thermal tolerance is negatively correlated with virulence in an opportunistic bacterial pathogen. Evol Appl 2018; 11:1700-1714. [PMID: 30344637 PMCID: PMC6183471 DOI: 10.1111/eva.12673] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 05/31/2018] [Accepted: 06/22/2018] [Indexed: 01/10/2023] Open
Abstract
Predicting the effects of global increase in temperatures on disease virulence is challenging, especially for environmental opportunistic bacteria, because pathogen fitness may be differentially affected by temperature within and outside host environment. So far, there is very little empirical evidence on the connections between optimal temperature range and virulence in environmentally growing pathogens. Here, we explored whether the virulence of an environmentally growing opportunistic fish pathogen, Flavobacterium columnare, is malleable to evolutionary changes via correlated selection on thermal tolerance. To this end, we experimentally quantified the thermal performance curves (TPCs) for maximum biomass yield of 49 F. columnare isolates from eight different geographic locations in Finland over ten years (2003-2012). We also characterized virulence profiles of these strains in a zebra fish (Danio rerio) infection model. We show that virulence among the strains increased over the years, but thermal generalism, and in particular tolerance to higher temperatures, was negatively associated with virulence. Our data suggest that temperature has a strong effect on the pathogen genetic diversity and therefore presumably also on disease dynamics. However, the observed increase in frequency and severity of F. columnare epidemics over the last decade cannot be directly linked to bacterial evolution due to increased mean temperature, but is most likely associated with factors related to increased length of growing season, or other time-dependent change in environment. Our study demonstrates that complex interactions between the host, the pathogen and the environment influence disease virulence of an environmentally growing opportunistic pathogen.
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Affiliation(s)
- Roghaieh Ashrafi
- Department of Biological and Environmental Science (and Nanoscience Center)Centre of Excellence in Biological InteractionsUniversity of JyväskyläJyväskyläFinland
| | - Matthieu Bruneaux
- Department of Biological and Environmental Science (and Nanoscience Center)Centre of Excellence in Biological InteractionsUniversity of JyväskyläJyväskyläFinland
| | - Lotta‐Riina Sundberg
- Department of Biological and Environmental Science (and Nanoscience Center)Centre of Excellence in Biological InteractionsUniversity of JyväskyläJyväskyläFinland
| | - Katja Pulkkinen
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
| | - Janne Valkonen
- Department of Biological and Environmental Science (and Nanoscience Center)Centre of Excellence in Biological InteractionsUniversity of JyväskyläJyväskyläFinland
| | - Tarmo Ketola
- Department of Biological and Environmental Science (and Nanoscience Center)Centre of Excellence in Biological InteractionsUniversity of JyväskyläJyväskyläFinland
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16
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Ben Hamed S, Tavares Ranzani-Paiva MJ, Tachibana L, de Carla Dias D, Ishikawa CM, Esteban MA. Fish pathogen bacteria: Adhesion, parameters influencing virulence and interaction with host cells. FISH & SHELLFISH IMMUNOLOGY 2018; 80:550-562. [PMID: 29966687 DOI: 10.1016/j.fsi.2018.06.053] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 06/04/2018] [Accepted: 06/29/2018] [Indexed: 06/08/2023]
Abstract
Wild fisheries are declining due to over-fishing, climate change, pollution and marine habitat destructions among other factors, and, concomitantly, aquaculture is increasing significantly around the world. Fish infections caused by pathogenic bacteria are quite common in aquaculture, although their seriousness depends on the season. Drug-supplemented feeds are often used to keep farmed fish free from the diseases caused by such bacteria. However, given that bacteria can survive well in aquatic environments independently of their hosts, bacterial diseases have become major impediments to aquaculture development. On the other hand, the indiscriminate uses of antimicrobial agents has led to resistant strains and the need to switch to other antibiotics, although it seems that an integrated approach that considers not only the pathogen but also the host and the environment will be the most effective method in the long-term to improve aquatic animal health. This review covers the mechanisms of bacterial pathogenicity and details the foundations underlying the interactions occurring between pathogenic bacteria and the fish host in the aquatic environment, as well as the factors that influence virulence. Understanding and linking the different phenomena that occur from adhesion to colonization of the host will offer novel and useful means to help design suitable therapeutic strategies for disease prevention and treatment.
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Affiliation(s)
- Said Ben Hamed
- Fishery Institute-APTA - SAA, Research Center of Aquaculture, Av. Francisco Matarazzo, 455, CEP. 05001-900, Sao Paulo, SP, Brazil
| | - Maria José Tavares Ranzani-Paiva
- Fishery Institute-APTA - SAA, Research Center of Aquaculture, Av. Francisco Matarazzo, 455, CEP. 05001-900, Sao Paulo, SP, Brazil
| | - Leonardo Tachibana
- Fishery Institute-APTA - SAA, Research Center of Aquaculture, Av. Francisco Matarazzo, 455, CEP. 05001-900, Sao Paulo, SP, Brazil
| | - Danielle de Carla Dias
- Fishery Institute-APTA - SAA, Research Center of Aquaculture, Av. Francisco Matarazzo, 455, CEP. 05001-900, Sao Paulo, SP, Brazil
| | - Carlos Massatoshi Ishikawa
- Fishery Institute-APTA - SAA, Research Center of Aquaculture, Av. Francisco Matarazzo, 455, CEP. 05001-900, Sao Paulo, SP, Brazil
| | - María Angeles Esteban
- Fish Innate Immune System Group, Department of Cell Biology & Histology, Faculty of Biology, Regional Campus of International Excellence, ''Campus Mare Nostrum'', University of Murcia, 30100, Murcia, Spain.
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17
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Wang L, Liu Z, Dai S, Yan J, Wise MJ. The Sit-and-Wait Hypothesis in Bacterial Pathogens: A Theoretical Study of Durability and Virulence. Front Microbiol 2017; 8:2167. [PMID: 29209284 PMCID: PMC5701638 DOI: 10.3389/fmicb.2017.02167] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Accepted: 10/23/2017] [Indexed: 12/20/2022] Open
Abstract
The intriguing sit-and-wait hypothesis predicts that bacterial durability in the external environment is positively correlated with their virulence. Since its first proposal in 1987, the hypothesis has been spurring debates in terms of its validity in the field of bacterial virulence. As a special case of the vector-borne transmission versus virulence tradeoff, where vector is now replaced by environmental longevity, there are only sporadic studies over the last three decades showing that environmental durability is possibly linked with virulence. However, no systematic study of these works is currently available and epidemiological analysis has not been updated for the sit-and-wait hypothesis since the publication of Walther and Ewald's (2004) review. In this article, we put experimental evidence, epidemiological data and theoretical analysis together to support the sit-and-wait hypothesis. According to the epidemiological data in terms of gain and loss of virulence (+/-) and durability (+/-) phenotypes, we classify bacteria into four groups, which are: sit-and-wait pathogens (++), vector-borne pathogens (+-), obligate-intracellular bacteria (--), and free-living bacteria (-+). After that, we dive into the abundant bacterial proteomic data with the assistance of bioinformatics techniques in order to investigate the two factors at molecular level thanks to the fast development of high-throughput sequencing technology. Sequences of durability-related genes sourced from Gene Ontology and UniProt databases and virulence factors collected from Virulence Factor Database are used to search 20 corresponding bacterial proteomes in batch mode for homologous sequences via the HMMER software package. Statistical analysis only identified a modest, and not statistically significant correlation between mortality and survival time for eight non-vector-borne bacteria with sit-and-wait potentials. Meanwhile, through between-group comparisons, bacteria with higher host-mortality are significantly more durable in the external environment. The results of bioinformatics analysis correspond well with epidemiological data, that is, non-vector-borne pathogens with sit-and-wait potentials have higher number of virulence and durability genes compared with other bacterial groups. However, the conclusions are constrained by the relatively small bacterial sample size and non-standardized experimental data.
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Affiliation(s)
- Liang Wang
- School of Medical Informatics, Xuzhou Medical University, Xuzhou, China
| | - Zhanzhong Liu
- Department of Clinical Pharmacology, Xuzhou Infectious Diseases Hospital, Xuzhou, China
| | - Shiyun Dai
- School of Anaesthesia, Xuzhou Medical University, Xuzhou, China
| | - Jiawei Yan
- Clinical Laboratory of Tuberculosis, Xuzhou Infectious Diseases Hospital, Xuzhou, China
| | - Michael J. Wise
- School of Computer Science and Software Engineering, University of Western Australia, Perth, WA, Australia
- The Marshall Centre for Infectious Diseases Research and Training, University of Western Australia, Perth, WA, Australia
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18
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Ketola T, Mikonranta L, Laakso J, Mappes J. Different food sources elicit fast changes to bacterial virulence. Biol Lett 2017; 12:20150660. [PMID: 26763215 DOI: 10.1098/rsbl.2015.0660] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Environmentally transmitted, opportunistic bacterial pathogens have a life cycle that alternates between hosts and environmental reservoirs. Resources are often scarce and fluctuating in the outside-host environment, whereas overcoming the host immune system could allow pathogens to establish a new, resource abundant and stable niche within the host. We tested if short-term exposure to different outside-host resource types and concentrations affect Serratia marcescens-(bacterium)'s virulence in Galleria mellonella (moth). As expected, virulence was mostly dictated by the bacterial dose, but we also found a clear increase in virulence when the bacterium had inhabited a low (versus high) resource concentration, or animal-based (versus plant-based) resources for 48 h prior to injection. The results suggest that temporal changes in pathogen's resource environment can induce very rapid changes in virulence and affect infection severity. Such changes could also play an important role in shifts from environmental lifestyle to pathogenicity or switches in host range and have implications for the management of opportunistic pathogens and disease outbreaks.
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Affiliation(s)
- T Ketola
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, Jyväskylä 40014, Finland
| | - L Mikonranta
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, Jyväskylä 40014, Finland
| | - J Laakso
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, Jyväskylä 40014, Finland Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science, University of Helsinki, PO Box 65, Helsinki 00014, Finland
| | - J Mappes
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, Jyväskylä 40014, Finland
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19
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Sundberg LR, Ketola T, Laanto E, Kinnula H, Bamford JKH, Penttinen R, Mappes J. Intensive aquaculture selects for increased virulence and interference competition in bacteria. Proc Biol Sci 2016; 283:20153069. [PMID: 26936249 DOI: 10.1098/rspb.2015.3069] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Although increased disease severity driven by intensive farming practices is problematic in food production, the role of evolutionary change in disease is not well understood in these environments. Experiments on parasite evolution are traditionally conducted using laboratory models, often unrelated to economically important systems. We compared how the virulence, growth and competitive ability of a globally important fish pathogen, Flavobacterium columnare, change under intensive aquaculture. We characterized bacterial isolates from disease outbreaks at fish farms during 2003-2010, and compared F. columnare populations in inlet water and outlet water of a fish farm during the 2010 outbreak. Our data suggest that the farming environment may select for bacterial strains that have high virulence at both long and short time scales, and it seems that these strains have also evolved increased ability for interference competition. Our results are consistent with the suggestion that selection pressures at fish farms can cause rapid changes in pathogen populations, which are likely to have long-lasting evolutionary effects on pathogen virulence. A better understanding of these evolutionary effects will be vital in prevention and control of disease outbreaks to secure food production.
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Affiliation(s)
- Lotta-Riina Sundberg
- University of Jyvaskyla, Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science (and Nanoscience Centre), PO Box 35, Jyvaskyla 40014, Finland
| | - Tarmo Ketola
- University of Jyvaskyla, Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science (and Nanoscience Centre), PO Box 35, Jyvaskyla 40014, Finland
| | - Elina Laanto
- University of Jyvaskyla, Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science (and Nanoscience Centre), PO Box 35, Jyvaskyla 40014, Finland
| | - Hanna Kinnula
- University of Jyvaskyla, Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science (and Nanoscience Centre), PO Box 35, Jyvaskyla 40014, Finland
| | - Jaana K H Bamford
- University of Jyvaskyla, Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science (and Nanoscience Centre), PO Box 35, Jyvaskyla 40014, Finland
| | - Reetta Penttinen
- University of Jyvaskyla, Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science (and Nanoscience Centre), PO Box 35, Jyvaskyla 40014, Finland
| | - Johanna Mappes
- University of Jyvaskyla, Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science (and Nanoscience Centre), PO Box 35, Jyvaskyla 40014, Finland
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20
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Penttinen R, Kinnula H, Lipponen A, Bamford JKH, Sundberg LR. High Nutrient Concentration Can Induce Virulence Factor Expression and Cause Higher Virulence in an Environmentally Transmitted Pathogen. MICROBIAL ECOLOGY 2016; 72:955-964. [PMID: 27193154 DOI: 10.1007/s00248-016-0781-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 05/04/2016] [Indexed: 05/13/2023]
Abstract
Environmentally transmitted opportunistic pathogens shuttle between two substantially different environments: outside-host and within-host habitats. These environments differ from each other especially with respect to nutrient availability. Consequently, the pathogens are required to regulate their behavior in response to environmental cues in order to survive, but how nutrients control the virulence in opportunistic pathogens is still poorly understood. In this study, we examined how nutrient level in the outside-host environment affects the gene expression of putative virulence factors of the opportunistic fish pathogen Flavobacterium columnare. The impact of environmental nutrient concentration on bacterial virulence was explored by cultivating the bacteria in various nutrient conditions, measuring the gene expression of putative virulence factors with RT-qPCR and, finally, experimentally challenging rainbow trout (Oncorhynchus mykiss) fry with these bacteria. Our results show that increased environmental nutrient concentration can increase the expression of putative virulence genes, chondroitinase (cslA) and collagenase, in the outside-host environment and may lead to more rapid fish mortality. These findings address that the environmental nutrients may act as significant triggers of virulence gene expression and therefore contribute to the interaction between an environmentally transmitted opportunistic pathogen and its host.
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Affiliation(s)
- Reetta Penttinen
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, Center of Excellence in Biological Interactions, P.O. Box 35, FI-40014, University of Jyvaskyla, Jyvaskyla, Finland.
| | - Hanna Kinnula
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, Center of Excellence in Biological Interactions, P.O. Box 35, FI-40014, University of Jyvaskyla, Jyvaskyla, Finland
| | - Anssi Lipponen
- University of Eastern Finland, A.I. Virtanen Institute for Molecular Sciences, P.O. Box 1627, FI-70211, Kuopio, Finland
| | - Jaana K H Bamford
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, Center of Excellence in Biological Interactions, P.O. Box 35, FI-40014, University of Jyvaskyla, Jyvaskyla, Finland
| | - Lotta-Riina Sundberg
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, Center of Excellence in Biological Interactions, P.O. Box 35, FI-40014, University of Jyvaskyla, Jyvaskyla, Finland
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21
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Louhi KR, Sundberg LR, Jokela J, Karvonen A. Interactions among bacterial strains and fluke genotypes shape virulence of co-infection. Proc Biol Sci 2015; 282:20152097. [PMID: 26674949 PMCID: PMC4707758 DOI: 10.1098/rspb.2015.2097] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 11/11/2015] [Indexed: 12/15/2022] Open
Abstract
Most studies of virulence of infection focus on pairwise host-parasite interactions. However, hosts are almost universally co-infected by several parasite strains and/or genotypes of the same or different species. While theory predicts that co-infection favours more virulent parasite genotypes through intensified competition for host resources, knowledge of the effects of genotype by genotype (G × G) interactions between unrelated parasite species on virulence of co-infection is limited. Here, we tested such a relationship by challenging rainbow trout with replicated bacterial strains and fluke genotypes both singly and in all possible pairwise combinations. We found that virulence (host mortality) was higher in co-infections compared with single infections. Importantly, we also found that the overall virulence was dependent on the genetic identity of the co-infecting partners so that the outcome of co-infection could not be predicted from the respective virulence of single infections. Our results imply that G × G interactions among co-infecting parasites may significantly affect host health, add to variance in parasite fitness and thus influence evolutionary dynamics and ecology of disease in unexpected ways.
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Affiliation(s)
- Katja-Riikka Louhi
- Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, 40014, Jyväskylä, Finland
| | - Lotta-Riina Sundberg
- Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, 40014, Jyväskylä, Finland Centre of Excellence in Biological Interactions, University of Jyväskylä, PO Box 35, 40014, Jyväskylä, Finland
| | - Jukka Jokela
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland ETH Zürich, Institute of Integrative Biology, 8092 Zürich, Switzerland
| | - Anssi Karvonen
- Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, 40014, Jyväskylä, Finland
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22
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Kinnula H, Mappes J, Valkonen JK, Sundberg LR. The Influence of Infective Dose on the Virulence of a Generalist Pathogen in Rainbow Trout (Oncorhynchus mykiss) and Zebra Fish (Danio rerio). PLoS One 2015; 10:e0139378. [PMID: 26421435 PMCID: PMC4589314 DOI: 10.1371/journal.pone.0139378] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 09/11/2015] [Indexed: 12/24/2022] Open
Abstract
Pathogen density and genetic diversity fluctuate in the outside-host environment during and between epidemics, affecting disease emergence and the severity and probability of infections. Although the importance of these factors for pathogen virulence and infection probability has been acknowledged, their interactive effects are not well understood. We studied how an infective dose in an environmentally transmitted opportunistic fish pathogen, Flavobacterium columnare, affects its virulence both in rainbow trout, which are frequently infected at fish farms, and in zebra fish, a host that is not naturally infected by F. columnare. We used previously isolated strains of confirmed high and low virulence in a single infection and in a co-infection. Infection success (measured as host morbidity) correlated positively with dose when the hosts were exposed to the high-virulence strain, but no response for the dose increase was found when the hosts were exposed to the low-virulence strain. Interestingly, the co-infection resulted in poorer infection success than the single infection with the high-virulence strain. The rainbow trout were more susceptible to the infection than the zebra fish but, in both species, the effects of the doses and the strains were qualitatively similar. We suggest that as an increase in dose can lead to increased host morbidity, both the interstrain interactions and differences in infectivity in different hosts may influence the severity and consequently the evolution of disease. Our results also confirm that the zebra fish is a good laboratory model to study F. columnare infection.
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Affiliation(s)
- Hanna Kinnula
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science, University of Jyvaskyla, Finland
- * E-mail:
| | - Johanna Mappes
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science, University of Jyvaskyla, Finland
| | - Janne K. Valkonen
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science, University of Jyvaskyla, Finland
| | - Lotta-Riina Sundberg
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science, University of Jyvaskyla, Finland
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23
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Abstract
Why is it that some parasites cause high levels of host damage (i.e. virulence) whereas others are relatively benign? There are now numerous reviews of virulence evolution in the literature but it is nevertheless still difficult to find a comprehensive treatment of the theory and data on the subject that is easily accessible to non-specialists. Here we attempt to do so by distilling the vast theoretical literature on the topic into a set of relatively few robust predictions. We then provide a comprehensive assessment of the available empirical literature that tests these predictions. Our results show that there have been some notable successes in integrating theory and data but also that theory and empiricism in this field do not ‘speak’ to each other very well. We offer a few suggestions for how the connection between the two might be improved.
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24
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Endosymbionts escape dead hydrothermal vent tubeworms to enrich the free-living population. Proc Natl Acad Sci U S A 2015; 112:11300-5. [PMID: 26283348 DOI: 10.1073/pnas.1501160112] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Theory predicts that horizontal acquisition of symbionts by plants and animals must be coupled to release and limited dispersal of symbionts for intergenerational persistence of mutualisms. For deep-sea hydrothermal vent tubeworms (Vestimentifera, Siboglinidae), it has been demonstrated that a few symbiotic bacteria infect aposymbiotic host larvae and grow in a newly formed organ, the trophosome. However, whether viable symbionts can be released to augment environmental populations has been doubtful, because (i) the adult worms lack obvious openings and (ii) the vast majority of symbionts has been regarded as terminally differentiated. Here we show experimentally that symbionts rapidly escape their hosts upon death and recruit to surfaces where they proliferate. Estimating symbiont release from our experiments taken together with well-known tubeworm density ranges, we suggest a few million to 1.5 billion symbionts seeding the environment upon death of a tubeworm clump. In situ observations show that such clumps have rapid turnover, suggesting that release of large numbers of symbionts may ensure effective dispersal to new sites followed by active larval colonization. Moreover, release of symbionts might enable adaptations that evolve within host individuals to spread within host populations and possibly to new environments.
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25
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Shoemaker CA, LaFrentz BR. Growth and survival of the fish pathogenic bacterium, Flavobacterium columnare, in tilapia mucus and porcine gastric mucin. FEMS Microbiol Lett 2015; 362:fnu060. [DOI: 10.1093/femsle/fnu060] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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26
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Zhang J, Laakso J, Mappes J, Laanto E, Ketola T, Bamford JK, Kunttu H, Sundberg LR. Association of colony morphotypes with virulence, growth and resistance against protozoan predation in the fish pathogenFlavobacterium columnare. FEMS Microbiol Ecol 2014; 89:553-62. [DOI: 10.1111/1574-6941.12356] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 04/08/2014] [Accepted: 05/13/2014] [Indexed: 01/09/2023] Open
Affiliation(s)
- Ji Zhang
- Centre of Excellence in Biological Interactions; Department of Biological and Environmental Science; University of Jyväskylä; Jyväskylä Finland
- Department of Biological and Environmental Science; University of Helsinki; Helsinki Finland
| | - Jouni Laakso
- Centre of Excellence in Biological Interactions; Department of Biological and Environmental Science; University of Jyväskylä; Jyväskylä Finland
- Department of Biological and Environmental Science; University of Helsinki; Helsinki Finland
| | - Johanna Mappes
- Centre of Excellence in Biological Interactions; Department of Biological and Environmental Science; University of Jyväskylä; Jyväskylä Finland
| | - Elina Laanto
- Centre of Excellence in Biological Interactions; Department of Biological and Environmental Science; University of Jyväskylä; Jyväskylä Finland
- Department of Biological and Environmental Science and Nanoscience Centre; University of Jyväskylä; Jyväskylä Finland
| | - Tarmo Ketola
- Centre of Excellence in Biological Interactions; Department of Biological and Environmental Science; University of Jyväskylä; Jyväskylä Finland
| | - Jaana K.H. Bamford
- Centre of Excellence in Biological Interactions; Department of Biological and Environmental Science; University of Jyväskylä; Jyväskylä Finland
- Department of Biological and Environmental Science and Nanoscience Centre; University of Jyväskylä; Jyväskylä Finland
| | - Heidi Kunttu
- Centre of Excellence in Biological Interactions; Department of Biological and Environmental Science; University of Jyväskylä; Jyväskylä Finland
| | - Lotta-Riina Sundberg
- Centre of Excellence in Biological Interactions; Department of Biological and Environmental Science; University of Jyväskylä; Jyväskylä Finland
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