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Baloch AA, Steinhagen D, Gela D, Kocour M, Piačková V, Adamek M. Immune responses in carp strains with different susceptibility to carp edema virus disease. PeerJ 2023; 11:e15614. [PMID: 37465154 PMCID: PMC10351508 DOI: 10.7717/peerj.15614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 06/01/2023] [Indexed: 07/20/2023] Open
Abstract
Carp edema virus disease (CEVD), also known as koi sleepy disease (KSD), represents a serious threat to the carp industry. The expression of immune-related genes to CEV infections could lead to the selection of crucial biomarkers of the development of the disease. The expression of a total of eleven immune-related genes encoding cytokines (IL-1β, IL-10, IL-6a, and TNF-α2), antiviral response (Mx2), cellular receptors (CD4, CD8b1, and GzmA), immunoglobulin (IgM), and genes encoding-mucins was monitored in gills of four differently KSD-susceptible strains of carp (Amur wild carp, Amur Sasan, AS; Ropsha scaly carp, Rop; Prerov scaly carp, PS; and koi) on days 6 and 11 post-infection. Carp strains were infected through two cohabitation infection trials with CEV genogroups I or IIa. The results showed that during the infection with both CEV genogroups, KSD-susceptible koi induced an innate immune response with significant up-regulation (p < 0.05) of IL-1β, IL-10, IL-6a, and TNF-α2 genes on both 6 and 11 days post-infection (dpi) compared to the fish sampled on day 0. Compared to koi, AS and Rop strains showed up-regulation of IL-6a and TNF-α2 but no other cytokine genes. During the infection with CEV genogroup IIa, Mx2 was significantly up-regulated in all strains and peaked on 6 dpi in AS, PS, and Rop. In koi, it remained high until 11 dpi. With genogroup I infection, Mx2 was up-expressed in koi on 6 dpi and in PS on both 6 and 11 dpi. No significant differences were noticed in selected mucin genes expression measured in gills of any carp strains exposed to both CEV genogroups. During both CEV genogroups infections, the expression levels of most of the genes for T cell response, including CD4, CD8b1, and GzmA were down-regulated in AS and koi at all time points compared to day 0 control. The expression data for the above experimental trials suggest that both CEV genogroups infections in common carp strains lead to activation of the same expression pattern regardless of the fish's susceptibility towards the virus. The expression of the same genes in AS and koi responding to CEV genogroup IIa infection in mucosal tissues such as gill, gut, and skin showed the significant up-regulation of all the cytokine genes in gill and gut tissues from koi carp at 5 dpi. Significant down-regulation of CD4 and GzmA levels were only detected in koi gill on 5 dpi but not in other tissues. AS carp displayed significant up-expression of Mx2 gene in all mucosal tissues on 5 dpi, whereas in koi, it was up-regulated in gill and gut only. In both carp strains, gill harbored a higher virus load on 5 dpi compared to the other tissues. The results showed that resistance to CEV could not be linked with the selected immune responses measured. The up-regulation of mRNA expression of most of the selected immune-related genes in koi gill and gut suggests that CEV induces a more systemic mucosal immune response not restricted to the target tissue of gills.
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Affiliation(s)
- Ali Asghar Baloch
- Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, University of South Bohemia in České Budějovice, Vodňany, Czech Republic
| | - Dieter Steinhagen
- Fish Disease Research Unit, Institute for Parasitology, University of Veterinary Medicine Hannover, Hannover, Germany
| | - David Gela
- Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, University of South Bohemia in České Budějovice, Vodňany, Czech Republic
| | - Martin Kocour
- Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, University of South Bohemia in České Budějovice, Vodňany, Czech Republic
| | - Veronika Piačková
- Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, University of South Bohemia in České Budějovice, Vodňany, Czech Republic
| | - Mikolaj Adamek
- Fish Disease Research Unit, Institute for Parasitology, University of Veterinary Medicine Hannover, Hannover, Germany
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Sun F, Wang C, Chen L, Weng G, Zheng Z. The intestinal bacterial community of healthy and diseased animals and its association with the aquaculture environment. Appl Microbiol Biotechnol 2019; 104:775-783. [PMID: 31781816 DOI: 10.1007/s00253-019-10236-z] [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] [Received: 05/17/2019] [Revised: 09/24/2019] [Accepted: 11/04/2019] [Indexed: 11/24/2022]
Abstract
Although increasing levels of attention have been targeted towards aquaculture-associated bacteria, the bacterial community of animal intestines and its relationship with the aquaculture environment need to be further investigated. In this study, we used high-throughput sequencing to analyze the bacterial community of pond water, sediment, and the intestines of diseased and healthy animals. Our data showed that Proteobacteria, Firmicutes, Cyanobacteria, and Bacteroidetes were the dominant taxa of bacteria across all samples and accounted for more than 90% of the total sequence. Difference analysis and Venn diagrams showed that most of the intestinal bacterial OTUs (operational taxonomic units) of diseased and healthy animals were the same as those of sediment and water, indicating that the aquaculture environment was the main source of intestinal bacteria. Compared with healthy animals, a considerable reduction of OTUs was evident in diseased animals. Welch's t test showed that the dominant bacterial taxa in sediment, water, and animal intestine were significantly different (p < 0.05) and each had its own unique dominant microorganisms. In addition, differences between the intestinal bacteria of healthy and diseased animals were represented by potential probiotics and pathogens, such as Bacillus, Vibrio, Oceanobacillus, and Lactococcus. Principal component analysis (PcoA) showed that a similar environment shaped a similar microbial structure. There was a large difference in the spectrum of intestinal bacteria in diseased animals; furthermore, the spectrum of intestinal bacteria in diseased animals was very different from the environment than in healthy animals. This study provides a theoretical basis for a relationship between the intestinal bacteria of healthy and diseased animals and the environment and provides guidance for environmental regulation and disease prevention in aquaculture areas.
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Affiliation(s)
- Fulin Sun
- State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510000, China. .,Daya Bay Marine Biology Research Station, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Shenzhen, 518000, China.
| | - Chunzhong Wang
- Putian Institute of Aquaculture Science of Fujian Province, Putian, 351100, China.
| | - Lijuan Chen
- Putian Tian Ran Xing Agriculture Development Co. Ltd., Putian, 351100, Fujian, China
| | - Guozhu Weng
- Putian Customs Comprehensive Technical Service Center, Putian, 351100, China
| | - Zhipeng Zheng
- Putian Tian Ran Xing Agriculture Development Co. Ltd., Putian, 351100, Fujian, China
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3
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Mou X, Spinard EJ, Hillman SL, Nelson DR. Isocitrate dehydrogenase mutation in Vibrio anguillarum results in virulence attenuation and immunoprotection in rainbow trout (Oncorhynchus mykiss). BMC Microbiol 2017; 17:217. [PMID: 29137620 PMCID: PMC5686843 DOI: 10.1186/s12866-017-1124-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 11/02/2017] [Indexed: 11/28/2022] Open
Abstract
Background Vibrio anguillarum is an extracellular bacterial pathogen that is a causative agent of vibriosis in finfish and crustaceans with mortality rates ranging from 30% to 100%. Mutations in central metabolism (glycolysis and the TCA cycle) of intracellular pathogens often result in attenuated virulence due to depletion of required metabolic intermediates; however, it was not known whether mutations in central metabolism would affect virulence in an extracellular pathogen such as V. anguillarum. Results Seven central metabolism mutants were created and characterized with regard to growth in minimal and complex media, expression of virulence genes, and virulence in juvenile rainbow trout (Oncorhynchus mykiss). Only the isocitrate dehydrogenase (icd) mutant was attenuated in virulence against rainbow trout challenged by either intraperitoneal injection or immersion. Further, the icd mutant was shown to be immunoprotective against wild type V. anguillarum infection. There was no significant decrease in the expression of the three hemolysin genes detected by qRT-PCR. Additionally, only the icd mutant exhibited a significantly decreased growth yield in complex media. Growth yield was directly related to the abundance of glutamate. A strain with a restored wild type icd gene was created and shown to restore growth to a wild type cell density in complex media and pathogenicity in rainbow trout. Conclusions The data strongly suggest that a decreased growth yield, resulting from the inability to synthesize α-ketoglutarate, caused the attenuation despite normal levels of expression of virulence genes. Therefore, the ability of an extracellular pathogen to cause disease is dependent upon the availability of host-supplied nutrients for growth. Additionally, a live vaccine strain could be created from an icd deletion strain. Electronic supplementary material The online version of this article (10.1186/s12866-017-1124-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xiangyu Mou
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI, 02881, USA.,Present Address: Division of Infectious Diseases, Massachusetts General Hospital, 65 Landsdowne St, Cambridge, MA, 02139, USA
| | - Edward J Spinard
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI, 02881, USA
| | - Shelby L Hillman
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI, 02881, USA
| | - David R Nelson
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI, 02881, USA.
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4
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Luo G, Huang L, Su Y, Qin Y, Xu X, Zhao L, Yan Q. flrA, flrB and flrC regulate adhesion by controlling the expression of critical virulence genes in Vibrio alginolyticus. Emerg Microbes Infect 2016; 5:e85. [PMID: 27485498 PMCID: PMC5034100 DOI: 10.1038/emi.2016.82] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 05/12/2016] [Accepted: 05/16/2016] [Indexed: 12/24/2022]
Abstract
Adhesion is an important virulence trait of Vibrio alginolyticus. Bacterial adhesion is influenced by environmental conditions; however, the molecular mechanism underlying this effect remains unknown. The expression levels of flrA, flrB and flrC were significantly downregulated in adhesion-deficient V. alginolyticus strains cultured under Cu2+, Pb2+, Hg2+ and low-pH stresses. Silencing these genes led to deficiencies in adhesion, motility, flagellar assembly, biofilm formation and exopolysaccharide (EPS) production. The expression levels of fliA, flgH, fliS, fliD, cheR, cheV and V12G01_22158 (Gene ID) were significantly downregulated in all of the RNAi groups, whereas the expression levels of toxT, ctxB, acfA, hlyA and tlh were upregulated in flrA- and flrC-silenced groups. These genes play a key role in the virulence mechanisms of most pathogenic Vibrio species. Furthermore, the expression of flrA, flrB and flrC was significantly influenced by temperature, salinity, starvation and pH. These results indicate that (1) flrA, flrB and flrC are important for V. alginolyticus adhesion; (2) flrA, flrB and flrC significantly influence bacterial adhesion, motility, biofilm formation and EPS production by controlling expression of key genes involved in those phenotypes; and (3) flrA, flrB and flrC regulate adhesion in the natural environment with different temperatures, pH levels, salinities and starvation time.
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Affiliation(s)
- Gang Luo
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, Fujian 361021, China
| | - Lixing Huang
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, Fujian 361021, China
| | - Yongquan Su
- College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian 361102, China.,State Key Laboratory of Large Yellow Croaker Breeding, Ningde, Fujian 352000, China
| | - Yingxue Qin
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, Fujian 361021, China
| | - Xiaojin Xu
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, Fujian 361021, China
| | - Lingmin Zhao
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, Fujian 361021, China
| | - Qingpi Yan
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, Fujian 361021, China.,State Key Laboratory of Large Yellow Croaker Breeding, Ningde, Fujian 352000, China
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Smith PA, Contreras JR, Rojas ME, Guajardo A, Díaz S, Carbonero A. Infectivity of Piscirickettsia salmonis in immersion-bath exposed rainbow trout Oncorhynchus mykiss (Walbaum) fry. JOURNAL OF FISH DISEASES 2015; 38:765-70. [PMID: 25168060 DOI: 10.1111/jfd.12288] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 06/19/2014] [Indexed: 05/20/2023]
Affiliation(s)
- P A Smith
- Department of Animal Pathology, Faculty of Veterinary Sciences, Pathology of Aquatic Animal Unit, University of Chile, Santiago, Chile
| | - J R Contreras
- Department of Animal Pathology, Faculty of Veterinary Sciences, Pathology of Aquatic Animal Unit, University of Chile, Santiago, Chile
| | - M E Rojas
- Department of Animal Pathology, Faculty of Veterinary Sciences, Pathology of Aquatic Animal Unit, University of Chile, Santiago, Chile
| | - A Guajardo
- Department of Animal Pathology, Faculty of Veterinary Sciences, Pathology of Aquatic Animal Unit, University of Chile, Santiago, Chile
| | - S Díaz
- Department of Animal Pathology, Faculty of Veterinary Sciences, Pathology of Aquatic Animal Unit, University of Chile, Santiago, Chile
| | - A Carbonero
- Department of Animal Health, University of Córdoba, Córdoba, Spain
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6
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Li X, Defoirdt T, Bossier P. Relation between virulence of Vibrio anguillarum strains and response to the host factors mucin, bile salts and cholesterol. J Appl Microbiol 2015; 119:25-32. [PMID: 25807847 DOI: 10.1111/jam.12813] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 03/18/2015] [Accepted: 03/20/2015] [Indexed: 11/28/2022]
Abstract
AIMS In this study, we investigated the responsiveness of 15 Vibrio anguillarum strains to three host factors (mucin, bile salts and cholesterol). METHODS AND RESULTS Three virulence-related phenotypes were investigated in this respect, i.e. motility, biofilm formation and exopolysaccharide production. Almost all V. anguillarum strains showed a significantly increased motility in the presence of either of the three host factors. Only five of the strains showed increased biofilm formation in the presence of host factors and only three strains showed increased exopolysaccharide production in the presence of the host factors. CONCLUSIONS There were no significant correlations between the three putatively virulence-linked phenotypes (in the absence of host factors) and virulence to sea bass larvae. There was no correlation between responsiveness to the host factors (percentage increase in motility, biofilm formation or exopolysaccharide production in the presence of the three host factors) and virulence to sea bass larvae. However, the responses of these virulence-related phenotypes upon the addition of either of the three host factors were significantly correlated with each other. This result suggests that the mechanisms by which V. anguillarum responds to these three host factors is linked. SIGNIFICANCE AND IMPACT OF THE STUDY Although the mechanism by which V. anguillarum responds to the host factors mucin, bile salts and cholesterol seems to be linked, there is no correlation between host factor responsiveness and virulence towards sea bass larvae. This emphasizes that one should be careful when extrapolating results obtained for one particular strain to reach general conclusions on a species of pathogenic bacteria.
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Affiliation(s)
- X Li
- Laboratory of Aquaculture & Artemia Reference Center, Ghent University, Ghent, Belgium
| | - T Defoirdt
- Laboratory of Aquaculture & Artemia Reference Center, Ghent University, Ghent, Belgium
| | - P Bossier
- Laboratory of Aquaculture & Artemia Reference Center, Ghent University, Ghent, Belgium
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7
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Ruiz P, Poblete M, Yáñez AJ, Irgang R, Toranzo AE, Avendaño-Herrera R. Cell-surface properties of Vibrio ordalii strains isolated from Atlantic salmon Salmo salar in Chilean farms. DISEASES OF AQUATIC ORGANISMS 2015; 113:9-23. [PMID: 25667332 DOI: 10.3354/dao02820] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Vibrio ordalii is the causative agent of atypical vibriosis and has the potential to cause severe losses in salmonid aquaculture, but the factors determining its virulence have not yet been elucidated. In this work, cell-surface-related properties of the isolates responsible for outbreaks in Atlantic salmon were investigated. We also briefly examined whether pathogenicity against fish varied for V. ordalii strains with differing cell-surface properties. Hydrocarbon adhesions indicated the hydrophobic character of V. ordalii, although only 4 of 18 isolates induced haemagglutination in Atlantic salmon erythrocytes. A minority of the studied isolates (6 of 18) and the type strain ATCC 33509T produced low-grade biofilm formation on polyethylene surface after 2 h post-inoculation (hpi), but no strains were slime producers. Interestingly, V. ordalii isolates showed wide differences in hydrophobicity. Therefore, we chose 3 V. ordalii isolates (Vo-LM-03, Vo-LM-18 and Vo-LM-16) as representative of each hydrophobicity group (strongly hydrophobic, relatively hydrophobic and quasi-hydrophilic, respectively) and ATCC 33509T was used in the pathogenicity studies. All tested V. ordalii strains except the type strain resisted the killing activity of Atlantic salmon mucus and serum, and could proliferate in these components. Moreover, all V. ordalii isolates adhered to SHK-1 cells, causing damage to fish cell membrane permeability after 16 hpi. Virulence testing using rainbow trout revealed that isolate Vo-LM-18 was more virulent than isolates Vo-LM-03 and Vo-LM-16, indicating some relationship between haemagglutination and virulence, but not with hydrophobicity.
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Affiliation(s)
- P Ruiz
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias Biológicas, Universidad Andrés Bello, Viña del Mar, Chile
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Li X, Bossier P, Dierckens K, Laureau S, Defoirdt T. Impact of mucin, bile salts and cholesterol on the virulence of Vibrio anguillarum towards gnotobiotic sea bass (Dicentrarchus labrax) larvae. Vet Microbiol 2015; 175:44-9. [DOI: 10.1016/j.vetmic.2014.10.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 10/25/2014] [Accepted: 10/30/2014] [Indexed: 10/24/2022]
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9
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C De B, Meena DK, Behera BK, Das P, Das Mohapatra PK, Sharma AP. Probiotics in fish and shellfish culture: immunomodulatory and ecophysiological responses. FISH PHYSIOLOGY AND BIOCHEMISTRY 2014; 40:921-971. [PMID: 24419543 DOI: 10.1007/s10695-013-9897-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 12/06/2013] [Indexed: 06/03/2023]
Abstract
Aquaculture is emerging as one of the most viable and promising enterprises for keeping pace with the surging need for animal protein, providing nutritional and food security to humans, particularly those residing in regions where livestock is relatively scarce. With every step toward intensification of aquaculture practices, there is an increase in the stress level in the animal as well as the environment. Hence, disease outbreak is being increasingly recognized as one of the most important constraints to aquaculture production in many countries, including India. Conventionally, the disease control in aquaculture has relied on the use of chemical compounds and antibiotics. The development of non-antibiotic and environmentally friendly agents is one of the key factors for health management in aquaculture. Consequently, with the emerging need for environmentally friendly aquaculture, the use of alternatives to antibiotic growth promoters in fish nutrition is now widely accepted. In recent years, probiotics have taken center stage and are being used as an unconventional approach that has numerous beneficial effects in fish and shellfish culture: improved activity of gastrointestinal microbiota and enhanced immune status, disease resistance, survival, feed utilization and growth performance. As natural products, probiotics have much potential to increase the efficiency and sustainability of aquaculture production. Therefore, comprehensive research to fully characterize the intestinal microbiota of prominent fish species, mechanisms of action of probiotics and their effects on the intestinal ecosystem, immunity, fish health and performance is reasonable. This review highlights the classifications and applications of probiotics in aquaculture. The review also summarizes the advancement and research highlights of the probiotic status and mode of action, which are of great significance from an ecofriendly, sustainable, intensive aquaculture point of view.
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Affiliation(s)
- Bidhan C De
- Central Inland Fisheries Research Institute, Barrackpore, Kolkata, 700120, West Bengal, India
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10
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Benhamed S, Guardiola FA, Mars M, Esteban MÁ. Pathogen bacteria adhesion to skin mucus of fishes. Vet Microbiol 2014; 171:1-12. [DOI: 10.1016/j.vetmic.2014.03.008] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 12/17/2013] [Accepted: 03/03/2014] [Indexed: 10/25/2022]
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11
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Li L, Mou X, Nelson DR. Characterization of Plp, a phosphatidylcholine-specific phospholipase and hemolysin of Vibrio anguillarum. BMC Microbiol 2013; 13:271. [PMID: 24279474 PMCID: PMC4222444 DOI: 10.1186/1471-2180-13-271] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 11/20/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Vibrio anguillarum is the causative agent of vibriosis in fish. Several extracellular proteins secreted by V. anguillarum have been shown to contribute to virulence. While two hemolysin gene clusters, vah1-plp and rtxACHBDE, have been previously identified and described, the activities of the protein encoded by the plp gene were not known. Here we describe the biochemical activities of the plp-encoded protein and its role in pathogenesis. RESULTS The plp gene, one of the components in vah1 cluster, encodes a 416-amino-acid protein (Plp), which has homology to lipolytic enzymes containing the catalytic site amino acid signature SGNH. Hemolytic activity of the plp mutant increased 2-3-fold on sheep blood agar indicating that plp represses vah1; however, hemolytic activity of the plp mutant decreased by 2-3-fold on fish blood agar suggesting that Plp has different effects against erythrocytes from different species. His6-tagged recombinant Plp protein (rPlp) was over-expressed in E. coli. Purified and re-folded active rPlp exhibited phospholipase A2 activity against phosphatidylcholine and no activity against phosphatidylserine, phosphatidylethanolamine, or sphingomyelin. Characterization of rPlp revealed broad optimal activities at pH 5-9 and at temperatures of 30-64°C. Divalent cations and metal chelators did not affect activity of rPlp. We also demonstrated that Plp was secreted using thin layer chromatography and immunoblot analysis. Additionally, rPlp had strong hemolytic activity towards rainbow trout erythrocytes, but not to sheep erythrocytes suggesting that rPlp is optimized for lysis of phosphatidylcholine-rich fish erythrocytes. Further, only the loss of the plp gene had a significant effect on hemolytic activity of culture supernatant on fish erythrocytes, while the loss of rtxA and/or vah1 had little effect. However, V. anguillarum strains with mutations in plp or in plp and vah1 exhibited no significant reduction in virulence compared to the wild type strain when used to infect rainbow trout. CONCLUSION The plp gene of V. anguillarum encoding a phospholipase with A2 activity is specific for phosphatidylcholine and, therefore, able to lyse fish erythrocytes, but not sheep erythrocytes. Mutation of plp does not affect the virulence of V. anguillarum in rainbow trout.
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Affiliation(s)
- Ling Li
- Department of Cell and Molecular Biology, University of Rhode Island, 120 Flagg Rd,, Kingston, RI 02881, USA.
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12
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Galindo-Villegas J, Mulero I, García-Alcazar A, Muñoz I, Peñalver-Mellado M, Streitenberger S, Scapigliati G, Meseguer J, Mulero V. Recombinant TNFα as oral vaccine adjuvant protects European sea bass against vibriosis: insights into the role of the CCL25/CCR9 axis. FISH & SHELLFISH IMMUNOLOGY 2013; 35:1260-71. [PMID: 23932985 DOI: 10.1016/j.fsi.2013.07.046] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Revised: 07/25/2013] [Accepted: 07/30/2013] [Indexed: 05/13/2023]
Abstract
Vibrio anguillarum is the main causative agent of vibriosis in cultured sea bass. Unfortunately, available vaccines against this disease do not achieve the desired protection. In this study, to accomplish uptake, processing, and presentation of luminal antigens, a commercial sea bass oral vaccine against V. anguillarum was improved with the addition of recombinant fish-self tumor necrosis factor α (rTNFα), as adjuvant. To explore mechanisms, systemic and local responses were analyzed through serum specific IgM titers, gene expression, lymphocytes spatial distribution in the gut, and in vitro functional assays. We found along the trial, over expressed transcripts of genes encoding cytokines and antimicrobial molecules at the gut of rTNFα supplied group. Orally immunized fish with vaccine alone confer protection against V. anguillarum challenge throughout a short time period. In contrast, adjuvant-treated group significantly extended the response. In both cases, achieved protection was independent of serum IgM. Yet, IgT transcripts were found to increase in the gut of rTNFα-treated fish. More importantly, fish treated with rTNFα showed a dramatic change of their T lymphocytes distribution and localization in gut mucosal tissue, suggesting specific antigen recognition and further intraepithelial T lymphocytes (IEL) activation. To determine the mechanism behind IEL infiltration, we characterized the constitutive and activated pattern of chemokines in sea bass hematopoietic tissues, identifying for the first time in fish gut, an intimate relation between the chemokine ligand/receptor CCL25/CCR9. Ex-vivo, chemotaxis analyses confirmed these findings. Together, our results demonstrate that improved oral vaccines targeting key cytokines may provide a means to selectively modulate fish immune defence.
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Affiliation(s)
- Jorge Galindo-Villegas
- Department of Cell Biology and Histology, Faculty of Biology, University of Murcia, 30100 Murcia, Spain.
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13
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Froelich B, Oliver J. Increases in the amounts of Vibrio spp. in oysters upon addition of exogenous bacteria. Appl Environ Microbiol 2013; 79:5208-13. [PMID: 23793640 PMCID: PMC3753945 DOI: 10.1128/aem.01110-13] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 06/18/2013] [Indexed: 11/20/2022] Open
Abstract
The bacterial pathogen Vibrio vulnificus is found naturally in brackish coastal waters but can be greatly concentrated by filter-feeding organisms such as shellfish. Numerous experiments in which exogenous V. vulnificus cells are added to oysters in an attempt to measure uptake and depuration have been performed. In nearly all cases, results have shown that laboratory-grown bacteria are rapidly taken up by the oysters but ultimately eliminated, while naturally present Vibrio populations in oysters are resistant to depuration. In this study, oysters harvested during winter months, with low culturable Vibrio concentrations, were incubated in aquaria supplemented with strains of V. vulnificus that were either genotypically or phenotypically distinct from the background bacteria. These exogenous cells were eliminated from the oysters, as previously seen, but other vibrios already inhabiting the oysters responded to the V. vulnificus inoculum by rapidly increasing in number and maintaining a large stable population. The presence of such an oyster-adapted Vibrio population would be expected to prevent colonization by exogenous V. vulnificus cells, thus explaining the rapid depuration of these added bacteria.
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Affiliation(s)
- Brett Froelich
- University of North Carolina at Charlotte, Charlotte, North Carolina, USA.
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14
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Larsen A, Tao Z, Bullard SA, Arias CR. Diversity of the skin microbiota of fishes: evidence for host species specificity. FEMS Microbiol Ecol 2013; 85:483-94. [DOI: 10.1111/1574-6941.12136] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 04/10/2013] [Accepted: 04/16/2013] [Indexed: 11/30/2022] Open
Affiliation(s)
- Andrea Larsen
- Department of Fisheries and Allied Aquacultures; Aquatic Microbiology Laboratory; Auburn University; Auburn AL USA
| | - Zhen Tao
- Department of Fisheries and Allied Aquacultures; Aquatic Microbiology Laboratory; Auburn University; Auburn AL USA
| | - Stephen A. Bullard
- Department of Fisheries and Allied Aquacultures; Aquatic Parasitology Laboratory; Auburn University; Auburn AL USA
| | - Covadonga R. Arias
- Department of Fisheries and Allied Aquacultures; Aquatic Microbiology Laboratory; Auburn University; Auburn AL USA
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15
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Chisada SI, Shimizu K, Kamada H, Matsunaga N, Okino N, Ito M. Vibrios adhere to epithelial cells in the intestinal tract of red sea bream,Pagrus major,utilizing GM4 as an attachment site. FEMS Microbiol Lett 2013; 341:18-26. [DOI: 10.1111/1574-6968.12082] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 01/08/2013] [Accepted: 01/09/2013] [Indexed: 11/29/2022] Open
Affiliation(s)
- Shin-ichi Chisada
- Department of Bioscience and Biotechnology; Graduate School of Bioresource and Bioenvironmental Sciences; Kyushu University; Fukuoka; Japan
| | - Kohei Shimizu
- Department of Bioscience and Biotechnology; Graduate School of Bioresource and Bioenvironmental Sciences; Kyushu University; Fukuoka; Japan
| | - Haruna Kamada
- Department of Bioscience and Biotechnology; Graduate School of Bioresource and Bioenvironmental Sciences; Kyushu University; Fukuoka; Japan
| | - Naoyuki Matsunaga
- Department of Bioscience and Biotechnology; Graduate School of Bioresource and Bioenvironmental Sciences; Kyushu University; Fukuoka; Japan
| | - Nozomu Okino
- Department of Bioscience and Biotechnology; Graduate School of Bioresource and Bioenvironmental Sciences; Kyushu University; Fukuoka; Japan
| | - Makoto Ito
- Department of Bioscience and Biotechnology; Graduate School of Bioresource and Bioenvironmental Sciences; Kyushu University; Fukuoka; Japan
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16
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Yeh YC, Lee CW, Pan YW, Hsu YJ, Hung HY, Chen YM, Lin HY, Chen TY, Yang HL, Wang HC. Identification and characterization of DSCAM isoforms isolated from orange-spotted grouper Epinephelus coioides. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2012; 38:148-159. [PMID: 22627126 DOI: 10.1016/j.dci.2012.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 05/01/2012] [Accepted: 05/06/2012] [Indexed: 06/01/2023]
Abstract
The Down syndrome cell adhesion molecule (DSCAM), an immunoglobulin (Ig) superfamily member, was first identified from human and subsequently isolated from both vertebrates and invertebrates. Recent studies have shown that the DSCAM molecule serves diverse functions in neurodevelopment, such as axon guidance and neuronal migration. Most studies on DSCAM, however, have focused on mammals and arthropods, and our present knowledge of bony fish DSCAM is still limited. In this study, orange-spotted grouper Epinephelus coioides was used as an animal model to explore the possible functions of DSCAM. Two DSCAM isoforms were isolated, namely EcDSCAM A and EcDSCAM B, with lengths of 1648 and 2025 amino acids, respectively. The classical domain structure (i.e. 9Ig-4FNIII-1Ig-2FNIII-Transmembrane domain-Cytoplasmic tail) was also found in the coding regions of these two EcDSCAMs. Phylogenetic analysis showed that in the vertebrate DSCAM clade, the EcDSCAMs and various teleost DSCAMs were clustered into a subclade. Real-time PCR revealed that EcDSCAM B is the major EcDSCAM isoform, with the expression of EcDSCAM B being significantly higher than that of EcDSCAM A. During the first 14days after hatching (dph), increases in the expression of the two EcDSCAMs were observed at 2-4 and 8-11dph. EcDSCAM is expressed mainly in the intestine, nerve-related tissues, and stomach. Optic nerve transection analysis showed that EcDSCAM was up-regulated during optic nerve regeneration after optic nerve injury. We also investigated whether DSCAM expression was affected by viral nervous necrosis (VNN) disease or vibriosis. We found that when grouper were challenged with nervous necrosis virus (NNV), there were no meaningful changes in DSCAM expression, but challenge with Vibrio anguillarum led to a decrease in EcDSCAM levels in the brain. This decrease may be related to the pathogenesis of V. anguillarum.
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Affiliation(s)
- Ying-Chun Yeh
- Institute of Biotechnology, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan 701, Taiwan
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Abstract
The two hemolysin gene clusters previously identified in Vibrio anguillarum, the vah1 cluster and the rtxACHBDE cluster, are responsible for the hemolytic and cytotoxic activities of V. anguillarum in fish. In this study, we used degenerate PCR to identify a positive hemolysin regulatory gene, hlyU, from the unsequenced V. anguillarum genome. The hlyU gene of V. anguillarum encodes a 92-amino-acid protein and is highly homologous to other bacterial HlyU proteins. An hlyU mutant was constructed, which exhibited an ∼5-fold decrease in hemolytic activity on sheep blood agar with no statistically significant decrease in cytotoxicity of the wild-type strain. Complementation of the hlyU mutation restored both hemolytic activity and cytotoxic activity. Both semiquantitative reverse transcription-PCR (RT-PCR) and quantitative real-time RT-PCR (qRT-PCR) were used to examine expression of the hemolysin genes under exponential and stationary-phase conditions in wild-type, hlyU mutant, and hlyU complemented strains. Compared to the wild-type strain, expression of rtx genes decreased in the hlyU mutant, while expression of vah1 and plp was not affected in the hlyU mutant. Complementation of the hlyU mutation restored expression of the rtx genes and increased vah1 and plp expression to levels higher than those in the wild type. The transcriptional start sites in both the vah1-plp and rtxH-rtxB genes' intergenic regions were determined using 5' random amplification of cDNA ends (5'-RACE), and the binding sites for purified HlyU were discovered using DNA gel mobility shift experiments and DNase protection assays.
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18
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González-Contreras A, Magariños B, Godoy M, Irgang R, Toranzo AE, Avendaño-Herrera R. Surface properties of Streptococcus phocae strains isolated from diseased Atlantic salmon, Salmo salar L. JOURNAL OF FISH DISEASES 2011; 34:203-215. [PMID: 21306587 DOI: 10.1111/j.1365-2761.2010.01228.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Streptococcus phocae is an emerging pathogen for Chilean Atlantic salmon, Salmo salar, but the factors determining its virulence are not yet elucidated. In this work, cell surface-related properties such as hydrophobicity and haemagglutination, adhesion to mucus and cell lines, capsule detection, survival and biofilm formation in skin mucus and serum resistance of the isolates responsible for outbreaks in Atlantic salmon and seals were examined. Adhesion to hydrocarbons and the results of salt aggregation tests indicated most of the S. phocae were strongly hydrophobic. All isolates exhibited a similar ability to attach to the Chinook salmon embryo (CHSE) cells line, but were not able to enter CHSE cells. Haemagglutination was not detected. Our data clearly indicate that S. phocae can resist the killing activity of mucus and serum and proliferate in them, which could be associated with the presence of a capsular layer around the cells. Pathogenicity studies using seal and fish isolates demonstrated mortality or pathological signs in fish injected only with the Atlantic salmon isolate. No mortalities or histopathological alterations were observed in fish injected with extracellular products.
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Affiliation(s)
- A González-Contreras
- Departamento de Ciencias Biológicas, Universidad Andres Bello, Viña del Mar, Chile
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Brackman G, Celen S, Baruah K, Bossier P, Van Calenbergh S, Nelis HJ, Coenye T. AI-2 quorum-sensing inhibitors affect the starvation response and reduce virulence in several Vibrio species, most likely by interfering with LuxPQ. Microbiology (Reading) 2009; 155:4114-4122. [DOI: 10.1099/mic.0.032474-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The increase of disease outbreaks caused by Vibrio species in aquatic organisms as well as in humans, together with the emergence of antibiotic resistance in Vibrio species, has led to a growing interest in alternative disease control measures. Quorum sensing (QS) is a mechanism for regulating microbial gene expression in a cell density-dependent way. While there is good evidence for the involvement of auto-inducer 2 (AI-2)-based interspecies QS in the control of virulence in multiple Vibrio species, only few inhibitors of this system are known. From the screening of a small panel of nucleoside analogues for their ability to disturb AI-2-based QS, an adenosine derivative with a p-methoxyphenylpropionamide moiety at C-3′ emerged as a promising hit. Its mechanism of inhibition was elucidated by measuring the effect on bioluminescence in a series of Vibrio harveyi AI-2 QS mutants. Our results indicate that this compound, as well as a truncated analogue lacking the adenine base, block AI-2-based QS without interfering with bacterial growth. The active compounds affected neither the bioluminescence system as such nor the production of AI-2, but most likely interfered with the signal transduction pathway at the level of LuxPQ in V. harveyi. The most active nucleoside analogue (designated LMC-21) was found to reduce the Vibrio species starvation response, to affect biofilm formation in Vibrio anguillarum, Vibrio vulnificus and Vibrio cholerae, to reduce pigment and protease production in V. anguillarum, and to protect gnotobiotic Artemia from V. harveyi-induced mortality.
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Affiliation(s)
- Gilles Brackman
- Laboratory of Pharmaceutical Microbiology, Ghent University, Harelbekestraat 72, B-9000 Ghent, Belgium
| | - Shari Celen
- Laboratory of Medicinal Chemistry, Ghent University, Harelbekestraat 72, B-9000 Ghent, Belgium
| | - Kartik Baruah
- Laboratory of Aquaculture and Artemia Reference Center, Ghent University, Rozier 44, 9000 Ghent, Belgium
| | - Peter Bossier
- Laboratory of Aquaculture and Artemia Reference Center, Ghent University, Rozier 44, 9000 Ghent, Belgium
| | - Serge Van Calenbergh
- Laboratory of Medicinal Chemistry, Ghent University, Harelbekestraat 72, B-9000 Ghent, Belgium
| | - Hans J. Nelis
- Laboratory of Pharmaceutical Microbiology, Ghent University, Harelbekestraat 72, B-9000 Ghent, Belgium
| | - Tom Coenye
- Laboratory of Pharmaceutical Microbiology, Ghent University, Harelbekestraat 72, B-9000 Ghent, Belgium
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20
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Identification and characterization of Epp, the secreted processing protease for the Vibrio anguillarum EmpA metalloprotease. J Bacteriol 2008; 190:6589-97. [PMID: 18689477 DOI: 10.1128/jb.00535-08] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The zinc metalloprotease EmpA is a virulence factor for the fish pathogen Vibrio anguillarum. Previous studies demonstrated that EmpA is secreted as a 46-kDa proenzyme that is activated extracellularly by the removal of an approximately 10-kDa propeptide. We hypothesized that a specific protease is responsible for processing secreted pro-EmpA into mature EmpA. To identify the protease responsible for processing pro-EmpA, a minitransposon mutagenesis (using mini-Tn10Km) clone bank of V. anguillarum was screened for reduced protease activity due to insertions in undescribed genes. One mutant with reduced protease activity was identified. The region containing the mini-Tn10Km was cloned, sequenced, and found to contain epp, an open reading frame encoding a putative protease. Further characterization of epp was done using strain M101, created by single-crossover insertional mutagenesis. Protease activity was absent in M101 cultures even when empA protease activity was induced by salmon gastrointestinal mucus. When the epp mutation was complemented with a wild-type copy of epp (M102), protease activity was restored. Western blot analysis of sterile filtered culture supernatants from wild-type (M93Sm) cells, M101 cells, and M102 cells revealed that only pro-EmpA was present in M101supernatants; both pro-EmpA and mature EmpA were detected in M93Sm and M102 supernatants. When sterile filtered culture supernatants from the empA mutant strain (M99) and M101 were mixed, protease activity was restored. Western blot analysis revealed that pro-EmpA in M101 culture supernatant was processed to mature EmpA only after mixing with M99 culture supernatant. These data show that Epp is the EmpA-processing protease.
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21
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Identification and characterization of a repeat-in-toxin gene cluster in Vibrio anguillarum. Infect Immun 2008; 76:2620-32. [PMID: 18378637 DOI: 10.1128/iai.01308-07] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vibrio anguillarum is the causative agent of vibriosis in fish. Hemolysins of V. anguillarum have been considered virulence factors during infection. One hemolysin gene, vah1, has been previously identified but does not account for all hemolytic activity. The mini-Tn10Km mutagenesis performed with a vah1 mutant resulted in a hemolysin-negative mutant. The region surrounding the mutation was cloned and sequenced, revealing a putative rtx operon with six genes (rtxACHBDE), where rtxA encodes an exotoxin, rtxC encodes an RtxA activator, rtxH encodes a conserved hypothetical protein, and rtxBDE encode the ABC transporters. Single mutations in rtx genes did not result in a hemolysin-negative phenotype. However, strains containing a mutation in vah1 and a mutation in an rtx gene resulted in a hemolysin-negative mutant, demonstrating that the rtx operon is a second hemolysin gene cluster in V. anguillarum M93Sm. Reverse transcription-PCR analysis revealed that the rtxC and rtxA genes are cotranscribed, as are the rtxBDE genes. Additionally, Vah1 and RtxA each have cytotoxic activity against Atlantic salmon kidney (ASK) cells. Single mutations in vah1 or rtxA attenuate the cytotoxicity of V. anguillarum M93Sm. A vah1 rtxA double mutant is no longer cytotoxic. Moreover, Vah1 and RtxA each have a distinct cytotoxic effect on ASK cells, Vah1 causes cell vacuolation, and RtxA causes cell rounding. Finally, wild-type and mutant strains were tested for virulence in juvenile Atlantic salmon. Only strains containing an rtxA mutation had reduced virulence, suggesting that RtxA is a major virulence factor for V. anguillarum.
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22
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Lemos ML, Osorio CR. Heme, an iron supply for vibrios pathogenic for fish. Biometals 2007; 20:615-26. [PMID: 17206385 DOI: 10.1007/s10534-006-9053-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2006] [Accepted: 11/28/2006] [Indexed: 11/30/2022]
Abstract
One of the main mechanisms present in gram-negative bacterial pathogens to obtain iron is the utilization of free heme or heme proteins from the host tissues. Vibrio anguillarum, the etiological agent of vibriosis in fish, and Photobacterium damselae subsp. piscicida, the causative agent of fish pasteurellosis, can acquire iron from free heme or heme-containing proteins present in the host tissues by a siderophore-independent mechanism. Similarly to other animal and human pathogens, the general mechanism for heme uptake in these two species consists in the presence of an outer membrane receptor that transport the heme molecule into the periplasm via a TonB-dependent process, and additional proteins that complete the transport of heme from the periplasm into the cell cytoplasm. Expression of heme uptake genes is iron-regulated at the transcriptional level by the repressor protein Fur. The heme uptake mechanisms are believed to contribute to virulence for fish. The existence of variability in the distribution of heme transport genes among strains suggests that gene inactivation and/or horizontal transfer might play a significant role in generating intraspecific genetic diversity.
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Affiliation(s)
- Manuel L Lemos
- Department of Microbiology and Parasitology, Institute of Aquaculture and Faculty of Biology, University of Santiago de Compostela, Campus Sur, Santiago de Compostela 15782, Spain.
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23
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Raeder ILU, Paulsen SM, Smalås AO, Willassen NP. Effect of fish skin mucus on the soluble proteome of Vibrio salmonicida analysed by 2-D gel electrophoresis and tandem mass spectrometry. Microb Pathog 2006; 42:36-45. [PMID: 17145162 DOI: 10.1016/j.micpath.2006.10.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2006] [Revised: 10/18/2006] [Accepted: 10/18/2006] [Indexed: 10/23/2022]
Abstract
Vibrio salmonicida is the causative agent of cold-water vibriosis in farmed marine fish species. Adherence of pathogenic bacteria to mucosal surfaces is considered to be the first steps in the infective processes, and proteins involved are regarded as virulence factors. The global protein expression profile of V. salmonicida, grown with and without the presence of fish skin mucus in the synthetic media, was compared. Increased levels of proteins involved in motility, oxidative stress responses, and general stress responses were demonstrated as an effect of growth in the presence of mucus compared to non-mucus containing media. Enhanced levels of the flagellar proteins FlaC, FlaD and FlaE indicate increased motility capacity, while enhanced levels of the heat shock protein DnaK and the chaperonin GroEL indicate a general stress response. In addition, we observed that peroxidases, TPx.Grx and AhpC, involved in the oxidative stress responses, were induced by mucus proteins. The addition of mucus to the culture medium did not significantly alter the growth rate of V. salmonicida. An analysis of mucus proteins suggests that the mucus layer harbours a protein species that potentially possesses catalytic activity against DNA, and a protein with iron chelating activity. This study represents the first V. salmonicida proteomic analysis, and provides specific insight into the proteins necessary for the bacteria to challenge the skin mucus barrier of the fish.
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Rock JL, Nelson DR. Identification and characterization of a hemolysin gene cluster in Vibrio anguillarum. Infect Immun 2006; 74:2777-86. [PMID: 16622215 PMCID: PMC1459744 DOI: 10.1128/iai.74.5.2777-2786.2006] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vibrio anguillarum is a causative agent of vibriosis in fish. Hemolytic activity has been suggested as a virulence factor by contributing to hemorrhagic septicemia and diarrhea. In order to identify and characterize the hemolysin genes and examine the role of hemolytic activity in virulence, a mini-Tn10Kan mutagenesis clone bank of V. anguillarum was screened. While no hemolysin-negative strains were observed, several mutants with two- to threefold-increased hemolytic activity were found. The region containing the insertion mutation was cloned, sequenced, and found to contain the V. anguillarum hemolysin (vah1) and two other open reading frames, coding for a putative lactonizing lipase (llpA) and a putative phospholipase (plp). The mini-Tn10Kan was inserted into plp. Site-directed mutagenesis of each gene revealed that mutations in vah1 and llpA did not affect hemolytic activity, but insertions into plp caused a two- to threefold increase in hemolysis. Double mutations in plp and either vah1 or llpA resulted in wild-type hemolytic activity. Complementation of plp restored hemolytic activity to wild-type levels. Spectrophotometric determination of hemolysin specific activity revealed that activity on a per cell basis peaked during the first 2 h of growth in LB20. Real-time quantitative reverse transcriptase PCR used to quantitate transcription of the hemolysin genes plp and vah1 in V. anguillarum wild-type strains M93Sm and NB10 revealed that transcription of plp and vah1 peaked at 2 h of growth in LB20. Additionally, expression of vah1 measured in the plp mutant strain, JL01, during the first 2 h of growth was >8 times higher than that in M93Sm. Mutations in plp and llpA did not affect virulence of V. anguillarum. The mutation in vah1 attenuated V. anguillarum virulence in fish. These data show that several genes are responsible for hemolytic activity in V. anguillarum. At least three genes (plp, llpA, and vah1) are responsible for one hemolytic activity. The data also suggest that plp acts as a negative regulator of vah1 and llpA.
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Affiliation(s)
- Jessica L Rock
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI 02881, USA
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25
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Mouriño S, Rodríguez-Ares I, Osorio CR, Lemos ML. Genetic variability of the heme uptake system among different strains of the fish pathogen Vibrio anguillarum: identification of a new heme receptor. Appl Environ Microbiol 2006; 71:8434-41. [PMID: 16332832 PMCID: PMC1317460 DOI: 10.1128/aem.71.12.8434-8441.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The ability to utilize heme compounds as iron sources was investigated in Vibrio anguillarum strains belonging to serotypes O1 to O10. All strains, regardless of their serotype or isolation origin could utilize hemin and hemoglobin as sole iron sources. Similarly, all of the isolates could bind hemin and Congo red, and this binding was mediated by cell envelope proteins. PCR and Southern hybridization were used to assay the occurrence of heme transport genes huvABCD, which have been previously described in serotype O1. Of 23 strains studied, two serotype O3 isolates proved negative for all huvABCD genes, whereas nine strains included in serotypes O2, O3, O4, O6, O7, and O10 tested negative for the outer membrane heme receptor gene huvA. A gene coding for a novel outer membrane heme receptor was cloned and characterized in a V. anguillarum serotype O3 strain lacking huvA. The new heme receptor, named HuvS, showed significant similarity to other outer membrane heme receptors described in Vibrionaceae, but little homology (39%) to HuvA. This heme receptor was present in 9 out of 11 of the V. anguillarum strains that tested negative for HuvA. Furthermore, complementation experiments demonstrated that HuvS could substitute for the HuvA function in Escherichia coli and V. anguillarum mutants. The huvS and huvA sequences alignment, as well as the analysis of their respective upstream and downstream DNA sequences, suggest that horizontal transfer and recombination might be responsible for generating this genetic diversity.
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Affiliation(s)
- Susana Mouriño
- Departamento de Microbiología y Parasitología, Instituto de Acuicultura y Facultad de Biología, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
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26
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Staroscik AM, Denkin SM, Nelson DR. Regulation of the Vibrio anguillarum metalloprotease EmpA by posttranslational modification. J Bacteriol 2005; 187:2257-60. [PMID: 15774867 PMCID: PMC1065222 DOI: 10.1128/jb.187.7.2257-2260.2005] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The zinc metalloprotease EmpA is a virulence factor in the fish pathogen Vibrio anguillarum. Previous studies have shown that two strains of V. anguillarum regulate empA differently. Strain M93Sm exhibits protease activity only in the presence of fish gastrointestinal mucus, while protease activity is detected in NB10 culture supernatant under all stationary-phase conditions. In this study, we use real-time reverse transcription-PCR to show that even in conditions where no protease activity is detected, empA transcription occurs. Western blot analysis revealed that EmpA is secreted as a approximately 48-kDa proenzyme and that activation occurs extracellularly by the removal of a approximately 10-kDa peptide. The presence of stable extracellular pro-EmpA in M93Sm culture supernatants suggests that activation of EmpA is not autolytic.
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Affiliation(s)
- Andrew M Staroscik
- Department of Cell and Molecular Biology, 117 Morrill Science Building, University of Rhode Island, Kingston, RI 02881.
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Ringø E, Schillinger U, Holzapfel W. Chapter 18 Antimicrobial activity of lactic acid bacteria isolated from aquatic animals and the use of lactic acid bacteria in aquaculture. MICROBIAL ECOLOGY IN GROWING ANIMALS 2005. [DOI: 10.1016/s1877-1823(09)70051-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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Gel shift analysis of the empA promoter region in Vibrio anguillarum. BMC Microbiol 2004; 4:42. [PMID: 15516264 PMCID: PMC529440 DOI: 10.1186/1471-2180-4-42] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2004] [Accepted: 10/29/2004] [Indexed: 12/02/2022] Open
Abstract
Background The induction of metalloprotease encoded by empA in Vibrio anguillarum occurs at high cell density in salmon intestinal mucus. Previously we have shown that there are significant differences in empA expression in two strains of V. anguillarum, M93Sm and NB10. It is hypothesized that differences in empA regulation are due to differences in binding of regulatory elements. Results Two strains of V. anguillarum, M93Sm and NB10, were examined and compared for the presence of DNA regulatory proteins that bind to and control the empA promoter region. Gel mobility shift assays, using a digoxigenin (DIG)-labeled oligomer containing a lux box-like element and the promoter for empA, were done to demonstrate the presence of a DNA-binding protein. Protein extracts from NB10 cells incubated in Luria Bertani broth + 2% NaCl (LB20), nine salts solution + 200 μg/ml mucus (NSSM), 3M (marine minimal medium), or NSS resulted in a gel mobility shift. No gel mobility shift was seen when protein extracts from either LB20- or NSSM-grown M93Sm cells were mixed with the DIG-labeled empA oligomer. The azocasein assay detected protease activity in all incubation conditions for NB10 culture supernatants. In contrast, protease activity was detected in M93Sm culture supernatants only when incubated in NSSM. Since the luxR homologue in V. anguillarum, vanT, has been cloned, sequenced, and shown to be required for protease activity, we wanted to determine if vanT mutants of NB10 exhibit the same gel shift observed in the wild-type. Site-directed mutagenesis was used to create vanT mutants in V. anguillarum M93Sm and NB10 to test whether VanT is involved with the gel mobility shift. Both vanT mutants, M02 and NB02, did not produce protease activity in any conditions. However, protein extracts from NB02 incubated in each condition still exhibited a gel shift when mixed with the DIG-labeled empA oligomer. Conclusions The data demonstrate that protein extracts of V. anguillarum NB10 cells contain a protein that binds to a 50 bp oligomer containing the empA promoter-lux box-like region. NB10 cells express empA during stationary phase in all growth conditions. The DNA binding protein is not present in M93Sm extracts. M93Sm cells express protease activity only when incubated at high cell density in fish gastrointestinal mucus. The gel shift observed with NB10 cells is not due to VanT binding. The data also suggest that the DNA binding protein is responsible for the less restrictive expression of empA in NB10 compared to M93Sm.
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30
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Denkin SM, Nelson DR. Regulation of Vibrio anguillarum empA metalloprotease expression and its role in virulence. Appl Environ Microbiol 2004; 70:4193-204. [PMID: 15240301 PMCID: PMC444792 DOI: 10.1128/aem.70.7.4193-4204.2004] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Atlantic salmon (Salmo salar) were challenged with Vibrio anguillarum strains M93Sm and NB10 and empA null mutants M99 and NB12. Both wild types were virulent when administered by intraperitoneal (i.p.) injection or anal intubation. NB12 was avirulent via either route of infection. M99 virulence was attenuated when delivered by intubation, but fully virulent by i.p. injection. Northern blot analysis revealed empA expression in M93Sm and NB10 cells incubated in mucus, while incubation in Luria-Bertani broth plus 2% NaCl (LB20) induced empA expression only in NB10. Nucleotide differences between M93Sm and NB10 empA sequences were found in regions located 207 and 229 bp upstream of the empA translational start. Reverse transcription-PCR and 5' rapid amplification of cDNA ends revealed the empA transcriptional start site 85 bp upstream of the translational start for both strains. A putative sigma(S)-dependent promoter was identified upstream of the transcriptional start in both strains. Site-directed mutagenesis was used to create rpoS mutants of M93Sm and NB10. Neither rpoS mutant exhibited protease activity. Since empA is expressed during stationary phase, the effects of conditioned medium on protease activity were examined. M99 conditioned LB20 supernatants stimulated protease activity in NB10 while allowing M93Sm to produce protease in LB20. Neither acyl homoserine lactones nor AI-2 induced protease activity. Conditioned LB20 supernatant from a V. anguillarum luxS mutant caused a more rapid induction of protease activity in wild-type cells. Our data show that expression of empA is differentially regulated in V. anguillarum strains NB10 and M93Sm and requires sigma(S), quorum-sensing molecules, and gastrointestinal mucus.
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Affiliation(s)
- Steven M Denkin
- Department of Cell and Molecular Biology, 117 Morrill Hall, University of Rhode Island, Kingston, RI 02881, USA
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Denkin SM, Nelson DR. Regulation of Vibrio anguillarum empA metalloprotease expression and its role in virulence. Appl Environ Microbiol 2004; 70:4193-4204. [PMID: 15240301 DOI: 10.1128/faem.70.7.4193-4204.2004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2023] Open
Abstract
Atlantic salmon (Salmo salar) were challenged with Vibrio anguillarum strains M93Sm and NB10 and empA null mutants M99 and NB12. Both wild types were virulent when administered by intraperitoneal (i.p.) injection or anal intubation. NB12 was avirulent via either route of infection. M99 virulence was attenuated when delivered by intubation, but fully virulent by i.p. injection. Northern blot analysis revealed empA expression in M93Sm and NB10 cells incubated in mucus, while incubation in Luria-Bertani broth plus 2% NaCl (LB20) induced empA expression only in NB10. Nucleotide differences between M93Sm and NB10 empA sequences were found in regions located 207 and 229 bp upstream of the empA translational start. Reverse transcription-PCR and 5' rapid amplification of cDNA ends revealed the empA transcriptional start site 85 bp upstream of the translational start for both strains. A putative sigma(S)-dependent promoter was identified upstream of the transcriptional start in both strains. Site-directed mutagenesis was used to create rpoS mutants of M93Sm and NB10. Neither rpoS mutant exhibited protease activity. Since empA is expressed during stationary phase, the effects of conditioned medium on protease activity were examined. M99 conditioned LB20 supernatants stimulated protease activity in NB10 while allowing M93Sm to produce protease in LB20. Neither acyl homoserine lactones nor AI-2 induced protease activity. Conditioned LB20 supernatant from a V. anguillarum luxS mutant caused a more rapid induction of protease activity in wild-type cells. Our data show that expression of empA is differentially regulated in V. anguillarum strains NB10 and M93Sm and requires sigma(S), quorum-sensing molecules, and gastrointestinal mucus.
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Affiliation(s)
- Steven M Denkin
- Department of Cell and Molecular Biology, 117 Morrill Hall, University of Rhode Island, Kingston, RI 02881, USA
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Adams MB, Nowak BF. Experimental amoebic gill disease of Atlantic salmon, Salmo salar L.: further evidence for the primary pathogenic role of Neoparamoeba sp. (Page, 1987). JOURNAL OF FISH DISEASES 2004; 27:105-113. [PMID: 15009252 DOI: 10.1111/j.1365-2761.2004.00522.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Amoebic gill disease (AGD) has been attributed to infection by Neoparamoeba sp. The causal mechanisms for AGD lesion development and the primary pathogenic role of Neoparamoeba sp. require elucidation. Three groups of Atlantic salmon were exposed to viable gill isolated amoebae, to sonicated amoebae, or to sea water containing viable amoebae without direct contact with gill epithelia. Fish were removed 8 days post-exposure and the gills assessed histologically for AGD. AGD occurred only when fish were exposed to viable trophozoites. Consequently, in an accompanying experiment, infection was evaluated histologically at 12, 24 and 48 h post-exposure in three groups of salmon, one group being mechanically injured 12 h prior to exposure. A progressive host response and significant increase (P < 0.001) in the numbers of attached amoebae was apparent over the 48-h duration in undamaged hemibranchs in both treatment groups. There were no significant differences to mucous cell populations. Attachment of Neoparamoeba sp. to damaged gill filaments was significantly reduced (P < 0.05) by 48 h post-exposure. These data further confirm and describe the primary pathogenic role of Neoparamoeba sp. and the early host response in AGD. Preliminary evidence suggests that lesions resulting from physical gill damage are not preferentially colonized by Neoparamoeba sp.
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Affiliation(s)
- M B Adams
- School of Aquaculture, Aquafin CRC Tasmanian Aquaculture and Fisheries Institute, University of Tasmania, Launceston, Tasmania, Australia.
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Characteristics of Na+-dependent respiratory chain in Vibrio anguillarum, a fish pathogen, in comparison with other marine Vibrios. FEMS Microbiol Ecol 2003; 44:225-30. [DOI: 10.1016/s0168-6496(03)00031-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Mazoy R, Osorio CR, Toranzo AE, Lemos ML. Isolation of mutants of Vibrio anguillarum defective in haeme utilisation and cloning of huvA, a gene coding for an outer membrane protein involved in the use of haeme as iron source. Arch Microbiol 2003; 179:329-38. [PMID: 12647036 DOI: 10.1007/s00203-003-0529-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2002] [Revised: 01/17/2003] [Accepted: 01/29/2003] [Indexed: 10/20/2022]
Abstract
The isolation of Vibrio anguillarum mutants lacking the ability to use haemin and haemoglobin as the only iron sources, as well as the identification of a gene involved in haeme utilisation are described. One of the isolated mutants defective in haeme utilisation lacked an iron-regulated outer membrane protein of 79-kDa. Although growth on haeme as iron source was completely abolished, the haemin and haemoglobin binding activities remained intact in the mutant, suggesting that the absent protein is not the only one involved in haeme binding. The wild-type phenotype in this mutant was restored by transformation with a cosmid clone (pML1) containing a 21-kb DNA fragment isolated from a gene library derived from the parental strain of V. anguillarum. Sequence analysis of pML1 subclones led to the finding of an ORF, huvA, that codes for a 79-kDa protein (HuvA) and whose sequence shows high identity with haeme receptors from Vibrio choleare (HutA) and Vibrio vulnificus (HupA). The sequence of huvA from the V. anguillarum haeme-utilisation mutant revealed a single mutation, leading to the synthesis of a truncated HuvA protein of 70 kDa. The parental strain and the cosmid-complemented mutant showed a higher degree of virulence for fish than the mutant strain in experimental infections in which fish were previously overloaded with haemin. This finding suggests that haeme uptake plays an important role in V. anguillarum multiplication in fish tissues when free haeme is available.
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Affiliation(s)
- Ramón Mazoy
- Departamento de Microbiología y Parasitología, Universidad de Santiago de Compostela, Facultad de Biología e Instituto de Acuicultura, 15782, Santiago de Compostela, Spain
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Fidopiastis PM, Miyamoto CM, Jobling MG, Meighen EA, Ruby EG. LitR, a new transcriptional activator in Vibrio fischeri, regulates luminescence and symbiotic light organ colonization. Mol Microbiol 2002; 45:131-43. [PMID: 12100554 DOI: 10.1046/j.1365-2958.2002.02996.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Vibrio fischeri is the bacterial symbiont within the light-emitting organ of the sepiolid squid Euprymna scolopes. Upon colonizing juvenile squids, bacterial symbionts grow on host-supplied nutrients, while providing a bioluminescence that the host uses during its nocturnal activities. Mutant bacterial strains that are unable to emit light have been shown to be defective in normal colonization. A 606 bp open reading frame was cloned from V. fischeri that encoded a protein, which we named LitR, that had about 60% identity to four related regulator proteins: Vibrio cholerae HapR, Vibrio harveyi LuxR, Vibrio parahaemolyticus OpaR and Vibrio vulnificus SmcR. When grown in culture, cells of V. fischeri strain PMF8, in which litR was insertionally inactivated, were delayed in the onset of luminescence induction and emitted only about 20% as much light per cell as its parent. Protein-binding studies suggested that LitR enhances quorum sensing by regulating the transcription of the luxR gene. Interestingly, when competed against its parent in mixed inocula, PMF8 became the predominant symbiont present in 83% of light organs. Thus, the litR mutation appears to represent a novel class of mutations in which the loss of a regulatory gene function enhances the bacterium's competence in initiating a benign infection.
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Affiliation(s)
- Pat M Fidopiastis
- Pacific Biomedical Research Center, University of Hawai'i, Honolulu, 96813, USA
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Larsen MH, Larsen JL, Olsen JE. Chemotaxis of Vibrio anguillarum to fish mucus: role of the origin of the fish mucus, the fish species and the serogroup of the pathogen. FEMS Microbiol Ecol 2001. [DOI: 10.1111/j.1574-6941.2001.tb00884.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Rowe HA, Poxton IR, Donachie W. Survival of Mannheimia (Pasteurella) haemolytica in tracheobronchial washings of sheep and cattle. Vet Microbiol 2001; 81:305-14. [PMID: 11390112 DOI: 10.1016/s0378-1135(01)00361-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The growth, morphology and long-term survival of a representative isolate of Mannheimia haemolytica serotypes A1 and A2 were monitored in ovine and bovine tracheobronchial washings. Both strains survived for at least 244 days in ovine tracheobronchial washings and 156 days in bovine tracheobronchial washings. The addition of fresh washings at these times prompted an increase for serotype A2 but no change in viability for serotype A1 in ovine tracheobronchial washings and an increase for both serotypes in bovine tracheobronchial washings. When growth and survival was compared using tracheobronchial washings from ruminant and non-ruminant species there was a trend towards longer survival in ruminant fluids.Long-term survival was associated with temporary or permanent change from normal size colonies to 'micro-colonies' on sheep blood agar. Subculture allowed reversion to normal colony morphology. Analysis showed these micro-colonies to consist of chains of elongated bacteria. M. haemolytica serotype A2 was more robust in its ability to withstand nutrient deprivation for long periods of time. These survival mechanisms may have important implications for pathogenesis.
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Affiliation(s)
- H A Rowe
- Moredun Research Institute, International Research Centre, Pentlands Science Park, Bush Loan, Penicuik, Midlothian, EH26 OPZ, Scotland, UK
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Secades P, Alvarez B, Guijarro JA. Purification and characterization of a psychrophilic, calcium-induced, growth-phase-dependent metalloprotease from the fish pathogen Flavobacterium psychrophilum. Appl Environ Microbiol 2001; 67:2436-44. [PMID: 11375148 PMCID: PMC92892 DOI: 10.1128/aem.67.6.2436-2444.2001] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Flavobacterium psychrophilum is a fish pathogen that commonly affects salmonids. This bacterium produced an extracellular protease with an estimated molecular mass of 55 kDa. This enzyme, designated Fpp1 (F. psychrophilum protease 1), was purified to electrophoretic homogeneity from the culture supernatant by using ammonium sulfate precipitation, ion-exchange chromatography, hydrophobic chromatography, and size exclusion chromatography. On the basis of its biochemical characteristics, Fpp1 can be included in the group of metalloproteases that have an optimum pH for activity of 6.5 and are inhibited by 1,10-phenanthroline, EDTA, or EGTA but not by phenylmethylsulfonyl fluoride. Fpp1 activity was dependent on calcium ions not only for its activity but also for its thermal stability. In addition to calcium, strontium and barium can activate the protein. The enzyme showed typical psychrophilic behavior; it had an activation energy of 5.58 kcal/mol and was more active at temperatures between 25 and 40 degrees C, and its activity decreased rapidly at 45 degrees C. Fpp1 cleaved gelatin, laminin, fibronectin, fibrinogen, collagen type IV, and, to a lesser extent, collagen types I and II. Fpp1 also degraded actin and myosin, basic elements of the fish muscular system. The presence of this enzyme in culture media was specifically dependent on the calcium concentration. Fpp1 production started early in the exponential growth phase and reached a maximum during this period. Addition of calcium during the stationary phase did not induce Fpp1 production at all. Besides calcium and the growth phase, temperature also seems to play a role in production of Fpp1. In this study we found that production of Fpp1 depends on factors such as calcium concentration, growth phase of the culture, and temperature. The combination of these parameters corresponds to the combination in the natural host during outbreaks of disease caused by F. psychrophilum. Consequently, we suggest that environmental host factors govern Fpp1 production.
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Affiliation(s)
- P Secades
- Area de Microbiología, Departamento de Biología Funcional, Facultad de Medicina, Instituto Universitario de Biotecnología de Asturias, Universidad de Oviedo, 33006 Oviedo, Spain
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Verschuere L, Rombaut G, Sorgeloos P, Verstraete W. Probiotic bacteria as biological control agents in aquaculture. Microbiol Mol Biol Rev 2000; 64:655-71. [PMID: 11104813 PMCID: PMC99008 DOI: 10.1128/mmbr.64.4.655-671.2000] [Citation(s) in RCA: 705] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
There is an urgent need in aquaculture to develop microbial control strategies, since disease outbreaks are recognized as important constraints to aquaculture production and trade and since the development of antibiotic resistance has become a matter of growing concern. One of the alternatives to antimicrobials in disease control could be the use of probiotic bacteria as microbial control agents. This review describes the state of the art of probiotic research in the culture of fish, crustaceans, mollusks, and live food, with an evaluation of the results obtained so far. A new definition of probiotics, also applicable to aquatic environments, is proposed, and a detailed description is given of their possible modes of action, i.e., production of compounds that are inhibitory toward pathogens, competition with harmful microorganisms for nutrients and energy, competition with deleterious species for adhesion sites, enhancement of the immune response of the animal, improvement of water quality, and interaction with phytoplankton. A rationale is proposed for the multistep and multidisciplinary process required for the development of effective and safe probiotics for commercial application in aquaculture. Finally, directions for further research are discussed.
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Affiliation(s)
- L Verschuere
- Laboratory of Microbial Ecology and Technology, Department of Biochemical and Microbiological Technology, Ghent University, 9000 Ghent, Belgium
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Ormonde P, Hörstedt P, O'Toole R, Milton DL. Role of motility in adherence to and invasion of a fish cell line by Vibrio anguillarum. J Bacteriol 2000; 182:2326-8. [PMID: 10735880 PMCID: PMC111286 DOI: 10.1128/jb.182.8.2326-2328.2000] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To understand further the role of the flagellum of Vibrio anguillarum in virulence, invasive and adhesive properties of isogenic motility mutants were analyzed by using a chinook salmon embryo cell line. Adhesion was unaffected but invasion of the cell line was significantly decreased in nonmotile or partially motile mutants, and the chemotactic mutant was hyperinvasive. These results suggest that active motility aids invasion by V. anguillarum, both in vivo and in vitro.
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Affiliation(s)
- P Ormonde
- Department of Cell and Molecular Biology, Pathology, Umeâ University, S-901 87 Umeå, Sweden
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41
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Alban PS, Johnson PW, Nelson DR. Serum-starvation-induced changes in protein synthesis and morphology of Borrelia burgdorferi. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 1):119-127. [PMID: 10658658 DOI: 10.1099/00221287-146-1-119] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
It has been demonstrated previously that motile Borrelia burgdorferi cells transform into non-motile cyst-forms when incubated for several weeks in BSKII (a complex medium) lacking rabbit serum. B. burgdorferi cells cannot synthesize fatty acids de novo and serum is thought to provide a source of fatty acids and lipids. When B. burgdorferi cells were serum-starved in defined RPMI medium, -90% of the cells formed spherical cysts within 48 h. Cyst formation was inhibited by tetracycline. Cyst opening and recovery of vegetative cells was rapidly induced by the addition of either BSKII or rabbit serum. The percentage of viable cells recovered from cysts ranged from 2.9% to 52-5%. Viability was inversely proportional to cyst age. Protein synthesis by B. burgdorferi during serum starvation was examined by labelling cells with Tran35S-Label and analysing the labelled proteins by two-dimensional gel electrophoresis and fluorography. The synthesis of over 20 proteins was induced during serum starvation. Western blots of proteins from vegetative cells and cysts probed with sera from either B. burgdorferi-infected humans or monkeys revealed that several cyst proteins were antigenic. These data suggest that cells of B. burgdorferi, although possessing a small genome and extremely limited biosynthetic capabilities, rapidly respond to conditions of serum starvation by inducing changes in protein synthesis and cell morphology. This study may help explain how cells of B. burgdorferi can survive periods of nutrient deprivation in different hosts and host tissues.
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Affiliation(s)
- P Scott Alban
- Department of Biochemistry, Microbiology, and Molecular Genetics1, and Electron Microscope Facility2, University of Rhode Island, Kingston, RI 02881, USA
| | - Paul W Johnson
- Department of Biochemistry, Microbiology, and Molecular Genetics1, and Electron Microscope Facility2, University of Rhode Island, Kingston, RI 02881, USA
| | - David R Nelson
- Department of Biochemistry, Microbiology, and Molecular Genetics1, and Electron Microscope Facility2, University of Rhode Island, Kingston, RI 02881, USA
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42
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Denkin SM, Nelson DR. Induction of protease activity in Vibrio anguillarum by gastrointestinal mucus. Appl Environ Microbiol 1999; 65:3555-60. [PMID: 10427048 PMCID: PMC91533 DOI: 10.1128/aem.65.8.3555-3560.1999] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The effect of gastrointestinal mucus on protease activity in Vibrio anguillarum was investigated. Protease activity was measured by using an azocasein hydrolysis assay. Cells grown to stationary phase in mucus (200 microg of mucus protein/ml) exhibited ninefold-greater protease activity than cells grown in Luria-Bertani broth plus 2% NaCl (LB20). Protease induction was examined with cells grown in LB20 and resuspended in mucus, LB20, nine-salts solution (NSS [a carbon-, nitrogen-, and phosphorus-free salt solution]), or marine minimal medium (3M) ( approximately 10(9) CFU/ml). Induction of protease activity occurred 60 to 90 min after addition of mucus and was >/=70-fold greater than protease activity measured in cells incubated in either LB20 or 3M. Mucus was fractionated into aqueous and chloroform-methanol-soluble fractions. The aqueous fraction supported growth of V. anguillarum cells, but did not induce protease activity. The chloroform-methanol-soluble fraction did not support growth, nor did it induce protease activity. When the two fractions were mixed, protease activity was induced. The chloroform-methanol-soluble fraction did not induce protease activity in cells growing in LB20. EDTA (50 mM) inhibited the protease induced by mucus. Upon addition of divalent cations, Mg(2+) (100 mM) was more effective than equimolar amounts of either Ca(2+) or Zn(2+) in restoring activity, suggesting that the mucus-inducible protease was a magnesium-dependent metalloprotease. An empA mutant strain of V. anguillarum did not exhibit protease activity after exposure to mucus, but did grow in mucus. Southern analysis and PCR amplification confirmed that V. anguillarum M93 contained empA. These data demonstrate that the empA metalloprotease of V. anguillarum is specifically induced by gastrointestinal mucus.
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Affiliation(s)
- S M Denkin
- Department of Biochemistry, Microbiology, and Molecular Genetics, University of Rhode Island, Kingston, Rhode Island 02881, USA
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43
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O'Toole R, Lundberg S, Fredriksson SA, Jansson A, Nilsson B, Wolf-Watz H. The chemotactic response of Vibrio anguillarum to fish intestinal mucus is mediated by a combination of multiple mucus components. J Bacteriol 1999; 181:4308-17. [PMID: 10400589 PMCID: PMC93933 DOI: 10.1128/jb.181.14.4308-4317.1999] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chemotactic motility has previously been shown to be essential for the virulence of Vibrio anguillarum in waterborne infections of fish. To investigate the mechanisms by which chemotaxis may function during infection, mucus was isolated from the intestinal and skin epithelial surfaces of rainbow trout. Chemotaxis assays revealed that V. anguillarum swims towards both types of mucus, with a higher chemotactic response being observed for intestinal mucus. Work was performed to examine the basis, in terms of mucus composition, of this chemotactic response. Intestinal mucus was analyzed by using chromatographic and mass spectrometric techniques, and the compounds identified were tested in a chemotaxis assay to determine the attractants present. A number of mucus-associated components, in particular, amino acids and carbohydrates, acted as chemoattractants for V. anguillarum. Importantly, only upon combination of these attractants into a single mixture were levels of chemotactic activity similar to those of intestinal mucus generated. A comparative analysis of skin mucus revealed its free amino acid and carbohydrate content to be considerably lower than that of the more chemotactically active intestinal mucus. To study whether host specificity exists in relation to vibrio chemotaxis towards mucus, comparisons with a human Vibrio pathogen were made. A cheR mutant of a Vibrio cholerae El Tor strain was constructed, and it was found that V. cholerae and V. anguillarum exhibit a chemotactic response to mucus from several animal sources in addition to that from the human jejunum and fish epithelium, respectively.
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Affiliation(s)
- R O'Toole
- Department of Cell and Molecular Biology, Umeå University, S-901 87 Umeå, Sweden.
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Balebona MC, Andreu MJ, Bordas MA, Zorrilla I, Moriñigo MA, Borrego JJ. Pathogenicity of Vibrio alginolyticus for cultured gilt-head sea bream (Sparus aurata L.). Appl Environ Microbiol 1998; 64:4269-75. [PMID: 9797276 PMCID: PMC106638 DOI: 10.1128/aem.64.11.4269-4275.1998] [Citation(s) in RCA: 117] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The in vivo and in vitro pathogenic activities of whole cells and extracellular products of Vibrio alginolyticus for cultured gilt-head sea bream were evaluated. The 50% lethal doses ranged from 5.4 x 10(4) to 1.0 x 10(6) CFU/g of body weight. The strains examined had the ability to adhere to skin, gill, and intestinal mucus of sea bream and to cultured cells of a chinook salmon embryo cell line. In addition, the in vitro ability of V. alginolyticus to adhere to mucus and skin cells of sea bream was demonstrated by scanning electron microscopy. The biological activities of extracellular products of V. alginolyticus were hydrolytic activities; the products were able to degrade sea bream mucus. V. alginolyticus was cytotoxic for fish cell lines and lethal for sea bream. Moreover, the extracellular products could degrade sea bream tissues. However, experiments performed with the bath immersion inoculation technique demonstrated that V. alginolyticus should be considered a pathogen for sea bream only when the mucus layer is removed and the skin is damaged.
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Affiliation(s)
- M C Balebona
- Departments of Microbiology, Faculty of Sciences, University of Malaga, Campus de Teatinos, 29071 Malaga, Spain
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45
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Bordas MA, Balebona MC, Rodriguez-Maroto JM, Borrego JJ, Morinigo MA. Chemotaxis of pathogenic Vibrio strains towards mucus surfaces of gilt-head sea bream (Sparus aurata L.). Appl Environ Microbiol 1998; 64:1573-5. [PMID: 9575135 PMCID: PMC106193 DOI: 10.1128/aem.64.4.1573-1575.1998] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Vibrio anguillarum and Vibrio alginolyticus exhibited significant adhesion to and chemotactic abilities towards mucus collected from the skin, gills, and intestine of gilt-head sea bream. Quadratic polynomial models for chemotaxis designed to estimate the influence of temperature demonstrated a differential bacterial chemotaxis depending of the source of the mucus, with the chemotaxis towards intestinal mucus being the least influenced.
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Affiliation(s)
- M A Bordas
- Department of Microbiology, University of Malaga, Spain
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