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Verebélyi V, Erdei N, Hardy T, Eszterbauer E. Description of Saprolegnia velencensis sp. n. (Oomycota), a novel water mold species from Lake Velence, Hungary. PLoS One 2024; 19:e0298814. [PMID: 38507310 PMCID: PMC10954141 DOI: 10.1371/journal.pone.0298814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 01/19/2024] [Indexed: 03/22/2024] Open
Abstract
Here, we describe a novel water mold species, Saprolegnia velencensis sp. n. from Lake Velence, in Hungary. Two strains (SAP239 and SAP241) were isolated from lake water, and characterized using morphological and molecular markers. In addition, phylogenetic analyses based on ITS-rDNA regions and on the RNA polymerase II B subunit (RPB2) gene complemented the study. The ITS-rDNA of the two strains was 100% identical, showed the highest similarity to that of S. ferax (with 94.4% identity), and they formed a separate cluster in both the ITS-rDNA and RPB2-based maximum likelihood phylogenetic trees with high bootstrap support. Although mature oogonia and antheridia were not seen under in vitro conditions, the S. velencensis sp. n. could be clearly distinguished from its closest relative, S. ferax, by the length and width of sporangia, as the new species had shorter and narrower sporangia (163.33±70.07 and 36.69±8.27 μm, respectively) than those of S. ferax. The two species also differed in the size of the secondary cysts (11.63±1.77 μm), which were slightly smaller in S. ferax. Our results showed that S. velencensis sp. n. could not be identified with any of the previously described water mold species, justifying its description as a new species.
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Affiliation(s)
| | - Noémi Erdei
- HUN-REN Veterinary Medical Research Institute, Budapest, Hungary
| | - Tímea Hardy
- HUN-REN Veterinary Medical Research Institute, Budapest, Hungary
| | - Edit Eszterbauer
- HUN-REN Veterinary Medical Research Institute, Budapest, Hungary
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Shreves KV, Saraiva M, Ruba T, Miller C, Scott EM, McLaggan D, van West P. Specific Phylotypes of Saprolegnia parasitica Associated with Atlantic Salmon Freshwater Aquaculture. J Fungi (Basel) 2024; 10:57. [PMID: 38248966 PMCID: PMC10820671 DOI: 10.3390/jof10010057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 12/13/2023] [Accepted: 12/28/2023] [Indexed: 01/23/2024] Open
Abstract
Saprolegniosis is a major destructive disease in freshwater aquaculture. The destructive economic impact of saprolegniosis on freshwater aquaculture necessitates further study on the range of Saprolegnia species within Atlantic salmon fish farms. This study undertook a thorough analysis of a total of 412 oomycete and fungal isolates that were successfully cultured and sequenced from 14 aquaculture sites in Scotland across a two-year sampling period. An ITS phylogenetic analysis of all isolates was performed according to whether they were isolated from fish or water samples and during enzootic or epizootic periods. Several genera of oomycetes were isolated from sampling sites, including Achlya, Leptolegnia, Phytophthora, and Pythium, but by far the most prevalent was Saprolegnia, accounting for 66% of all oomycetes isolated. An analysis of the ITS region of Saprolegnia parasitica showed five distinct phylotypes (S2-S6); S1 was not isolated from any site. Phylotype S2 was the most common and most widely distributed phylotype, being found at 12 of the 14 sampling sites. S2 was overwhelmingly sampled from fish (93.5%) and made up 91.1% of all S. parasitica phylotypes sampled during epizootics, as well as 67.2% of all Saprolegnia. This study indicates that a single phylotype may be responsible for Saprolegnia outbreaks in Atlantic salmon fish farms, and that water sampling and spore counts alone may be insufficient to predict Saprolegnia outbreaks in freshwater aquaculture.
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Affiliation(s)
- Kypher Varin Shreves
- International Centre for Aquaculture Research and Development (ICARD), Aberdeen Oomycete Laboratory, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK; (K.V.S.); (M.S.); (T.R.); (D.M.)
| | - Marcia Saraiva
- International Centre for Aquaculture Research and Development (ICARD), Aberdeen Oomycete Laboratory, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK; (K.V.S.); (M.S.); (T.R.); (D.M.)
| | - Tahmina Ruba
- International Centre for Aquaculture Research and Development (ICARD), Aberdeen Oomycete Laboratory, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK; (K.V.S.); (M.S.); (T.R.); (D.M.)
- Department of Pathology, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
| | - Claire Miller
- School Mathematics and Statistics, University of Glasgow, Glasgow G12 8TA, UK; (C.M.); (E.M.S.)
| | - E. Marian Scott
- School Mathematics and Statistics, University of Glasgow, Glasgow G12 8TA, UK; (C.M.); (E.M.S.)
| | - Debbie McLaggan
- International Centre for Aquaculture Research and Development (ICARD), Aberdeen Oomycete Laboratory, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK; (K.V.S.); (M.S.); (T.R.); (D.M.)
| | - Pieter van West
- International Centre for Aquaculture Research and Development (ICARD), Aberdeen Oomycete Laboratory, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK; (K.V.S.); (M.S.); (T.R.); (D.M.)
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Erdei N, Hardy T, Verebélyi V, Weiperth A, Baska F, Eszterbauer E. New Insights into the Morphological Diversity of Saprolegnia parasitica (Oomycota) Strains under In Vitro Culture Conditions. J Fungi (Basel) 2023; 9:982. [PMID: 37888238 PMCID: PMC10607735 DOI: 10.3390/jof9100982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 09/17/2023] [Accepted: 09/27/2023] [Indexed: 10/28/2023] Open
Abstract
Saprolegnia parasitica Coker, 1923 is a primary fish pathogen and one of the most common water molds in freshwater ecosystems. In our study, nineteen strains of S. parasitica were isolated, identified, and characterized using morphological and genetic markers. On the basis of the abundance of zoosporangia, gemmae, the formation of gemma chains, and the induction of zoospore release, three morphotypes were differentiated. A species-level molecular identification of isolates was performed using the ITS 1 and 2 regions. A total of six genotypes were distinguished based on partial DNA sequences of the genes RNA polymerase II subunit B (RPB2) and serine hydroxymethyltransferase (SHMT). In five settings of in vitro culture conditions differing in the mineral content and the temperature of water and in the presence of a host or bait, we found that the addition of fish skin extract boosted the formation of asexual reproductive and persistent vegetative structures in cultures, whereas an unfavorable environment did not support the formation of these structures in vitro.
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Affiliation(s)
- Noémi Erdei
- HUN-REN Veterinary Medical Research Institute, 1143 Budapest, Hungary; (N.E.); (T.H.)
| | - Tímea Hardy
- HUN-REN Veterinary Medical Research Institute, 1143 Budapest, Hungary; (N.E.); (T.H.)
| | - Viktória Verebélyi
- HUN-REN Veterinary Medical Research Institute, 1143 Budapest, Hungary; (N.E.); (T.H.)
| | - András Weiperth
- Department of Freshwater Fish Ecology, Institute of Aquaculture and Environmental Safety, Hungarian University of Agriculture and Life Sciences, 2100 Gödöllő, Hungary
| | - Ferenc Baska
- Department of Exotic Animal and Wildlife Medicine, University of Veterinary Medicine Budapest, 1078 Budapest, Hungary
| | - Edit Eszterbauer
- HUN-REN Veterinary Medical Research Institute, 1143 Budapest, Hungary; (N.E.); (T.H.)
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Pavić D, Grbin D, Hudina S, Prosenc Zmrzljak U, Miljanović A, Košir R, Varga F, Ćurko J, Marčić Z, Bielen A. Tracing the oomycete pathogen Saprolegnia parasitica in aquaculture and the environment. Sci Rep 2022; 12:16646. [PMID: 36198674 PMCID: PMC9534867 DOI: 10.1038/s41598-022-16553-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 07/12/2022] [Indexed: 11/25/2022] Open
Abstract
Saprolegnia parasitica causes saprolegniosis, a disease responsible for significant economic losses in aquaculture and declines of fish populations in the wild, but the knowledge of its distribution and prevalence in the environment is limited. We developed a fast, sensitive and specific S. parasitica droplet digital PCR (ddPCR) assay and demonstrated its applicability for the detection and quantification of the pathogen in environmental samples: swab DNA collected from the host (trout skin, surface of eggs) and environmental DNA extracted from water. The developed assay was used to assess how abiotic (i.e. physico-chemical parameters of the water) and biotic (health status of the host) factors influence the S. parasitica load in the environment. The pathogen load in water samples was positively correlated with some site-specific abiotic parameters such as electrical conductivity (EC) and calcium, while fluorides were negatively correlated, suggesting that physico-chemical parameters are important for determining S. parasitica load in natural waters. Furthermore, skin swabs of injured trout had significantly higher pathogen load than swabs collected from healthy fish, confirming that S. parasitica is a widespread opportunistic pathogen. Our results provide new insights into various environmental factors that influence the distribution and abundance of S. parasitica.
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Affiliation(s)
- Dora Pavić
- Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, 10000, Zagreb, Croatia
| | - Dorotea Grbin
- Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, 10000, Zagreb, Croatia.,Department of Biology, Faculty of Science, University of Zagreb, 10000, Zagreb, Croatia
| | - Sandra Hudina
- Department of Biology, Faculty of Science, University of Zagreb, 10000, Zagreb, Croatia
| | | | - Anđela Miljanović
- Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, 10000, Zagreb, Croatia
| | - Rok Košir
- Labena Ltd, BIA Separations CRO - Molecular Biology Laboratory, 1000, Ljubljana, Slovenia
| | - Filip Varga
- Department of Seed Science and Technology, Faculty of Agriculture, University of Zagreb, 10000, Zagreb, Croatia.,Centre of Excellence for Biodiversity and Molecular Plant Breeding, CoE CroP-BioDiv), 10000, Zagreb, Croatia
| | - Josip Ćurko
- Department of Food Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, 10000, Zagreb, Croatia
| | - Zoran Marčić
- Department of Biology, Faculty of Science, University of Zagreb, 10000, Zagreb, Croatia
| | - Ana Bielen
- Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, 10000, Zagreb, Croatia.
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Pavić D, Grbin D, Gregov M, Ćurko J, Vladušić T, Šver L, Miljanović A, Bielen A. Variations in the Sporulation Efficiency of Pathogenic Freshwater Oomycetes in Relation to the Physico-Chemical Properties of Natural Waters. Microorganisms 2022; 10:microorganisms10030520. [PMID: 35336096 PMCID: PMC8955207 DOI: 10.3390/microorganisms10030520] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 02/16/2022] [Accepted: 02/25/2022] [Indexed: 01/27/2023] Open
Abstract
Oomycete pathogens in freshwaters, such as Saprolegnia parasitica and Aphanomyces astaci, are responsible for fish/crayfish population declines in the wild and disease outbreaks in aquaculture. Although the formation of infectious zoospores in the laboratory can be triggered by washing their mycelium with natural water samples, the physico-chemical properties of the water that might promote sporulation are still unexplored. We washed the mycelia of A. astaci and S. parasitica with a range of natural water samples and observed differences in sporulation efficiency. The results of Partial Least Squares Regression (PLS-R) multivariate analysis showed that SAC (spectral absorption coefficient measured at 254 nm), DOC (dissolved organic carbon), ammonium-N and fluoride had the strongest positive effect on sporulation of S. parasitica, while sporulation of A. astaci was not significantly correlated with any of the analyzed parameters. In agreement with this, the addition of environmentally relevant concentrations of humic acid, an important contributor to SAC and DOC, to the water induced sporulation of S. parasitica but not of A. astaci. Overall, our results point to the differences in ecological requirements of these pathogens, but also present a starting point for optimizing laboratory protocols for the induction of sporulation.
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Hierweger MM, Koch MC, Rupp M, Maes P, Di Paola N, Bruggmann R, Kuhn JH, Schmidt-Posthaus H, Seuberlich T. Novel Filoviruses, Hantavirus, and Rhabdovirus in Freshwater Fish, Switzerland, 2017. Emerg Infect Dis 2021; 27:3082-3091. [PMID: 34808081 PMCID: PMC8632185 DOI: 10.3201/eid2712.210491] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
European perch (Perca fluviatilis) are increasingly farmed as a human food source. Viral infections of European perch remain largely unexplored, thereby putting farm populations at incalculable risk for devastating fish epizootics and presenting a potential hazard to consumers. To address these concerns, we applied metatranscriptomics to identify disease-associated viruses in European perch farmed in Switzerland. Unexpectedly, in clinically diseased fish we detected novel freshwater fish filoviruses, a novel freshwater fish hantavirus, and a previously unknown rhabdovirus. Hantavirus titers were high, and we demonstrated virus in macrophages and gill endothelial cells by using in situ hybridization. Rhabdovirus titers in organ samples were low, but virus could be isolated on cell culture. Our data add to the hypothesis that filoviruses, hantaviruses, and rhabdoviruses are globally distributed common fish commensals, pathogens, or both. Our findings shed new light on negative-sense RNA virus diversity and evolution.
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Sarowar MN, Cusack R, Duston J. Saprolegnia molecular phylogeny among farmed teleosts in Nova Scotia, Canada. JOURNAL OF FISH DISEASES 2019; 42:1745-1760. [PMID: 31637741 DOI: 10.1111/jfd.13090] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 09/04/2019] [Indexed: 06/10/2023]
Abstract
To identify the pathogens causing saprolegniosis among farmed fish in Nova Scotia, 172 infected tissues and 23 water samples were collected from six species of teleosts: Atlantic salmon (Salmo salar), brown trout (Salmo trutta), Arctic charr (Salvelinus alpinus), brook trout (Salvelinus fontinalis), striped bass (Morone saxatilis) and rainbow trout (Oncorhynchus mykiss) at nine facilities over a 600 km range. Following laboratory culture, 132 isolates were recovered. Six species of oomycetes were identified from analysis of the internal transcribed spacer (ITS) sequence of the nrDNA: Saprolegnia parasitica, Saprolegnia ferax, Saprolegnia diclina, Saprolegnia aenigmatica, Saprolegnia torulosa, Saprolegnia sp. and Pythiopsis cymosa. Further phylogenetic analyses of the ITS and cytochrome c oxidase subunit 1 (Cox1) regions revealed four strains of Saprolegnia parasitica (named here as S1, S2, S3 and S4), of which S1 and S2 were common (37% and 42% of the isolates), and two strains of S. ferax. Among S. parasitica, S2 and S3 are more closely related to each other than to S1 based on the phylogenetic analyses and predicted RNA secondary structure of the ITS region. Sexual structures with a similar morphology were formed by S1 and S3 in vitro, but were not formed by S2.
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Affiliation(s)
- Mohammad Nasif Sarowar
- Department of Animal Science and Aquaculture, Agricultural Campus, Dalhousie University, Bible Hill, Canada
| | - Roland Cusack
- Nova Scotia Department of Fisheries and Aquaculture, Agricultural Campus, Hancock Veterinary Building, Bible Hill, Canada
| | - James Duston
- Department of Animal Science and Aquaculture, Agricultural Campus, Dalhousie University, Bible Hill, Canada
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