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Karami AM, Duan Y, Kania PW, Buchmann K. Responses towards eyefluke (Diplostomum pseudospathaceum) in different genetic lineages of rainbow trout. PLoS One 2022; 17:e0276895. [PMID: 36301982 PMCID: PMC9612474 DOI: 10.1371/journal.pone.0276895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 10/17/2022] [Indexed: 11/18/2022] Open
Abstract
Marker-assisted selective breeding of fish with higher levels of resistance towards specific pathogens may improve fish health, but the impact of host genotype on susceptibility to multiple pathogen infections is still poorly investigated. This study examined the resistance in rainbow trout Oncorhynchus mykiss towards infection with the eye fluke Diplostomum pseudospathaceum. We used genetically selected rainbow trout, carrying SNPs associated with resistance towards the parasitic ciliate Ichthyophthirius multifiliis, and exposed the fish to eye fluke cercariae. We showed that fish partly resistant to I. multifiliis were more susceptible to eye fluke invasion. The expression of immune relevant genes (encoding innate and adaptive factors) was also affected as these genotypes responded less strongly to a secondary fluke infection. The complexity of genome architecture in disease resistance towards multiple pathogens is discussed.
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Affiliation(s)
- Asma M. Karami
- Laboratory of Aquatic Pathobiology, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
- * E-mail:
| | - Yajiao Duan
- Laboratory of Aquatic Pathobiology, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Per W. Kania
- Laboratory of Aquatic Pathobiology, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Kurt Buchmann
- Laboratory of Aquatic Pathobiology, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
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2
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Saleh M, Abdel-Baki AAS, Dkhil MA, El-Matbouli M, Al-Quraishy S. Proteins of the Ciliated Protozoan Parasite Ichthyophthirius multifiliis Identified in Common Carp Skin Mucus. Pathogens 2021; 10:pathogens10070790. [PMID: 34206679 PMCID: PMC8308598 DOI: 10.3390/pathogens10070790] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/18/2021] [Accepted: 06/19/2021] [Indexed: 12/24/2022] Open
Abstract
The skin mucus is the fish primary defense barrier protecting from infections via the skin epidermis. In a previous study, we have investigated the proteome of common carp (Cyprinus carpio) skin mucus at two different time points (1 and 9 days) post-exposure to Ichthyophthirius multifiliis. Applying a nano-LC ESI MS/MS technique, we have earlier revealed that the abundance of 44 skin mucus proteins has been differentially regulated including proteins associated with host immune responses and wound healing. Herein, in skin mucus samples, we identified six proteins of I. multifiliis associated with the skin mucus in common carp. Alpha and beta tubulins were detected in addition to the elongation factor alpha, 26S proteasome regulatory subunit, 26S protease regulatory subunit 6B, and heat shock protein 90. The identified proteins are likely involved in motility, virulence, and general stress during parasite growth and development after parasite attachment and invasion. Two KEGG pathways, phagosome and proteasome, were identified among these parasite proteins, mirroring the proteolytic and phagocytic activities of this parasite during host invasion, growth, and development, which represent a plausible host invasion strategy of this parasite. The results obtained from this study can support revealing molecular aspects of the interplay between carp and I. multifiliis and may help us understand the I. multifiliis invasion strategy at the skin mucus barrier. The data may advance the development of novel drugs, vaccines, and diagnostics suitable for the management and prevention of ichthyophthiriosis in fish.
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Affiliation(s)
- Mona Saleh
- Clinical Division of Fish Medicine, University of Veterinary Medicine, 1210 Vienna, Austria;
- Correspondence: ; Tel.: +43-(12)-5077-4736
| | - Abdel-Azeem S. Abdel-Baki
- Zoology Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (A.-A.S.A.-B.); (M.A.D.); (S.A.-Q.)
- Zoology Department, Faculty of Science, Beni-Suef University, Beni-Suef 62521, Egypt
| | - Mohamed A. Dkhil
- Zoology Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (A.-A.S.A.-B.); (M.A.D.); (S.A.-Q.)
- Department of Zoology and Entomology, Faculty of Science, Helwan University, Cairo 11795, Egypt
| | - Mansour El-Matbouli
- Clinical Division of Fish Medicine, University of Veterinary Medicine, 1210 Vienna, Austria;
| | - Saleh Al-Quraishy
- Zoology Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (A.-A.S.A.-B.); (M.A.D.); (S.A.-Q.)
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3
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Saleh M, Kumar G, Abdel-Baki AAS, Dkhil MA, El-Matbouli M, Al-Quraishy S. Quantitative proteomic profiling of immune responses to Ichthyophthirius multifiliis in common carp skin mucus. FISH & SHELLFISH IMMUNOLOGY 2019; 84:834-842. [PMID: 30385245 DOI: 10.1016/j.fsi.2018.10.078] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 10/23/2018] [Accepted: 10/28/2018] [Indexed: 06/08/2023]
Abstract
Ichthyophthirius multifiliis, a ciliated protozoan parasite, causes ichthyophthiriasis and leads to considerable economic losses to the aquaculture industry. Understanding the fish immune response and host-parasite interactions could support developing novel strategies for better disease management and control. Fish skin mucus is the first line of defence against infections through the epidermis. Yet, the common carp, Cyprinus carpio, protein-based defence strategies against infection with I. multifiliis at this barrier remain elusive. The skin mucus proteome of common carp was investigated at 1 day and 9 days post-exposure with I. multifiliis. Using nano-LC ESI MS/MS and statistical analysis, the abundance of 19 immune related and signal transduction proteins was found to be differentially regulated in skin mucus of common carp in response to I. multifiliis. The analysis revealed increased abundance values of epithelial chloride channel protein, galactose-specific lectin nattection, high choriolytic enzyme 1 (nephrosin), lysozyme C, granulin and protein-glutamine gamma-glutamyltransferase 2 in I. multifiliis-exposed carp skin mucus. Multiple lectins and a diverse array of distinct serpins with protease inhibitor activity were identified likely implicated in lectin pathway activation and regulation of proteolysis, indicating that these proteins contribute to the carp innate immune system and the protective properties of skin mucus. The results obtained from this proteomic analysis enables a better understanding of fish host response to parasitic infection and gives insights into the key role skin mucus plays in protecting fish against deleterious effects of I. multifiliis.
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Affiliation(s)
- Mona Saleh
- Clinical Division of Fish Medicine, University of Veterinary Medicine, Vienna, Austria.
| | - Gokhlesh Kumar
- Clinical Division of Fish Medicine, University of Veterinary Medicine, Vienna, Austria
| | - Abdel-Azeem S Abdel-Baki
- Zoology Department, College of Science, King Saud University, Riyadh, Saudi Arabia; Zoology Department, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt
| | - Mohamed A Dkhil
- Zoology Department, College of Science, King Saud University, Riyadh, Saudi Arabia; Department of Zoology and Entomology, Faculty of Science, Helwan University, Cairo, Egypt
| | - Mansour El-Matbouli
- Clinical Division of Fish Medicine, University of Veterinary Medicine, Vienna, Austria
| | - Saleh Al-Quraishy
- Zoology Department, College of Science, King Saud University, Riyadh, Saudi Arabia
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4
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Reyes-Becerril M, Alamillo E, Trasviña A, Hirono I, Kondo H, Jirapongpairoj W, Ascencio-Valle F, Angulo C. In vivo and in vitro studies using larval and adult antigens from Neobenedenia melleni on immune response in yellowtail (Seriola lalandi). JOURNAL OF FISH DISEASES 2017; 40:1497-1509. [PMID: 28422295 DOI: 10.1111/jfd.12620] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 01/10/2017] [Accepted: 01/20/2017] [Indexed: 06/07/2023]
Abstract
Neobenedenia melleni is a monogenean parasite that causes significant mortality and economic losses in fish aquaculture. Changes in the antigenic composition of this parasite occur during its developmental stages. In this study, we evaluated humoral parameters in serum and transcriptional immune responses of yellowtail naturally infected with N. melleni. In addition, in vitro assays were performed to study the stimulatory effects of antigens from larvae and adults on spleen leucocytes from non-infected fish at 6 and 24 h post-stimulation. The results showed enhanced total protein, myeloperoxidase and antiprotease activities in N. melleni-infected fish compared with non-infected ones. The induction of Toll-like receptors (TLRs) and pro-inflammatory cytokines in spleen leucocytes during natural infection with N. melleni suggests that these immune-related genes play an important role in the initiation of the immune defence mechanism for controlling parasite infection. Interestingly, the magnitude of in vitro responses of spleen leucocytes was dependent on the parasitic stage. An important stimulation of gene expression by adult antigens on spleen leucocytes was observed. Differential expression patterns of TLRs and target cytokines in yellowtail leucocytes in both in vivo and in vitro studies suggest that the quality of yellowtail immune response is conditioned by N. melleni development.
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Affiliation(s)
- M Reyes-Becerril
- Immunology and Vaccinology Group, Centro de Investigaciones Biológicas del Noroeste (CIBNOR), La Paz, Mexico
| | - E Alamillo
- Immunology and Vaccinology Group, Centro de Investigaciones Biológicas del Noroeste (CIBNOR), La Paz, Mexico
| | - A Trasviña
- Immunology and Vaccinology Group, Centro de Investigaciones Biológicas del Noroeste (CIBNOR), La Paz, Mexico
| | - I Hirono
- Laboratory of Genome Science, Tokyo University of Marine Science and Technology, Tokyo, Japan
| | - H Kondo
- Laboratory of Genome Science, Tokyo University of Marine Science and Technology, Tokyo, Japan
| | - W Jirapongpairoj
- Laboratory of Genome Science, Tokyo University of Marine Science and Technology, Tokyo, Japan
| | - F Ascencio-Valle
- Immunology and Vaccinology Group, Centro de Investigaciones Biológicas del Noroeste (CIBNOR), La Paz, Mexico
| | - C Angulo
- Immunology and Vaccinology Group, Centro de Investigaciones Biológicas del Noroeste (CIBNOR), La Paz, Mexico
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5
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Wei J, Li H, Yu H. Ichthyophthiriasis: emphases on the epizootiology. Lett Appl Microbiol 2013; 57:91-101. [DOI: 10.1111/lam.12079] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 03/26/2013] [Accepted: 03/27/2013] [Indexed: 12/22/2022]
Affiliation(s)
- J.Z. Wei
- School of Life Science; Foshan University; Foshan Guangdong China
| | - H. Li
- School of Life Science; Foshan University; Foshan Guangdong China
| | - H. Yu
- School of Life Science; Foshan University; Foshan Guangdong China
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6
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Ling F, Wang JG, Lu C, Wang GX, Lui YH, Gong XN. Effects of aqueous extract of Capsicum frutescens (Solanaceae) against the fish ectoparasite Ichthyophthirius multifiliis. Parasitol Res 2012; 111:841-8. [PMID: 22526288 DOI: 10.1007/s00436-012-2907-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Accepted: 03/19/2012] [Indexed: 10/28/2022]
Abstract
Ichthyophthirius multifiliis is an important fish ectoparasite that often results in significant economic losses to freshwater aquaculture. The search of alternative substances to control infections of I. multifiliis became stringent after malachite green, an effective and widely used chemotherapeutant, is banned on fish farms because of its carcinogenicity and teratogenicity. In this study, the effects of the aqueous extract of Capsicum frutescens, which is readily available and affordable, were evaluated under in vitro and in vivo conditions. The results in the in vitro conditions showed that the aqueous extracts of C. frutescens with the ratios (V (SS)/V (T)-V (SS), the volume of stock solution; V (T), the volume of total solution) of 1:32 and 1:64 led to more than 70 % mortality of I. multifiliis theronts during 4 h of exposure and significantly reduced the survival of the tomonts and the total number of theronts released by the tomonts within 22 h (P < 0.05). A 96-h bioassay was carried out to determine the acute toxicity of the aqueous extract of C. frutescens to goldfish. No visible effect was observed in the treatments with the aqueous extracts of C. frutescens with the ratios (V (SS)/V (T)) of 1:32, 1:64 and 1:128, while in the other treatments, the erratic behaviour of fish was noted. In addition, in vitro tests demonstrated that the aqueous extract of C. frutescens had an adverse effect on I. multifiliis trophonts in situ. Fish treated with the aqueous extracts of C. frutescens in ratios V (SS)/V (T) of 1:32 and 1:64 carried significantly fewer parasites than the control and the other treatments (P < 0.05). These results suggest, therefore, that aqueous extracts of C. frutescens have potential for the control of ichthyophthiriasis in the aquaculture industry, though further phytochemical studies will need to be performed for isolation and identification of the active compounds.
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Affiliation(s)
- Fei Ling
- College of Animal Science and Technology, Northwest A&F University, Yangling 712100, People's Republic of China.
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7
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Luo XC, Xie MQ, Zhu XQ, Li AX. Some characteristics of host–parasite relationship for Cryptocaryon irritans isolated from South China. Parasitol Res 2008; 102:1269-75. [DOI: 10.1007/s00436-008-0904-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Accepted: 01/22/2008] [Indexed: 11/29/2022]
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9
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Cuesta A, Muñoz P, Rodríguez A, Salinas I, Sitjà-Bobadilla A, Alvarez-Pellitero P, Esteban MA, Meseguer J. Gilthead seabream (Sparus aurataL.) innate defence against the parasiteEnteromyxum leei(Myxozoa). Parasitology 2005; 132:95-104. [PMID: 16393358 DOI: 10.1017/s0031182005008759] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2005] [Revised: 07/08/2005] [Accepted: 07/08/2005] [Indexed: 11/07/2022]
Abstract
The humoral innate immune response of gilthead seabream (Sparus aurataL.) against the myxozoanEnteromyxum leeihas been studied. At 10, 22, 38, 52 and 108 days of cohabitation fish were sampled to examine gut histology and to determine serum innate immune parameters and the mRNA expression of pro-inflammatory cytokines (IL-1β and TNFα) in head-kidney. The parasite was successfully transmitted to 45% of the recipient fish and prevalence reached a maximum (62·5%) at the last sampling time (108 days). Recipient fish started to die after 74 days of cohabitation. In general, alternative complement activity was higher whereas the peroxidase level was lower in recipient fish than in controls. Moreover, IL-1β mRNA expression increased while the TNFα gene expression decreased in recipient fish. These data demonstrate the involvement of complement activity in the defence mechanisms of the gilthead seabream against the myxosporeanE. leei. Within the recipient fish group, few differences were observed in the studied immune parameters betweenE. leei-parasitized and non-parasitized recipient fish. Parasitological and immunological implications ofE. leeiinfections in Mediterranean fish farms are discussed.
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Affiliation(s)
- A Cuesta
- Fish Innate Immune System Group, Department of Cell Biology, Faculty of Biology, University of Murcia, 30100 Murcia, Spain
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10
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Matthews RA. Ichthyophthirius multifiliis Fouquet and Ichthyophthiriosis in Freshwater Teleosts. ADVANCES IN PARASITOLOGY 2005; 59:159-241. [PMID: 16182866 DOI: 10.1016/s0065-308x(05)59003-1] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The ciliate Ichthyophthirius multifiliis is an important pathogen of freshwater teleosts occurring in both temperate and tropical regions throughout the world. The disease, ichthyophthiriosis, accounts for significant economic losses to the aquaculture industry, including the ornamental fish trade, and epizootics in wild fish populations can result in mass kills. This review attempts to provide a comprehensive overview of the biology of the parasite, covering the free-living and parasitic stages in the life cycle, host-parasite interactions, and the immune response of host and immune evasion strategies by the parasite. Emphasis on the immunological aspects of infection within the fish host, including molecular studies of i-antigens, reflects the current interest in this subject area and the quest to develop a recombinant vaccine against the disease. The current status of methods for the control of ichthyophthiriosis is discussed, together with new approaches in combating this important disease.
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Affiliation(s)
- R A Matthews
- School of Biological Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK.
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11
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Browman HI, Boxaspen K, Kuhn P. The effect of light on the settlement of the salmon louse, Lepeophtheirus salmonis, on Atlantic salmon, Salmo salar L. JOURNAL OF FISH DISEASES 2004; 27:701-8. [PMID: 15575878 DOI: 10.1111/j.1365-2761.2004.00592.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The salmon louse, Lepeophtheirus salmonis, is an ectoparasitic copepod that infests both wild and farmed salmonid fish. Salmon lice are a major disease problem in the farming of Atlantic salmon, Salmo salar L., and the possibility of salmon lice playing a role in the decline of wild anadromous stocks has also been raised. Lepeophtheirus salmonis can detect a range of stimuli (pressure/moving water, chemicals and light) in the external environment. However, the response thresholds to various stimuli, and the spatial and temporal scales over which they operate in the context of host location, are largely unknown. In this context, we attempted to determine whether salmon lice copepodids settle onto hosts more effectively, or at different locations on the fish's body, under different qualities of light. Lice settlement trials were conducted under three lighting conditions; L1: unpolarized under ultraviolet A (UVA)-through visible; L2: unpolarized without UVA (control); L3: 100% linearly polarized without UVA. A dark control was also conducted. No statistically significant difference in lice settlement was found. While changes in light intensity are involved in host detection at spatial scales on the order of metres, the results presented here suggest that it is not the primary sensory modality underlying host location at smaller spatial scales (cm to mm).
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Affiliation(s)
- H I Browman
- Institute of Marine Research - Austevoll, N-5392 Storebø, Norway.
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Paramá A, Iglesias R, Alvarez MF, Sanmartín ML, Leiro J. Chemotactic responses of the fish-parasitic scuticociliate Philasterides dicentrarchi to blood and blood components of the turbot Scophthalmus maximus, evaluated using a new microplate multiassay. J Microbiol Methods 2004; 58:361-6. [PMID: 15279940 DOI: 10.1016/j.mimet.2004.04.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2004] [Revised: 03/11/2004] [Accepted: 04/28/2004] [Indexed: 11/22/2022]
Abstract
This study describes a new capillary-type microplate multiassay for characterization of protozoal chemotactic responses, allowing up to 32 assays to be run simultaneously. We used the new multiassay to evaluate the chemoattractant activity of turbot blood components and turbot cells for the facultative parasite Philasterides dicentrarchi, which is responsible for significant losses in turbot farming. Preliminary tests indicated that the assay requires 3-4 h for detection of chemoattractant activity, that it can be performed effectively using the ciliate axenic culture medium, and that it distinguishes clearly between different concentrations of chemoattractant. Application of the assay indicated that whole blood and serum from normal turbot, and especially infected turbot, have strong chemoattractant activity for P. dicentrarchi trophozoites, whereas neither turbot blood cells nor other turbot cells nor bacteria were significant chemoattractants. These results raise the possibility that turbot serum components are involved in host detection and host invasion by P. dicentrarchi, in line with previous findings indicating that turbot with skin lesions show increased susceptibility to P. dicentrarchi infection.
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Affiliation(s)
- A Paramá
- Laboratorio de Parasitología, Instituto de Investigación y Análisis Alimentarios, Universidad de Santiago de Compostela, C/ Constantino Candeira, s/n, Santiago de Compostela 15782, Spain
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13
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Haas W, Stiegeler P, Keating A, Kullmann B, Rabenau H, Schönamsgruber E, Haberl B. Diplostomum spathaceum cercariae respond to a unique profile of cues during recognition of their fish host. Int J Parasitol 2002; 32:1145-54. [PMID: 12117497 DOI: 10.1016/s0020-7519(02)00089-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
During its normal life cycle, Diplostomum spathaceum cercariae attach to and invade fish intermediate hosts. They are also known to attach to various other aquatic animals in response to water currents, touch and carbon dioxide. The purpose of this study was to identify the specific stimuli used by D. spathaceum cercariae to recognise the appropriate fish host. We characterised the host cues which stimulate them to remain on the host (enduring contact) and to penetrate the skin. Cercariae were exposed to animal skin tissues and fish skin surface mucus, their extracts and chemical modifications integrated into agar or offered via membrane filters. Enduring contact was stimulated by hydrophilic extracts Mr<3kDa, which were sensitive to oxidation of carbohydrates. The stimulating cues are probably small molecular carbohydrates, as monosaccharides stimulated enduring contacts, but amino acids, urea, electrolytes and peptides did not. Penetration was stimulated by hydrophilic macromolecules, Mr>30kDa, and by lipids. The hydrophilic stimuli were protease resistant and precipitable with Alcian blue and they were sensitive to alkaline cleavage, to digestion with lysozyme and neuraminidase as well as to oxidation of sialic acids. They were considered to be glycoproteins with O-glycosidically linked carbohydrate chains and bound sialic acids as signal structures. The lipophilic penetration stimuli were contained exclusively in the fatty acid fractions, and the stimulating characteristics of these fatty acids resembled the stimulating penetrations in other cercarial species. Diplostomum spathaceum cercariae respond to a unique profile of cues in their sequence of host-recognition phases. These cues differ from those used in other fish parasites studied to date and underline the diversity of fish recognition strategies.
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Affiliation(s)
- Wilfried Haas
- Institute for Zoology I, University Erlangen-Nuernberg, Staudtstrasse 5, D-91058 Erlangen, Germany.
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Abstract
A review is given of (mainly recent) work on the biodiversity, ecology, biogeography and practical importance of marine parasites. Problems in estimating species numbers have been thoroughly discussed for free-living species, and the main points of these discussions are reviewed here. Even rough estimates of the richness of most parasite groups in the oceans are premature for the following reasons: species numbers of host groups, in particular in the deep sea and the meiofauna, are not known; most host groups have been examined only insufficiently for parasites or not at all; even in some of the best known groups, latitudinal, longitudinal and depth gradients in species richness are only poorly understood or not known at all; effects of hosts on parasite morphology and geographical variation have been studied only in a few cases; there are few studies using techniques of molecular biology to distinguish sibling species. Estimates of species richness in the best known groups, trematodes, monogeneans and copepods of marine fishes, are given. Parasites are found in almost all taxa of eukaryotes, but most parasitic species are concentrated in a few taxa. Important aspects of the ecology of marine parasites are discussed. It is emphasized that host specificity and host ranges should be distinguished, and an index that permits calculation of host specificity is discussed. The same index can be applied to measure site specificity. Central problems in ecology are the importance of interspecific competition and whether equilibrium or non-equilibrium conditions prevail. Marine parasites are among the few groups of organisms that have been extensively examined in this regard. A holistic approach, i.e. application of many methods, has unambiguously shown that metazoan ecto- (and probably endo-) parasites of marine fish live in largely non-saturated niche space under non-equilibrium conditions, i.e. they live in assemblages rather than in communities structured by competition. Nestedness occurs in such assemblages, but it can be explained by characteristics of the species themselves. There is little agreement on which other factors are involved in "structuring" parasite assemblages. Few studies on metapopulations of marine parasites have been made. A new approach, that of fuzzy chaos modelling, is discussed. It is likely that marine parasites are commonly found in metapopulations consisting of many subpopulations, and they are ideally suited to test the predictions of fuzzy chaos. Some recent studies on functional ecology and morphology--especially with regard to host, site and mate finding--are discussed, and attention is drawn to the amazing variety of sensory receptors in some marine parasites. Effects of parasites on hosts, and some studies on the evolution and speciation of marine parasites are discussed as well. A detailed overview of biogeographical studies is given, with respect to latitudinal gradients in species diversity, reproductive strategies and host ranges/specificity. Studies of marine parasites have contributed significantly to giving a non-equilibrium explanation for latitudinal diversity gradients. Recent studies on longitudinal and depth gradients are discussed, as well as parasites in brackish water, parasites as indicators of zoogeographical regions and barriers, and parasites as biological tags. The practical importance of marine parasites in mariculture, as monitors of pollution, agents of human disease, the use of parasites for controlling introduced marine pests, and some related aspects, are also discussed.
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Affiliation(s)
- Klaus Rohde
- School of Biological Sciences, University of New England, Armidale, NSW 2351, Australia.
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15
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Buchmann K, Sigh J, Nielsen CV, Dalgaard M. Host responses against the fish parasitizing ciliate Ichthyophthirius multifiliis. Vet Parasitol 2001; 100:105-16. [PMID: 11522410 DOI: 10.1016/s0304-4017(01)00487-3] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Recent studies have shown that fish are able to mount protective immune responses against various parasites. One of the best characterized parasite-host system in this context is the ciliate Ichthyophthirius multifiliis (Ich) parasitizing a range of freshwater fishes. Both specific and non-specific host defence mechanisms are responsible for the protection of fish against challenge infections with this ciliate. The specific humoral components comprise at least specific antibodies. The non-specific humoral elements included are the alternative complement pathway and probably lectins. Cellular factors involved in the specific response are B-cells and putative T-cells. The non-specific effector cells recognized are various leukocytes. In addition, goblet-cells and mast cells (EGC-cells) may have a function. The NCC-cell (suggested analogue to NK-cells in mammals) seems to play a role in the non-specific response. This well documented protective response in freshwater fishes against Ich has urged the development of anti-parasitic vaccines. Indeed, such products based on formalin killed parasites have been developed and found to offer the vaccinated host a satisfactory protection. However, the collection of parasites for vaccine production is extremely laborious. It involves keeping infected fish due to the fact that in vitro propagation of the parasite is still insufficiently developed. Gaining knowledge of amino acid sequences and its encoding DNA-sequences for the protective antigens (i-antigens) in the parasite was a major breakthrough. That achievement made it possible to produce a recombinant protein in E. coli and preliminary results indicated a certain protection of fish vaccinated with this product. Recent work has shown that the free-living and easily cultivated ciliate Tetrahymena can be transformed and express the i-antigen. This path seems to be promising for future development of vaccines against Ich. A novel approach in fish is the development of DNA-vaccines. Successful DNA-vaccination trials have been conducted in fish against viral infections and the technology also makes it possible to develop a DNA-vaccine against Ich. Other approaches to immuno-protection against Ich have been the use of heterologous vaccines. Thus, both bath and injection vaccination using live or killed (un-transformed) Tetrahymena has been reported to offer treated fish a certain level of protection. Such protection could be explained by non-specific reactions and the efficacy and duration of this vaccination type should be further evaluated.
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Affiliation(s)
- K Buchmann
- Department of Veterinary Microbiology, Section of Fish Diseases, Royal Veterinary and Agricultural University, 4 Stigbøjlen, DK-1870 C Frederiksberg, Denmark.
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