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Slinning MS, Nthiga TM, Eichner C, Khadija S, Rome LH, Nilsen F, Dondrup M. Major vault protein is part of an extracellular cement material in the Atlantic salmon louse (Lepeophtheirus salmonis). Sci Rep 2024; 14:15240. [PMID: 38956386 PMCID: PMC11219742 DOI: 10.1038/s41598-024-65683-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 06/24/2024] [Indexed: 07/04/2024] Open
Abstract
Major vault protein (MVP) is the main component of the vault complex, which is a highly conserved ribonucleoprotein complex found in most eukaryotic organisms. MVP or vaults have previously been found to be overexpressed in multidrug-resistant cancer cells and implicated in various cellular processes such as cell signaling and innate immunity. The precise function of MVP is, however, poorly understood and its expression and probable function in lower eukaryotes are not well characterized. In this study, we report that the Atlantic salmon louse expresses three full-length MVP paralogues (LsMVP1-3). Furthermore, we extended our search and identified MVP orthologues in several other ecdysozoan species. LsMVPs were shown to be expressed in various tissues at both transcript and protein levels. In addition, evidence for LsMVP to assemble into vaults was demonstrated by performing differential centrifugation. LsMVP was found to be highly expressed in cement, an extracellular material produced by a pair of cement glands in the adult female salmon louse. Cement is important for the formation of egg strings that serve as protective coats for developing embryos. Our results imply a possible novel function of LsMVP as a secretory cement protein. LsMVP may play a role in structural or reproductive functions, although this has to be further investigated.
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Affiliation(s)
- Malene Skuseth Slinning
- Sea Lice Research Centre (SLRC), Department of Biological Sciences, University of Bergen, Pb. 7803, 5020, Bergen, Norway
| | - Thaddaeus Mutugi Nthiga
- Sea Lice Research Centre (SLRC), Department of Biological Sciences, University of Bergen, Pb. 7803, 5020, Bergen, Norway
| | - Christiane Eichner
- Sea Lice Research Centre (SLRC), Department of Biological Sciences, University of Bergen, Pb. 7803, 5020, Bergen, Norway
| | - Syeda Khadija
- Department of Biological Chemistry, David Geffen School of Medicine and the California NanoSystems Institute, University of California Los Angeles, Los Angeles, CA, 90095, USA
| | - Leonard H Rome
- Department of Biological Chemistry, David Geffen School of Medicine and the California NanoSystems Institute, University of California Los Angeles, Los Angeles, CA, 90095, USA
| | - Frank Nilsen
- Sea Lice Research Centre (SLRC), Department of Biological Sciences, University of Bergen, Pb. 7803, 5020, Bergen, Norway
| | - Michael Dondrup
- SLRC, Computational Biology Unit (CBU), Department of Informatics, University of Bergen, Pb. 7803, 5020, Bergen, Norway.
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Midtbø HMD, Eichner C, Hamre LA, Dondrup M, Flesland L, Tysseland KH, Kongshaug H, Borchel A, Skoge RH, Nilsen F, Øvergård AC. Salmon louse labial gland enzymes: implications for host settlement and immune modulation. Front Genet 2024; 14:1303898. [PMID: 38299097 PMCID: PMC10828956 DOI: 10.3389/fgene.2023.1303898] [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: 09/28/2023] [Accepted: 12/18/2023] [Indexed: 02/02/2024] Open
Abstract
Salmon louse (Lepeophtheirus salmonis) is a skin- and blood-feeding ectoparasite, infesting salmonids. While feeding, labial gland proteins from the salmon louse may be deposited on the Atlantic salmon (Salmo salar) skin. Previously characterized labial gland proteins are involved in anti-coagulation and may contribute to inhibiting Atlantic salmon from mounting a sufficient immune response against the ectoparasite. As labial gland proteins seem to be important in the host-parasite interaction, we have, therefore, identified and characterized ten enzymes localized to the labial gland. They are a large group of astacins named L. salmonis labial gland astacin 1-8 (LsLGA 1-8), one serine protease named L. salmonis labial gland serine protease 1 (LsLGSP1), and one apyrase named L. salmonis labial gland apyrase 1 (LsLGAp1). Protein domain predictions showed that LsLGA proteins all have N-terminal ShK domains, which may bind to potassium channels targeting the astacins to its substrate. LsLGA1 and -4 are, in addition, expressed in another gland type, whose secrete also meets the host-parasite interface. This suggests that LsLGA proteins may have an anti-microbial function and may prevent secondary infections in the wounds. LsLGAp1 is predicted to hydrolyze ATP or AMP and is, thereby, suggested to have an immune dampening function. In a knockdown study targeting LsLGSP1, a significant increase in IL-8 and MMP13 at the skin infestation site was seen under LsLGSP1 knockdown salmon louse compared to the control, suggesting that LsLGSP1 may have an anti-inflammatory effect. Moreover, most of the identified labial gland proteins are expressed in mature copepodids prior to host settlement, are not regulated by starvation, and are expressed at similar or higher levels in lice infesting the salmon louse-resistant pink salmon (Oncorhynchus gorbuscha). This study, thereby, emphasizes the importance of labial gland proteins for host settlement and their immune dampening function. This work can further contribute to anti-salmon louse treatment such as vaccine development, functional feed, or gene-edited salmon louse-resistant Atlantic salmon.
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Affiliation(s)
| | - Christiane Eichner
- Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Lars Are Hamre
- Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Michael Dondrup
- Sea Lice Research Centre, Department of Informatics, University of Bergen, Bergen, Norway
| | - Linn Flesland
- Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Bergen, Norway
| | | | - Heidi Kongshaug
- Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Andreas Borchel
- Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Renate Hvidsten Skoge
- Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Frank Nilsen
- Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Aina-Cathrine Øvergård
- Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Bergen, Norway
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3
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Robinson NA, Robledo D, Sveen L, Daniels RR, Krasnov A, Coates A, Jin YH, Barrett LT, Lillehammer M, Kettunen AH, Phillips BL, Dempster T, Doeschl‐Wilson A, Samsing F, Difford G, Salisbury S, Gjerde B, Haugen J, Burgerhout E, Dagnachew BS, Kurian D, Fast MD, Rye M, Salazar M, Bron JE, Monaghan SJ, Jacq C, Birkett M, Browman HI, Skiftesvik AB, Fields DM, Selander E, Bui S, Sonesson A, Skugor S, Østbye TK, Houston RD. Applying genetic technologies to combat infectious diseases in aquaculture. REVIEWS IN AQUACULTURE 2023; 15:491-535. [PMID: 38504717 PMCID: PMC10946606 DOI: 10.1111/raq.12733] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 07/24/2022] [Accepted: 08/16/2022] [Indexed: 03/21/2024]
Abstract
Disease and parasitism cause major welfare, environmental and economic concerns for global aquaculture. In this review, we examine the status and potential of technologies that exploit genetic variation in host resistance to tackle this problem. We argue that there is an urgent need to improve understanding of the genetic mechanisms involved, leading to the development of tools that can be applied to boost host resistance and reduce the disease burden. We draw on two pressing global disease problems as case studies-sea lice infestations in salmonids and white spot syndrome in shrimp. We review how the latest genetic technologies can be capitalised upon to determine the mechanisms underlying inter- and intra-species variation in pathogen/parasite resistance, and how the derived knowledge could be applied to boost disease resistance using selective breeding, gene editing and/or with targeted feed treatments and vaccines. Gene editing brings novel opportunities, but also implementation and dissemination challenges, and necessitates new protocols to integrate the technology into aquaculture breeding programmes. There is also an ongoing need to minimise risks of disease agents evolving to overcome genetic improvements to host resistance, and insights from epidemiological and evolutionary models of pathogen infestation in wild and cultured host populations are explored. Ethical issues around the different approaches for achieving genetic resistance are discussed. Application of genetic technologies and approaches has potential to improve fundamental knowledge of mechanisms affecting genetic resistance and provide effective pathways for implementation that could lead to more resistant aquaculture stocks, transforming global aquaculture.
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Affiliation(s)
- Nicholas A. Robinson
- Nofima ASTromsøNorway
- Sustainable Aquaculture Laboratory—Temperate and Tropical (SALTT)School of BioSciences, The University of MelbourneMelbourneVictoriaAustralia
| | - Diego Robledo
- The Roslin Institute and Royal (Dick) School of Veterinary StudiesThe University of EdinburghEdinburghUK
| | | | - Rose Ruiz Daniels
- The Roslin Institute and Royal (Dick) School of Veterinary StudiesThe University of EdinburghEdinburghUK
| | | | - Andrew Coates
- Sustainable Aquaculture Laboratory—Temperate and Tropical (SALTT)School of BioSciences, The University of MelbourneMelbourneVictoriaAustralia
| | - Ye Hwa Jin
- The Roslin Institute and Royal (Dick) School of Veterinary StudiesThe University of EdinburghEdinburghUK
| | - Luke T. Barrett
- Sustainable Aquaculture Laboratory—Temperate and Tropical (SALTT)School of BioSciences, The University of MelbourneMelbourneVictoriaAustralia
- Institute of Marine Research, Matre Research StationMatredalNorway
| | | | | | - Ben L. Phillips
- Sustainable Aquaculture Laboratory—Temperate and Tropical (SALTT)School of BioSciences, The University of MelbourneMelbourneVictoriaAustralia
| | - Tim Dempster
- Sustainable Aquaculture Laboratory—Temperate and Tropical (SALTT)School of BioSciences, The University of MelbourneMelbourneVictoriaAustralia
| | - Andrea Doeschl‐Wilson
- The Roslin Institute and Royal (Dick) School of Veterinary StudiesThe University of EdinburghEdinburghUK
| | - Francisca Samsing
- Sydney School of Veterinary ScienceThe University of SydneyCamdenAustralia
| | | | - Sarah Salisbury
- The Roslin Institute and Royal (Dick) School of Veterinary StudiesThe University of EdinburghEdinburghUK
| | | | | | | | | | - Dominic Kurian
- The Roslin Institute and Royal (Dick) School of Veterinary StudiesThe University of EdinburghEdinburghUK
| | - Mark D. Fast
- Atlantic Veterinary CollegeThe University of Prince Edward IslandCharlottetownPrince Edward IslandCanada
| | | | | | - James E. Bron
- Institute of AquacultureUniversity of StirlingStirlingScotlandUK
| | - Sean J. Monaghan
- Institute of AquacultureUniversity of StirlingStirlingScotlandUK
| | - Celeste Jacq
- Blue Analytics, Kong Christian Frederiks Plass 3BergenNorway
| | | | - Howard I. Browman
- Institute of Marine Research, Austevoll Research Station, Ecosystem Acoustics GroupTromsøNorway
| | - Anne Berit Skiftesvik
- Institute of Marine Research, Austevoll Research Station, Ecosystem Acoustics GroupTromsøNorway
| | | | - Erik Selander
- Department of Marine SciencesUniversity of GothenburgGothenburgSweden
| | - Samantha Bui
- Institute of Marine Research, Matre Research StationMatredalNorway
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Small, charged proteins in salmon louse (Lepeophtheirus salmonis) secretions modulate Atlantic salmon (Salmo salar) immune responses and coagulation. Sci Rep 2022; 12:7995. [PMID: 35568726 PMCID: PMC9107468 DOI: 10.1038/s41598-022-11773-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Accepted: 04/28/2022] [Indexed: 11/08/2022] Open
Abstract
Little is known about glandular proteins secreted from the skin- and blood-feeding ectoparasite salmon louse (Lepeophtheirus salmonis). The labial gland has ducts extending into the oral cavity of the lice, and the present study aimed to identify novel genes expressed by this gland type and to investigate their role in modulation of host parameters at the lice feeding site. Five genes associated with labial gland function were identified and named Lepeophteirus salmonis labial gland protein (LsLGP) 1-4 and 1 like (LsLGP1L). All LsLGPs were predicted to be small charged secreted proteins not encoding any known protein domains. Functional studies revealed that LsLGP1 and/or LsLGP1L regulated the expression of other labial gland genes. Immune dampening functions were indicated for LsLGP2 and 3. Whereas LsLGP2 was expressed throughout the parasitic life cycle and found to dampen inflammatory cytokines, LsLGP3 displayed an increased expression in mobile stages and appeared to dampen adaptive immune responses. Expression of LsLGP4 coincided with moulting to the mobile pre-adult I stage where hematophagous feeding is initiated, and synthetic LsLGP4 decreased the clotting time of Atlantic salmon plasma. Results from the present study confirm that the salmon louse secretes immune modulating and anti-coagulative proteins with a potential application in new immune based anti-salmon louse treatments.
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Feng Y, Lei X, Zhang L, Wan H, Pan H, Wu J, Zou M, Zhu L, Mi Y. COPB2: a transport protein with multifaceted roles in cancer development and progression. Clin Transl Oncol 2021; 23:2195-2205. [PMID: 34101128 PMCID: PMC8455385 DOI: 10.1007/s12094-021-02630-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 04/22/2021] [Indexed: 11/29/2022]
Abstract
The Coatomer protein complex subunit beta 2 (COPB2) is involved in the formation of the COPI coatomer protein complex and is responsible for the transport of vesicles between the Golgi apparatus and the endoplasmic reticulum. It plays an important role in maintaining the integrity of these cellular organelles, as well as in maintaining cell homeostasis. More importantly, COPB2 plays key roles in embryonic development and tumor progression. COPB2 is regarded as a vital oncogene in several cancer types and has been implicated in tumor cell proliferation, survival, invasion, and metastasis. Here, we summarize the current knowledge on the roles of COPB2 in cancer development and progression in the context of the hallmarks of cancer.
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Affiliation(s)
- Y Feng
- Wuxi Medical College, Jiangnan University, Wuxi, 214122, Jiangsu Province, China.,Department of Urology, Affiliated Hospital of Jiangnan University, Wuxi, 214122, Jiangsu Province, China
| | - X Lei
- Wuxi Medical College, Jiangnan University, Wuxi, 214122, Jiangsu Province, China
| | - L Zhang
- Department of Urology, Affiliated Changzhou No. 2 People's Hospital of Nanjing Medical University, Changzhou, 213003, Jiangsu Province, China
| | - H Wan
- Wuxi Medical College, Jiangnan University, Wuxi, 214122, Jiangsu Province, China.,Department of Urology, Affiliated Hospital of Jiangnan University, Wuxi, 214122, Jiangsu Province, China
| | - H Pan
- Department of Urology, Affiliated Hospital of Jiangnan University, Wuxi, 214122, Jiangsu Province, China
| | - J Wu
- Department of Burns and Plastic Surgery, Affiliated Hospital of Jiangnan University, Wuxi, 214122, Jiangsu Province, China
| | - M Zou
- Wuxi Clinical Medicine School of Integrated Chinese and Western Medicine, Nanjing University of Chinese Medicine, Wuxi, 214122, Jiangsu Province, China
| | - L Zhu
- Department of Urology, Affiliated Hospital of Jiangnan University, Wuxi, 214122, Jiangsu Province, China.
| | - Y Mi
- Department of Urology, Affiliated Hospital of Jiangnan University, Wuxi, 214122, Jiangsu Province, China.
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6
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Dalvin S, Eichner C, Dondrup M, Øvergård AC. Roles of three putative salmon louse (Lepeophtheirus salmonis) prostaglandin E 2 synthases in physiology and host-parasite interactions. Parasit Vectors 2021; 14:206. [PMID: 33874988 PMCID: PMC8056522 DOI: 10.1186/s13071-021-04690-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 03/16/2021] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND The salmon louse (Lepeophtheirus salmonis) is a parasite of salmonid fish. Atlantic salmon (Salmo salar) exhibit only a limited and ineffective immune response when infested with this parasite. Prostaglandins (PGs) have many biological functions in both invertebrates and vertebrates, one of which is the regulation of immune responses. This has led to the suggestion that prostaglandin E2 (PGE2) is important in the salmon louse host-parasite interaction, although studies of a salmon louse prostaglandin E2 synthase (PGES) 2 gene have not enabled conformation of this hypothesis. The aim of the present study was, therefore, to characterize two additional PGES-like genes. METHODS Lepeophtheirus salmonis microsomal glutathione S-transferase 1 like (LsMGST1L) and LsPGES3L were investigated by sequencing, phylogenetics, transcript localization and expression studies. Moreover, the function of these putative PGES genes in addition to the previously identified LsPGES2 gene was analyzed in double stranded (ds) RNA-mediated knockdown (KD) salmon louse. RESULTS Analysis of the three putative LsPGES genes showed a rather constitutive transcript level throughout development from nauplius to the adult stages, and in a range of tissues, with the highest levels in the ovaries or gut. DsRNA-mediated KD of these transcripts did not produce any characteristic changes in phenotype, and KD animals displayed a normal reproductive output. The ability of the parasite to infect or modulate the immune response of the host fish was also not affected by KD. CONCLUSIONS Salmon louse prostaglandins may play endogenous roles in the management of reproduction and oxidative stress and may be a product of salmon louse blood digestions.
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Affiliation(s)
- Sussie Dalvin
- Institute of Marine Research, SLCR-Sea Lice Research Centre, Nordnes, P. box 1870, 5817, Bergen, Norway
| | - Christiane Eichner
- Department of Biological Sciences, SLCR-Sea Lice Research Centre, University of Bergen, P. box 7803, 5020, Bergen, Norway
| | - Michael Dondrup
- Department of Informatics, SLRC-Sea Lice Research Centre, University of Bergen, P. box 7803, 5020, Bergen, Norway
| | - Aina-Cathrine Øvergård
- Department of Biological Sciences, SLCR-Sea Lice Research Centre, University of Bergen, P. box 7803, 5020, Bergen, Norway.
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Heggland EI, Tröße C, Eichner C, Nilsen F. Heavy and light chain homologs of ferritin are essential for blood-feeding and egg production of the ectoparasitic copepod Lepeophtheirus salmonis. Mol Biochem Parasitol 2019; 232:111197. [PMID: 31251953 DOI: 10.1016/j.molbiopara.2019.111197] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 06/13/2019] [Accepted: 06/19/2019] [Indexed: 12/21/2022]
Abstract
The salmon louse, Lepeophtheirus salmonis, is a hematophagous ectoparasite of salmonid fish. Due to its blood-feeding activity, the louse is exposed to great amounts of iron, which is an essential, yet potentially toxic mineral. The major known iron storage protein is ferritin, which the salmon louse encodes four genes of (LsFer1-4). Two of the ferritins are predicted to be secreted. These are one of the heavy chain homologs (LsFer1) and the light chain homolog (LsFer2). Here, we perform functional studies and characterize the two secreted ferritins. Our results show that knocking down LsFer1 and LsFer2 both negatively affect the parasite's physiology, as it is not able to properly feed and reproduce. In a starvation experiment, the transcript levels of both LsFer1 and LsFer2 decrease during the starvation period. Combined, these results demonstrate the importance of these genes for the normal parasite biology, and they could thus potentially be targets for pest management.
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Affiliation(s)
- Erna Irene Heggland
- Department of Biological Sciences & Sea Lice Research Centre (SLRC), University of Bergen, Norway.
| | | | - Christiane Eichner
- Department of Biological Sciences & Sea Lice Research Centre (SLRC), University of Bergen, Norway
| | - Frank Nilsen
- Department of Biological Sciences & Sea Lice Research Centre (SLRC), University of Bergen, Norway
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Tarrant AM, Nilsson B, Hansen BW. Molecular physiology of copepods - from biomarkers to transcriptomes and back again. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2019; 30:230-247. [DOI: 10.1016/j.cbd.2019.03.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 03/14/2019] [Accepted: 03/16/2019] [Indexed: 12/31/2022]
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9
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Heggland EI, Eichner C, Støve SI, Martinez A, Nilsen F, Dondrup M. A scavenger receptor B (CD36)-like protein is a potential mediator of intestinal heme absorption in the hematophagous ectoparasite Lepeophtheirus salmonis. Sci Rep 2019; 9:4218. [PMID: 30862948 PMCID: PMC6414551 DOI: 10.1038/s41598-019-40590-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 02/19/2019] [Indexed: 02/01/2023] Open
Abstract
Intestinal absorption of heme has remained enigmatic for years, even though heme provides the most bioavailable form of iron. The salmon louse, Lepeophtheirus salmonis, is a heme auxotrophic ectoparasite feeding on large quantities of blood from its host, the salmon. Here we show that a scavenging CD36-like receptor is a potential mediator of heme absorption in the intestine of the salmon louse. The receptor was characterized by a heme binding assay using recombinantly expressed protein, in situ hybridization and immunohistochemistry, as well as functional knockdown studies in the louse. A computational structural model of the receptor predicted a binding pocket for heme, as also supported by in silico docking. The mRNA and protein were expressed exclusively in the intestine of the louse. Further, knocking down the transcript resulted in lower heme levels in the adult female louse, production of shorter egg strings, and an overall lower hatching success of the eggs. Finally, starving the lice caused the transcript expression of the receptor to decrease. To our knowledge, this is the first time a CD36-like protein has been suggested to be an intestinal heme receptor.
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Affiliation(s)
- Erna Irene Heggland
- Department of Biological Sciences & Sea Lice Research Centre (SLRC), University of Bergen, Bergen, Norway
| | - Christiane Eichner
- Department of Biological Sciences & Sea Lice Research Centre (SLRC), University of Bergen, Bergen, Norway
| | - Svein Isungset Støve
- Department of Biomedicine & K.G. Jebsen Centre for Neuropsychiatric Disorders, University of Bergen, Bergen, Norway
| | - Aurora Martinez
- Department of Biomedicine & K.G. Jebsen Centre for Neuropsychiatric Disorders, University of Bergen, Bergen, Norway
| | - Frank Nilsen
- Department of Biological Sciences & Sea Lice Research Centre (SLRC), University of Bergen, Bergen, Norway
| | - Michael Dondrup
- Department of Informatics & Sea Lice Research Centre (SLRC), University of Bergen, Bergen, Norway.
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10
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Økland AL, Nylund A, Øvergård AC, Skoge RH, Kongshaug H. Genomic characterization, phylogenetic position and in situ localization of a novel putative mononegavirus in Lepeophtheirus salmonis. Arch Virol 2019; 164:675-689. [PMID: 30535526 PMCID: PMC6394706 DOI: 10.1007/s00705-018-04119-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Accepted: 11/15/2018] [Indexed: 11/28/2022]
Abstract
The complete genome sequence of a novel mononegavirus, Lepeophtheirus salmonis negative-stranded RNA virus 1 (LsNSRV-1), obtained from a salmonid ectoparasite, Lepeophtheirus salmonis was determined. The viral genome contains five open reading frames encoding three unknown proteins (ORF I, II and III), a putative glycoprotein (G), and a large (L) protein. Phylogenetic analysis placed LsNSRV-1 in the recently established mononegaviral family Artoviridae. LsNSRV-1 showed a prevalence of around 97% and was detected in all L. salmonis developmental stages. Viral genomic and antigenomic RNA was localized to nerve tissue, connective tissue, epithelial cells of the gut, subepidermal tissue, exocrine and cement glands, as well as the testis, vas deferens and spermatophore sac of male L. salmonis and the ovaries and oocytes of females. Viral RNA was detected in both the cytoplasm and the nucleoli of infected cells, and putative nuclear export and localization signals were found within the ORF I, III and L proteins, suggesting nuclear replication of LsNSRV-1. RNA interference (RNAi) was induced twice during development by the introduction of a double-stranded RNA fragment of ORF I, resulting in a transient knockdown of viral RNA. A large variation in the knockdown level was seen in adult males and off springs of knockdown animals, whereas the RNA level was more stable in adult females. Together with the localization of viral RNA within the male spermatophore and female oocytes and the amplification of viral RNA in developing embryos, this suggests that LsNSRV-1 is transmitted both maternally and paternally. Small amounts of viral RNA were detected at the site where chalimi were attached to the skin of Atlantic salmon (Salmo salar). However, as the RNAi-mediated treatment did not result in LsNSRV-1-negative offspring and the virus failed to replicate in the tested fish cell cultures, it is difficult to investigate the influence of secreted LsNSRV-1 on the salmon immune response.
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Affiliation(s)
- Arnfinn Lodden Økland
- Fish Disease Research Group, Department of Biological Sciences, University of Bergen, Thormøhlensgt. 55, Pb. 7803, 5020, Bergen, Norway.
| | - Are Nylund
- Fish Disease Research Group, Department of Biological Sciences, University of Bergen, Thormøhlensgt. 55, Pb. 7803, 5020, Bergen, Norway
| | - Aina-Cathrine Øvergård
- Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Thormøhlensgt. 55, Pb. 7803, 5020, Bergen, Norway
| | - Renate Hvidsten Skoge
- Fish Disease Research Group, Department of Biological Sciences, University of Bergen, Thormøhlensgt. 55, Pb. 7803, 5020, Bergen, Norway
| | - Heidi Kongshaug
- Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Thormøhlensgt. 55, Pb. 7803, 5020, Bergen, Norway
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11
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Øvergård AC, Hamre LA, Grotmol S, Nilsen F. Salmon louse rhabdoviruses: Impact on louse development and transcription of selected Atlantic salmon immune genes. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2018; 86:86-95. [PMID: 29747070 DOI: 10.1016/j.dci.2018.04.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 04/27/2018] [Accepted: 04/27/2018] [Indexed: 06/08/2023]
Abstract
Recently, it has been shown that the salmon louse (Lepeophtheirus salmonis) is commonly infected by one or two vertically transmitted Lepeophtheirus salmonis rhabdoviruses (LsRVs). As shown in the present study, the viruses have limited effect on louse survival, developmental rate and fecundity. Since the LsRVs were confirmed to be present in the louse salivary glands, the salmon cutaneous immune response towards LsRV positive and negative lice was analyzed. In general, L. salmonis increased the expression of IL1β, IL8 and IL4/13A at the attachment site, in addition to the non-specific cytotoxic cell receptor protein 1 (NCCRP-1). Interestingly, LsRV free lice induced a higher skin expression of IL1β, IL8, and NCCRP-1 than the LsRV infected lice. The inflammatory response is important for louse clearance, and the present results suggest that the LsRVs can be beneficial for the louse by dampening inflammation. Further research is, however; needed to ascertain whether this is a direct modulatory effect of secreted virions, or if virus replication is altering the level of louse salivary gland proteins.
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Affiliation(s)
- Aina-Cathrine Øvergård
- SLRC - Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Thormøhlensgt. 55, Pb. 7803, 5020, Bergen, Norway.
| | - Lars Are Hamre
- SLRC - Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Thormøhlensgt. 55, Pb. 7803, 5020, Bergen, Norway.
| | - Sindre Grotmol
- SLRC - Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Thormøhlensgt. 55, Pb. 7803, 5020, Bergen, Norway.
| | - Frank Nilsen
- SLRC - Sea Lice Research Centre, Department of Biological Sciences, University of Bergen, Thormøhlensgt. 55, Pb. 7803, 5020, Bergen, Norway.
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12
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Borchel A, Nilsen F. A novel gene-family involved in spermatophore generation in the economically important salmon louse Lepeophtheirus salmonis. Mol Reprod Dev 2018; 85:478-489. [PMID: 29633415 DOI: 10.1002/mrd.22984] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Revised: 04/03/2018] [Accepted: 04/04/2018] [Indexed: 11/06/2022]
Abstract
The salmon louse (Lepeophtheirus salmonis) is an important parasite of Atlantic salmon (Salmo salar). It is widely spread in aquaculture facilities and leads to economic losses every year. As it has developed resistances against many common treatments, new control methods must be established. Here we characterize a novel gene family of the salmon louse, consisting of two genes, which has not been described in other species before. We analyzed temporal expression patterns of both genes, the localization of mRNA and protein. An RNAi mediated gene knockdown lead to information about the function of the protein. Overall, these two genes are expressed only in sperm ducts of male sea lice. The mucin-like proteins can additionally be found in the wall of spermatophores, which are responsible for sperm transfer to females. Knockdown showed that both genes are essential for successful fertilization of females. Overall, all results indicate that the two analyzed genes are necessary for reproduction in sea lice as they are essential for the formation of a wall surrounding the spermatophores, which is needed for fertilization. Therefore, we name them Mucin-like spermatophore wall protein 1 & 2 (MLSWP1 & MLSWP2). Analysis of sequence data from other copepod species suggests that MLSWPs are present in many copepod species and may also play a similar role in reproduction in those species.
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Affiliation(s)
- Andreas Borchel
- SLRC-SeaLiceResearch Centre, Department of Biology, University of Bergen, Bergen, Norway
| | - Frank Nilsen
- SLRC-SeaLiceResearch Centre, Department of Biology, University of Bergen, Bergen, Norway
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13
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Sandlund L, Kongshaug H, Nilsen F, Dalvin S. Molecular characterization and functional analysis of components of the TOR pathway of the salmon louse, Lepeophtheirus salmonis (Krøyer, 1838). Exp Parasitol 2018; 188:83-92. [PMID: 29625096 DOI: 10.1016/j.exppara.2018.04.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 03/16/2018] [Accepted: 04/02/2018] [Indexed: 11/27/2022]
Abstract
The salmon louse Lepeophtheirus salmonis (Copepods, Caligida) is a marine ectoparasite infecting salmonid fishes in the northern hemisphere. At present, salmon lice infections are the most severe disease problem in the salmon farming industry causing significant economic losses. Due to development of resistance towards available chemotherapeutants, it is clear that new chemotherapeutants or non-chemical control methods are essential to manage the parasite in the future. The TOR signaling pathway is present in all metazoans and is a major regulator of cellular activity according to nutrient availability. In this study, we identified the TOR pathway genes in salmon louse; LsTSC1, LsTSC2, LsRheb, LsTOR, LsRaptor and LsRictor. RNA interference mediated gene silencing was performed to elucidate the functional role of each member of the pathway. Our results show that interference of the TOR signaling pathway either directly or indirectly inhibits many biological processes including egg maturation. In addition, the effect of gene knock-down results in more comprehensive physiological defects when targeting TORC1 and the upstream regulator Rheb. This is the first report on the TOR pathway in the salmon louse and that our research contributes to the basic knowledge of the parasite that could lead to development of novel treatment methods.
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Affiliation(s)
- Liv Sandlund
- SLRC-Sea Lice Research Center, Institute of Marine Research, 5817 Bergen, Norway
| | - Heidi Kongshaug
- SLRC-Sea Lice Research Center, Department of Biology, University of Bergen, Thormøhlensgt. 55, 5008 Bergen, Norway
| | - Frank Nilsen
- SLRC-Sea Lice Research Center, Department of Biology, University of Bergen, Thormøhlensgt. 55, 5008 Bergen, Norway
| | - Sussie Dalvin
- SLRC-Sea Lice Research Center, Institute of Marine Research, 5817 Bergen, Norway.
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14
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Stutzer C, Richards SA, Ferreira M, Baron S, Maritz-Olivier C. Metazoan Parasite Vaccines: Present Status and Future Prospects. Front Cell Infect Microbiol 2018; 8:67. [PMID: 29594064 PMCID: PMC5859119 DOI: 10.3389/fcimb.2018.00067] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 02/26/2018] [Indexed: 12/21/2022] Open
Abstract
Eukaryotic parasites and pathogens continue to cause some of the most detrimental and difficult to treat diseases (or disease states) in both humans and animals, while also continuously expanding into non-endemic countries. Combined with the ever growing number of reports on drug-resistance and the lack of effective treatment programs for many metazoan diseases, the impact that these organisms will have on quality of life remain a global challenge. Vaccination as an effective prophylactic treatment has been demonstrated for well over 200 years for bacterial and viral diseases. From the earliest variolation procedures to the cutting edge technologies employed today, many protective preparations have been successfully developed for use in both medical and veterinary applications. In spite of the successes of these applications in the discovery of subunit vaccines against prokaryotic pathogens, not many targets have been successfully developed into vaccines directed against metazoan parasites. With the current increase in -omics technologies and metadata for eukaryotic parasites, target discovery for vaccine development can be expedited. However, a good understanding of the host/vector/pathogen interface is needed to understand the underlying biological, biochemical and immunological components that will confer a protective response in the host animal. Therefore, systems biology is rapidly coming of age in the pursuit of effective parasite vaccines. Despite the difficulties, a number of approaches have been developed and applied to parasitic helminths and arthropods. This review will focus on key aspects of vaccine development that require attention in the battle against these metazoan parasites, as well as successes in the field of vaccine development for helminthiases and ectoparasites. Lastly, we propose future direction of applying successes in pursuit of next generation vaccines.
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Affiliation(s)
- Christian Stutzer
- Tick Vaccine Group, Department of Genetics, University of Pretoria, Pretoria, South Africa
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15
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Øvergård AC, Hamre LA, Kongshaug H, Nilsen F. RNAi-mediated treatment of two vertically transmitted rhabdovirus infecting the salmon louse (Lepeophtheirus salmonis). Sci Rep 2017; 7:14030. [PMID: 29070796 PMCID: PMC5656668 DOI: 10.1038/s41598-017-14282-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 10/06/2017] [Indexed: 12/21/2022] Open
Abstract
Rhabdoviruses are a family of enveloped negative-sense single-stranded RNA viruses infecting a variety of hosts. Recently, two vertically transmitted salmon louse (Lepeophtheirus salmonis) rhabdoviruses (LsRV) have been identified. The prevalence of these viruses was measured along the Norwegian coast and found to be close to 100%, and with the present lack of suitable cell lines to propagate these viruses, it is challenging to obtain material to study their host impact and infection routes. Thus, virus free lice strains were established from virus infected lice carrying one or both LsRVs by treating them with N protein dsRNA twice during development. The viral replication of the N protein was specifically down-regulated following introduction of virus-specific dsRNA, and virus-free lice strains were maintained for several generations. A preliminary study on infection routes suggested that the LsRV-No9 is maternally transmitted, and that the virus transmits from males to females horizontally. The ability to produce virus free strains allows for further studies on transmission modes and how these viruses influences on the L.salmonis interaction with its salmonid host. Moreover, this study provides a general fundament for future studies on how vertically transmitted rhabdoviruses influence the biology of their arthropod hosts.
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Affiliation(s)
- Aina-Cathrine Øvergård
- SLCR-Sea Lice Research Centre, Department of Biology, University of Bergen, Thormøhlensgt. 55, Pb. 7803, NO-5020, Bergen, Norway.
| | - Lars Are Hamre
- SLCR-Sea Lice Research Centre, Department of Biology, University of Bergen, Thormøhlensgt. 55, Pb. 7803, NO-5020, Bergen, Norway
| | - Heidi Kongshaug
- SLCR-Sea Lice Research Centre, Department of Biology, University of Bergen, Thormøhlensgt. 55, Pb. 7803, NO-5020, Bergen, Norway
| | - Frank Nilsen
- SLCR-Sea Lice Research Centre, Department of Biology, University of Bergen, Thormøhlensgt. 55, Pb. 7803, NO-5020, Bergen, Norway
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16
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Øvergård AC, Eichner C, Nilsen F, Dalvin S. Molecular characterization and functional analysis of a salmon louse (Lepeophtheirus salmonis, Krøyer 1838) heme peroxidase with a potential role in extracellular matrixes. Comp Biochem Physiol A Mol Integr Physiol 2017; 206:1-10. [DOI: 10.1016/j.cbpa.2017.01.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 01/03/2017] [Accepted: 01/08/2017] [Indexed: 01/05/2023]
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17
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Øvergård AC, Hamre LA, Harasimczuk E, Dalvin S, Nilsen F, Grotmol S. Exocrine glands ofLepeophtheirus salmonis(Copepoda: Caligidae): Distribution, developmental appearance, and site of secretion. J Morphol 2016; 277:1616-1630. [DOI: 10.1002/jmor.20611] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 08/19/2016] [Accepted: 08/26/2016] [Indexed: 11/11/2022]
Affiliation(s)
- Aina-Cathrine Øvergård
- Disease and Pathogen Transmission; SLCR-Sea Lice Research Centre, Institute of Marine Research; Nordnesgaten 50, Pb. 1870 Nordnes Bergen NO-5817 Norway
| | - Lars A. Hamre
- Department of Biology; SLCR-Sea Lice Research Centre, University of Bergen; Thormøhlensgt. 55, Pb. 7803 Bergen NO-5020 Norway
| | - Ewa Harasimczuk
- Disease and Pathogen Transmission; SLCR-Sea Lice Research Centre, Institute of Marine Research; Nordnesgaten 50, Pb. 1870 Nordnes Bergen NO-5817 Norway
| | - Sussie Dalvin
- Disease and Pathogen Transmission; SLCR-Sea Lice Research Centre, Institute of Marine Research; Nordnesgaten 50, Pb. 1870 Nordnes Bergen NO-5817 Norway
| | - Frank Nilsen
- Department of Biology; SLCR-Sea Lice Research Centre, University of Bergen; Thormøhlensgt. 55, Pb. 7803 Bergen NO-5020 Norway
| | - Sindre Grotmol
- Department of Biology; SLCR-Sea Lice Research Centre, University of Bergen; Thormøhlensgt. 55, Pb. 7803 Bergen NO-5020 Norway
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18
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Sandlund L, Nilsen F, Male R, Dalvin S. The ecdysone receptor (EcR) is a major regulator of tissue development and growth in the marine salmonid ectoparasite, Lepeophtheirus salmonis (Copepoda, Caligidae). Mol Biochem Parasitol 2016; 208:65-73. [DOI: 10.1016/j.molbiopara.2016.06.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 06/15/2016] [Accepted: 06/20/2016] [Indexed: 01/23/2023]
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19
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Eichner C, Øvergård AC, Nilsen F, Dalvin S. Molecular characterization and knock-down of salmon louse (Lepeophtheirus salmonis) prostaglandin E synthase. Exp Parasitol 2015; 159:79-93. [DOI: 10.1016/j.exppara.2015.09.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 06/23/2015] [Accepted: 09/03/2015] [Indexed: 11/29/2022]
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20
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Tröße C, Kongshaug H, Dondrup M, Nilsen F. Characterisation of iron regulatory protein 1A and 1B in the blood-feeding copepod Lepeophtheirus salmonis. Exp Parasitol 2015; 157:1-11. [DOI: 10.1016/j.exppara.2015.06.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 04/21/2015] [Accepted: 06/15/2015] [Indexed: 11/29/2022]
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21
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Molecular characterisation and functional analysis of LsChi2, a chitinase found in the salmon louse (Lepeophtheirus salmonis salmonis, Krøyer 1838). Exp Parasitol 2015; 151-152:39-48. [DOI: 10.1016/j.exppara.2015.01.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 01/22/2015] [Accepted: 01/26/2015] [Indexed: 12/18/2022]
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22
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Marr EJ, Sargison ND, Nisbet AJ, Burgess STG. RNA interference for the identification of ectoparasite vaccine candidates. Parasite Immunol 2015; 36:616-26. [PMID: 25065384 DOI: 10.1111/pim.12132] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 07/23/2014] [Indexed: 12/21/2022]
Abstract
Ectoparasites present a major challenge for disease management globally. With drug resistance increasingly observed in many disease-causing species, the need for novel control measures is pressing. Ever-expanding genomic resources from 'next generation' sequencing are now available for a number of arthropod ectoparasites, necessitating an effective means of screening these data for novel candidates for vaccine antigens or targets for chemotherapeutics. Such in vitro screening methods must be developed if we are to make discoveries in a timely and cost-effective manner. This review will discuss the potential that RNA interference (RNAi) has demonstrated thus far in the context of arthropod ectoparasites and the potential roles for this technology in the development of novel methods for parasite control.
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Affiliation(s)
- E J Marr
- Division of Vaccines and Diagnostics, Pentlands Science Park, Moredun Research Institute, Bush Loan, Penicuik, Edinburgh, UK; Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Roslin, Midlothian, UK
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23
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Steigen A, Karlsbakk E, Plarre H, Watanabe K, Øvergård AC, Brevik Ø, Nylund A. A new intracellular bacterium, Candidatus Similichlamydia labri sp. nov. (Chlamydiaceae) producing epitheliocysts in ballan wrasse, Labrus bergylta (Pisces, Labridae). Arch Microbiol 2014; 197:311-8. [PMID: 25416125 PMCID: PMC4326665 DOI: 10.1007/s00203-014-1061-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 11/11/2014] [Indexed: 11/25/2022]
Abstract
Certain wrasse species (Labridae) are used as cleaner fish in salmon farms on the Norwegian coast, reducing salmon louse intensities. The pathogen repertoire of wrasse in Norway is poorly known, and the objective of the present study is to describe a novel intracellular bacterium detected in Norwegian Labrus bergylta. Histological examination of gill tissues from ballan wrasse, L. bergylta, revealed epitheliocysts occurring basally to the secondary lamellae in the interlamellar epithelium. Ultrastructurally, these had bacteria-filled inclusions with thickened membranes and radiating ray-like structures (actinae). 16S rRNA gene sequences from the gill bacteria showed the highest (97.1 %) similarity to Candidatus Similichlamydia latridicola from the gills of the latrid marine fish Latris lineata in Australia and 94.9 % similarity to Candidatus Actinochlamydia clariae, causing epitheliocystis in the freshwater catfish Clarias gariepinus in Uganda. A total of 47 gill samples from L. bergylta from Western Norway were screened by real time RT-PCR with an assay targeting Candidatus Actinochlamydiaceae 16S rRNA. Prevalence was 100 %. We propose the name Candidatus Similichlamydia labri sp. nov. for this new agent producing gill epitheliocysts in L. bergylta.
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Affiliation(s)
- Andreas Steigen
- Department of Biology, University of Bergen, Bergen, Norway,
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24
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Økland AL, Nylund A, Øvergård AC, Blindheim S, Watanabe K, Grotmol S, Arnesen CE, Plarre H. Genomic characterization and phylogenetic position of two new species in Rhabdoviridae infecting the parasitic copepod, salmon louse (Lepeophtheirus salmonis). PLoS One 2014; 9:e112517. [PMID: 25402203 PMCID: PMC4234470 DOI: 10.1371/journal.pone.0112517] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 10/03/2014] [Indexed: 01/15/2023] Open
Abstract
Several new viruses have emerged during farming of salmonids in the North Atlantic causing large losses to the industry. Still the blood feeding copepod parasite, Lepeophtheirus salmonis, remains the major challenge for the industry. Histological examinations of this parasite have revealed the presence of several virus-like particles including some with morphologies similar to rhabdoviruses. This study is the first description of the genome and target tissues of two new species of rhabdoviruses associated with pathology in the salmon louse. Salmon lice were collected at different Atlantic salmon (Salmo salar) farming sites on the west coast of Norway and prepared for histology, transmission electron microscopy and Illumina sequencing of the complete RNA extracted from these lice. The nearly complete genomes, around 11,600 nucleotides encoding the five typical rhabdovirus genes N, P, M, G and L, of two new species were obtained. The genome sequences, the putative protein sequences, and predicted transcription strategies for the two viruses are presented. Phylogenetic analyses of the putative N and L proteins indicated closest similarity to the Sigmavirus/Dimarhabdoviruses cluster, however, the genomes of both new viruses are significantly diverged with no close affinity to any of the existing rhabdovirus genera. In situ hybridization, targeting the N protein genes, showed that the viruses were present in the same glandular tissues as the observed rhabdovirus-like particles. Both viruses were present in all developmental stages of the salmon louse, and associated with necrosis of glandular tissues in adult lice. As the two viruses were present in eggs and free-living planktonic stages of the salmon louse vertical, transmission of the viruses are suggested. The tissues of the lice host, Atlantic salmon, with the exception of skin at the attachment site for the salmon louse chalimi stages, were negative for these two viruses.
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Affiliation(s)
| | - Are Nylund
- Department of Biology, University of Bergen, 5020 Bergen, Norway
| | | | | | | | - Sindre Grotmol
- Department of Biology, University of Bergen, 5020 Bergen, Norway
- SLRC-Sea Lice Research Center, Department of Biology, University of Bergen, 5020 Bergen, Norway
| | | | - Heidrun Plarre
- Department of Biology, University of Bergen, 5020 Bergen, Norway
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25
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Eichner C, Nilsen F, Grotmol S, Dalvin S. A method for stable gene knock-down by RNA interference in larvae of the salmon louse (Lepeophtheirus salmonis). Exp Parasitol 2014; 140:44-51. [PMID: 24632188 DOI: 10.1016/j.exppara.2014.03.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 01/29/2014] [Accepted: 03/06/2014] [Indexed: 10/25/2022]
Abstract
The salmon louse (Lepeophtheirus salmonis), an ectoparasitic copepod of salmonid fish, is a major threat to aquaculture in Norway, Ireland, Scotland and Canada. Due to rise in resistance against existing pesticides, development of novel drugs or vaccines is necessary. Posttranscriptional gene silencing by RNA interference (RNAi), when established in a high throughput system is a potential method for evaluation of molecular targets for new medical compounds or vaccine antigens. Successful use of RNAi has been reported in several stages of salmon lice. However, when we employed a previously described protocol for planktonic stages, no reproducible down-regulation of target genes was gained. In the present study, we describe a robust method for RNAi, where nauplius larvae are soaked in seawater added double stranded RNA (dsRNA). In order to test for when dsRNA may be introduced, and for the efficacy and duration of RNAi, we performed a series of experiments on accurately age determined larvae, ranging from the hatching egg to the copepodid with a salmon louse coatomer and a putative prostaglandin E synthase gene. Presumptive knock-down was monitored by real time PCR. Significant gene silencing was obtained only when nauplius I larvae were exposed to dsRNA during the period in which they molted to nauplius II. A knock down effect could be detected 2days after soaking, and it remained stable until the last measurement, on day 12. Soaking nauplius I larvae, knock-down was verified for six additional genes with a putative role in molting. For one chitinase, a loss-of-function phenotype with abnormal swimming was obtained. Hence, RNAi, induced in the nauplius, may facilitate studies of the molecular biology of the louse, such as the function of specific genes in developmental processes and physiology, host recognition, host-parasite interaction, and, in extension, the engineering of novel medicines.
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Affiliation(s)
- Christiane Eichner
- SLCR-Sea Lice Research Center, Department of Biology, University of Bergen, Thormøhlensgt. 55, 5008 Bergen, Norway.
| | - Frank Nilsen
- SLCR-Sea Lice Research Center, Department of Biology, University of Bergen, Thormøhlensgt. 55, 5008 Bergen, Norway
| | - Sindre Grotmol
- SLCR-Sea Lice Research Center, Department of Biology, University of Bergen, Thormøhlensgt. 55, 5008 Bergen, Norway
| | - Sussie Dalvin
- SLCR-Sea Lice Research Center, Institute of Marine Research, 5817 Bergen, Norway
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