1
|
Esteban MÁ. A review of soluble factors and receptors involved in fish skin immunity: The tip of the iceberg. FISH & SHELLFISH IMMUNOLOGY 2024; 145:109311. [PMID: 38128682 DOI: 10.1016/j.fsi.2023.109311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 12/12/2023] [Accepted: 12/14/2023] [Indexed: 12/23/2023]
Abstract
The immune system of fish possesses soluble factors, receptors, pathways and cells very similar to those of the other vertebrates' immune system. Throughout evolutionary history, the exocrine secretions of organisms have accumulated a large reservoir of soluble factors that serve to protect organisms from microbial pathogens that could disrupt mucosal barrier homeostasis. In parallel, a diverse set of recognition molecules have been discovered that alert the organism to the presence of pathogens. The known functions of both the soluble factors and receptors mentioned above encompass critical aspects of host defense, such as pathogen binding and neutralization, opsonization, or modulation of inflammation if present. The molecules and receptors cooperate and are able to initiate the most appropriate immune response in an attempt to eliminate pathogens before host infection can begin. Furthermore, these recognition molecules, working in coordination with soluble defence factors, collaboratively erect a robust and perfectly coordinated defence system with complementary specificity, activity and tissue distribution. This intricate network constitutes an immensely effective defence mechanism for fish. In this context, the present review focuses on some of the main soluble factors and recognition molecules studied in the last decade in the skin mucosa of teleost fish. However, knowledge of these molecules is still very limited in all teleosts. Therefore, further studies are suggested throughout the review that would help to better understand the functions in which the proteins studied are involved.
Collapse
Affiliation(s)
- María Ángeles Esteban
- Immunobiology for Aquaculture Group, Department of Cell Biology and Histology, Faculty of Biology, University of Murcia, 30100, Murcia, Spain.
| |
Collapse
|
2
|
Ibrahim D, I Abdel Rahman MM, M Abd El-Ghany A, A A Hassanen E, A Al-Jabr O, A Abd El-Wahab R, Zayed S, Abd El Khalek Salem M, Nabil El Tahawy S, Youssef W, A Tolba H, E Dawod R, Taha R, H Arisha A, T Y Kishawy A. Chlorella vulgaris extract conjugated magnetic iron nanoparticles in nile tilapia (Oreochromis niloticus): Growth promoting, immunostimulant and antioxidant role and combating against the synergistic infection with Ichthyophthirius multifiliis and Aeromonashydrophila. FISH & SHELLFISH IMMUNOLOGY 2024; 145:109352. [PMID: 38171430 DOI: 10.1016/j.fsi.2023.109352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 12/25/2023] [Accepted: 12/29/2023] [Indexed: 01/05/2024]
Abstract
Nile tilapia reared under intensive conditions was more susceptible for Ichthyophthirius multifilii (I. multifiliis) infection eliciting higher mortality, lower productive rate and further bacterial coinfection with Aeromonas hydrophila (A. hydrophila). The higher potency of magnetic field of iron oxide nanoparticles (NPs) can kill pathogens through inhibiting their viability. Herein, coating of Chlorella vulgaris extract (ChVE) with magnetic iron oxide NPs (Mag iron NPs) can create an external magnetic field that facilitates their release inside the targeted tissues. Thus, the current study is focused on application of new functionalized properties of Mag iron NPs in combination with ChVE and their efficacy to alleviate I. multifiliis and subsequent infection with A. hydrophila in Nile tilapia. Four hundred fingerlings were divided into: control group (with no additives), three groups fed control diet supplemented with ChVE, Mag iron NPs and ChVE@Mag iron NPs for 90 days. At the end of feeding trial fish were challenged with I. multifiliis and at 9 days post challenge was coinfected by A. hydrophila. A remarkable higher growth rate and an improved feed conversion ratio were detected in group fed ChVE@Mag iron-NPs. The maximum expression of antioxidant enzymes in skin and gills tissues (GSH-Px, CAT, and SOD) which came in parallel with higher serum activities of these enzymes was identified in groups received ChVE@Mag iron-NPs. Furthermore, group fed a combination of ChVE and Mag iron-NPs showed a boosted immune response (higher lysozyme, IgM, ACH50, and MPO) prior to challenge with I. multifiliis. In contrast, fish fed ChVE@Mag iron-NPs supplemented diet had lower infection (decreased by 62%) and mortality rates (decreased by 84%), as well as less visible white spots (decreased by 92 % at 12 dpi) on the body surfaces and mucous score. Interestingly, post I. multifiliis the excessive inflammatory response in gill and skin tissues was subsided by feeding on ChVE@Mag iron-NPs as proved by down regulation of IL-1β, TNFα, COX-2 and iNOS and upregulation of IL-10, and IgM, IgT and Muc-2 genes. Notably, group exposed to I. multifiliis-showed higher mortality when exposed to Aeromonas hydrophilia (increased by 43 %) while group fed ChVE@Mag iron-NPs exhibited lower morality (2%). Moreover, the bacterial loads of A. hydrophilia in fish infected by I. multifiliis and fed control diet were higher than those received dietary supplement of ChVE, Mag iron-NPs and the most reduced load was obtained in group fed ChVE@Mag iron-NPs at 7 dpi. In conclusion, ChVE@Mag iron-NPs fed fish had stronger immune barrier and antioxidant functions of skin and gills, and better survival following I. multifiliis and A. hydrophilia infection.
Collapse
Affiliation(s)
- Doaa Ibrahim
- Department of Nutrition and Clinical Nutrition, Faculty of Veterinary Medicine, Zagazig University, Zagazig 44511, Egypt.
| | | | - Amany M Abd El-Ghany
- Department of Parasitology, Faculty of Veterinary Medicine, Zagazig University, Zagazig 44511, Egypt
| | - Eman A A Hassanen
- Department of Parasitology, Faculty of Veterinary Medicine, Zagazig University, Zagazig 44511, Egypt
| | - Omar A Al-Jabr
- Department of Microbiology, College of Veterinary Medicine, King Faisal University, P.O. Box 400, Al-Ahsa 31982, Saudi Arabia
| | - Reham A Abd El-Wahab
- Biochemistry Department, Animal Health Research Institute (AHRI), Mansoura Branch, Agriculture Research Center (ARC), 246 Dokki, Giza 12618, Egypt
| | - Shimaa Zayed
- Biochemistry Department, Animal Health Research Institute (AHRI), Mansoura Branch, Agriculture Research Center (ARC), 246 Dokki, Giza 12618, Egypt
| | - Mona Abd El Khalek Salem
- Department of Fish Diseases, Animal Health Research Institute (AHRI), Agriculture Research Center, Mansoura, Egypt
| | - Shimaa Nabil El Tahawy
- Department of Clinical Pathology, Zagazig Branch, Animal Health Research Institute, Agriculture Research Center, Zagazig 44516, Egypt
| | - Wessam Youssef
- Biotechnology Department, Animal Health Research Institute (AHRI), 246 Dokki, Giza 12618, Egypt
| | - Heba A Tolba
- Department of Fish Health and Management, Central Laboratory of Aquaculture Research (CLAR), AboHamad, Agriculture Research Center (ARC), Egypt
| | - Rehab E Dawod
- Department of Bacteriology, Animal Health Institute, Damietta Branch, Agriculture Research Center (ARC), Dokki, Giza, Egypt
| | - Rahma Taha
- Department of Zoology, Animal Immunology and Physiology, Faculty of Science, Zagazig University, Zagazig 44511, Egypt
| | - Ahmed H Arisha
- Department of Animal Physiology and Biochemistry, Faculty of Veterinary Medicine, Badr University in Cairo (BUC), Badr City, Cairo, Egypt; Department of Physiology, Faculty of Veterinary Medicine, Zagazig University, Zagazig 44511, Egypt
| | - Asmaa T Y Kishawy
- Department of Nutrition and Clinical Nutrition, Faculty of Veterinary Medicine, Zagazig University, Zagazig 44511, Egypt
| |
Collapse
|
3
|
Yang H, Wang Z, Xiao J, Hu J, Tu X, Gu Z. Integrated morphological and transcriptome profiles reveal a highly-developed extrusome system associated to virulence in the notorious fish parasite, Ichthyophthirius multifiliis. Virulence 2023; 14:2242622. [PMID: 37551042 PMCID: PMC10411306 DOI: 10.1080/21505594.2023.2242622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 07/12/2023] [Accepted: 07/25/2023] [Indexed: 08/09/2023] Open
Abstract
Ichthyophthirius multifiliis is an obligate parasitic ciliate that causes severe economic damage in aquaculture. The parasite contains numerous extrusive organelles (extrusomes) that assist in its pathogenesis and reproduction. However, the structure of these extrusomes and the molecular profiles involved in exocytosis remain unclear. In the present study, through comparative ultrastructural observations across the life cycle of I. multifiliis, we demonstrated that all three of its life stages (theront, trophont, and tomont) exhibited an abundance of extrusomes. In addition, two different types of extrusomes were identified according to their unique structures. Type I extrusomes (mucocysts) are crystalline, oval-shaped, 0.7-1.4 × 0.6-1.1 μm, and distributed as "rosettes" below the trophont membrane. Type II extrusomes, 2.0-3.0 × 0.2-0.3 μm, are rod-shaped with tubular cores and identified as toxicysts, the aggregation of which in the anterior part of the theront and cortex of the trophont revealed their potential roles in I. multifiliis invasion. This was confirmed by our transcriptome investigations of the three stages of I. multifiliis, which revealed that a set of genes involved in proteolysis and DNA/protein biogenesis was highly expressed in the theront and trophont. Furthermore, to map the molecular mechanisms of extrusome release, we characterized 25 Rab family genes in I. multifiliis and determined their expression profiles across the life cycle, reflecting the distribution patterns of the two extrusomes. Collectively, our data revealed that a highly developed extrusome system could play a potential role in the virulence of I. multifiliis, which facilitates a better understanding of the parasite's development.
Collapse
Affiliation(s)
- Hao Yang
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
- Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, China
- National Aquatic Animal Diseases Para-Reference Laboratory (HZAU), Wuhan, China
| | - Zhe Wang
- Marine College, Shandong University, Weihai, China
| | - Jieyin Xiao
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
- Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, China
- National Aquatic Animal Diseases Para-Reference Laboratory (HZAU), Wuhan, China
| | - Jingbo Hu
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
- Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, China
- National Aquatic Animal Diseases Para-Reference Laboratory (HZAU), Wuhan, China
| | - Xiao Tu
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
- Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, China
- National Aquatic Animal Diseases Para-Reference Laboratory (HZAU), Wuhan, China
| | - Zemao Gu
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
- Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, China
- National Aquatic Animal Diseases Para-Reference Laboratory (HZAU), Wuhan, China
- Hubei Hongshan Laboratory, Wuhan, China
| |
Collapse
|
4
|
Abdelrazek SMR, Connon RE, Sanchez C, Atencio B, Mauduit F, Lehman B, Hallett SL, Atkinson SD, Foott JS, Daniels ME. Responses to pathogen exposure in sentinel juvenile fall-run Chinook salmon in the Sacramento River, CA. CONSERVATION PHYSIOLOGY 2023; 11:coad066. [PMID: 37649642 PMCID: PMC10465009 DOI: 10.1093/conphys/coad066] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 08/04/2023] [Accepted: 08/22/2023] [Indexed: 09/01/2023]
Abstract
This study investigated how the deployment of juvenile Chinook salmon in ambient river conditions and the subsequent exposure to and infection by pathogens was associated with the changes in the expression of genes involved in immune system functioning, general stress and host development. Juvenile fish were deployed in sentinel cages for 21 days in the Sacramento River, CA, USA. Gill, kidney and intestinal tissue were sampled at 0, 7, 14 and 21 days post-deployment. Pathogen detection and host response were assessed by a combination of molecular and histopathological evaluation. Our findings showed that fish became infected by the parasites Ceratonova shasta, Parvicapsula minibicornis and Ichthyophthirius multifiliis, and to a lesser extent, the bacteria Flavobacterium columnare and Rickettsia-like organisms. Co-infection was common among sentinel fish. Expression of investigated genes was altered following deployment and was often associated with pathogen abundance. This study provides a foundation for future avenues of research investigating pathogens that affect out-migrating Chinook salmon in the Sacramento River, and offers crucial knowledge related to conservation efforts.
Collapse
Affiliation(s)
- Samah M R Abdelrazek
- Department of Anatomy, Physiology and Cell Biology, University of California, Davis, Davis, CA 95616, USA
| | - Richard E Connon
- Department of Anatomy, Physiology and Cell Biology, University of California, Davis, Davis, CA 95616, USA
| | - Camilo Sanchez
- Department of Anatomy, Physiology and Cell Biology, University of California, Davis, Davis, CA 95616, USA
| | - Benjamin Atencio
- Institute of Marine Sciences, University of California, Santa Cruz, Affiliated with Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Santa Cruz, CA 95060, USA
| | - Florian Mauduit
- Department of Anatomy, Physiology and Cell Biology, University of California, Davis, Davis, CA 95616, USA
| | - Brendan Lehman
- Institute of Marine Sciences, University of California, Santa Cruz, Affiliated with Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Santa Cruz, CA 95060, USA
| | - Sascha L Hallett
- Department of Microbiology, Oregon State University, Corvallis, OR 97331, USA
| | - Stephen D Atkinson
- Department of Microbiology, Oregon State University, Corvallis, OR 97331, USA
| | - J. Scott Foott
- California Nevada Fish Health Center, U.S. Fish and Wildlife Service, Anderson, CA 96007, USA
| | - Miles E Daniels
- Institute of Marine Sciences, University of California, Santa Cruz, Affiliated with Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Santa Cruz, CA 95060, USA
| |
Collapse
|
5
|
Ugelvik MS, Dalvin S. The effect of different intensities of the ectoparasitic salmon lice (Lepeophtheirus salmonis) on Atlantic salmon (Salmo salar). JOURNAL OF FISH DISEASES 2022; 45:1133-1147. [PMID: 35612902 PMCID: PMC9544591 DOI: 10.1111/jfd.13649] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 04/29/2022] [Accepted: 05/02/2022] [Indexed: 06/01/2023]
Abstract
The effect of different intensities of the ectoparasitic salmon lice (Lepeophtheirus salmonis) on stress, growth and the expression of immune and wound healing transcripts in the skin of Atlantic salmon (Salmo salar) was investigated. Lice infection success and survival were similar at the chalimus and preadult stage in the low and high dose group, but infection success and survival were significantly lower in the high than in the low dose group at the adult stage. The expression of investigated transcripts was not correlated to lice intensities, but several of them were significantly differently expressed locally in the skin at the site of lice attachment in infected fish compared to controls. This included an up-regulation of pro-inflammatory markers at the site of lice attachment (e.g., interleukin 1-beta, interleukin 8 and the acute phase protein serum amyloid A), a reduction of markers of adaptive immunity (cluster of differentiation 8-alpha and immunoglobulin M) and decreased expression of the anti-inflammatory cytokine interleukin 10.
Collapse
|
6
|
Fu YW, Liu WD, Chen HZ, Lin DJ, Hou TL, Guo SQ, Zhang QZ. Antiparasitical efficacy of sophoraflavanone G isolated from Sophora flavescens against parasitic protozoa Ichthyophthirius multifiliis. Vet Parasitol 2022; 306:109731. [DOI: 10.1016/j.vetpar.2022.109731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 04/30/2022] [Accepted: 05/19/2022] [Indexed: 10/18/2022]
|
7
|
Ying C, Fang X, Wang H, Yang Y, Xu P, Liu K, Yin G. Anisakidae parasitism activated immune response and induced liver fibrosis in wild anadromous Coilia nasus. JOURNAL OF FISH BIOLOGY 2022; 100:958-969. [PMID: 35229303 DOI: 10.1111/jfb.15027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 02/24/2022] [Accepted: 02/25/2022] [Indexed: 06/14/2023]
Abstract
Anisakidae nematode larvae is one of the most common parasites in wild anadromous Coilia nasus. This study aims to explore the mechanism of the C. nasus immune response to the parasitism of Anisakid nematode larvae. Results found that Anisakid nematode larvae parasitism caused liver injury as evidenced by histomorphology results as well as high levels of aminotransferase and aspertate aminotransferase. Furthermore, Anisakid nematode larvae parasitism induced an immune response in the host, which was characterized by the elevated populations of macrophages and neutrophils in the liver and head-kidney in the Anisakidae-infected group compared to the noninfected group. The expression of immunoglobulin IgM and IgD in the liver and head-kidney was also increased in the Anisakidae-infected group. The Anisakidae-infected group showed higher activity of antioxidant enzymes catalase and superoxide dismutase, which indicates severe oxidative stress, and increased production of pro-inflammatory cytokines, TNF-α, IL-6 as well as MCP-1 in the liver compared with the noninfected group. As a result of inflammation, livers of hosts in the Anisakidae-infected group showed fibrosis, and elevated expression of associated proteins including α-smooth muscle actin, fibronectin, collagen type I and type III compared with the noninfected group. We demonstrated that Anisakid nematode larvae parasitism results in injury and fibrosis in the liver, and triggers immune cell infiltration and inflammation in the liver and head-kidney of C. nasus. Altogether, the results provide a foundation for building an interaction between parasite and host, and will contribute to C. nasus population and fishery resource protection.
Collapse
Affiliation(s)
- Congping Ying
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, China
| | - Xin Fang
- Scientific Observing and Experimental Station of Fishery Resources and Environment in the Lower Reaches of the Changjiang River, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, CAFS, WuXi, China
| | - Honglan Wang
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
| | - Yanping Yang
- Scientific Observing and Experimental Station of Fishery Resources and Environment in the Lower Reaches of the Changjiang River, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, CAFS, WuXi, China
| | - Pao Xu
- Scientific Observing and Experimental Station of Fishery Resources and Environment in the Lower Reaches of the Changjiang River, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, CAFS, WuXi, China
| | - Kai Liu
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, China
- Scientific Observing and Experimental Station of Fishery Resources and Environment in the Lower Reaches of the Changjiang River, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, CAFS, WuXi, China
| | - Guojun Yin
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, China
- Scientific Observing and Experimental Station of Fishery Resources and Environment in the Lower Reaches of the Changjiang River, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, CAFS, WuXi, China
| |
Collapse
|
8
|
Su N, Hu CB, Shao T, Jin CY, Li H, Ji JF, Qin LL, Fan DD, Lin AF, Xiang LX, Shao JZ. Functional role of CD40 and CD154 costimulatory signals in IgZ-mediated immunity against bacterial infection. FISH AND SHELLFISH IMMUNOLOGY REPORTS 2021; 2:100038. [DOI: 10.1016/j.fsirep.2021.100038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 11/11/2021] [Accepted: 11/11/2021] [Indexed: 01/18/2023] Open
|
9
|
Shiota K, Sukeda M, Prakash H, Kondo M, Nakanishi T, Nagasawa T, Nakao M, Somamoto T. Local immune responses to two stages of Ichthyophthirius multifiliis in ginbuna crucian carp. FISH & SHELLFISH IMMUNOLOGY 2021; 118:19-24. [PMID: 34450269 DOI: 10.1016/j.fsi.2021.08.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 08/16/2021] [Accepted: 08/16/2021] [Indexed: 06/13/2023]
Abstract
Ichthyophthirius multifiliis is a ciliated protozoan parasite and is known to infect many freshwater teleosts. Characterizing the immune system in epithelial tissues, where the parasites penetrate and settle, is key to understanding host-parasite interactions. This study examined local immune responses in vivo to the infective stage (theront and trophont) of the parasites using intra-fin administration, which has been developed to analyze in vivo immune responses using fish fin. CD8α+ and CD4+ T-cell compositions were increased significantly in the fin cavity injected with theront or trophont antigens. The expression of GATA-3 and T-bet mRNA, which regulate differentiation of helper T-cells, was upregulated significantly in leukocytes from the trophont antigen-injected site. In contrast, the percentages of macrophages and neutrophils, which are innate immunity components, were decreased significantly in the injection sites. These results suggest that I. multifiliis antigens inhibit the migration of macrophages and neutrophils, and T-cells are the first responders to I. multifiliis. Thus, to better understand the interaction of host immunity and I. multifiliis, further studies should focus on exploring the inhibitory factors from I. multifiliis or examining innate functions of teleost T-cells.
Collapse
Affiliation(s)
- Koumei Shiota
- Laboratory of Marine Biochemistry, Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, 819-0395, Japan
| | - Masaki Sukeda
- Laboratory of Marine Biochemistry, Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, 819-0395, Japan; Goto Aquaculture Institute Co., Ltd, Sayama City, Saitama, 350-1332, Japan
| | - Harsha Prakash
- Laboratory of Marine Biochemistry, Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, 819-0395, Japan
| | - Masakazu Kondo
- Department of Applied Aquabiology, National Fisheries University, Japan Fisheries Research and Education Agency, Shimonoseki, Yamaguchi, 759-6595, Japan
| | - Teruyuki Nakanishi
- Goto Aquaculture Institute Co., Ltd, Sayama City, Saitama, 350-1332, Japan
| | - Takahiro Nagasawa
- Laboratory of Marine Biochemistry, Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, 819-0395, Japan
| | - Miki Nakao
- Laboratory of Marine Biochemistry, Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, 819-0395, Japan
| | - Tomonori Somamoto
- Laboratory of Marine Biochemistry, Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, 819-0395, Japan.
| |
Collapse
|
10
|
Cheng GF, Kong WG, Zhai X, Mu QJ, Dong ZR, Zhan MT, Xu Z. Molecular cloning and expression analysis of CD79a and CD79b in rainbow trout (Oncorhynchus mykiss) after bacterial, parasitic, and viral infection. FISH & SHELLFISH IMMUNOLOGY 2021; 118:385-395. [PMID: 34563671 DOI: 10.1016/j.fsi.2021.09.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 09/16/2021] [Accepted: 09/18/2021] [Indexed: 06/13/2023]
Abstract
CD79a and CD79b heterodimers are important components that consist of B cell receptor compound, which play a crucial role in transduction activation signal of the antigen binding BCR, and B cell development and antibody production. In order to investigate the characters and potential functions of CD79a and CD79b in rainbow trout (Oncorhynchus mykiss), we firstly cloned and analyzed the expression of CD79a and CD79b and found that the cDNA sequences of CD79a and CD79b both contained open reading frame of 711 and 645 bp in length for encoding the protein of 237 and 215 amino acid residues, respectively. The predicted amino acid sequences from trout were highly conserved with those of other teleost fishes in structure. Phylogenetic tree was constructed to analyze the evolutionary relationship between the trout and other known species, the result indicated that CD79a and CD79b of trout clustered at high bootstrap values with Salmo salar. Moreover, three trout infection models with F. columnare G4, I. multifiliis and infectious hematopoietic necrosis virus (IHNV) were constructed, which resulted in morphological changes and serious lesions in skin and gills. Importantly, the high expression of CD79a and CD79b occurred in skin, gills, and followed by head kidney in response to bacterial, parasitic, and viral infection, as its expression was closely related to that of Igs. Our findings indicated that CD79a and CD79b play vital roles in both systemic and mucosal immune responses of rainbow trout during bacterial, parasitic, and viral infection, which will contribute to explore the roles of CD79 subunits in B cell signaling during ontogeny and disease.
Collapse
Affiliation(s)
- Gao-Feng Cheng
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Wei-Guang Kong
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, 430072, China
| | - Xue Zhai
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Qing-Jiang Mu
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Zhao-Ran Dong
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Meng-Ting Zhan
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Zhen Xu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, 430072, China.
| |
Collapse
|
11
|
Holzer AS, Piazzon MC, Barrett D, Bartholomew JL, Sitjà-Bobadilla A. To React or Not to React: The Dilemma of Fish Immune Systems Facing Myxozoan Infections. Front Immunol 2021; 12:734238. [PMID: 34603313 PMCID: PMC8481699 DOI: 10.3389/fimmu.2021.734238] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 09/01/2021] [Indexed: 11/13/2022] Open
Abstract
Myxozoans are microscopic, metazoan, obligate parasites, belonging to the phylum Cnidaria. In contrast to the free-living lifestyle of most members of this taxon, myxozoans have complex life cycles alternating between vertebrate and invertebrate hosts. Vertebrate hosts are primarily fish, although they are also reported from amphibians, reptiles, trematodes, mollusks, birds and mammals. Invertebrate hosts include annelids and bryozoans. Most myxozoans are not overtly pathogenic to fish hosts, but some are responsible for severe economic losses in fisheries and aquaculture. In both scenarios, the interaction between the parasite and the host immune system is key to explain such different outcomes of this relationship. Innate immune responses contribute to the resistance of certain fish strains and species, and the absence or low levels of some innate and regulatory factors explain the high pathogenicity of some infections. In many cases, immune evasion explains the absence of a host response and allows the parasite to proliferate covertly during the first stages of the infection. In some infections, the lack of an appropriate regulatory response results in an excessive inflammatory response, causing immunopathological consequences that are worse than inflicted by the parasite itself. This review will update the available information about the immune responses against Myxozoa, with special focus on T and B lymphocyte and immunoglobulin responses, how these immune effectors are modulated by different biotic and abiotic factors, and on the mechanisms of immune evasion targeting specific immune effectors. The current and future design of control strategies for myxozoan diseases is based on understanding this myxozoan-fish interaction, and immune-based strategies such as improvement of innate and specific factors through diets and additives, host genetic selection, passive immunization and vaccination, are starting to be considered.
Collapse
Affiliation(s)
- Astrid S Holzer
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czechia
| | - M Carla Piazzon
- Fish Pathology Group, Institute of Aquaculture Torre de la Sal - Consejo Superior de Investigaciones Científicas (IATS-CSIC), Castellón, Spain
| | - Damien Barrett
- Department of Microbiology, Oregon State University, Corvallis, OR, United States
| | - Jerri L Bartholomew
- Department of Microbiology, Oregon State University, Corvallis, OR, United States
| | - Ariadna Sitjà-Bobadilla
- Fish Pathology Group, Institute of Aquaculture Torre de la Sal - Consejo Superior de Investigaciones Científicas (IATS-CSIC), Castellón, Spain
| |
Collapse
|
12
|
Salinas I, Fernández-Montero Á, Ding Y, Sunyer JO. Mucosal immunoglobulins of teleost fish: A decade of advances. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2021; 121:104079. [PMID: 33785432 PMCID: PMC8177558 DOI: 10.1016/j.dci.2021.104079] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 03/22/2021] [Accepted: 03/22/2021] [Indexed: 05/03/2023]
Abstract
Immunoglobulins (Igs) are complex glycoproteins that play critical functions in innate and adaptive immunity of all jawed vertebrates. Given the unique characteristics of mucosal barriers, secretory Igs (sIgs) have specialized to maintain homeostasis and keep pathogens at bay at mucosal tissues from fish to mammals. In teleost fish, the three main IgH isotypes, IgM, IgD and IgT/Z can be found in different proportions at the mucosal secretions of the skin, gills, gut, nasal, buccal, and pharyngeal mucosae. Similar to the role of mammalian IgA, IgT plays a predominant role in fish mucosal immunity. Recent studies in IgT have illuminated the primordial role of sIgs in both microbiota homeostasis and pathogen control at mucosal sites. Ten years ago, IgT was discovered to be an immunoglobulin class specialized in mucosal immunity. Aiming at this 10-year anniversary, the goal of this review is to summarize the current status of the field of fish Igs since that discovery, while identifying knowledge gaps and future avenues that will move the field forward in both basic and applied science areas.
Collapse
Affiliation(s)
- Irene Salinas
- Center for Evolutionary and Theoretical Immunology (CETI), Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA.
| | - Álvaro Fernández-Montero
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Yang Ding
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - J Oriol Sunyer
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
| |
Collapse
|
13
|
Survival of metazoan parasites in fish: Putting into context the protective immune responses of teleost fish. ADVANCES IN PARASITOLOGY 2021; 112:77-132. [PMID: 34024360 DOI: 10.1016/bs.apar.2021.03.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Defence mechanisms of fish can be divided into specific and non-specific that act in concert and are often interdependent. Most fish in both wild and cultured populations are vulnerable to metazoan parasites. Endoparasitic helminths include several species of digeneans, cestodes, nematodes, and acanthocephalans. Although they may occur in large numbers, helminth infections rarely result in fish mortality. Conversely, some ectoparasites cause mass mortality in farmed fish. Given the importance of fish innate immunity, this review addresses non-specific defence mechanisms of fish against metazoan parasites, with emphasis on granulocyte responses involving mast cells, neutrophils, macrophages, rodlet cells, and mucous cells. Metazoan parasites are important disease agents that affect wild and farmed fish and can induce high economic loss and, as pathogen organisms, deserve considerable attention. The paper will provide our light and transmission electron microscopy data on metazoan parasites-fish innate immune and neuroendocrine systems. Insights about the structure and functions of the cell types listed above and a brief account of the effects and harms of each metazoan taxon to specific fish apparati/organs will be presented.
Collapse
|
14
|
Shivam S, El-Matbouli M, Kumar G. Development of Fish Parasite Vaccines in the OMICs Era: Progress and Opportunities. Vaccines (Basel) 2021; 9:179. [PMID: 33672552 PMCID: PMC7923790 DOI: 10.3390/vaccines9020179] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 02/16/2021] [Accepted: 02/17/2021] [Indexed: 02/07/2023] Open
Abstract
Globally, parasites are increasingly being recognized as catastrophic agents in both aquaculture sector and in the wild aquatic habitats leading to an estimated annual loss between 1.05 billion and 9.58 billion USD. The currently available therapeutic and control measures are accompanied by many limitations. Hence, vaccines are recommended as the "only green and effective solution" to address these concerns and protect fish from pathogens. However, vaccine development warrants a better understanding of host-parasite interaction and parasite biology. Currently, only one commercial parasite vaccine is available against the ectoparasite sea lice. Additionally, only a few trials have reported potential vaccine candidates against endoparasites. Transcriptome, genome, and proteomic data at present are available only for a limited number of aquatic parasites. Omics-based interventions can be significant in the identification of suitable vaccine candidates, finally leading to the development of multivalent vaccines for significant protection against parasitic infections in fish. The present review highlights the progress in the immunobiology of pathogenic parasites and the prospects of vaccine development. Finally, an approach for developing a multivalent vaccine for parasitic diseases is presented. Data sources to prepare this review included Pubmed, google scholar, official reports, and websites.
Collapse
Affiliation(s)
- Saloni Shivam
- Clinical Division of Fish Medicine, University of Veterinary Medicine Vienna, 1210 Vienna, Austria; (S.S.); (M.E.-M.)
- Central Marine Fisheries Research Institute, Karwar 581301, India
| | - Mansour El-Matbouli
- Clinical Division of Fish Medicine, University of Veterinary Medicine Vienna, 1210 Vienna, Austria; (S.S.); (M.E.-M.)
| | - Gokhlesh Kumar
- Clinical Division of Fish Medicine, University of Veterinary Medicine Vienna, 1210 Vienna, Austria; (S.S.); (M.E.-M.)
| |
Collapse
|
15
|
Jaafar R, Ødegård J, Mathiessen H, Karami AM, Marana MH, von Gersdorff Jørgensen L, Zuo S, Nielsen T, Kania PW, Buchmann K. Quantitative trait loci (QTL) associated with resistance of rainbow trout Oncorhynchus mykiss against the parasitic ciliate Ichthyophthirius multifiliis. JOURNAL OF FISH DISEASES 2020; 43:1591-1602. [PMID: 32944955 PMCID: PMC7692903 DOI: 10.1111/jfd.13264] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/20/2020] [Accepted: 08/23/2020] [Indexed: 06/11/2023]
Abstract
The parasitic ciliate Ichthyophthirius multifiliis has a low host specificity eliciting white spot disease (WSD) in a wide range of freshwater fishes worldwide. The parasite multiplies rapidly whereby the infection may reach problematic levels in a host population within a few days. The parasite targets both wild and cultured fish but the huge economic impact of the protozoan is associated with mortality, morbidity and treatment in aquacultural enterprises. We have investigated the potential for genetic selection of WSD-resistant strains of rainbow trout. Applying the DNA typing system Affymetrix® and characterizing the genome of the individual fish by use of 57,501 single nucleotide polymorphisms (SNP) and their location on the rainbow trout chromosomes, we have genetically characterized rainbow trout with different levels of natural resistance towards WSD. Quantitative trait loci (QTL) used for the selection of breeders with specific markers for resistance are reported. We found a significant association between resistance towards I. multifiliis infection and SNP markers located on the two specific rainbow trout chromosomes Omy 16 and Omy 17. Comparing the expression of immune-related genes in fish-with and without clinical signs-we recorded no significant difference. However, trout surviving the infection showed high expression levels of genes encoding IgT, T-cell receptor TCRβ, C3, cathelicidins 1 and 2 and SAA, suggesting these genes to be associated with protection.
Collapse
Affiliation(s)
- R Jaafar
- Laboratory of Aquatic PathobiologyDepartment of Veterinary and Animal SciencesFaculty of Health and Medical SciencesUniversity of CopenhagenFrederiksberg C.Denmark
| | | | - H Mathiessen
- Laboratory of Aquatic PathobiologyDepartment of Veterinary and Animal SciencesFaculty of Health and Medical SciencesUniversity of CopenhagenFrederiksberg C.Denmark
| | - A M Karami
- Laboratory of Aquatic PathobiologyDepartment of Veterinary and Animal SciencesFaculty of Health and Medical SciencesUniversity of CopenhagenFrederiksberg C.Denmark
| | - M H Marana
- Laboratory of Aquatic PathobiologyDepartment of Veterinary and Animal SciencesFaculty of Health and Medical SciencesUniversity of CopenhagenFrederiksberg C.Denmark
| | - L von Gersdorff Jørgensen
- Laboratory of Aquatic PathobiologyDepartment of Veterinary and Animal SciencesFaculty of Health and Medical SciencesUniversity of CopenhagenFrederiksberg C.Denmark
| | - S Zuo
- Laboratory of Aquatic PathobiologyDepartment of Veterinary and Animal SciencesFaculty of Health and Medical SciencesUniversity of CopenhagenFrederiksberg C.Denmark
| | | | - P W Kania
- Laboratory of Aquatic PathobiologyDepartment of Veterinary and Animal SciencesFaculty of Health and Medical SciencesUniversity of CopenhagenFrederiksberg C.Denmark
| | - K Buchmann
- Laboratory of Aquatic PathobiologyDepartment of Veterinary and Animal SciencesFaculty of Health and Medical SciencesUniversity of CopenhagenFrederiksberg C.Denmark
| |
Collapse
|
16
|
Buchmann K. Immune response to Ichthyophthirius multifiliis and role of IgT. Parasite Immunol 2020; 42:e12675. [PMID: 31587318 PMCID: PMC7507210 DOI: 10.1111/pim.12675] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 09/19/2019] [Accepted: 10/02/2019] [Indexed: 12/24/2022]
Abstract
The parasitic ciliate Ichthyophthirius multifiliis causes white spot disease in freshwater fish worldwide. The theront penetrates external surfaces of the naïve fish where it develops into the feeding trophont stage and elicits a protective immune response both at the affected site as well as at the systemic level. The present work compiles data and presents an overall model of the protective reactions induced. A wide spectrum of inflammatory reactions are established upon invasion but the specific protection is provided by adaptive factors. Immunoglobulin IgT is involved in protection of surfaces in several fish species and is thereby one of the first adaptive immune molecules reacting with the penetrating theront. IgT producing lymphocytes occur in epithelia, dispersed or associated with lymphoid cell aggregations (skin epidermis, fins, gills, nostrils and buccal cavities) but they are also present in central immune organs such as the head kidney, spleen and liver. When theronts invade immunized fish skin, they are encountered by host factors which opsonize the parasite and may result in complement activation, phagocytosis or cell-mediated killing. However, antibody (IgT, IgM and IgD) binding to parasite cilia has been suggested to alter parasite behaviour and induce an escape reaction, whereby specific IgT (or other classes of immunoglobulin in fish surfaces) takes a central role in protection against the parasite.
Collapse
Affiliation(s)
- Kurt Buchmann
- Department of Veterinary and Animal ScienceFaculty of Health and Medical SciencesUniversity of CopenhagenFrederiksberg CDenmark
| |
Collapse
|
17
|
Models suggest pathogen risks to wild fish can be mitigated by acquired immunity in freshwater aquaculture systems. Sci Rep 2020; 10:7513. [PMID: 32372052 PMCID: PMC7200699 DOI: 10.1038/s41598-020-64023-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 04/08/2020] [Indexed: 11/08/2022] Open
Abstract
The interaction of pathogens between wild and farmed aquatic animal populations is a concern that remains unclear and controversial. Ichthyophthirius multifiliis, a ciliated protozoan parasite, is a pathogen of freshwater finfish species with geographic and host range that causes significant economic losses in aquaculture. Flow-through farming systems may facilitate the transfer of such a parasite with free-living stages between farmed and wild stocks. Here, experimental and field study infection data are used to describe the infection dynamics of Ichthyophthirius multifiliis in rainbow trout using a simple macroparasite model by including host resistance. The study considered flow-through farming systems with a single or two age-class compartments and simulated the transfer of the parasite between farmed and wild fish populations. Results suggest that aquaculture can promote the prevalence of the resistance in wild stocks by increasing the parasite population in the wild environment. At the same time, acquired resistance in the farmed fish population may protect the wild fish population from lethal effects of the parasite by reducing the total parasite population. This study offers a promising mathematical basis for understanding the effects of freshwater aquaculture in disease spread in wildlife, developing risk assessment modeling, and exploring new ways of aquaculture management.
Collapse
|
18
|
Chen X, Wang B, Nie J, You P. A survey of gyrodactylid parasites on the fins of Homatula variegata in central China. PLoS One 2020; 15:e0230320. [PMID: 32187220 PMCID: PMC7080252 DOI: 10.1371/journal.pone.0230320] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 02/26/2020] [Indexed: 11/17/2022] Open
Abstract
In this study, two parasites on the fins of Homatula variegata were recorded from March to September 2016. A dissection mirror was used to examine the distribution and quantity of the ectoparasitic Gyrodactylus sp. and Paragyrodactylus variegatus on the host Homatula variegata in different seasons. The present study explored possible explanations for the site specificity of gyrodactylid parasites in 442 Homatula variegata infected with 4307 Gyrodactylus sp. (species identification is incomplete, only characterized to the genus level) and 1712 Paragyrodactylus variegatus. These two gyrodactylid parasites were collected from fish fins, and the fish were harvested in China's Qinling Mountains.The results indicated that the highest number of Gyrodactylus sp., which was numerically the dominant species, appeared on the fish fins in April, while the highest number of Paragyrodactylus variegatus was found on the fish fins in March. The two parasite species appeared to be partitioned spatially, with Gyrodactylus sp. occurring more frequently on pectoral and pelvic fins, and P. variegatus occurring more frequently on caudal fins. However, Gyrodactylus sp. appeared to occur on fish of all lengths, while P. variegatus tended to occur more abundantly on shorter fish rather than on longer fish. At lower Gyrodactylus sp. infection levels (<100), the pelvic and pectoral fins were the main locations of attachment, followed by the dorsal fin. For infections of more than 100 parasites, more samples of Gyrodactylus sp. were located on the pectoral fin. For a low number of Paragyrodactylus variegatus infections (<100), the pelvic and pectoral fins were the preferred locations of attachment, followed by the caudal fin. Between April and September, there were many monogenean parasites on fish fins, and the fish size was within the range of 5-10 cm. However, when a fish was longer than 10 cm long, the number of parasites on its fins greatly decreased.
Collapse
Affiliation(s)
- Xiaoning Chen
- College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, China.,Shaanxi Key Laboratory for Animal Conservation, Shaanxi Institute of Zoology, Xi'an, Shaanxi, China
| | - Biao Wang
- College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, China
| | - Jianzhen Nie
- College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, China
| | - Ping You
- College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, China
| |
Collapse
|
19
|
Review on Immersion Vaccines for Fish: An Update 2019. Microorganisms 2019; 7:microorganisms7120627. [PMID: 31795391 PMCID: PMC6955699 DOI: 10.3390/microorganisms7120627] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 11/25/2019] [Accepted: 11/26/2019] [Indexed: 01/11/2023] Open
Abstract
Immersion vaccines are used for a variety of aquacultured fish to protect against infectious diseases caused by bacteria and viruses. During immersion vaccination the antigens are taken up by the skin, gills or gut and processed by the immune system, where the resulting response may lead to protection. The lack of classical secondary responses following repeated immersion vaccination may partly be explained by the limited uptake of antigens by immersion compared to injection. Administration of vaccines depends on the size of the fish. In most cases, immersion vaccination is inferior to injection vaccination with regard to achieved protection. However, injection is problematic in small fish, and fry as small as 0.5 gram may be immersion vaccinated when they are considered adaptively immunocompetent. Inactivated vaccines are, in many cases, weakly immunogenic, resulting in low protection after immersion vaccination. Therefore, during recent years, several studies have focused on different ways to augment the efficacy of these vaccines. Examples are booster vaccination, administration of immunostimulants/adjuvants, pretreatment with low frequency ultrasound, use of live attenuated and DNA vaccines, preincubation in hyperosmotic solutions, percutaneous application of a multiple puncture instrument and application of more suitable inactivation chemicals. Electrostatic coating with positively charged chitosan to obtain mucoadhesive vaccines and a more efficient delivery of inactivated vaccines has also been successful.
Collapse
|