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Tang H, Zhang J, Zhu L, Jiang X, Pei C, Li L, Kong X. Characteristics of CD4-1 gene and its immune responses against Aeromonas veronii infection by activating NF-κB signaling in Qihe crucian carp Carassius auratus. Fish Shellfish Immunol 2024; 145:109318. [PMID: 38142019 DOI: 10.1016/j.fsi.2023.109318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 12/17/2023] [Accepted: 12/18/2023] [Indexed: 12/25/2023]
Abstract
CD4-1 found in bony fish contains four extracellular immunoglobulin (Ig)-like domains similar to that of mammalian CD4, which is crucial for the activation of CD4+ helper T-cell. However, there is limited knowledge regarding the molecular markers, immune functions and regulation mechanism of CD4-1 in teleosts due to their vast diversity. In this study, we cloned and characterized two isoforms of Qihe crucian carp CD4-1, designated as CaCD4-1.1 and CaCD4-1.2. We further explored their expression responses upon stimulation with Aeromonas veronii, and the regulation of their immune responses against A. veronii by NF-κB. The ORF of CaCD4-1.1 and CaCD4-1.2 cDNA encoded 477 and 466 amino acids, respectively. Both proteins contained seven conserved cysteine residues in the extracellular domain, and a CCC motif in their cytoplasm, respectively. However, CaCD4-1.1 exhibited a relatively limited similarity with CaCD4-1.2 in the ectodomain. The quantitative real-time polymerase chain reaction (qRT-PCR) analysis revealed that the mRNA expression of CaCD4-1.1 and CaCD4-1.2 exhibited differential constitutive expression across all examined tissues. Furthermore, the expression level of CD4-1.2 was higher than that of CD4-1.1 in the gills, head kidney, and spleen of Qihe crucian carp subjected to A. veronii challenge, while it was lower in the trunk kidney. Inhibition of NF-κB activity resulted in a decrease in the expression levels of CD4-1.1 and CD4-1.2 mRNA in the gill, while inducing an increase in expression levels in the spleen, in accordance with the observed ultrastructural changes in both organs. Interestingly, the impact of NF-κB on the mRNA expression level of CD4-1.1 appears to be stronger than that of CD4-1.2. Our results suggest that CaCD4-1.1 and CaCD4-1.2 could be expressed on T cells and antigen-sampling cells that exhibit similar characteristics to mammalian M cells, respectively, and differentially regulated by NF-κB in adaptive immune responses against bacterial infection. This research contributes to a better understanding of the crucial role of CD4-1 in the immune response of Qihe crucian carp and provide novel insights for the prevention and treatment of fish diseases in aquaculture.
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Affiliation(s)
- Hairong Tang
- Engineering Lab of Henan Province for Aquatic Animal Disease Control, College of Fisheries, Henan Normal University, Henan province, PR China
| | - Jie Zhang
- Engineering Lab of Henan Province for Aquatic Animal Disease Control, College of Fisheries, Henan Normal University, Henan province, PR China
| | - Lei Zhu
- Engineering Lab of Henan Province for Aquatic Animal Disease Control, College of Fisheries, Henan Normal University, Henan province, PR China
| | - Xinyu Jiang
- Engineering Lab of Henan Province for Aquatic Animal Disease Control, College of Fisheries, Henan Normal University, Henan province, PR China
| | - Chao Pei
- Engineering Lab of Henan Province for Aquatic Animal Disease Control, College of Fisheries, Henan Normal University, Henan province, PR China
| | - Li Li
- Engineering Lab of Henan Province for Aquatic Animal Disease Control, College of Fisheries, Henan Normal University, Henan province, PR China
| | - Xianghui Kong
- Engineering Lab of Henan Province for Aquatic Animal Disease Control, College of Fisheries, Henan Normal University, Henan province, PR China.
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Bela-Ong DB, Thompson KD, Kim HJ, Park SB, Jung TS. CD4 + T lymphocyte responses to viruses and virus-relevant stimuli in teleost fish. Fish Shellfish Immunol 2023; 142:109007. [PMID: 37625734 DOI: 10.1016/j.fsi.2023.109007] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/31/2023] [Accepted: 08/17/2023] [Indexed: 08/27/2023]
Abstract
Fish diseases caused by viruses are a major threat to aquaculture. Development of disease protection strategies for sustainable fish aquaculture requires a better understanding of the immune mechanisms involved in antiviral defence. The innate and adaptive arms of the vertebrate immune system collaborate to mount an effective defence against viral pathogens. The T lymphocyte components of the adaptive immune system, comprising two major classes (helper T, Th or CD4+ and cytotoxic T lymphocytes, CTLs or CD8+ T cells), are responsible for cell-mediated immune responses. In particular, CD4+ T cells and their different subsets orchestrate the actions of various other immune cells during immune responses, making CD4+ T cells central drivers of responses to pathogens and vaccines. CD4+ T cells are also present in teleost fish. Here we review the literature that reported the use of antibodies against CD4 in a few teleost fish species and transcription profiling of Th cell-relevant genes in the context of viral infections and virus-relevant immunomodulation. Studies reveal massive CD4+ T cell proliferation and expression of key cytokines, transcription factors, and effector molecules that evoke mammalian Th cell responses. We also discuss gaps in the current understanding and evaluation of teleost CD4+ T cell responses and how development and application of novel tools and approaches to interrogate such responses could bridge these gaps. A greater understanding of fish Th cell responses will further illuminate the evolution of vertebrate adaptive immunity, inform strategies to address viral infections in aquaculture, and could further foster fish as model organisms.
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Affiliation(s)
- Dennis Berbulla Bela-Ong
- Laboratory of Aquatic Animal Diseases, Research Institute of Natural Science, College of Veterinary Medicine, Gyeongsang National University, 501-201, 501 Jinju-daero, Jinju-si, Gyeongsangnam-do, 52828, Republic of Korea.
| | - Kim D Thompson
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, EH26 0PZ, Scotland, United Kingdom
| | - Hyoung Jun Kim
- WOAH Reference Laboratory for VHS, National Institute of Fisheries Science, Busan, 46083, Republic of Korea
| | - Seong Bin Park
- Coastal Research and Extension Center, Mississippi State University, Pascagula, MS, 39567, USA
| | - Tae Sung Jung
- Laboratory of Aquatic Animal Diseases, Research Institute of Natural Science, College of Veterinary Medicine, Gyeongsang National University, 501-201, 501 Jinju-daero, Jinju-si, Gyeongsangnam-do, 52828, Republic of Korea.
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Tian HF, Xing J, Tang XQ, Chi H, Sheng XZ, Zhan WB. Cluster of differentiation antigens: essential roles in the identification of teleost fish T lymphocytes. Mar Life Sci Technol 2022; 4:303-316. [PMID: 37073166 PMCID: PMC10077257 DOI: 10.1007/s42995-022-00136-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 05/25/2022] [Indexed: 05/03/2023]
Abstract
Cluster of differentiation (CD) antigens are cell surface molecules expressed on leukocytes and other cells associated with the immune system. Antibodies that react with CD antigens are known to be one of the most essential tools for identifying leukocyte subpopulations. T lymphocytes, as an important population of leukocytes, play essential roles in the adaptive immune system. Many of the CD antigens expressed on T lymphocytes are used as surface markers for T lymphocyte classification, including CD3, CD4 and CD8 molecules. In this review, we summarize the recent advances in the identification of CD molecules on T lymphocytes in teleosts, with emphasis on the functions of CD markers in the classification of T lymphocyte subsets. We notice that genes encoding CD3, co-receptors CD4 and CD8 have been cloned in several fish species and antibodies have been developed to study protein expression in morphological and functional contexts. T lymphocytes can be divided into CD4+ and CD8+ cells discriminated by the expression of CD4 and CD8 molecules in teleost, which are functionally similar to mammalian helper T cells (Th) and cytotoxic T cells (Tc), respectively. Further studies are still needed on the particular characteristics of teleost T cell repertoires and adaptive responses, and results will facilitate the health management and development of vaccines for fish.
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Affiliation(s)
- Hong-fei Tian
- Laboratory of Pathology and Immunology of Aquatic Animals, KLMME, Fisheries College, Ocean University of China, Qingdao, 266003 China
| | - Jing Xing
- Laboratory of Pathology and Immunology of Aquatic Animals, KLMME, Fisheries College, Ocean University of China, Qingdao, 266003 China
- Laboratory for Marine Fisheries Science and Food Production Processes, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266237 China
| | - Xiao-qian Tang
- Laboratory of Pathology and Immunology of Aquatic Animals, KLMME, Fisheries College, Ocean University of China, Qingdao, 266003 China
| | - Heng Chi
- Laboratory of Pathology and Immunology of Aquatic Animals, KLMME, Fisheries College, Ocean University of China, Qingdao, 266003 China
| | - Xiu-zhen Sheng
- Laboratory of Pathology and Immunology of Aquatic Animals, KLMME, Fisheries College, Ocean University of China, Qingdao, 266003 China
| | - Wen-bin Zhan
- Laboratory of Pathology and Immunology of Aquatic Animals, KLMME, Fisheries College, Ocean University of China, Qingdao, 266003 China
- Laboratory for Marine Fisheries Science and Food Production Processes, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266237 China
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Ashfaq H, Soliman H, Fajmann S, Sexl V, El-Matbouli M, Saleh M. Kinetics of CD4-1+ lymphocytes in brown trout after exposure to viral haemorrhagic septicaemia virus. J Fish Dis 2021; 44:1553-1562. [PMID: 34160839 DOI: 10.1111/jfd.13476] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/31/2021] [Accepted: 06/01/2021] [Indexed: 06/13/2023]
Abstract
T-helper cells express CD4 as a co-receptor that binds to major histocompatibility complex class II to synchronize the immune response against upcoming threats via mediating several cytokines. We have previously reported the presence of CD4 homologues in brown trout. The study of cellular immune responses in brown trout is limited by the availability of specific antibodies. We here describe the generation of a polyclonal antibody against CD4-1 that allows for the investigation of CD4+ cells. We used this novel tool to study CD4+ cells in different tissues during viral haemorrhagic septicaemia infection (VHSV) using flow cytometric technique. Flow cytometric analyses revealed an enhanced level of surface CD4-1 expression in the infected group in major lymphoid organs and in the intestine. These results suggest an important role for the T-helper cells within the immune response against viruses, comparable to the immune response in higher vertebrates.
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Affiliation(s)
- Hassan Ashfaq
- Clinical Division of Fish Medicine, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Hatem Soliman
- Clinical Division of Fish Medicine, University of Veterinary Medicine Vienna, Vienna, Austria
- Department of Aquatic Animal Medicine and Management, Faculty of Veterinary Medicine, Assiut University, Assiut, Egypt
| | - Sabine Fajmann
- Institute of Pharmacology and Toxicology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Veronika Sexl
- Institute of Pharmacology and Toxicology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Mansour El-Matbouli
- Clinical Division of Fish Medicine, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Mona Saleh
- Clinical Division of Fish Medicine, University of Veterinary Medicine Vienna, Vienna, Austria
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Chun JH, Jung JW, Kim YR, Lazarte JMS, Kim SW, Kim J, Thompson KD, Kim HJ, Jung TS. Poly (I:C)-Potentiated Vaccination Enhances T Cell Response in Olive Flounder ( Paralichthys olivaceus) Providing Protection against Viral Hemorrhagic Septicemia Virus (VHSV). Vaccines (Basel) 2021; 9:482. [PMID: 34068522 PMCID: PMC8151365 DOI: 10.3390/vaccines9050482] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/28/2021] [Accepted: 04/28/2021] [Indexed: 12/16/2022] Open
Abstract
Viral hemorrhagic septicemia (VHS), caused by viral hemorrhagic septicemia virus (VHSV), is a viral disease affecting teleosts, and is the major cause of virus-related deaths in olive flounder (Paralichthys olivaceus). Research has focused on ways to control VHS, and recently, the use of polyinosinic-polycytidylic acid poly (I:C)-potentiated vaccination has been investigated, whereby fish are injected with poly (I:C) and then with live pathogenic virus, resulting in a significant decrease in VHSV-related mortality. T cell responses were investigated in the present study after vaccinating olive flounder with poly (I:C)-potentiated vaccination to understand the ability of poly (I:C) to induce T cell immunity. Stimulation of T cell responses with the poly (I:C)-potentiated vaccination was confirmed by examining levels of CD3+ T cells, CD4-1+ T cells and CD4-2+ T cells. Higher levels of CD4-2+ T cells were found in vaccinated fish than CD4-1+ T cells, believed to result from a synergistic effect between poly (I:C) administration and pathogenic VHSV immunization. More importantly, the role of CD4-2+ T cells in the antiviral response was clearly evident. The results of this study suggest that the outstanding protection obtained with the poly (I:C)-potentiated vaccination is due to the robust immune response initiated by the CD4-2+ T cells.
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Affiliation(s)
- Jin Hong Chun
- Laboratory of Aquatic Animal Diseases, Research Institute of Natural Science, College of Veterinary Medicine, Gyeongsang National University, 501-201, 501, Jinju-daero, Jinju-si 52828, Korea; (J.H.C.); (J.W.J.); (Y.R.K.); (J.M.S.L.); (S.W.K.); (J.K.)
| | - Jae Wook Jung
- Laboratory of Aquatic Animal Diseases, Research Institute of Natural Science, College of Veterinary Medicine, Gyeongsang National University, 501-201, 501, Jinju-daero, Jinju-si 52828, Korea; (J.H.C.); (J.W.J.); (Y.R.K.); (J.M.S.L.); (S.W.K.); (J.K.)
| | - Young Rim Kim
- Laboratory of Aquatic Animal Diseases, Research Institute of Natural Science, College of Veterinary Medicine, Gyeongsang National University, 501-201, 501, Jinju-daero, Jinju-si 52828, Korea; (J.H.C.); (J.W.J.); (Y.R.K.); (J.M.S.L.); (S.W.K.); (J.K.)
| | - Jassy Mary S. Lazarte
- Laboratory of Aquatic Animal Diseases, Research Institute of Natural Science, College of Veterinary Medicine, Gyeongsang National University, 501-201, 501, Jinju-daero, Jinju-si 52828, Korea; (J.H.C.); (J.W.J.); (Y.R.K.); (J.M.S.L.); (S.W.K.); (J.K.)
| | - Si Won Kim
- Laboratory of Aquatic Animal Diseases, Research Institute of Natural Science, College of Veterinary Medicine, Gyeongsang National University, 501-201, 501, Jinju-daero, Jinju-si 52828, Korea; (J.H.C.); (J.W.J.); (Y.R.K.); (J.M.S.L.); (S.W.K.); (J.K.)
| | - Jaesung Kim
- Laboratory of Aquatic Animal Diseases, Research Institute of Natural Science, College of Veterinary Medicine, Gyeongsang National University, 501-201, 501, Jinju-daero, Jinju-si 52828, Korea; (J.H.C.); (J.W.J.); (Y.R.K.); (J.M.S.L.); (S.W.K.); (J.K.)
| | - Kim D. Thompson
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, UK;
| | - Hyoung Jun Kim
- Pathology Research Division, OIE Reference Laboratory for Viral Haemorrhagic Septicaemia (VHS), National Institute of Fisheries Science, 216, Gijanghaean-ro, Gijang-eup, Busan 46083, Korea;
| | - Tae Sung Jung
- Laboratory of Aquatic Animal Diseases, Research Institute of Natural Science, College of Veterinary Medicine, Gyeongsang National University, 501-201, 501, Jinju-daero, Jinju-si 52828, Korea; (J.H.C.); (J.W.J.); (Y.R.K.); (J.M.S.L.); (S.W.K.); (J.K.)
- Centre for Marine Bioproducts Development, Flinders University, Bedford Park, SA 5042, Australia
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Jung JW, Lee AR, Kim J, Kim YR, Lazarte JMS, Lee JS, Thompson KD, Kim H, Jung TS. Elucidating the Functional Roles of Helper and Cytotoxic T Cells in the Cell-Mediated Immune Responses of Olive Flounder ( Paralichthys olivaceus). Int J Mol Sci 2021; 22:ijms22020847. [PMID: 33467734 PMCID: PMC7829854 DOI: 10.3390/ijms22020847] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/12/2021] [Accepted: 01/12/2021] [Indexed: 11/29/2022] Open
Abstract
In higher vertebrates, helper and cytotoxic T cells, referred to as CD4 and CD8 T lymphocytes, respectively, are mainly associated with adaptive immunity. The adaptive immune system in teleosts involves T cells equivalent to those found in mammals. We previously generated monoclonal antibodies (mAbs) against olive flounder (Paralichthys olivaceus) CD4 T cells, CD4-1 and CD4-2, and used these to describe the olive flounder’s CD4 Tcell response during a viral infection. In the present study, we successfully produced mAbs against CD8 T lymphocytes and their specificities were confirmed using immuno-blotting, immunofluorescence staining, flow cytometry analysis andreverse transcription polymerase chain reaction (RT-PCR). The results showed that these mAbs are specific for CD8 T lymphocytes. We also investigated variations in CD4 and CD8 T cells populations, and analyzed the expression of immune-related genes expressed by these cells in fish infected with nervous necrosis virus or immunized with thymus dependent and independent antigens. We found that both CD4 and CD8 T lymphocyte populations significantly increased in these fish and Th1-related genes were up-regulated compared to the control group. Collectively, these findings suggest that the CD4 and CD8 T lymphocytes in olive flounder are similar to the helper and cytotoxic T cells found in mammals, and Th1 and cytotoxic immune responses are primarily involved in the early adaptive immune response against extracellular antigens.
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Affiliation(s)
- Jae Wook Jung
- Laboratory of Aquatic Animal Diseases, Research Institute of Natural Science, College of Veterinary Medicine, Gyeongsang National University, 501-201, 501, Jinju-daero, Jinju-si 52828, Korea; (J.W.J.); (A.R.L.); (J.K.); (Y.R.K.); (J.M.S.L.); (J.S.L.)
| | - Ae Rin Lee
- Laboratory of Aquatic Animal Diseases, Research Institute of Natural Science, College of Veterinary Medicine, Gyeongsang National University, 501-201, 501, Jinju-daero, Jinju-si 52828, Korea; (J.W.J.); (A.R.L.); (J.K.); (Y.R.K.); (J.M.S.L.); (J.S.L.)
| | - Jaesung Kim
- Laboratory of Aquatic Animal Diseases, Research Institute of Natural Science, College of Veterinary Medicine, Gyeongsang National University, 501-201, 501, Jinju-daero, Jinju-si 52828, Korea; (J.W.J.); (A.R.L.); (J.K.); (Y.R.K.); (J.M.S.L.); (J.S.L.)
| | - Young Rim Kim
- Laboratory of Aquatic Animal Diseases, Research Institute of Natural Science, College of Veterinary Medicine, Gyeongsang National University, 501-201, 501, Jinju-daero, Jinju-si 52828, Korea; (J.W.J.); (A.R.L.); (J.K.); (Y.R.K.); (J.M.S.L.); (J.S.L.)
| | - Jassy Mary S. Lazarte
- Laboratory of Aquatic Animal Diseases, Research Institute of Natural Science, College of Veterinary Medicine, Gyeongsang National University, 501-201, 501, Jinju-daero, Jinju-si 52828, Korea; (J.W.J.); (A.R.L.); (J.K.); (Y.R.K.); (J.M.S.L.); (J.S.L.)
| | - Jung Suk Lee
- Laboratory of Aquatic Animal Diseases, Research Institute of Natural Science, College of Veterinary Medicine, Gyeongsang National University, 501-201, 501, Jinju-daero, Jinju-si 52828, Korea; (J.W.J.); (A.R.L.); (J.K.); (Y.R.K.); (J.M.S.L.); (J.S.L.)
| | - Kim D. Thompson
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik EH26 0PZ, UK;
| | - Hyeongsu Kim
- Inland Aquaculture Research, National Institute of Fisheries Science, #55, 25gil, Yeomyeong-ro, Jinhae-gu, Changwon-si 51688, Korea;
| | - Tae Sung Jung
- Laboratory of Aquatic Animal Diseases, Research Institute of Natural Science, College of Veterinary Medicine, Gyeongsang National University, 501-201, 501, Jinju-daero, Jinju-si 52828, Korea; (J.W.J.); (A.R.L.); (J.K.); (Y.R.K.); (J.M.S.L.); (J.S.L.)
- Centre for Marine Bioproducts Development, Flinders University, Bedford Park 5042, Australia
- Correspondence: ; Tel.: +82-10-8545-9310; Fax: +82-55-762-6733
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Jung JW, Chun JH, Lee JS, Kim SW, Lee AR, Kim J, Lazarte JMS, Kim YR, Kim HJ, Thompson KD, Jung TS. Characterization of CD4-Positive Lymphocytes in the Antiviral Response of Olive Flounder ( Paralichthys oliveceus) to Nervous Necrosis Virus. Int J Mol Sci 2020; 21:E4180. [PMID: 32545330 DOI: 10.3390/ijms21114180] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 06/10/2020] [Accepted: 06/10/2020] [Indexed: 12/11/2022] Open
Abstract
The presence of CD4 T lymphocytes has been described for several teleost species, while many of the main T cell subsets have not been characterized at a cellular level, because of a lack of suitable tools for their identification, e.g., monoclonal antibodies (mAbs) against cell markers. We previously described the tissue distribution and immune response related to CD3ε and CD4-1 T cells in olive flounder (Paralichthys oliveceus) in response to a viral infection. In the present study, we successfully produce an mAb against CD4-2 T lymphocytes from olive flounder and confirmed its specificity using immuno-blotting, immunofluorescence staining, flow cytometry analysis and reverse transcription polymerase chain reaction (RT-PCR). Using these mAbs, we were able to demonstrate that the CD3ε T cell populations contain both types of CD4+ cells, with the majority of the CD4 T cell subpopulations being CD4-1+/CD4-2+ cells, determined using two-color flow cytometry analysis. We also examined the functional activity of the CD4-1 and CD4-2 cells in vivo in response to a viral infection, with the numbers of both types of CD4 T cells increasing significantly during the virus infection. Collectively, these findings suggest that the CD4 T lymphocytes in olive flounder are equivalent to the helper T cells in mammals in terms of their properties and function, and it is the CD4-2 T lymphocytes rather than the CD4-1 T cells that play an important role in the Th1 immune response against viral infections in olive flounder.
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Abstract
The outbreaks of viral encephalopathy and retinopathy (VER), caused by nervous necrosis virus (NNV), represent one of the main infectious threats for marine aquaculture worldwide. Since the first description of the disease at the end of the 1980s, a considerable amount of research has gone into understanding the mechanisms involved in fish infection, developing reliable diagnostic methods, and control measures, and several comprehensive reviews have been published to date. This review focuses on host–virus interaction and epidemiological aspects, comprising viral distribution and transmission as well as the continuously increasing host range (177 susceptible marine species and epizootic outbreaks reported in 62 of them), with special emphasis on genotypes and the effect of global warming on NNV infection, but also including the latest findings in the NNV life cycle and virulence as well as diagnostic methods and VER disease control.
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