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Fujiwara-Nagata E, Rochat T, Lee BH, Lallias D, Rigaudeau D, Duchaud E. Host specificity and virulence of Flavobacterium psychrophilum: a comparative study in ayu (Plecoglossus altivelis) and rainbow trout (Oncorhynchus mykiss) hosts. Vet Res 2024; 55:75. [PMID: 38867318 PMCID: PMC11167770 DOI: 10.1186/s13567-024-01326-6] [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: 12/24/2023] [Accepted: 04/28/2024] [Indexed: 06/14/2024] Open
Abstract
Flavobacterium psychrophilum, the causative agent of bacterial cold-water disease, is a devastating, worldwide distributed, fish pathogen causing significant economic loss in inland fish farms. Previous epidemiological studies showed that prevalent clonal complexes (CC) differ in fish species affected with disease such as rainbow trout, coho salmon and ayu, indicating significant associations between particular F. psychrophilum genotypes and host species. Yet, whether the population structure is driven by the trade of fish and eggs or by host-specific pathogenicity is uncertain. Notably, all F. psychrophilum isolates retrieved from ayu belong to Type-3 O antigen (O-Ag) whereas only very few strains retrieved from other fish species possess this O-Ag, suggesting a role in outbreaks affecting ayu. Thus, we investigated the links between genotype and pathogenicity by conducting comparative bath infection challenges in two fish hosts, ayu and rainbow trout, for a collection of isolates representing different MLST genotypes and O-Ag. Highly virulent strains in one host species exhibited low to no virulence in the other. F. psychrophilum strains associated with ayu and possessing Type-3 O-Ag demonstrated significant variability in pathogenicity in ayu, ranging from avirulent to highly virulent. Strikingly, F. psychrophilum strains retrieved from rainbow trout and possessing the Type-3 O-Ag were virulent for rainbow trout but not for ayu, indicating that Type-3 O-Ag alone is not sufficient for pathogenicity in ayu, nor does it prevent pathogenicity in rainbow trout. This study revealed that the association between a particular CC and host species partly depends on the pathogen's adaptation to specific host species.
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Affiliation(s)
| | - Tatiana Rochat
- Université Paris-Saclay, INRAE, UVSQ, VIM, Jouy-en-Josas, France.
| | - Bo-Hyung Lee
- Université Paris-Saclay, INRAE, UVSQ, VIM, Jouy-en-Josas, France
| | | | | | - Eric Duchaud
- Université Paris-Saclay, INRAE, UVSQ, VIM, Jouy-en-Josas, France
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Knupp C, Soto E, Loch TP. Varying Flavobacterium psychrophilum shedding dynamics in three bacterial coldwater disease-susceptible salmonid (Family Salmonidae) species. Microbiol Spectr 2024; 12:e0360123. [PMID: 38112454 PMCID: PMC10846279 DOI: 10.1128/spectrum.03601-23] [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: 11/14/2023] [Accepted: 11/22/2023] [Indexed: 12/21/2023] Open
Abstract
Flavobacterium psychrophilum causes bacterial coldwater disease (BCWD) and is responsible for substantial losses in farm and hatchery-reared salmonids (Family Salmonidae). Although F. psychrophilum infects multiple economically important salmonids and is transmitted horizontally, the extent of knowledge regarding F. psychrophilum shedding rates and duration is limited to rainbow trout (Oncorhynchus mykiss). Concurrently, hundreds of F. psychrophilum sequence types (STs) have been described using multilocus sequence typing (MLST), and evidence suggests that some variants have distinct phenotypes, including differences in host associations. Whether shedding dynamics differ among F. psychrophilum variants and/or salmonids remains unknown. Thus, three F. psychrophilum isolates (e.g., US19, US62, and US87) in three MLST STs (e.g., ST13, ST277, and ST275) with apparent host associations for coho salmon (O. kisutch), Atlantic salmon (Salmo salar), or rainbow trout were intramuscularly injected into each respective fish species. Shedding rates of live and dead fish were determined by quantifying F. psychrophilum loads in water via quantitative PCR. Both live and dead Atlantic and coho salmon shed F. psychrophilum, as did live and dead rainbow trout. Regardless of salmonid species, dead fish shed F. psychrophilum at higher rates (e.g., up to ~108-1010 cells/fish/hour) compared to live fish (up to ~107-109 cells/fish/hour) and for a longer duration (5-35 days vs 98 days); however, shedding dynamics varied by F. psychrophilum variant and/or host species, a matter that may complicate BCWD management. Findings herein expand knowledge on F. psychrophilum shedding dynamics across multiple salmonid species and can be used to inform future BCWD management strategies.IMPORTANCEFlavobacterium psychrophilum causes bacterial coldwater disease (BCWD) and rainbow trout fry syndrome, both of which cause substantial losses in farmed and hatchery-reared salmon and trout populations worldwide. This study provides insight into F. psychrophilum shedding dynamics in rainbow trout (Oncorhynchus mykiss) and, for the first time, coho salmon (O. kisutch) and Atlantic salmon (Salmo salar). Findings revealed that live and dead fish of all fish species shed the bacterium. However, dead fish shed F. psychrophilum at higher rates than living fish, emphasizing the importance of removing dead fish in farms and hatcheries. Furthermore, shedding dynamics may differ according to F. psychrophilum genetic variant and/or fish species, a matter that may complicate BCWD management. Overall, study results provide deeper insight into F. psychrophilum shedding dynamics and will guide future BCWD management strategies.
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Affiliation(s)
- Christopher Knupp
- Michigan State University-Aquatic Animal Health Laboratory, East Lansing, Michigan, USA
- Department of Fisheries and Wildlife, College of Agriculture and Natural Resources, Michigan State University, East Lansing, Michigan, USA
| | - Esteban Soto
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Thomas P. Loch
- Michigan State University-Aquatic Animal Health Laboratory, East Lansing, Michigan, USA
- Department of Fisheries and Wildlife, College of Agriculture and Natural Resources, Michigan State University, East Lansing, Michigan, USA
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
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Deng F, Wang D, Yu Y, Lu T, Li S. Systemic immune response of rainbow trout exposed to Flavobacterium psychrophilum infection. FISH & SHELLFISH IMMUNOLOGY 2024; 144:109305. [PMID: 38128681 DOI: 10.1016/j.fsi.2023.109305] [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: 07/05/2023] [Revised: 11/28/2023] [Accepted: 12/13/2023] [Indexed: 12/23/2023]
Abstract
Bacterial cold-water disease (BCWD) caused by Flavobacterium psychrophilum is one of the most serious bacterial diseases leading to significant economic loss for rainbow trout (Oncorhynchus mykiss) aquaculture. However, little is known about the systemic immune response of rainbow trout against F. psychrophilum infection. This study investigated the immune response of rainbow trout to F. psychrophilum infection using multiple experiments, including bacterial load detection, phagocyte activity assessment, enzyme activity evaluation, and gene expression profiling. Results showed that the spleen index and intestinal pathogen load reached a peak at 3 days post-infection, with strong pro-inflammatory gene expression observed in rainbow trout. Leukocytes RBA and PKA were significantly elevated in the spleen, blood and intestine at 7 days post-infection. Heat map analysis demonstrated that the spleen had a more substantial pro-inflammatory response compared to the intestine post-infection and exhibited higher expression levels of immune-related genes, including IgM, il1β, il6, cd4, cd8a, cd8b, c1q, chathelicidin, inos, and lysozyme. Both Th1 and Th2 polarized responses in the spleen were activated, with Th2 (il4/13a, gata3) (FC > 4) being more intense than Th1 (tnfα, t-bet) (FC > 2). Tight junction proteins exhibited down-regulation followed by up-regulation post-infection. Collectively, the results of this study expand our current understanding of the immune response of rainbow trout post F. psychrophilum infection but also provide new avenues for investigation in salmonid aquaculture.
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Affiliation(s)
- Furong Deng
- Key Laboratory of Aquatic Animal Diseases and Immune Technology of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, China
| | - Di Wang
- Key Laboratory of Aquatic Animal Diseases and Immune Technology of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, China.
| | - Yang Yu
- Key Laboratory of Aquatic Animal Diseases and Immune Technology of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, China; College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China
| | - Tongyan Lu
- Key Laboratory of Aquatic Animal Diseases and Immune Technology of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, China
| | - Shaowu Li
- Key Laboratory of Aquatic Animal Diseases and Immune Technology of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, China.
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Knupp C, Loch TP. Immersion challenge of three salmonid species (family Salmonidae) with three multilocus sequence typing variants of Flavobacterium psychrophilum provides evidence of differential host specificity. JOURNAL OF FISH DISEASES 2023. [PMID: 37974459 DOI: 10.1111/jfd.13889] [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: 07/06/2023] [Revised: 10/27/2023] [Accepted: 11/02/2023] [Indexed: 11/19/2023]
Abstract
Bacterial coldwater disease (BCWD), caused by Flavobacterium psychrophilum, results in significant losses among multiple salmonid (family Salmonidae) species. Molecular epidemiology and serotyping studies have suggested that some variants are host specific; however, these associations have not been evaluated by cross-challenging fish species with putatively host-associated F. psychrophilum isolates via more natural (i.e. immersion) exposure routes. To this end, F. psychrophilum isolates US19-COS, US62-ATS and US87-RBT, each originally recovered from diseased coho salmon (Oncorhynchus kisutch), Atlantic salmon (Salmo salar) or rainbow trout (O. mykiss), and belonging to a host-associated multilocus sequence typing clonal complex (e.g. CC-ST9, CC-ST232 or CC-ST10), were PCR-serotyped, evaluated for proteolytic activity, and used to challenge adipose fin-clipped 4-month old Atlantic salmon, coho salmon and rainbow trout via immersion. Findings showed US87-RBT caused disease and mortality only in rainbow trout (e.g. 56.7% survival probability). US19-COS and US62-ATS caused more mortality in coho salmon and Atlantic salmon but also caused disease in both other host species, albeit to a lesser extent. Observed survival differences may be due to variant antigenic/virulence determinants as differences in serotype and proteolytic activity were discovered. Collectively, results highlight the intricacies of F. psychrophilum-host interactions and provide further in vivo evidence that some F. psychrophilum MLST variants are host specific, which may have implications for the development of BCWD prevention and control strategies.
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Affiliation(s)
- Christopher Knupp
- Aquatic Animal Health Laboratory, Michigan State University, East Lansing, Michigan, USA
- Department of Fisheries and Wildlife, College of Agriculture and Natural Resources, Michigan State University, East Lansing, Michigan, USA
| | - Thomas P Loch
- Aquatic Animal Health Laboratory, Michigan State University, East Lansing, Michigan, USA
- Department of Fisheries and Wildlife, College of Agriculture and Natural Resources, Michigan State University, East Lansing, Michigan, USA
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
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Ilardi P, Valdes S, Rivera J, Irgang R, Avendaño-Herrera R. Co-occurrence of heterogeneous Flavobacterium psychrophilum isolates within the same Chilean farm and during the same infectious outbreak. JOURNAL OF FISH DISEASES 2023; 46:1085-1096. [PMID: 37357563 DOI: 10.1111/jfd.13828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 06/13/2023] [Accepted: 06/14/2023] [Indexed: 06/27/2023]
Abstract
Flavobacterium psychrophilum is a pathogenic bacterium affecting Chilean salmonid farms. High antigenic and genetic diversity exists among Chilean F. psychrophilum isolates, but the distribution thereof among farms is poorly understood. These epidemiological data are key for developing isolate-specific vaccines. The present study isolated F. psychrophilum in diseased Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) from five freshwater farms between 2018 and 2019. Each farm only raised one salmonid species and was geographically separated from and did not share culturing water with the other farms. Antigenic and genetic analyses were conducted to shed light on the possibility of isolates coexisting within the same farm during outbreaks. A total of 68 Chilean F. psychrophilum isolates were recovered from skin lesions, gills, fins, kidney and spleen of moribund and live fish. Among the 68 Chilean isolates, mPCR-serotyping indicated three major serotypes (i.e. 23.5% type 0; 47.1% type 2; and 26.5% type 4) and, to a lesser degree, serotype 1 (2.9%). Sixteen antigenic groups were detected by slide agglutination. Genetic characterizations by 16S rRNA alleles identified 71% of the isolates as the virulent genogroup CSF259-93 allele. A predominant serotype was associated with each farm, with types 0 and 4 related to Atlantic salmon and types 1 and 2 to rainbow trout. Notwithstanding, several antigenic groups coexisted within some farms. Likewise, the experimental intramuscular challenges (n = 20) demonstrated that the type-2 isolates from rainbow trout were the most pathogenic among isolates recovered from infectious outbreaks in Atlantic salmon, especially as compared to those from types-0 and -4. These results allow us to suggest that prevention measures, specifically vaccines, should be developed according to dominant isolates and with specificity to each farm, that is the use of autogenous or site-specific vaccines.
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Affiliation(s)
- Pedro Ilardi
- Farmacología en Aquacultura Veterinaria FAV S.A., Investigación y Desarrollo, Santiago, Chile
| | - Sara Valdes
- Farmacología en Aquacultura Veterinaria FAV S.A., Laboratorio de Investigación y Desarrollo, Puerto Varas, Chile
| | - Javier Rivera
- Centro Experimental Farmacología en Aquacultura Veterinaria FAV S.A. Abbott (CEFA), Puerto Varas, Chile
| | - Rute Irgang
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Viña del Mar, Chile
- Centro FONDAP Interdisciplinary Center for Aquaculture Research (INCAR), Universidad Andrés Bello, Viña del Mar, Chile
| | - Ruben Avendaño-Herrera
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Viña del Mar, Chile
- Centro FONDAP Interdisciplinary Center for Aquaculture Research (INCAR), Universidad Andrés Bello, Viña del Mar, Chile
- Centro de Investigación Marina Quintay (CIMARQ), Universidad Andrés Bello, Quintay, Chile
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Sayed M, Narayanan L, Essa M, Lawrence M, Karsi A, Abdelhamed H. Secreted Extracellular Products of Flavobacterium covae as Potential Immunogenic Factors for Protection against Columnaris Disease in Channel Catfish ( Ictalurus punctatus). Pathogens 2023; 12:808. [PMID: 37375498 DOI: 10.3390/pathogens12060808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 05/25/2023] [Accepted: 06/03/2023] [Indexed: 06/29/2023] Open
Abstract
Columnaris disease caused by Flavobacterium covae leads to substantial economic losses in commercially important fish species worldwide. The US channel catfish (Ictalurus punctatus) industry is particularly vulnerable to this disease. Therefore, there is an urgent need to develop a vaccine to reduce the economic losses caused by this disease. Secreted extracellular products (SEPs) are considered to be essential bacterial virulence factors that often provide immunogenicity and protection. The current study sought to identify the main SEPs of F. covae and to evaluate their potential to provide protection in channel catfish against columnaris disease. SDS-PAGE analysis of SEPs revealed five protein bands with molecular weights ranging from 13 to 99 kDa. Mass spectrometry analysis showed that these SEPs were hypothetical protein (AWN65_11950), zinc-dependent metalloprotease (AWN65_10205), DNA/RNA endonuclease G (AWN65_02330), outer membrane protein beta-barrel domain (AWN65_12620), and chondroitin-sulfate-ABC endolyase/exolyase (AWN65_08505). Catfish fingerlings were vaccinated with SEPs, SEPs emulsified with mineral oil adjuvant, or heat-inactivated SEPs, or they were sham-immunized through intraperitoneal (IP) injection. After 21 days, an F. covae challenge showed 58.77% and 46.17% survival in the catfish vaccinated with the SEPs and the SEPs emulsified with adjuvant compared to the sham-vaccinated control (100% mortality within 120 h post-infection). However, the heat-inactivated SEPs failed to provide significant protection (23.15% survival). In conclusion, although SEPs contain potentially important immunogenic proteins, further work is needed to optimize their use for long-lasting protection against columnaris disease in fish. These results are significant given the economic impact of columnaris disease on fish farming worldwide.
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Affiliation(s)
- Mohamed Sayed
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA
- Department of Fish Diseases and Management, Faculty of Veterinary Medicine, Beni-Suef University,Beni-Suef 62511, Egypt
| | - Lakshmi Narayanan
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA
| | - Manal Essa
- Department of Fish Diseases and Management, Faculty of Veterinary Medicine, Beni-Suef University,Beni-Suef 62511, Egypt
| | - Mark Lawrence
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA
| | - Attila Karsi
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA
| | - Hossam Abdelhamed
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA
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Vinh NT, Dong HT, Lan NGT, Sangsuriya P, Salin KR, Chatchaiphan S, Senapin S. Immunological response of 35 and 42 days old Asian seabass (Lates calcarifer, Bloch 1790) fry following immersion immunization with Streptococcus iniae heat-killed vaccine. FISH & SHELLFISH IMMUNOLOGY 2023; 138:108802. [PMID: 37178986 DOI: 10.1016/j.fsi.2023.108802] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 04/16/2023] [Accepted: 05/07/2023] [Indexed: 05/15/2023]
Abstract
Early disease prevention by vaccination requires understanding when fry fish develop specific immunity to a given pathogen. In this research, we explored the immune responses of Asian seabass (Lates calcarifer) at the stages of 35- and 42- days post-hatching (dph) to an immersive heat-killed Streptococcus iniae (Si) vaccine to determine whether fish can produce specific antibodies against the pathogen. The vaccinated fish of each stage (V35 and V42) were immersed with the Si vaccine at 107 CFU/ml for 3 h, whereas the control groups (C35 and C42) were immersed with tryptic soy broth (TSB) in the same manner. Specific antibodies were measured by enzyme-linked immunosorbent assay (ELISA) before and post-immunization (i.e., 0, 7, and 14 days post-immunization, dpi). Expression of innate (TNFα and IL-1β) and adaptive (MHCI, MHCII, CD4, CD8, IgM-like, IgT-like, and IgD-like) immune-related genes were evaluated at the same time points with the addition of 1 dpi. The results showed that a subset of immunized fish from both V35 and V42 fry could elicit specific antibodies (IgM) against Si at 14 dpi. All tested innate and adaptive immune genes upregulated at 7 dpi among fish in V35 group. Interestingly, 42 dph fish appeared to respond to the Si vaccine faster than that of 35 dph, as a significant increase in transcripts was observed in CD4, IL-1β, IgM-like, and IgD-like at 1 dpi; and specific antibody titers of some fish, although not all, were higher than a threshold (p = 0.05) since 7 dpi. In conclusion, this study reveals that 35-42 dph Asian seabass fry can elicit specific immunity to Si immersion vaccine, suggesting that early vaccination of 35 dph fry Asian seabass is feasible.
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Affiliation(s)
- Nguyen Tien Vinh
- Aquaculture and Aquatic Resources Management, Department of Food Agriculture and Bioresources, School of Environment, Resources and Development, Asian Institute of Technology, Pathum Thani, Thailand
| | - Ha Thanh Dong
- Aquaculture and Aquatic Resources Management, Department of Food Agriculture and Bioresources, School of Environment, Resources and Development, Asian Institute of Technology, Pathum Thani, Thailand.
| | - Nguyen Giang Thu Lan
- School of Biotechnology, International University, Vietnam National University, Ho Chi Minh City, Viet Nam; Center of Excellence in Fish Infectious Diseases (CE FID), Department of Veterinary Microbiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Pakkakul Sangsuriya
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani, Thailand; Aquatic Molecular Genetics and Biotechnology Research Team, BIOTEC, NSTDA, Pathum Thani, Thailand
| | - Krishna R Salin
- Aquaculture and Aquatic Resources Management, Department of Food Agriculture and Bioresources, School of Environment, Resources and Development, Asian Institute of Technology, Pathum Thani, Thailand
| | - Satid Chatchaiphan
- Department of Aquaculture, Faculty of Fisheries, Kasetsart University, Bangkok, Thailand
| | - Saengchan Senapin
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani, Thailand; Fish Heath Platform, Center of Excellence for Shrimp Molecular Biology and Biotechnology (Centex Shrimp), Faculty of Science, Mahidol University, Bangkok, Thailand.
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