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Zhou ZY, Bai SJ, Lu CW, Yang B, Wang J, Lian S, Jian ZR, Wang EL, Wang GX, Liu T. Nocardia seriolae mediates liver granulomatous chronic inflammation in Micropterus salmoides through pyroptosis. JOURNAL OF FISH DISEASES 2023; 46:321-332. [PMID: 36644875 DOI: 10.1111/jfd.13746] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 12/13/2022] [Accepted: 12/16/2022] [Indexed: 06/17/2023]
Abstract
Granulomatous diseases caused by Nocardia seriously endanger the health of cultured fish. These bacteria are widely distributed, but prevention and treatment methods are very limited. Chronic granulomatous inflammation is an important pathological feature of Nocardia infection. However, the molecular mechanisms of granuloma formation and chronic inflammation are still unclear. Constructing a granuloma infection model of Nocardia is the key to exploring the pathogenesis of the disease. In this study, we established a granuloma model in the liver of largemouth bass (Micropterus salmoides) and assessed the infection process of Nocardia seriolae at different concentrations by analysing relevant pathological features. By measuring the expression of pro-inflammatory cytokines, transcription factors and a pyroptosis-related protein, we revealed the close relationship between pyroptosis and chronic inflammation of granulomas. We further analysed the immunofluorescence results and the expression of pyroptosis-related protein of macrophage infected by N. seriolae and found that N. seriolae infection induced macrophage pyroptosis in vitro. These results were proved by flow cytometry analysis of infection experiment in vivo. Our results indicated that the pyroptosis effect may be the key to inducing chronic inflammation in the fish liver and further mediating granuloma formation. In this study, we explored the molecular mechanism underlying chronic inflammation of granulomas and developed research ideas for understanding the occurrence and development of granulomatous diseases in fish.
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Affiliation(s)
- Zheng-Yang Zhou
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Shang-Jie Bai
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Chen-Wang Lu
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Bin Yang
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Jun Wang
- Key Laboratory of Sichuan Province for Fishes Conservation and Utilization in the Upper Reaches of the Yangtze River, Neijiang Normal University, Neijiang, Sichuan, China
| | - Sheng Lian
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Zheng-Ran Jian
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Er-Long Wang
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Gao-Xue Wang
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Tao Liu
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
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2
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Díaz-Ibarrola D, Martínez D, Vargas-Lagos C, Saravia J, Vargas-Chacoff L. Transcriptional modulation of immune genes in gut of Sub-Antarctic notothenioid fish Eleginops maclovinus challenged with Francisella noatunensis subsp. noatunensis. FISH & SHELLFISH IMMUNOLOGY 2022; 124:56-65. [PMID: 35367625 DOI: 10.1016/j.fsi.2022.03.044] [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: 01/29/2022] [Revised: 03/22/2022] [Accepted: 03/28/2022] [Indexed: 06/14/2023]
Abstract
The search for functional foods that improve the immune response has traditionally been focused on lymphoid tissue and the intestinal mucosa. However, it is unknown whether there is a different immune response in different portions of the gut following exposure to a bacterial pathogen. We challenged Eleginops maclovinus intraperitoneally (i.p) with Francisella noatunensis subsp. noatunensis and measured mRNA transcripts related to innate and adaptive immune responses in different parts of the gut (foregut, midgut and hindgut). We used control (i.p only with bacterial culture medium), low dose (i.p of F. noatunensis at 1 × 101 bact/μL), medium dose (i.p of F. noatunensis at 1 × 105 bact/μL) and high dose (i.p of F. noatunensis at 1 × 1010 bact/μL) groups in our experiments. We sampled fish at days 1, 3, 7, 14, 21, and 28 post-injection. We observed tissue-specific expression of TLR1, TLR5, TLR8, MHCI, MHCII and IgM, and transcription of these immune markers was lower in foregut and higher in midgut and hindgut. We detected Francisella genetic material (DNA) in fish stimulated with a high dose from day 1-28 in foregut, midgut, and hindgut. However, we could only detect Francisella DNA in fish stimulated the medium and low dose at later timepoints in the foregut (21-28 days post injection "dpi") and hindgut (low dose from day 7-28 dpi). Our results suggest that the immune responses to bacterial pathogens occur throughout the gut, but certain segments may be more susceptible to infection because of their cellular morphology (anterior, middle and posterior).
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Affiliation(s)
- Daniela Díaz-Ibarrola
- Laboratorio de Fisiología de Peces, Instituto de Ciencias Marinas y Limnológicas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile; Centro Fondap de Investigación de Altas Latitudes (IDEAL), Universidad Austral de Chile, Valdivia, Chile; Escuela de Graduados, Programa de Doctorado en Ciencias de la Acuicultura, Universidad Austral de Chile, Puerto Montt, Chile.
| | - Danixa Martínez
- Laboratorio de Fisiología de Peces, Instituto de Ciencias Marinas y Limnológicas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile; Laboratorio de Inmunología y Estrés de Organismos Acuáticos, Instituto de Patología Animal, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Valdivia, Chile
| | - Carolina Vargas-Lagos
- Laboratorio de Fisiología de Peces, Instituto de Ciencias Marinas y Limnológicas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile; Centro Fondap de Investigación de Altas Latitudes (IDEAL), Universidad Austral de Chile, Valdivia, Chile
| | - Julia Saravia
- Laboratorio de Fisiología de Peces, Instituto de Ciencias Marinas y Limnológicas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile; Centro Fondap de Investigación de Altas Latitudes (IDEAL), Universidad Austral de Chile, Valdivia, Chile; Escuela de Graduados, Programa de Doctorado en Ciencias de la Acuicultura, Universidad Austral de Chile, Puerto Montt, Chile
| | - Luis Vargas-Chacoff
- Laboratorio de Fisiología de Peces, Instituto de Ciencias Marinas y Limnológicas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile; Centro Fondap de Investigación de Altas Latitudes (IDEAL), Universidad Austral de Chile, Valdivia, Chile; Millennium Institute Biodiversity of Antarctic and Subantarctic Ecosystems, BASE, University Austral of Chile, Valdivia, Chile.
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3
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Chang CH, Poudyal S, Pulpipat T, Wang PC, Chen SC. Pathological Manifestations of Francisella orientalis in the Green Texas Cichlid ( Herichthys cyanoguttatus). Animals (Basel) 2021; 11:ani11082284. [PMID: 34438742 PMCID: PMC8388529 DOI: 10.3390/ani11082284] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 07/22/2021] [Accepted: 07/30/2021] [Indexed: 11/26/2022] Open
Abstract
Simple Summary The following study demonstrates the pathological manifestations of an emerging virulent bacterium, Francisella orientalis, in an ornamental cichlid fish, the green Texas cichlid (Herichthys cyanoguttatus). This study was conducted to prove that Francisella orientalis can cause a disease in the green Texas cichlid that is similar to natural infection. Francisella orientalis was discovered for the first time in green Texas cichlid by our team in Taiwan in 2015. The present study simply tried to prove the susceptibility of Francisella orientalis in green Texas cichlid by conducting a challenge experiment, where healthy fish were injected with a dose of the bacteria. After the challenge, the healthy fish showed the same disease progression as was seen in the case of natural outbreak. The mortality rate, clinical symptoms, gross findings, and histopathological findings were similar to natural infection. Francisella orientalis could also be recovered in artificial media from challenged fish, thus indicating that the bacteria had multiplied inside the fish. These findings prove that green Texas cichlid (Herichthys cyanoguttatus) is susceptible to Francisela orientalis, and new management and vaccination strategies are necessary in the farming of this fish. This study also helps by adding to the knowledge of the growing host base for Francisella orientalis. Abstract Francisella orientalis (Fo) is considered to be one of the major pathogens of tilapia because of the high mortalities observed during outbreaks. Other cichlids belonging to the same family (Cichlidae) as tilapia are also quite susceptible to this pathogen. On various occasions, Fo has also been isolated from other warm water fish, including three-line grunt, hybrid striped bass, French grunt, Caesar grunt, and Indo-Pacific reef fish. However, only a few studies have reported the pathogenicity of Francisella orientalis in ornamental cichlid fish. This study fulfills Koch’s postulates by showing that a strain of Fo obtained from green Texas cichlid (Herichthys cyanoguttatus) was able to produce the same pathogenicity in healthy fish. A mortality of 100% was observed after healthy green Texas cichlid were experimentally injected with Fo at a dose of 8.95 × 105 CFU/fish. DNA extracted from the organs of predilection (spleen, head kidney) gave positive results by PCR for all fish that died during the experimental period. Spleen and head kidney presented with multifocal white nodules in the affected fish, corresponding to typical vacuolated granulomas on histopathological examination of the tissues. Based on the results of this study, it is evident that Fo can indeed infect green Texas cichlid and produce a disease typical of francisellosis.
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Affiliation(s)
- Chia-Hsuan Chang
- Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan;
| | - Sayuj Poudyal
- International Degree Program of Ornamental Fish Technology and Aquatic Animal Health, International College, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan;
| | - Theeraporn Pulpipat
- Department of Farm Resources and Production Medicine, Faculty of Veterinary Medicine, Kasetsart University Kamphaeng Saen Campus, Nakhon Pathom 73140, Thailand;
| | - Pei-Chi Wang
- Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan;
- Southern Taiwan Fish Diseases Research Center, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan
- Research Center for Fish Vaccine and Diseases, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan
- Correspondence: (P.-C.W.); (S.-C.C.); Tel.: +886-8-7740569 (P.-C.W. & S.-C.C.)
| | - Shih-Chu Chen
- Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan;
- International Degree Program of Ornamental Fish Technology and Aquatic Animal Health, International College, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan;
- Southern Taiwan Fish Diseases Research Center, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan
- Research Center for Fish Vaccine and Diseases, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan
- Research Center for Animal Biologics, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan
- Correspondence: (P.-C.W.); (S.-C.C.); Tel.: +886-8-7740569 (P.-C.W. & S.-C.C.)
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The Use of Extracellular Membrane Vesicles for Immunization against Francisellosis in Nile Tilapia ( Oreochromis niloticus) and Atlantic Cod ( Gadus morhua L.). Vaccines (Basel) 2021; 9:vaccines9010034. [PMID: 33435503 PMCID: PMC7827370 DOI: 10.3390/vaccines9010034] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 12/31/2020] [Accepted: 01/04/2021] [Indexed: 11/17/2022] Open
Abstract
Francisellosis in fish is caused by the facultative intracellular Gram-negative bacterial pathogens Francisella noatunensis ssp. noatunensis and Francisella orientalis. The disease is affecting both farmed and wild fish worldwide and no commercial vaccines are currently available. In this study, we tested isolated membrane vesicles (MVs) as possible vaccine candidates based on previous trials in zebrafish (Danio rerio) indicating promising vaccine efficacy. Here, the MV vaccine-candidates were tested in their natural hosts, Atlantic cod (Gadus morhua L.) and Nile tilapia (Oreochromis niloticus). Injection of MVs did not display any toxicity or other negative influence on the fish and gene expression analysis indicated an influence on the host immune response. However, unlike in other tested fish species, a protective immunity following vaccine application and immunization period could not be detected in the Atlantic cod or tilapia. Further in vivo studies are required to achieve a better understanding of the development of immunological memory in different fish species.
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Silva TJ, Casal G, Soares EC, Rocha S, Santos EL, Oliveira E, Azevedo C. Ultrastructure of intracytoplasmic Rickettsia-like infection of the gills of the teleost Archosargus probatocephalus (Sparidae) in northeastern Brazil. ACTA ACUST UNITED AC 2020; 29:e010020. [PMID: 33027426 DOI: 10.1590/s1984-29612020067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 07/01/2020] [Indexed: 11/22/2022]
Abstract
A histopathological survey was conducted to investigate the presence of microparasites in fish Archosargus probatocephalus in a river near Maceió, Brazil. Light microscope observations of fragments of gill showed the presence of small cysts containing numerous myxospores that were morphologically identified as Henneguya. Transmission electron microscopy observations further revealed several gill cells containing groups of prokaryotic cells within large cytoplasmic vacuoles. Each infected host cell displayed a single vacuole containing a variable number of Rickettsia-like cells (up to 11), some of which presented the dumbbell shape characteristic of binary fission. The Rickettsia-like cells were pleomorphic, without a nucleus and with chromatin dispersed in the cytoplasm. They had a thin electron-dense wall of Gram-negative type. The morphology of these prokaryotic was similar to those of the order Rickettsiales and was described as a Rickettsia-like organism. Histopathological evaluation showed that several vacuole membranes had a lysed appearance. Some had ruptured, thus allowing direct contact between the Rickettsia-like organism and the cytoplasm of the host cell. The rupturing of the branchial epithelium may have contributed towards reduction of the surface area of the gills, but it is not possible to say that this was the cause of the host's death.
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Affiliation(s)
- Themis Jesus Silva
- Laboratório de Aquicultura, Centro de Ciências Agrárias - CECA, Universidade Federal de Alagoas - UFAL, Rio Largo, AL, Brasil
| | - Graça Casal
- Laboratório de Patologia Animal, Centro Interdisciplinar de Investigação Marinha e Ambiental - CIIMAR, Universidade do Porto, Porto - UP, Portugal.,Instituto Universitário de Ciências da Saúde, Instituto de Investigação e Formação Avançada em Ciências e Tecnologias da Saúde - CESPU, Gandra, Portugal
| | - Emerson Carlos Soares
- Laboratório de Aquicultura, Centro de Ciências Agrárias - CECA, Universidade Federal de Alagoas - UFAL, Rio Largo, AL, Brasil
| | - Sónia Rocha
- Laboratório de Patologia Animal, Centro Interdisciplinar de Investigação Marinha e Ambiental - CIIMAR, Universidade do Porto, Porto - UP, Portugal.,Laboratório de Biologia Celular, Instituto de Ciências Biomédicas - ICBAS, Universidade do Porto - UP, Porto, Portugal
| | - Elton Lima Santos
- Laboratório de Aquicultura, Centro de Ciências Agrárias - CECA, Universidade Federal de Alagoas - UFAL, Rio Largo, AL, Brasil
| | - Elsa Oliveira
- Laboratório de Biologia Celular, Instituto de Ciências Biomédicas - ICBAS, Universidade do Porto - UP, Porto, Portugal
| | - Carlos Azevedo
- Laboratório de Patologia Animal, Centro Interdisciplinar de Investigação Marinha e Ambiental - CIIMAR, Universidade do Porto, Porto - UP, Portugal.,Laboratório de Biologia Celular, Instituto de Ciências Biomédicas - ICBAS, Universidade do Porto - UP, Porto, Portugal
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6
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Poudyal S, Pulpipat T, Wang PC, Chen SC. Comparison of the pathogenicity of Francisella orientalis in Nile tilapia (Oreochromis niloticus), Asian seabass (Lates calcarifer) and largemouth bass (Micropterus salmoides) through experimental intraperitoneal infection. JOURNAL OF FISH DISEASES 2020; 43:1097-1106. [PMID: 32700447 DOI: 10.1111/jfd.13217] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 06/20/2020] [Accepted: 06/22/2020] [Indexed: 06/11/2023]
Abstract
Francisella orientalis is a highly virulent, emerging bacterium that causes mass mortalities in tilapia. This pathogen also affects numerous other warm-water fish species, including three-line grunt, hybrid striped bass and various ornamental fish. This study sheds light on two new species of fish that are susceptible to F. orientalis. Asian seabass and largemouth bass showed variable levels of susceptibility in a bacterial challenge experiment. After intraperitoneally injected with a dose of 106 CFU/fish, a total of 64.28% and 21.42% mortalities were obtained in Asian seabass and largemouth bass, respectively. Meanwhile, Nile tilapia showed acute mortality of 100%. All fish showed typical lesions of francisellosis, including multifocal granulomas in the spleen and head kidney. Immunohistochemical analysis revealed strong positive signals inside the granulomas of all fish. The bacterial recovery in solid media from infected fish was highest in Nile tilapia (85.71%), followed by Asian seabass (35.71%) and largemouth bass (21.42%). PCR results tested 100% positive for Nile tilapia, and 78.57% and 21.42% for Asian seabass and largemouth bass, respectively. In conclusion, Asian seabass and largemouth bass are susceptible to this pathogen, which warrants new management strategies when employing predation polyculture systems of these species with tilapia.
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Affiliation(s)
- Sayuj Poudyal
- International Degree Program of Ornamental Fish Technology and Aquatic Animal Health, International College, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Theeraporn Pulpipat
- Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Pei-Chi Wang
- Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
- Southern Taiwan Fish Diseases Research Center, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
- Research Center for Fish Vaccine and Diseases, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Shih-Chu Chen
- International Degree Program of Ornamental Fish Technology and Aquatic Animal Health, International College, National Pingtung University of Science and Technology, Pingtung, Taiwan
- Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
- Southern Taiwan Fish Diseases Research Center, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
- Research Center for Fish Vaccine and Diseases, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
- Research Center for Animal Biologics, National Pingtung University of Science and Technology, Pingtung, Taiwan
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López-Crespo RA, Martínez-Chavarría LC, Lugo-García AT, Romero-Romero LP, García-Márquez LJ, Reyes-Matute A. Outbreak of francisellosis (Francisella noatunensis subsp. orientalis) in cultured neon jewel cichlids Hemichromis bimaculatus from Morelos, Mexico. DISEASES OF AQUATIC ORGANISMS 2019; 137:125-130. [PMID: 31854330 DOI: 10.3354/dao03429] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Francisellosis is a disease caused by different species of the bacterial genus Francisella and has been diagnosed in a wide variety of animals, including fish. Francisellosis in fish is characterized by the development of non-specific clinical signs as well as the presence of numerous granulomas in several organs (mainly spleen and kidney). Ten neon jewel cichlids Hemichromis bimaculatus were submitted for diagnosis from a farm located in Morelos, Mexico. Gross examination, wet preparations, cytology, histopathology and PCR were performed. Affected fish showed lethargy, erratic swimming, imbalance and gasping. At the post mortem examination, multiple granulomas were observed in the kidney and spleen. Microscopically, granulomatous inflammation was observed in several organs. Species-specific PCR assay using DNA from the affected tissues of H. bimaculatus as a template demonstrated the presence of F. noatunensis subsp. orientalis (Fno) by amplifying a hypothetical protein gene of the Fno species. The end diagnosis of francisellosis is important for Mexican ornamental aquaculture, since it is necessary to implement measures for treatment, prevention, control and diagnosis. This is the first report of francisellosis in the neon jewel cichlid.
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Affiliation(s)
- Rubén A López-Crespo
- Departamento de Patología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, CP 04510, Ciudad de México, México
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8
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Chang CT, Benedict S, Whipps CM. Transmission of Mycobacterium chelonae and Mycobacterium marinum in laboratory zebrafish through live feeds. JOURNAL OF FISH DISEASES 2019; 36:681-4. [PMID: 31418901 DOI: 10.1111/jfd.12071] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Accepted: 11/14/2012] [Indexed: 05/04/2023]
Abstract
The zebrafish (Danio rerio) is a popular vertebrate model organism used in a wide range of research fields. Mycobacteriosis, caused by Mycobacterium species, is particularly concerning because it is a common disease associated with chronic infections in these fish. Infections are also a source of uncontrolled experimental variance that may influence research results. Live feeds for zebrafish are common and include paramecia (Paramecium caudatum), brine shrimp (Artemia franciscana) and rotifers (Branchionus spp.). Although nutritionally beneficial, live feeds may pose a biosecurity risk. In this study, we investigate transmission of Mycobacterium chelonae and Mycobacterium marinum through these three live feeds. We show that all three live feeds ingest both M. marinum and M. chelonae and can transmit mycobacterial infections to zebrafish. This observation emphasizes the need for live feeds to be included in the consideration of potential biosecurity risks. This study is of importance to other beyond the zebrafish community, including those of additional aquatic models and those using live feeds for other types of aquaculture.
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Affiliation(s)
- Carolyn T Chang
- Department of Environment and Forest Biology, State University of New York College of Environmental Science and Forestry, Syracuse, New York
| | - Samuel Benedict
- Department of Environment and Forest Biology, State University of New York College of Environmental Science and Forestry, Syracuse, New York
| | - Christopher M Whipps
- Department of Environment and Forest Biology, State University of New York College of Environmental Science and Forestry, Syracuse, New York
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9
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Nguyen VV, Dong HT, Senapin S, Gangnonngiw W, Pirarat N, Kayansamruaj P, Rung-Ruangkijkrai T, Rodkhum C. Transmission of Francisella noatuensis subsp. orientalis from subclinically infected hybrid red tilapia broodstock (Oreochromis sp.) to their offspring. Microb Pathog 2019; 136:103670. [PMID: 31430526 DOI: 10.1016/j.micpath.2019.103670] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Revised: 05/27/2019] [Accepted: 08/13/2019] [Indexed: 11/15/2022]
Abstract
Francisella noatunensis subsp. orientalis (Fno) has been reported as an important bacterial pathogen causing significant mortality (30-95%) in farmed tilapia in broad geographic areas. However, we found that there was a proportion of broodfish in our laboratory that appeared to be healthy but which tested positive for Fno. We therefore hypothesized that Fno might be able to be transmitted from subclinically infected tilapia mouthbrooders to their offspring through the current practice of fry production in tilapia hatcheries. To prove this, experimentally infected hybrid red tilapia broodstock were mated and their offspring were examined for the presence of Fno. In this study, three pairs of infected broodfish were mated for natural spawning and fertilized eggs from each couple were then collected from the female mouths for artificial incubation. The newly hatched larvae were cultured for 30 days and sample collection was performed at different developmental stages i.e. yolk-sac larvae, 5 and 30-day old fry. The results showed that the ovary and testis of all 3 pairs of the broodstock, as well as their fertilized eggs and offspring were Fno positive by Fno-specific PCR and in situ DNA hybridization. In summary, this study revealed that with the current practice in tilapia hatcheries, Fno might be able to transmit from subclinically infected tilapia mouthbrooders to their offspring. Therefore, using Fno-free broodfish in tilapia hatcheries should be considered in order to produce Fno-free tilapia fry.
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Affiliation(s)
- Vuong Viet Nguyen
- Department of Microbiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand; Research Institute of Aquaculture No. 1 (RIA1), Dinh Bang, Tu Son, Bac Ninh, Viet Nam
| | - Ha Thanh Dong
- Faculty of Science and Technology, Suan Sunandha Rajabhat University, Bangkok, Thailand.
| | - Saengchan Senapin
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani, Thailand; Center of Excellence for Shrimp Molecular Biology and Biotechnology (Centex Shrimp), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Warachin Gangnonngiw
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathumthani, Thailand; Center of Excellence for Shrimp Molecular Biology and Biotechnology (Centex Shrimp), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Nopadon Pirarat
- Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, 10330, Thailand
| | | | - Tilladit Rung-Ruangkijkrai
- Department of Veterinary Anatomy, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
| | - Channarong Rodkhum
- Department of Microbiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand; Fish Infectious Diseases Research Unit (FID RU), Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand.
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Vargas-Lagos C, Martínez D, Oyarzún R, Avendaño-Herrera R, Yáñez AJ, Pontigo JP, Vargas-Chacoff L. High doses of Francisella noatunensis induces an immune response in Eleginops maclovinus. FISH & SHELLFISH IMMUNOLOGY 2019; 90:1-11. [PMID: 31015063 DOI: 10.1016/j.fsi.2019.04.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 04/05/2019] [Accepted: 04/08/2019] [Indexed: 06/09/2023]
Abstract
Francisella noatunensis subsp. noatunensis, the etiological agent of Francisellosis, affects a large number of farmed species such as Salmo salar. This species coexists with several native species in the same ecosystem, including Eleginops maclovinus. Our objective was to evaluate the susceptibility, presence of clinical symptoms, and the ability of Eleginops maclovinus to respond to Francisella infection. For this, healthy individuals were inoculated with 1.5 × 101, 1.5 × 105, and 1.5 × 1010 bact/μL of Francisella by intraperitoneal injection, subsequently the fish were sampled on days 1, 3, 7, 14, 21, and 28 post injection (dpi). At the end of the experiment, no mortality, nor internal and external clinical signs were observed, although in the high dose anaemia was detected. Additionally, bacteria were detected in all three doses, however there was replication at day 28 only in the liver in the high dose. Analysis of gene expression by qPCR showed that the spleen generated an immune response against infection from day 1 dpi, however at day 7 dpi most of the genes suffered repressed expression; observing over expression of the genes C3, NLRC3, NLRC5, MHCI, IgM. In contrast, expression in the anterior kidney did not vary significantly during the challenge. IgM quantification showed the production of antibodies in the medium and high doses. This study provides new knowledge about Francisella infection and the long-lasting and specific immune response generated by Eleginops maclovinus. It also demonstrates its susceptibility to Francisellosis where there is a difference in the immune response according to the tissue.
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Affiliation(s)
- C Vargas-Lagos
- Programa de Magíster en Ciencias, Mención Microbiología, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile; Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile; (c)Interdisciplinary Center for Aquaculture Research (INCAR), Concepción, Chile; Centro FONDAP-IDEAL, Universidad Austral de Chile, Valdivia, Chile.
| | - D Martínez
- Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile; Programa de Doctorado en Ciencias de La Acuicultura, Universidad Austral de Chile, Puerto Montt, Chile
| | - R Oyarzún
- Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile; Programa de Doctorado en Ciencias de La Acuicultura, Universidad Austral de Chile, Puerto Montt, Chile
| | - R Avendaño-Herrera
- (c)Interdisciplinary Center for Aquaculture Research (INCAR), Concepción, Chile; Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas, Universidad Andrés Bello, Viña Del Mar, Chile
| | - A J Yáñez
- (c)Interdisciplinary Center for Aquaculture Research (INCAR), Concepción, Chile; Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
| | - J P Pontigo
- Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile
| | - L Vargas-Chacoff
- Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile; Centro FONDAP-IDEAL, Universidad Austral de Chile, Valdivia, Chile.
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11
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Complete genome sequencing of sixteen Francisella noatunensis subsp. orientalis isolates: A genomic approach for molecular characterization and spread dynamics of this clonal population. Genomics 2018; 110:442-449. [PMID: 30367926 DOI: 10.1016/j.ygeno.2018.10.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 10/09/2018] [Accepted: 10/19/2018] [Indexed: 11/23/2022]
Abstract
Francisella noatunensis subsp. orientalis (FNO) is an important emerging pathogen associated with disease outbreaks in farm-raised Nile tilapia. FNO genetic diversity using PCR-based typing, no intra-species discrimination was achieved among isolates/strains from different countries, thus demonstrating a clonal behaviour pattern. In this study, we aimed to evaluate the population structure of FNO isolates by comparing whole-genome sequencing data. The analysis of recombination showed that Brazilian isolates group formed a clonal population; whereas other lineages are also supported by this analysis for isolates from foreign countries. The whole-genome multilocus sequence typing (wgMLST) analysis showed varying numbers of dissimilar alleles, suggesting that the Brazilian clonal population are in expansion. Each Brazilian isolate could be identified as a single node by high-resolution gene-by-gene approach, presenting slight genetic differences associated to mutational events. The common ancestry node suggests a single entry into the country before 2012, and the rapid dissemination of this infectious agent may be linked to market sales of infected fingerlings.
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12
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Liu S, Jiang Z, Deng Y, Wu Y, Zhang J, Zhao C, Huang D, Huang X, Trevathan-Tackett SM. Effects of nutrient loading on sediment bacterial and pathogen communities within seagrass meadows. Microbiologyopen 2018. [PMID: 29521006 PMCID: PMC6182560 DOI: 10.1002/mbo3.600] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Eutrophication can play a significant role in seagrass decline and habitat loss. Microorganisms in seagrass sediments are essential to many important ecosystem processes, including nutrient cycling and seagrass ecosystem health. However, current knowledge of the bacterial communities, both beneficial and detrimental, within seagrass meadows in response to nutrient loading is limited. We studied the response of sediment bacterial and pathogen communities to nutrient enrichment on a tropical seagrass meadow in Xincun Bay, South China Sea. The bacterial taxonomic groups across all sites were dominated by the Gammaproteobacteria and Firmicutes. Sites nearest to the nutrient source and with the highest NH4+ and PO43− content had approximately double the relative abundance of putative denitrifiers Vibrionales, Alteromonadales, and Pseudomonadales. Additionally, the relative abundance of potential pathogen groups, especially Vibrio spp. and Pseudoalteromonas spp., was approximately 2‐fold greater at the sites with the highest nutrient loads compared to sites further from the source. These results suggest that proximity to sources of nutrient pollution increases the occurrence of potential bacterial pathogens that could affect fishes, invertebrates and humans. This study shows that nutrient enrichment does elicit shifts in bacterial community diversity and likely their function in local biogeochemical cycling and as a potential source of infectious diseases within seagrass meadows.
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Affiliation(s)
- Songlin Liu
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China, Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Zhijian Jiang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China, Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
| | - Yiqin Deng
- Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou, China
| | - Yunchao Wu
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China, Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Jingping Zhang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China, Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
| | - Chunyu Zhao
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China, Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Delian Huang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China, Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xiaoping Huang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China, Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Stacey M Trevathan-Tackett
- School of Life and Environmental Sciences, Centre for Integrative Ecology, Deakin University, Vic., Australia
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13
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Sebastião FA, Pilarski F, Kearney MT, Soto E. Molecular detection of Francisella noatunensis subsp. orientalis in cultured Nile tilapia (Oreochromis niloticus L.) in three Brazilian states. JOURNAL OF FISH DISEASES 2017; 40:1731-1735. [PMID: 28449216 DOI: 10.1111/jfd.12636] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 02/21/2017] [Accepted: 02/22/2017] [Indexed: 06/07/2023]
Affiliation(s)
- F A Sebastião
- Department of Medicine & Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA
- Centro de Aquicultura da UNESP, Univ Estadual Paulista, Jaboticabal, SP, Brazil
| | - F Pilarski
- Centro de Aquicultura da UNESP, Univ Estadual Paulista, Jaboticabal, SP, Brazil
| | - M T Kearney
- Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
| | - E Soto
- Department of Medicine & Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA
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14
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Brenz Y, Winther-Larsen HC, Hagedorn M. Expanding Francisella models: Pairing up the soil amoeba Dictyostelium with aquatic Francisella. Int J Med Microbiol 2017; 308:32-40. [PMID: 28843671 DOI: 10.1016/j.ijmm.2017.08.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 07/31/2017] [Accepted: 08/04/2017] [Indexed: 12/19/2022] Open
Abstract
The bacterial genus Francisella comprises highly pathogenic species that infect mammals, arthropods, fish and protists. Understanding virulence and host defense mechanisms of Francisella infection relies on multiple animal and cellular model systems. In this review, we want to summarize the most commonly used Francisella host model platforms and highlight novel, alternative model systems using aquatic Francisella species. Established mouse and macrophage models contributed extensively to our understanding of Francisella infection. However, murine and human cells display significant differences in their response to Francisella infection. The zebrafish and the amoeba Dictyostelium are well-established model systems for host-pathogen interactions and open up opportunities to investigate bacterial virulence and host defense. Comparisons between model systems using human and fish pathogenic Francisella species revealed shared virulence strategies and pathology between them. Hence, zebrafish and Dictyostelium might complement current model systems to find new vaccine candidates and contribute to our understanding of Francisella infection.
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Affiliation(s)
- Yannick Brenz
- Department of Parasitology, Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Straße 74, 20359 Hamburg, Germany.
| | - Hanne C Winther-Larsen
- Centre for Integrative Microbial Evolution (CIME) and Department of Pharmaceutical Biosciences, University of Oslo, Sem Sælands vei 3, 0371 Oslo, Norway.
| | - Monica Hagedorn
- Department of Life Sciences and Chemistry, Jacobs University, Campus Ring 1, 28759 Bremen, Germany.
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Bakkemo KR, Mikkelsen H, Johansen A, Robertsen B, Seppola M. Francisella noatunensis subsp. noatunensis invades, survives and replicates in Atlantic cod cells. DISEASES OF AQUATIC ORGANISMS 2016; 121:149-159. [PMID: 27667812 DOI: 10.3354/dao03043] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Systemic infection caused by the facultative intracellular bacterium Francisella noatunensis subsp. noatunensis remains a disease threat to Atlantic cod Gadus morhua L. Future prophylactics could benefit from better knowledge on how the bacterium invades, survives and establishes infection in its host cells. Here, facilitated by the use of a gentamicin protection assay, this was studied in primary monocyte/macrophage cultures and an epithelial-like cell line derived from Atlantic cod larvae (ACL cells). The results showed that F. noatunensis subsp. noatunensis is able to invade primary monocyte/macrophages, and that the actin-polymerisation inhibitor cytochalasin D blocked internalisation, demonstrating that the invasion is mediated through phagocytosis. Interferon gamma (IFNγ) treatment of cod macrophages prior to infection enhanced bacterial invasion, potentially by stimulating macrophage activation in an early step in host defence against F. noatunensis subsp. noatunensis infections. We measured a rapid drop of the initial high levels of internalised bacteria in macrophages, indicating the presence and action of a cellular immune defence mechanism before intracellular bacterial replication took place. Low levels of bacterial internalisation and replication were detected in the epithelial-like ACL cells. The capacity of F. noatunensis subsp. noatunensis to enter, survive and even replicate within an epithelial cell line may play an important role in its ability to infect live fish and transverse epithelial barriers to reach the bacterium's main target cells-the macrophage.
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16
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Ortega C, Mancera G, Enríquez R, Vargas A, Martínez S, Fajardo R, Avendaño-Herrera R, Navarrete MJ, Romero A. First identification of Francisella noatunensis subsp. orientalis causing mortality in Mexican tilapia Oreochromis spp. DISEASES OF AQUATIC ORGANISMS 2016; 120:205-215. [PMID: 27503916 DOI: 10.3354/dao02999] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Francisellosis, an emerging disease in tilapia Oreochromis spp., is caused by the facultative, intracellular bacterium Francisella noatunensis subsp. orientalis, which is present in various countries where tilapia farming is commercially important. We confirmed the presence of francisellosis in Mexican tilapia cultures in association with an outbreak during the second semester of 2012. Broodstock fish presented a mortality rate of approximately 40%, and disease was characterized by histologically classified granulomas, or whitish nodules, in different organs, mainly the spleen and kidney. Through DNA obtained from infected tissue and pure cultures in a cysteine heart medium supplemented with hemoglobin, F. noatunensis subsp. orientalis was initially confirmed through the amplification and analysis of the 16S rRNA gene and the internal transcribed spacer region. Phylogenetic analysis of these genes demonstrated close similarity with previously reported F. noatunensis subsp. orientalis sequences obtained from infected tilapia from various countries. The identification of this subspecies as the causative agent of the outbreak was confirmed using the iglC gene as a target sequence, which showed 99.5% identity to 2 F. noatunensis subsp. orientalis strains (Ethime-1 and Toba04). These findings represent the first documented occurrence of francisellosis in Mexican tilapia cultures, which highlights the importance of establishing preventative measures to minimize the spread of this disease within the Mexican aquaculture industry.
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Affiliation(s)
- Cesar Ortega
- Centro de Investigación y Estudios Avanzados en Salud Animal (CIESA), Facultad de Medicina Veterinaria y Zootecnia, Universidad Autónoma del Estado de México, Carretera Toluca-Atlacomulco Km. 15.5, Toluca 50200, Mexico
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17
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Jantrakajorn S, Wongtavatchai J. Francisella Infection in Cultured Tilapia in Thailand and the Inflammatory Cytokine Response. JOURNAL OF AQUATIC ANIMAL HEALTH 2016; 28:97-106. [PMID: 27196982 DOI: 10.1080/08997659.2015.1135198] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Francisella infections developed in freshwater Nile Tilapia Oreochromis niloticus and red tilapia Oreochromis spp. farms in Thailand during 2012-2014. The diseased fish were lethargic and pale in color and showed numerous white nodules in their enlarged spleens. Histopathological examination and electron microscopy suggested that the white nodules were multifocal granulomas consisting of coccobacilli within vacuolated cells. Isolation of Francisella-like bacteria was achieved from 42 of 100 samples, while polymerase chain reaction confirmed Francisella infections in all samples. Analysis of the 16S rRNA gene from samples obtained from three different geographical culture areas revealed more than 99% similarity with F. noatunensis subsp. orientalis. The influence of Francisella infection on inflammatory cytokines was determined on splenic cells of fish intraperitoneally injected with the bacteria (0.8 × 10(5) colony-forming units per fish). Infected tilapia showed significantly greater expression of the pro-inflammatory genes interleukin-1β (IL-1β) and tumor necrotic factor-α (TNF-α) within 24 h postinjection (hpi) and for up to 96 hpi. However, down-regulation of an anti-inflammatory gene, transforming growth factor-β (TGF-β) was observed as early as 24 hpi. This investigation demonstrates that an imbalance between pro- and anti-inflammatory cytokines in response to the infection may account for the substantial number of granulomas in fish hematopoietic tissues that was found in the later stage of the disease. Received September 9, 2015; accepted December 13, 2015.
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Affiliation(s)
- Sasibha Jantrakajorn
- a Faculty of Veterinary Science , Prince of Songkla University , Songkhla , Thailand
- b Department of Veterinary Medicine , Chulalongkorn University , Bangkok , Thailand
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18
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Propst CN, Pylypko SL, Blower RJ, Ahmad S, Mansoor M, van Hoek ML. Francisella philomiragia Infection and Lethality in Mammalian Tissue Culture Cell Models, Galleria mellonella, and BALB/c Mice. Front Microbiol 2016; 7:696. [PMID: 27252681 PMCID: PMC4877389 DOI: 10.3389/fmicb.2016.00696] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 04/26/2016] [Indexed: 12/15/2022] Open
Abstract
Francisella (F.) philomiragia is a Gram-negative bacterium with a preference for brackish environments that has been implicated in causing bacterial infections in near-drowning victims. The purpose of this study was to characterize the ability of F. philomiragia to infect cultured mammalian cells, a commonly used invertebrate model, and, finally, to characterize the ability of F. philomiragia to infect BALB/c mice via the pulmonary (intranasal) route of infection. This study shows that F. philomiragia infects J774A.1 murine macrophage cells, HepG2 cells and A549 human Type II alveolar epithelial cells. However, replication rates vary depending on strain at 24 h. F. philomiragia infection after 24 h was found to be cytotoxic in human U937 macrophage-like cells and J774A.1 cells. This is in contrast to the findings that F. philomiragia was non-cytotoxic to human hepatocellular carcinoma cells, HepG2 cells and A549 cells. Differential cytotoxicity is a point for further study. Here, it was demonstrated that F. philomiragia grown in host-adapted conditions (BHI, pH 6.8) is sensitive to levofloxacin but shows increased resistance to the human cathelicidin LL-37 and murine cathelicidin mCRAMP when compared to related the Francisella species, F. tularensis subsp. novicida and F. tularensis subsp. LVS. Previous findings that LL-37 is strongly upregulated in A549 cells following F. tularensis subsp. novicida infection suggest that the level of antimicrobial peptide expression is not sufficient in cells to eradicate the intracellular bacteria. Finally, this study demonstrates that F. philomiragia is lethal in two in vivo models; Galleria mellonella via hemocoel injection, with a LD50 of 1.8 × 103, and BALB/c mice by intranasal infection, with a LD50 of 3.45 × 103. In conclusion, F. philomiragia may be a useful model organism to study the genus Francisella, particularly for those researchers with interest in studying microbial ecology or environmental strains of Francisella. Additionally, the Biosafety level 2 status of F. philomiragia makes it an attractive model for virulence and pathogenesis studies.
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Affiliation(s)
- Crystal N Propst
- School of Systems Biology, George Mason University, Manassas, VA USA
| | | | - Ryan J Blower
- School of Systems Biology, George Mason University, Manassas, VA USA
| | - Saira Ahmad
- School of Systems Biology, George Mason University, Manassas, VA USA
| | | | - Monique L van Hoek
- School of Systems Biology, George Mason University, Manassas, VAUSA; National Center for Biodefense and Infectious Diseases, George Mason University, Manassas, VAUSA
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19
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Brudal E, Lampe EO, Reubsaet L, Roos N, Hegna IK, Thrane IM, Koppang EO, Winther-Larsen HC. Vaccination with outer membrane vesicles from Francisella noatunensis reduces development of francisellosis in a zebrafish model. FISH & SHELLFISH IMMUNOLOGY 2015; 42:50-57. [PMID: 25449706 DOI: 10.1016/j.fsi.2014.10.025] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 10/17/2014] [Accepted: 10/17/2014] [Indexed: 06/04/2023]
Abstract
Infection of fish with the facultative intracellular bacterium Francisella noatunensis remains an unresolved problem for aquaculture industry worldwide as it is difficult to vaccinate against without using live attenuated vaccines. Outer membrane vesicles (OMVs) are biological structures shed by Gram-negative bacteria in response to various environmental stimuli. OMVs have successfully been used to vaccinate against both intracellular and extracellular pathogens, due to an ability to stimulate innate, cell-mediated and humoral immune responses. We show by using atomic force and electron microscopy that the fish pathogenic bacterium F. noatunensis subspecies noatunensis (F.n.n.) shed OMVs both in vitro into culture medium and in vivo in a zebrafish infection model. The main protein constituents of the OMV are IglC, PdpD and PdpA, all known Francisella virulence factors, in addition to the outer membrane protein FopA and the chaperonin GroEL, as analyzed by mass spectrometry. The vesicles, when used as a vaccine, reduced proliferation of the bacterium and protected zebrafish when subsequently challenged with a high dose of F.n.n. without causing adverse effects for the host. Also granulomatous responses were reduced in F.n.n.-challenged zebrafish after OMV vaccination. Taken together, the data support the possible use of OMVs as vaccines against francisellosis in fish.
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Affiliation(s)
- Espen Brudal
- Section for Microbiology, Immunology and Parasitology, Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, PO Box 8146 Dep, 0033 Oslo, Norway; Laboratory for Microbial Dynamics (LaMDa), School of Pharmacy, University of Oslo, PO Box 1068 Blindern, 0316 Oslo, Norway
| | - Elisabeth O Lampe
- Laboratory for Microbial Dynamics (LaMDa), School of Pharmacy, University of Oslo, PO Box 1068 Blindern, 0316 Oslo, Norway; Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, PO Box 1068 Blindern, 0316 Oslo, Norway
| | - Léon Reubsaet
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of Oslo, PO Box 1068 Blindern, 0316 Oslo, Norway
| | - Norbert Roos
- Department of Biosciences, University of Oslo, PO Box 1068 Blindern, 0316 Oslo, Norway
| | - Ida K Hegna
- Laboratory for Microbial Dynamics (LaMDa), School of Pharmacy, University of Oslo, PO Box 1068 Blindern, 0316 Oslo, Norway; Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, PO Box 1068 Blindern, 0316 Oslo, Norway
| | - Ida Marie Thrane
- Laboratory for Microbial Dynamics (LaMDa), School of Pharmacy, University of Oslo, PO Box 1068 Blindern, 0316 Oslo, Norway; Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, PO Box 1068 Blindern, 0316 Oslo, Norway
| | - Erling O Koppang
- Section for Anatomy and Pathology, Department of Basic Sciences and Aquatic Medicine, Norwegian University of Life Sciences, PO Box 8146 Dep, 0033 Oslo, Norway
| | - Hanne C Winther-Larsen
- Laboratory for Microbial Dynamics (LaMDa), School of Pharmacy, University of Oslo, PO Box 1068 Blindern, 0316 Oslo, Norway; Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, PO Box 1068 Blindern, 0316 Oslo, Norway.
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TaqMan real-time PCR assays for single-nucleotide polymorphisms which identify Francisella tularensis and its subspecies and subpopulations. PLoS One 2014; 9:e107964. [PMID: 25238067 PMCID: PMC4169575 DOI: 10.1371/journal.pone.0107964] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 08/18/2014] [Indexed: 01/01/2023] Open
Abstract
Francisella tularensis, the etiologic agent of tularemia and a Class A Select Agent, is divided into three subspecies and multiple subpopulations that differ in virulence and geographic distribution. Given these differences, there is a need to rapidly and accurately determine if a strain is F. tularensis and, if it is, assign it to subspecies and subpopulation. We designed TaqMan real-time PCR genotyping assays using eleven single nucleotide polymorphisms (SNPs) that were potentially specific to closely related groups within the genus Francisella, including numerous subpopulations within F. tularensis species. We performed extensive validation studies to test the specificity of these SNPs to particular populations by screening the assays across a set of 565 genetically and geographically diverse F. tularensis isolates and an additional 21 genetic near-neighbor (outgroup) isolates. All eleven assays correctly determined the genetic groups of all 565 F. tularensis isolates. One assay differentiates F. tularensis, F. novicida, and F. hispaniensis from the more genetically distant F. philomiragia and Francisella-like endosymbionts. Another assay differentiates F. tularensis isolates from near neighbors. The remaining nine assays classify F. tularensis-confirmed isolates into F. tularensis subspecies and subpopulations. The genotyping accuracy of these nine assays diminished when tested on outgroup isolates (i.e. non F. tularensis), therefore a hierarchical approach of assay usage is recommended wherein the F. tularensis-specific assay is used before the nine downstream assays. Among F. tularensis isolates, all eleven assays were highly sensitive, consistently amplifying very low concentrations of DNA. Altogether, these eleven TaqMan real-time PCR assays represent a highly accurate, rapid, and sensitive means of identifying the species, subspecies, and subpopulation of any F. tularensis isolate if used in a step-wise hierarchical scheme. These assays would be very useful in clinical, epidemiological, and/or forensic investigations involving F. tularensis.
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Establishment of three Francisella infections in zebrafish embryos at different temperatures. Infect Immun 2014; 82:2180-94. [PMID: 24614659 DOI: 10.1128/iai.00077-14] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Francisella spp. are facultative intracellular pathogens identified in increasingly diverse hosts, including mammals. F. noatunensis subsp. orientalis and F. noatunensis subsp. noatunensis infect fish inhabiting warm and cold waters, respectively, while F. tularensis subsp. novicida is highly infectious for mice and has been widely used as a model for the human pathogen F. tularensis. Here, we established zebrafish embryo infection models of fluorescently labeled F. noatunensis subsp. noatunensis, F. noatunensis subsp. orientalis, and F. tularensis subsp. novicida at 22, 28, and 32°C, respectively. All infections led to significant bacterial growth, as shown by reverse transcription-quantitative PCR (RT-qPCR), and to a robust proinflammatory immune response, dominated by increased transcription of tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β). F. noatunensis subsp. orientalis was the most virulent, F. noatunensis subsp. noatunensis caused chronic infection, and F. tularensis subsp. novicida showed moderate virulence and led to formation of relatively small granuloma-like structures. The use of transgenic zebrafish strains with enhanced green fluorescent protein (EGFP)-labeled immune cells revealed their detailed interactions with Francisella species. All three strains entered preferentially into macrophages, which eventually assembled into granuloma-like structures. Entry into neutrophils was also observed, though the efficiency of this event depended on the route of infection. The results demonstrate the usefulness of the zebrafish embryo model for studying infections caused by different Francisella species at a wide range of temperatures and highlight their interactions with immune cells.
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Khairnar K, Raut MP, Chandekar RH, Sanmukh SG, Paunikar WN. Novel bacteriophage therapy for controlling metallo-beta-lactamase producing Pseudomonas aeruginosa infection in catfish. BMC Vet Res 2013; 9:264. [PMID: 24369750 PMCID: PMC3913374 DOI: 10.1186/1746-6148-9-264] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 12/23/2013] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND The bacteriophage therapy is an effective antimicrobial approach with potentially important applications in medicine and biotechnology which can be seen as an additional string in the bow. Emerging drug resistant bacteria in aquaculture industry due to unrestricted use of antibiotics warrants more sustainable and environmental friendly strategies for controlling fish infections.The isolated bacteria from fish lesions was characterised based on isolation on selective and differential medium like Pseudomonas agar, gram staining, biochemical tests and 16SrRNA sequencing. The metallo-beta-lactamase (MBL) producing bacterial isolate was evaluated using Imipenem - Ethylenediaminetetraacetic acid (EDTA) disk method. The specific bacteriophage was isolated and concentrated using coal bed developed in our lab at CSIR-NEERI. The isolated and enriched bacteriophage was characterised by nucleotide sequencing and electron microscopy. The phage therapy was applied for treating ulcerative lesion in fish. RESULTS The pathogenic bacterium responsible for causing ulcerative lesions in catfish species (Clarias gariepinus) was identified as Pseudomonas aeruginosa. One out of twenty P. aeruginosa isolate showing multi drug resistance (MDR) was incidentally found to be MBL producing as determined by Imipenem-EDTA disk method. The phage therapy effectively cured the ulcerative lesions of the infected fish in 8-10 days of treatment, with a sevenfold reduction of the lesion with untreated infection control. CONCLUSION Bacteriophage therapy can have potential applications soon as an alternative or as a complement to antibiotic treatment in the aquaculture. We present bacteriophage therapy as a treatment method for controlling MDR P. aeruginosa infection in C. gariepinus. To the best of our knowledge this is a first report of application of phage therapy against MBL producing P. aeruginosa isolated from aquatic ecosystem.
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Affiliation(s)
- Krishna Khairnar
- Environmental Virology Cell, Council for Scientific and Industrial Research - National Environmental Engineering Research Institute (CSIR-NEERI), Nehru Marg, Nagpur 440020, Maharashtra, India
| | - Mahendra P Raut
- Departments of Chemical and Biological Engineering, ChELSI, University Of Sheffield, Office No: D72, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD, UK
| | - Rajshree H Chandekar
- Environmental Virology Cell, Council for Scientific and Industrial Research - National Environmental Engineering Research Institute (CSIR-NEERI), Nehru Marg, Nagpur 440020, Maharashtra, India
| | - Swapnil G Sanmukh
- Environmental Virology Cell, Council for Scientific and Industrial Research - National Environmental Engineering Research Institute (CSIR-NEERI), Nehru Marg, Nagpur 440020, Maharashtra, India
| | - Waman N Paunikar
- Environmental Virology Cell, Council for Scientific and Industrial Research - National Environmental Engineering Research Institute (CSIR-NEERI), Nehru Marg, Nagpur 440020, Maharashtra, India
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Francisella noatunensis subsp. orientalis pathogenesis analyzed by experimental immersion challenge in Nile tilapia, Oreochromis niloticus (L.). Vet Microbiol 2013; 164:77-84. [DOI: 10.1016/j.vetmic.2013.01.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 01/18/2013] [Accepted: 01/22/2013] [Indexed: 10/27/2022]
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Brudal E, Winther-Larsen HC, Colquhoun DJ, Duodu S. Evaluation of reference genes for reverse transcription quantitative PCR analyses of fish-pathogenic Francisella strains exposed to different growth conditions. BMC Res Notes 2013; 6:76. [PMID: 23452832 PMCID: PMC3599356 DOI: 10.1186/1756-0500-6-76] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 02/27/2013] [Indexed: 12/20/2022] Open
Abstract
Background Reverse transcription quantitative PCR has become a powerful technique to monitor mRNA transcription in response to different environmental conditions in many bacterial species. However, correct evaluation of data requires accurate and reliable use of reference genes whose transcription does not change during the course of the experiment. In the present study exposure to different growth conditions was used to validate the transcription stability of eight reference gene candidates in three strains from two subspecies of Francisella noatunensis, a pathogen causing disease in both warm and cold water fish species. Results Relative transcription levels for genes encoding DNA gyrase (gyrA), RNA polymerase beta subunit (rpoB), DNA polymerase I (polA), cell division protein (ftsZ), outer membrane protein (fopA), riboflavin biosynthesis protein (ribC), 16S ribosomal RNA (16S rRNA) and DNA helicases (uvrD) were quantified under exponential, stationary and iron-restricted growth conditions. The suitability of selected reference genes for reliable interpretation of gene expression data was tested using the virulence-associated intracellular growth locus subunit C (iglC) gene. Conclusion Although the transcription stability of the reference genes was slightly different in the three strains studied, fopA, ftsZ and polA proved to be the most stable and suitable for normalization of gene transcription in Francisella noatunensis ssp.
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Affiliation(s)
- Espen Brudal
- Section for Microbiology, Immunology and Parasitology, Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, PO Box 8146 Dep, Oslo 0033, Norway
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Duodu S, Larsson P, Sjödin A, Soto E, Forsman M, Colquhoun DJ. Real-time PCR assays targeting unique DNA sequences of fish-pathogenic Francisella noatunensis subspecies noatunensis and orientalis. DISEASES OF AQUATIC ORGANISMS 2012; 101:225-234. [PMID: 23324419 DOI: 10.3354/dao02514] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Specific identification and differentiation of the 2 subspecies of the fish pathogen Francisella noatunensis, namely, F. noatunensis subsp. noatunensis and F. noatunensis subsp. orientalis, remains a major diagnostic challenge. Following whole-genome sequencing and analysis of representatives of all major subclades of the genus Francisella, specific genomic regions were identified for each of the subspecies of this fish pathogen. Two specific real-time quantitative PCR assays, directed at hypothetical genes within these regions were developed. Specificity was confirmed by lack of signal and cross-reactivity with the closest relative, F. philomiragia, and other common bacterial fish pathogens. Both assays, used either as monoplex or multiplex, have a limit of detection of 10 genome equivalents. The quantitative sensitivity of the assays was not affected by the presence of kidney tissues or DNA from Atlantic cod Gadus morhua or tilapia Oreochromis sp.
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Affiliation(s)
- Samuel Duodu
- Section for Bacteriology, Norwegian Veterinary Institute, PO Box 750, Sentrum, 0106 Oslo, Norway.
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Soto E, Revan F. Culturability and persistence of Francisella noatunensis subsp. orientalis (syn. Francisella asiatica) in sea- and freshwater microcosms. MICROBIAL ECOLOGY 2012; 63:398-404. [PMID: 21881943 DOI: 10.1007/s00248-011-9932-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Accepted: 08/17/2011] [Indexed: 05/31/2023]
Abstract
Francisella noatunensis subsp. orientalis (syn. Francisella asiatica), the causative agent of franciselliosis in warm-water fish, is a Gram-negative facultative intracellular bacterium. Although it has been characterized as one of the most pathogenic bacteria in fish, the water conditions that allow for its survival and infectious capacities outside the fish host are not known. Data obtained in this project indicate that both temperature and salinity are important factors in the culturability and persistence of F. noatunensis subsp. orientalis in both sea- and freshwater microcosms. These results indicate that culturable F. noatunensis subsp. orientalis persist for longer periods of time and at higher numbers in seawater, and its persistence is inversely related to water temperature. Moreover, the pathogenic properties of the bacteria suspended in water microcosms appear to decrease after only 24 h and become non-infective after 2 days in the absence of the fish host.
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Affiliation(s)
- Esteban Soto
- Department of Pathobiology, School of Veterinary Medicine, Basseterre, Ross University School of Veterinary Medicine, West Farm, Basseterre, St. Kitts, West Indies.
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Brevik OJ, Ottem KF, Kamaishi T, Watanabe K, Nylund A. Francisella halioticida sp. nov., a pathogen of farmed giant abalone (Haliotis gigantea) in Japan. J Appl Microbiol 2011; 111:1044-56. [PMID: 21883728 DOI: 10.1111/j.1365-2672.2011.05133.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
AIMS In 2005, a Francisella sp. was isolated from diseased cultured giant abalone (Haliotis gigantea) in Japan. The aim of this study was to clarify the taxonomic status of this Francisella sp. Shimane-1 isolate in relation to the four described Francisella species. METHODS AND RESULTS The 16S rRNA gene and several housekeeping genes of the Shimane-1 were compared to isolates of the four recognized species within the Francisella genus. DNA-DNA hybridization (DDH) and biochemical profile comparison were performed with the two phylogenetically closely related species, Francisella philomiragia and Francisella noatunensis. Results show that the Shimane-1 is genetically different from all described Francisella species and differs phenotypically from F. philomiragia and F. noatunensis. The average DDH similarity of Francisella sp. Shimane-1 to F. noatunensis ssp. noatunensis (NCIMB14265(T)) and to F. philomiragia (DSM7535(T)) was 49·2 and 61%, respectably, clearly supporting the establishment of Shimane-1 as a new species within the Francisella genus. CONCLUSIONS The phenotypic and genetic results presented in this study suggest the establishment of Shimane-1 as a novel species, for which the name Francisella halioticida sp. nov. (=LMG26062(T), =DSM23729(T)) is proposed. SIGNIFICANCE AND IMPACT OF THE STUDY This study clarifies the taxonomic position and characteristics of a novel mollusc pathogenic Francisella species.
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Affiliation(s)
- O J Brevik
- Department of Biology, University of Bergen, Bergen, Norway.
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Soto E, Baumgartner W, Wiles J, Hawke JP. Francisella asiatica as the causative agent of piscine francisellosis in cultured tilapia (Oreochromis sp.) in the United States. J Vet Diagn Invest 2011; 23:821-5. [DOI: 10.1177/1040638711407058] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Francisella asiatica is a Gram-negative, pleomorphic, facultative intracellular, bacterial pathogen that causes acute to chronic disease in a wide variety of warm-water cultured and wild fish species. Outbreaks of francisellosis in warm water fish have been documented in Taiwan, Japan, United Kingdom, Hawaii, and Latin America (including Costa Rica) but the organism has only been reported from the United States on one occasion from hybrid striped bass in California. In 2010, the bacterium was detected from diseased tilapia by culture on cystine heart agar supplemented with hemoglobin and by utilizing an F. asiatica–specific real-time polymerase chain reaction assay. The tilapia ( Oreochromis niloticus) were cultured in an indoor, closed, recirculating aquaculture facility in the Midwest of the United States. The identity of isolates recovered from diseased fish was confirmed as F. asiatica by amplification and sequence comparison of the 16S ribosomal RNA and intracellular growth locus C ( iglC) gene. Gross and microscopic examination of affected tissues revealed the presence of marked anterior renomegaly and splenomegaly with severe granulomatous disease.
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Affiliation(s)
- Esteban Soto
- Louisiana State University, Department of Pathobiological Sciences, School of Veterinary Medicine, Baton Rouge, LA (Soto, Baumgartner, Wiles, Hawke)
- Ross University, Department of Pathobiology, School of Veterinary Medicine, St. Kitts, West Indies (Soto)
| | - Wes Baumgartner
- Louisiana State University, Department of Pathobiological Sciences, School of Veterinary Medicine, Baton Rouge, LA (Soto, Baumgartner, Wiles, Hawke)
- Ross University, Department of Pathobiology, School of Veterinary Medicine, St. Kitts, West Indies (Soto)
| | - Judy Wiles
- Louisiana State University, Department of Pathobiological Sciences, School of Veterinary Medicine, Baton Rouge, LA (Soto, Baumgartner, Wiles, Hawke)
- Ross University, Department of Pathobiology, School of Veterinary Medicine, St. Kitts, West Indies (Soto)
| | - John P. Hawke
- Louisiana State University, Department of Pathobiological Sciences, School of Veterinary Medicine, Baton Rouge, LA (Soto, Baumgartner, Wiles, Hawke)
- Ross University, Department of Pathobiology, School of Veterinary Medicine, St. Kitts, West Indies (Soto)
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Colquhoun DJ, Duodu S. Francisella infections in farmed and wild aquatic organisms. Vet Res 2011; 42:47. [PMID: 21385413 PMCID: PMC3060124 DOI: 10.1186/1297-9716-42-47] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Accepted: 03/08/2011] [Indexed: 01/08/2023] Open
Abstract
Over the last 10 years or so, infections caused by bacteria belonging to a particular branch of the genus Francisella have become increasingly recognised in farmed fish and molluscs worldwide. While the increasing incidence of diagnoses may in part be due to the development and widespread availability of molecular detection techniques, the domestication of new organisms has undoubtedly instigated emergence of clinical disease in some species. Francisellosis in fish develops in a similar fashion independent of host species and is commonly characterised by the presence of multi-organ granuloma and high morbidity, with varying associated mortality levels. A number of fish species are affected including Atlantic cod, Gadus morhua; tilapia, Oreochromis sp.; Atlantic salmon, Salmo salar; hybrid striped bass, Morone chrysops × M. saxatilis and three-lined grunt, Parapristipoma trilinineatum. The disease is highly infectious and often prevalent in affected stocks. Most, if not all strains isolated from teleost fish belong to either F. noatunensis subsp. orientalis in warm water fish species or Francisella noatunensis subsp. noatunensis in coldwater fish species. The disease is quite readily diagnosed following histological examination and identification of the aetiological bacterium by culture on cysteine rich media or PCR. The available evidence may indicate a degree of host specificity for the various Francisella strains, although this area requires further study. No effective vaccine is currently available. Investigation of the virulence mechanisms and host response shows similarity to those known from Francisella tularensis infection in mammals. However, no evidence exists for zoonotic potential amongst the fish pathogenic Francisella.
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Affiliation(s)
- Duncan J Colquhoun
- Section for Fish health, National Veterinary Institute, Postbox 750 sentrum, 0106 Oslo, Norway.
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Birkbeck TH, Feist SW, Verner-Jeffreys DW. Francisella infections in fish and shellfish. JOURNAL OF FISH DISEASES 2011; 34:173-187. [PMID: 21306585 DOI: 10.1111/j.1365-2761.2010.01226.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A series of recent reports have implicated bacteria from the family Francisellaceae as the cause of disease in farmed and wild fish and shellfish species such as Atlantic cod, Gadus morhua L., tilapia, Oreochromis spp., Atlantic salmon, Salmo salar L., three-line grunt, Parapristipoma trilineatum (Thunberg), ornamental cichlid species, hybrid striped bass Morone chrysops x M. saxatilis and, recently, a shellfish species, the giant abalone, Haliotisgigantea Gmelin. The range of taxa affected will very probably rise as it is likely that there has been considerable under-reporting to date of these disease agents. In common with other Francisella species, their isolation and culture require specialized solid and liquid media containing cysteine and a source of iron. This likely restricted earlier efforts to identify them correctly as the cause of disease in aquatic animals. The most information to date relates to disease in cod, caused by F. noatunensis and tilapia, caused by F. noatunensis subsp. orientalis (also termed F. asiatica), both causing granulomatous inflammatory reactions. Mortalities in both species can be high and, as the disease can likely be transferred via live fish movements, they pose a significant threat to tilapia and cod aquaculture operations. Although the fish-pathogenic Francisella species are classified in the same genus as the human pathogens F. tularensis, causative agent of tularemia, and F. philomiragia, the risk to humans from the fish and shellfish pathogenic Francisella species is considered very low.
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Affiliation(s)
- T H Birkbeck
- University of London Marine Biological Station, Millport, Isle of Cumbrae, Scotland, UK
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Schrallhammer M, Schweikert M, Vallesi A, Verni F, Petroni G. Detection of a novel subspecies of Francisella noatunensis as endosymbiont of the ciliate Euplotes raikovi. MICROBIAL ECOLOGY 2011; 61:455-464. [PMID: 21110016 DOI: 10.1007/s00248-010-9772-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Accepted: 11/04/2010] [Indexed: 05/30/2023]
Abstract
Francisella are facultative intracellular bacteria causing severe disease in a broad range of animals. Two species are notable: Francisella tularensis, the causative organism of tularemia and a putative warfare agent, and Francisella noatunensis, an emerging fish pathogen causing significant losses in wild and farmed fish. Although various aspects of Francisella biology have been intensively studied, their natural reservoir in periods between massive outbreaks remains mysterious. Protists have been suspected to serve as a disguised vector of Francisella and co-culturing attempts demonstrate that some species are able to survive and multiply within protozoan cells. Here, we report the first finding of a natural occurrence of Francisella sp. as a protist endosymbiont. By molecular and morphological approaches, we identified intracellular bacteria localized in a strain of the marine ciliate Euplotes raikovi, isolated from the coast of Adriatic Sea. Phylogenetic analysis placed these endosymbionts within the genus Francisella, in close but distinct association with F. noatunensis. We suggest the establishment of a novel subspecies within F. noatunensis and propose the cytoplasmatic endosymbiont of E. raikovi as "Candidatus F. noatunensis subsp. endociliophora" subsp. nov.
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Affiliation(s)
- Martina Schrallhammer
- Dipartimento di Biologia, Università di Pisa, Via A Volta 4/6, IT-56126 Pisa, Italy.
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Kulkarni A, Caipang CMA, Korsnes K, Brinchmann MF, Kiron V. Molecular diagnosis of francisellosis, a systemic granulomatous inflammatory disease in Atlantic cod, Gadus morhua L. Vet Res Commun 2010; 35:67-77. [PMID: 21125329 DOI: 10.1007/s11259-010-9451-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2010] [Indexed: 10/18/2022]
Abstract
A PCR-based assay for the detection of Francisella noatunensis causing francisellosis in Atlantic cod, Gadus morhua has been developed. Seven sets of primers targeting the flanking regions of the genes (rpoA, sdhA, atpA, rpoB, pgm, groEL and 16S rRNA) of the pathogen were designed. Among the primers, groEL was found to be the most suitable gene candidate for detecting the pathogen, due to its high sensitivity at various annealing temperatures and specificity in detection. The detection limit of the assay was 100 pg of bacterial DNA per milliliter or 100 fg bacterial DNA (approximately 50 genome equivalents) per PCR reaction, however, the sensitivity of the reaction decreased by 1 log dilution in the presence of 1 mg mL(-1) of serum and mucus samples as inhibitors. Nevertheless, the assay can potentially be used as a direct and non-lethal method to detect the pathogen in fish. Thus this PCR assay is a specific and sensitive molecular method to diagnose francisellosis in Atlantic cod, and will be helpful for controlling the infection through prompt detection of the disease in farms.
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Affiliation(s)
- Amod Kulkarni
- Faculty of Biosciences and Aquaculture, Bodø University College, Bodø 8049, Norway
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Duodu S, Colquhoun D. Monitoring the survival of fish-pathogenic Francisella in water microcosms. FEMS Microbiol Ecol 2010; 74:534-41. [PMID: 20977492 DOI: 10.1111/j.1574-6941.2010.00973.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
In this report, the survival behaviour of fish pathogenic Francisella in water microcosms was investigated under laboratory conditions. Two isolates of Francisella noatunensis (NCIMB14265(T) and PQ 1106), from fish held in seawater and freshwater, were inoculated into natural (nonsterile) and sterile sea- and freshwater microcosms, respectively, and monitored under different temperature conditions (4, 8 and 12 °C) over a period of 60 days. The culturability of the strains was inversely related to the water temperature. Strain NCIMB14265(T) was found to survive longer in seawater than PQ 1106 held in freshwater at equivalent temperatures. The survival of both strains was higher in sterile than in nonsterile microcosms. These results were confirmed by quantitative PCR analysis targeting the succinate dehydrogenase (sdhA) gene. A cell viability assay coupled with FISH analyses showed that F. noatunensis cells enter a viable but not culturable (VBNC) state after a period in water. However, although metabolically active, the VBNC cells were not pathogenic to cod (Gadhus morhua) following an intraperitoneal challenge, under the conditions tested. The data presented contribute to a better understanding of the behaviour of F. noatunensis in natural seawater and freshwater environments, and show the need for further investigation of the role of VBNC cells in the environmental transmission of this pathogen.
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Affiliation(s)
- Samuel Duodu
- Section for Fish Health, National Veterinary Institute, Oslo, Norway.
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Verhoeven AB, Durham-Colleran MW, Pierson T, Boswell WT, Van Hoek ML. Francisella philomiragia biofilm formation and interaction with the aquatic protist Acanthamoeba castellanii. THE BIOLOGICAL BULLETIN 2010; 219:178-188. [PMID: 20972262 DOI: 10.1086/bblv219n2p178] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The bacterium Francisella philomiragia has been isolated from environmental samples originating from around the globe. F. philomiragia-related strains cause francisellosis of both farmed and wild fish. In addition, occasional human infections caused by F. philomiragia are found in victims of near-drowning and patients with chronic granulomatous disease. We have shown that F. philomiragia forms in vitro biofilms with increased formation at 25 °C over 37 °C conditions. We found that F. philomiragia can form a biofilm in a co-culture with live Acanthamoeba castellanii, an aquatic amoeba. Interestingly, amoeba-conditioned supernatant has an inhibitory effect on production of biofilm by F. philomiragia, whereas Francisella-conditioned supernatant has no effect on growth of amoebae. We have shown that F. philomiragia can infect A. castellanii after only 5 days of co-incubation and that it infects A. castellanii more quickly than the related species F. novicida does. Our studies point to a potentially overlooked interaction between F. philomiragia and Acanthamoeba. This relationship in the marine lifecycle of F. philomiragia may support the persistence of the bacterium in waterways and its ability to infect fish. An understanding of the persistence of this organism in aquatic systems through biofilm formation and its interaction with Acanthamoeba will be important in developing prevention strategies for this pathogen.
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Affiliation(s)
- Anne B Verhoeven
- Department of Molecular and Microbiology, National Center for Biodefense and Infectious Diseases, George Mason University, Manassas, Virginia 20110, USA
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In vitro and in vivo efficacy of florfenicol for treatment of Francisella asiatica infection in tilapia. Antimicrob Agents Chemother 2010; 54:4664-70. [PMID: 20713674 DOI: 10.1128/aac.00206-10] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Francisella asiatica is a recently described, Gram-negative, facultative intracellular fish pathogen, known to be the causative agent of francisellosis in warm-water fish. Francisellosis outbreaks have increased in frequency among commercial aquaculture operations and have caused severe economic losses in every case reported. The lack of effective treatments for piscine francisellosis led us to investigate the potential efficacy of florfenicol for inhibition of F. asiatica in vitro and as an oral therapeutic agent in vivo. The MIC of florfenicol for F. asiatica, as determined by the broth dilution method, was 2 μg/ml, which indicates its potential efficacy as a therapeutic agent for treatment of francisellosis. The intracellular susceptibility of the bacterium to florfenicol in tilapia head kidney-derived macrophages (THKDM) was also investigated. Addition of florfenicol to the medium at 10 μg/ml was sufficient to significantly reduce bacterial loads in the THKDM in vitro. Cytotoxicity assays done in infected THKDM also demonstrated drug efficacy in vivo, as determined by lactate dehydrogenase (LDH) release. Levels of LDH released from infected THKDM were significantly lower in macrophages treated with florfenicol (P < 0.001) than in untreated cells. In medicated-feed trials, fish were fed 15 mg of florfenicol/kg of fish body weight for 10 days, and the feeding was initiated at either 1, 3, or 6 days postchallenge. Immersion challenges resulted in 30% mean percent survival in nontreated fish, and fish receiving medicated feed administered at 1 and 3 days postinfection showed higher mean percent survival (100% and 86.7%, respectively). A significant decrease (P < 0.001) in bacterial numbers (number of CFU/g of spleen tissue) was observed in treated groups compared to nontreated infected fish at both 1 and 3 days postchallenge. There were no differences in bacterial burden in the spleens between fish treated 6 days postchallenge and untreated controls. In conclusion, if florfenicol is administered during early stages of infection, it has the potential for effectively treating piscine francisellosis, including the capacity for intracellular penetration and bacterial clearance.
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Soto E, Wiles J, Elzer P, Macaluso K, Hawke JP. Attenuated Francisella asiatica iglC mutant induces protective immunity to francisellosis in tilapia. Vaccine 2010; 29:593-8. [PMID: 20600508 DOI: 10.1016/j.vaccine.2010.06.040] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Revised: 05/15/2010] [Accepted: 06/10/2010] [Indexed: 11/18/2022]
Abstract
Francisella asiatica is a Gram-negative, facultative intracellular bacteria that causes fish francisellosis. Fish francisellosis is a severe sub-acute to chronic granulomatous disease with high mortalities and high infectivity rates in cultured and wild fish. To date, there is no approved vaccine for this widespread emergent disease. The goal of this study was to characterize the efficacy of a defined F. asiatica mutant (ΔiglC) as a live attenuated vaccine against subsequent immersion challenge with the wild-type (WT) organism. In previous work, the ΔiglC was found to be attenuated upon intraperitoneal injection and immersion challenges. In vitro, the ΔiglC exhibited reduced growth in tilapia head-kidney derived macrophages, and was significantly attenuated (p<0.001) as demonstrated by cytopathogenic and apoptosis assays. In this study, the ΔiglC was tested to determine its ability to protect tilapia against challenge with high doses (lethal dose 80) of WT bacteria. Naïve tilapia vaccinated by immersion with a suspension of the ΔiglC and subsequently challenged with WT F. asiatica were protected (90% mean percent survival) from the lethal challenges. F. asiatica-specific antibodies produced in response to immunization with the ΔiglC were subsequently found to protect naïve tilapia against high-dose F. asiatica challenge in passive immunization experiments. Significant protection (p<0.001) was obtained when fish were passively immunized and challenged with 10(4) and 10(5)CFU/fish of WT F. asiatica; but not when challenged with 10(6)CFU/fish. This is the first report of a defined live attenuated strain providing protection against F. asiatica in fish.
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Affiliation(s)
- Esteban Soto
- Department of Pathobiological Sciences, Louisiana State University (LSU)-School of Veterinary Medicine, Skip Bertman Dr., Baton Rouge, LA 70803, USA
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Interaction of Francisella asiatica with tilapia (Oreochromis niloticus) innate immunity. Infect Immun 2010; 78:2070-8. [PMID: 20160018 DOI: 10.1128/iai.01308-09] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Members of the genus Francisella are facultative intracellular bacteria that cause important diseases in a wide variety of animals worldwide, including humans and fish. Several genes that are important for intramacrophage survival have been identified, including the iglC gene, which is found in the iglABCD operon in the Francisella sp. pathogenicity island (FPI). In the present study, we examined the interaction of wild-type Francisella asiatica and a Delta iglC mutant strain with fish serum and head kidney-derived macrophages (HKDM). Both the wild-type and the mutant strains were resistant to killing by normal and heat-inactivated sera. The wild-type F. asiatica is able to invade tilapia head kidney-derived macrophages and replicate vigorously within them, causing apoptosis and cytotoxicity in the macrophages at 24 and 36 h postinfection. The Delta iglC mutant, however, is defective for survival, replication, and the ability to cause cytotoxicity in HKDM, but the ability is restored when the mutant is complemented with the iglC gene. Uptake by the HKDM was mediated partially by complement and partially by macrophage mannose receptors, as demonstrated by in vitro assays. Light and electron microscopy analysis of the infected macrophages revealed intracellular bacteria present in a tight vacuole at 2 h postinoculation and the presence of numerous bacteria in spacious vacuoles at 12 h postinfection, with some bacteria free in the cytoplasm.
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Oyston PCF, Griffiths R. Francisella virulence: significant advances, ongoing challenges and unmet needs. Expert Rev Vaccines 2010; 8:1575-85. [PMID: 19863250 DOI: 10.1586/erv.09.114] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Francisella tularensis, the causative agent of tularemia, is an organism of concern as a potential biowarfare agent. Progress towards understanding the molecular basis of pathogenicity has been hampered by a lack of tools with which to manipulate the pathogen. However, the availability of genome sequence data for a range of strains and the development of a range of plasmids and mutagenesis protocols for use in Francisella has resulted in a huge advance in understanding. No licensed vaccine is yet available. Various approaches towards a new vaccine are being evaluated, but novel adjuvants and delivery systems are needed to induce the complex response required for immunity. Better animal models to more accurately represent human responses to infection are also required.
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Soto E, Fernandez D, Hawke JP. Attenuation of the fish pathogen Francisella sp. by mutation of the iglC* gene. JOURNAL OF AQUATIC ANIMAL HEALTH 2009; 21:140-149. [PMID: 20043398 DOI: 10.1577/h08-056.1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Fish francisellosis is an emergent disease caused by gram-negative facultative intracellular bacteria of the genus Francisella. Different strains of the bacterium have caused high mortalities in warmwater and coldwater fish species. Francisella sp. isolates from fish have been found to share more than 97% identity to the human pathogen Francisella tularensis upon 16S ribosomal RNA sequence comparison. Homologue genes of the F. tularensis intracellular growth locus (iglA*, iglB*, iglC*, and iglD*) were identified from LADL 07-285A, a clinical isolate obtained from diseased Nile tilapia Oreochromis niloticus. The iglABCD operon DNA sequence comparison revealed that Francisella LADL 07-285A had 94% identity with F. philomiragia subsp. philomiragia and 83% identity with F. tularensis subsp. novicida U112. The functions of the conserved proteins corresponding to the genes are elusive but appear to be essential for the ability of Francisella sp. to survive within macrophages and cause disease. An insertion mutation was made in the iglC* gene of LADL 07-285A by allelic exchange, and the iglC* mutant was found to be attenuated after intraperitoneal and immersion challenges in Nile tilapia. Laboratory challenge methods for inducing francisellosis in Nile tilapia were evaluated by intraperitoneal injection and immersion with serial dilutions of Francisella LADL 07-285A. The dose lethal to 50% of test fish at 40 d postchallenge was 10(-5.3) (about 1.2 X 10(3) colony-forming units/fish) by intraperitoneal injection and was 10(-1) (2.3 X 10(7) colony-forming units/mL of tank water) by immersion.
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Affiliation(s)
- Esteban Soto
- Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana 70803, USA
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Soto E, Hawke JP, Fernandez D, Morales JA. Francisella sp., an emerging pathogen of tilapia, Oreochromis niloticus (L.), in Costa Rica. JOURNAL OF FISH DISEASES 2009; 32:713-722. [PMID: 19515205 DOI: 10.1111/j.1365-2761.2009.01070.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Francisella sp. is an emergent bacterial pathogen that causes acute to chronic disease in warm and cold water cultured and wild fish species. During the past 3 years, the bacterium has been detected in tilapia, Oreochromis niloticus, cultured in Costa Rica. Infected fish presented non-specific clinical signs, such as erratic swimming, anorexia, anaemia, exophthalmia and high mortality. Upon macroscopic and microscopic examination, several internal organs (mainly spleen and kidney) were enlarged and contained white nodules. Histological examination revealed the presence of multifocal granulomatous lesions, with the presence of numerous small, pleomorphic, cocco-bacilli. The bacteria were isolated from infected tilapia on selective media and grown on several media with and without antibiotics. Specific PCR primers to the Francisella genus were used to confirm the preliminary diagnoses. In comparison with several bacterial 16S rRNA sequences, our isolate was found to share 99% identity with other Fransicella spp. isolated from fish, and more than 97% identity to the human pathogen Francisella tularensis. Koch's postulates were fulfilled after experimental intraperitoneal and gill exposure challenges.
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Affiliation(s)
- E Soto
- Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Skip Bertman Drive, Baton Rouge, LA 70803, USA
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Ottem KF, Nylund A, Karlsbakk E, Friis-Møller A, Kamaishi T. Elevation of Francisella philomiragia subsp. noatunensis Mikalsen et al. (2007) to Francisella noatunensis comb. nov. [syn. Francisella piscicida Ottem et al. (2008) syn. nov.] and characterization of Francisella noatunensis subsp. orientalis subsp. nov., two important fish pathogens. J Appl Microbiol 2009; 106:1231-43. [PMID: 19187160 DOI: 10.1111/j.1365-2672.2008.04092.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS This study was conducted to clarify the taxonomic status of Francisella sp. strain Ehime-1, a fish pathogen, in relation to the fish pathogens F. piscicida and F. philomiragia subsp. noatunensis and to F. philomiragia subsp. philomiragia. METHODS AND RESULTS Francisella sp. Ehime-1 was compared to F. piscicida, F. philomiragia subsp. noatunensis and several F. philomiragia subsp. philomiragia isolates through sequencing of the 16S rRNA-gene and several house-keeping genes and determination of biochemical and phenotypic properties. Results show that F. piscicida is indistinguishable from F. philomiragia subsp. noatunensis by sequence and phenotypic traits. Francisella sp. Ehime-1 and F. philomiragia subsp. noatunensis are clearly separated from F. philomiragia. Francisella sp. Ehime-1 is biochemically, phenotypically and genetically different from F. philomiragia subsp. noatunensis (=F. piscicida), but DNA-DNA hybridization does not clearly support establishment as a separate species (level of relatedness 64% and 73.4%, mean 68.7%). CONCLUSIONS We propose to elevate F. philomiragia subsp. noatunensis to species rank as F. noatunensis comb. nov., while F. piscicida is considered a heterotypic synonym of F. noatunensis comb. nov. Evidence suggests that Francisella sp. Ehime-1 represents a novel subspecies of F. noatunensis, for which the name F. noatunensis subsp. orientalis subsp. nov. is proposed (=DSM21254(T), = LMG24544(T)). SIGNIFICANCE AND IMPACT OF THE STUDY This study contributes to the taxonomy and characteristics of fish-pathogenic Francisella spp.
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Affiliation(s)
- K F Ottem
- Department of Biology, University of Bergen, Norway.
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Host immune response and acute disease in a zebrafish model of Francisella pathogenesis. Infect Immun 2008; 77:914-25. [PMID: 19047404 DOI: 10.1128/iai.01201-08] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Members of the bacterial genus Francisella are highly virulent and infectious pathogens. New models to study Francisella pathogenesis in evolutionarily distinct species are needed to provide comparative insight, as the mechanisms of host resistance and pathogen virulence are not well understood. We took advantage of the recent discovery of a novel species of Francisella to establish a zebrafish/Francisella comparative model of pathogenesis and host immune response. Adult zebrafish were susceptible to acute Francisella-induced disease and suffered mortality in a dose-dependent manner. Using immunohistochemical analysis, we localized bacterial antigens primarily to lymphoid tissues and livers of zebrafish following infection by intraperitoneal injection, which corresponded to regions of local cellular necrosis. Francisella sp. bacteria replicated rapidly in these tissues beginning 12 h postinfection, and bacterial titers rose steadily, leveled off, and then decreased by 7 days postinfection. Zebrafish mounted a significant tissue-specific proinflammatory response to infection as measured by the upregulation of interleukin-1beta (IL-1beta), gamma interferon, and tumor necrosis factor alpha mRNA beginning by 6 h postinfection and persisting for up to 7 days postinfection. In addition, exposure of zebrafish to heat-killed bacteria demonstrated that the significant induction of IL-1beta was highly specific to live bacteria. Taken together, the pathology and immune response to acute Francisella infection in zebrafish share many features with those in mammals, highlighting the usefulness of this new model system for addressing both general and specific questions about Francisella host-pathogen interactions via an evolutionary approach.
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Read A, Vogl SJ, Hueffer K, Gallagher LA, Happ GM. Francisella genes required for replication in mosquito cells. JOURNAL OF MEDICAL ENTOMOLOGY 2008; 45:1108-1116. [PMID: 19058636 DOI: 10.1603/0022-2585(2008)45[1108:fgrfri]2.0.co;2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Francisella tularensis, a potential bioterrorism agent, is transmitted by arthropod vectors and causes tularemia in many mammals, including humans. Francisella novicida causes disease with similar pathology in mice. We show that F. novicida invades hemocyte-like cells of the SualB cell line derived from Anopheles gambiae and replicates vigorously within these cells. We used transposon knockouts of single genes of F. novicida to show that bacterial growth within these insect cells is dependent on virulence factors encoded in a bacterial pathogenicity island that has been linked to replication in mammalian macrophages. The virulence factors MglA, IglA, IglB, IglC, and IglD as well as PdpA and PdpB were necessary for efficient growth in insect cells, but PdpC and PdpD were not required. The SualB cell line presents a valuable model to study the interactions between this important pathogen and insect vectors.
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Affiliation(s)
- Amanda Read
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
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