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Esposito G, Bergagna S, Colussi S, Shahin K, Rosa R, Volpatti D, Faggio C, Mossotto C, Gabetti A, Maganza A, Bozzetta E, Prearo M, Pastorino P. Changes in blood serum parameters in farmed rainbow trout (Oncorhynchus mykiss) during a piscine lactococcosis outbreak. JOURNAL OF FISH DISEASES 2024:e13994. [PMID: 38953153 DOI: 10.1111/jfd.13994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2024] [Revised: 06/12/2024] [Accepted: 06/17/2024] [Indexed: 07/03/2024]
Abstract
The aquaculture sector plays a vital role in global food security, yet it grapples with significant challenges posed by infectious diseases. Piscine lactococcosis is one of the significant threats in rainbow trout aquaculture due to its potential to cause severe economic losses through mortalities, reduced growth rates, and increased susceptibility to other pathogens. It poses challenges in disease management strategies, impacting the sustainability and profitability of rainbow trout farming. The current study focuses on the variations in serum blood parameters of farmed rainbow trout Oncorhynchus mykiss during a lactococcosis outbreak caused by Lactococcus garvieae. Blood samples were collected for biochemical analysis, fish were examined for parasites and bacteria, and DNA from bacterial colonies was PCR-amplified and sequenced for identification. Overall, 13 biochemical parameters, including proteins, enzymes, lipids, chemicals, and minerals, were measured in serum blood samples from both diseased and healthy fish. The results indicate significant alterations in the levels of these parameters during the outbreak, highlighting the impact of infections on the blood profile of farmed rainbow trout. Urea levels were significantly higher in diseased fish compared to controls, and creatinine, phosphorus, and magnesium also showed similar trends. Alanine aminotransferase and total protein levels were higher in control fish. Chloride levels differed significantly between groups. Iron levels were higher in controls and lower in diseased fish. No significant differences were found in other parameters. This study reveals significant changes in serum blood parameters of rainbow trout during a lactococcosis outbreak caused by L. garvieae. These changes highlight the potential of these parameters as tools for monitoring health status, stress, and aquaculture management. Continuous monitoring can provide valuable insights into disease severity and overall fish health, aiding in the development of improved management practices. The presented data contribute to understanding the pathophysiology of piscine lactococcosis and developing effective mitigation strategies for farmed rainbow trout.
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Affiliation(s)
- Giuseppe Esposito
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Turin, Italy
| | - Stefania Bergagna
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Turin, Italy
| | - Silvia Colussi
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Turin, Italy
| | - Khalid Shahin
- Aquatic Animal Diseases Laboratory, Aquaculture Department, National Institute of Oceanography and Fisheries, Suez, Egypt
| | - Roberta Rosa
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Turin, Italy
| | - Donatella Volpatti
- Dipartimento di Scienze Agroalimentari, Ambientali e Animali, University of Udine, Udine, Italy
| | - Caterina Faggio
- Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche e Ambientali, University of Messina, Messina, Italy
- Dipartimento di Biotecnologie Marine Ecosostenibili, Stazione Zoologica Anton Dohrn, Naples, Italy
| | - Camilla Mossotto
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Turin, Italy
| | - Alice Gabetti
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Turin, Italy
| | - Alessandra Maganza
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Turin, Italy
| | - Elena Bozzetta
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Turin, Italy
| | - Marino Prearo
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Turin, Italy
| | - Paolo Pastorino
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Turin, Italy
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Chan YX, Cao H, Jiang S, Li X, Fung KK, Lee CH, Sridhar S, Chen JHK, Ho PL. Genomic investigation of Lactococcus formosensis, Lactococcus garvieae, and Lactococcus petauri reveals differences in species distribution by human and animal sources. Microbiol Spectr 2024; 12:e0054124. [PMID: 38687062 PMCID: PMC11237765 DOI: 10.1128/spectrum.00541-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Accepted: 04/16/2024] [Indexed: 05/02/2024] Open
Abstract
Lactococcus garvieae is a fish pathogen that can cause diseases in humans and cows. Two genetically related species, Lactococcus formosensis and Lactococcus petauri, may be misidentified as L. garvieae. It is unclear if these species differ in host specificity and virulence genes. This study analyzed the genomes of 120 L. petauri, 53 L. formosensis, and 39 L. garvieae isolates from various sources. The genetic diversity and virulence gene content of these isolates were compared. The results showed that 77 isolates previously reported as L. garvieae were actually L. formosensis or L. petauri. The distribution of the three species varied across different collection sources, with L. petauri being predominant in human infections, human fecal sources, and rainbow trout, while L. formosensis was more common in bovine isolates. The genetic diversity of isolates within each species was high and similar. Using a genomic clustering method, L. petauri, L. formosensis, and L. garvieae were divided into 45, 22, and 13 clusters, respectively. Most rainbow trout and human isolates of L. petauri belonged to different clusters, while L. formosensis isolates from bovine and human sources were also segregated into separate clusters. In L. garvieae, most human isolates were grouped into three clusters that also included isolates from food or other sources. Non-metric multidimensional scaling ordination revealed the differential association of 15 virulence genes, including 14 adherence genes and a bile salt hydrolase gene, with bacterial species and certain collection sources. In conclusion, this work provides evidence of host specificity among the three species. IMPORTANCE Lactococcus formosensis and Lactococcus petauri are two newly discovered bacteria, which are closely related to Lactococcus garvieae, a pathogen that affects farmed rainbow trout, as well as causes cow mastitis and human infections. It is unclear whether the three bacteria differ in their host preference and the presence of genes that contribute to the development of disease. This study shows that L. formosensis and L. petauri were commonly misidentified as L. garvieae. The three bacteria showed different distribution patterns across various sources. L. petauri was predominantly found in human infections and rainbow trout, while L. formosensis was more commonly detected in cow mastitis. Fifteen genes displayed a differential distribution among the three bacteria from certain sources, indicating a genetic basis for the observed host preference. This work indicates the importance of differentiating the three bacteria in diagnostic laboratories for surveillance and outbreak investigation purposes.
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Affiliation(s)
- You-Xiang Chan
- Department of Microbiology, University of Hong Kong, Hong Kong, China
| | - Huiluo Cao
- Department of Microbiology, University of Hong Kong, Hong Kong, China
| | - Shuo Jiang
- Department of Microbiology, University of Hong Kong, Hong Kong, China
| | - Xin Li
- Department of Microbiology, University of Hong Kong, Hong Kong, China
- Carol Yu Centre for Infection, University of Hong Kong, Hong Kong, China
- Department of Microbiology, Queen Mary Hospital, Hospital Authority, Hong Kong, China
| | - Ka-Kin Fung
- Department of Clinical Pathology, Pamela Youde Nethersole Eastern Hospital, Hospital Authority, Hong Kong, China
| | - Chung-Ho Lee
- Department of Clinical Pathology, Kwong Wah Hospital, Hospital Authority, Hong Kong, China
| | - Siddharth Sridhar
- Department of Microbiology, University of Hong Kong, Hong Kong, China
- Carol Yu Centre for Infection, University of Hong Kong, Hong Kong, China
- Department of Microbiology, Queen Mary Hospital, Hospital Authority, Hong Kong, China
| | | | - Pak-Leung Ho
- Department of Microbiology, University of Hong Kong, Hong Kong, China
- Carol Yu Centre for Infection, University of Hong Kong, Hong Kong, China
- Department of Microbiology, Queen Mary Hospital, Hospital Authority, Hong Kong, China
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Jantrakajorn S, Suyapoh W, Wongtavatchai J. Characterization of Lactococcus garvieae and Streptococcus agalactiae in cultured red tilapia Oreochromis sp. in Thailand. JOURNAL OF AQUATIC ANIMAL HEALTH 2024; 36:192-202. [PMID: 38632692 DOI: 10.1002/aah.10217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Revised: 01/04/2024] [Accepted: 02/20/2024] [Indexed: 04/19/2024]
Abstract
OBJECTIVE Acute mortality with clinical symptoms of streptococcal-like infections was observed in red tilapia Oreochromis sp. cultured in floating cages in Prachin Buri Province, Thailand, during May 2023. Herein, we identified an emerging pathogen, Lactococcus garvieae, as the etiological agent. METHODS After bacterial isolation from the brain and kidney of diseased fish, identification was performed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and the VITEK 2 system. Sequencing of the 16S ribosomal RNA (rRNA) gene and phylogenetic analysis were applied to confirm bacterial species. Antimicrobial susceptibility testing was conducted. Histopathological findings in the brain, kidney, spleen, liver, and heart were evaluated. RESULT From 20 fish samples, L. garvieae (n = 18 isolates) and Streptococcus agalactiae (n = 2 isolates) were identified. A phylogenetic tree of the 16S rRNA gene revealed that Thai isolates of either L. garvieae or S. agalactiae clustered with reference piscine isolates from intercontinental locations. Our isolates showed resistance against quinolones while being susceptible to other antimicrobials. Histopathological changes demonstrated severe septicemic conditions, with more invasive lesions-especially in the heart and liver-being apparent in L. garvieae-infected fish compared to S. agalactiae-infected fish. CONCLUSION This study represents the first reported outbreak of L. garvieae with a concurrent S. agalactiae infection in farmed red tilapia in Thailand.
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Affiliation(s)
| | - Watcharapol Suyapoh
- Faculty of Veterinary Science, Prince of Songkla University, Songkhla, Thailand
- World Health Organization Collaborating Center for Research and Control of Opisthorchiasis (Southeast Asian Liver Fluke Disease), Tropical Disease Research Center, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Janenuj Wongtavatchai
- Department of Veterinary Medicine, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
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Heckman TI, Yazdi Z, Older CE, Griffin MJ, Waldbieser GC, Chow AM, Medina Silva I, Anenson KM, García JC, LaFrentz BR, Slavic D, Toohey-Kurth KL, Yant P, Fritz HM, Henderson EE, McDowall R, Cai H, Adkison M, Soto E. Redefining piscine lactococcosis. Appl Environ Microbiol 2024; 90:e0234923. [PMID: 38597602 PMCID: PMC11107168 DOI: 10.1128/aem.02349-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Accepted: 03/10/2024] [Indexed: 04/11/2024] Open
Abstract
Piscine lactococcosis is a significant threat to cultured and wild fish populations worldwide. The disease typically presents as a per-acute to acute hemorrhagic septicemia causing high morbidity and mortality, recalcitrant to antimicrobial treatment or management interventions. Historically, the disease was attributed to the gram-positive pathogen Lactococcus garvieae. However, recent work has revealed three distinct lactococcosis-causing bacteria (LCB)-L. garvieae, L. petauri, and L. formosensis-which are phenotypically and genetically similar, leading to widespread misidentification. An update on our understanding of lactococcosis and improved methods for identification are urgently needed. To this end, we used representative isolates from each of the three LCB species to compare currently available and recently developed molecular and phenotypic typing assays, including whole-genome sequencing (WGS), end-point and quantitative PCR (qPCR) assays, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), API 20 Strep and Biolog systems, fatty acid methyl ester analysis (FAME), and Sensititre antimicrobial profiling. Apart from WGS, sequencing of the gyrB gene was the only method capable of consistent and accurate identification to the species and strain level. A qPCR assay based on a putative glycosyltransferase gene was also able to distinguish L. petauri from L. garvieae/formosensis. Biochemical tests and MALDI-TOF MS showed some species-specific patterns in sugar and fatty acid metabolism or protein profiles but should be complemented by additional analyses. The LCB demonstrated overlap in host and geographic range, but there were relevant differences in host specificity, regional prevalence, and antimicrobial susceptibility impacting disease treatment and prevention. IMPORTANCE Lactococcosis affects a broad range of host species, including fish from cold, temperate, and warm freshwater or marine environments, as well as several terrestrial animals, including humans. As such, lactococcosis is a disease of concern for animal and ecosystem health. The disease is endemic in European and Asian aquaculture but is rapidly encroaching on ecologically and economically important fish populations across the Americas. Piscine lactococcosis is difficult to manage, with issues of vaccine escape, ineffective antimicrobial treatment, and the development of carrier fish or biofilms leading to recurrent outbreaks. Our understanding of the disease is also widely outdated. The accepted etiologic agent of lactococcosis is Lactococcus garvieae. However, historical misidentification has masked contributions from two additional species, L. petauri and L. formosensis, which are indistinguishable from L. garvieae by common diagnostic methods. This work is the first comprehensive characterization of all three agents and provides direct recommendations for species-specific diagnosis and management.
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Affiliation(s)
- Taylor I. Heckman
- Department of Medicine & Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Zeinab Yazdi
- Department of Medicine & Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Caitlin E. Older
- USDA-ARS, Warmwater Aquaculture Research Unit, Stoneville, Mississippi, USA
| | - Matt J. Griffin
- College of Veterinary Medicine, Mississippi State University, Stoneville, Mississippi, USA
| | | | - Alexander M. Chow
- Department of Medicine & Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Isabella Medina Silva
- Department of Medicine & Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Kelsey M. Anenson
- Department of Medicine & Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Julio C. García
- USDA-ARS, Aquatic Animal Health Research Unit, Auburn, Alabama, USA
| | | | - Durda Slavic
- Animal Health Laboratory, University of Guelph, Ontario, Canada
| | - Kathy L. Toohey-Kurth
- California Animal Health and Food Safety Laboratory, University of California, Davis, California, USA
| | - Paula Yant
- California Animal Health and Food Safety Laboratory, University of California, Davis, California, USA
| | - Heather M. Fritz
- California Animal Health and Food Safety Laboratory, University of California, Davis, California, USA
| | - Eileen E. Henderson
- California Animal Health and Food Safety Laboratory, University of California, Davis, California, USA
| | | | - Hugh Cai
- Animal Health Laboratory, University of Guelph, Ontario, Canada
| | - Mark Adkison
- California Department of Fish and Wildlife, Rancho Cordova, California, USA
| | - Esteban Soto
- Department of Medicine & Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA
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Neupane S, Rao S, Yan WX, Wang PC, Chen SC. First identification, molecular characterization, and pathogenicity assessment of Lactococcus garvieae isolated from cultured pompano in Taiwan. JOURNAL OF FISH DISEASES 2023; 46:1295-1309. [PMID: 37578999 DOI: 10.1111/jfd.13848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 07/28/2023] [Accepted: 07/31/2023] [Indexed: 08/16/2023]
Abstract
Lactococcosis, caused by Lactococcus garvieae, is an acute hemorrhagic septicemia in fish recorded in marine and freshwater aquaculture during the summer months. In 2020-2021, several sea cage Pompano farms recorded sudden fish mortality events. Based on the results of phenotypic and biochemical tests, L. garvieae was predicted to be the cause. PCR with L. garvieae specific primers (pLG1 and pLG2) targeting the 16S rRNA region further confirmed the etiological agent as L. garvieae after amplifying an 1100 base pairs (bp) product. Furthermore, the 16S rRNA sequences of the two representative strains (AOD109-196-2B and AOD110-215-2B) shared 99.81% identity with L. garvieae (GenBank accession number: MT597707.1). The genetic profiles of the strains were classified using pulsed-field gel electrophoresis after digestion with SmaI and ApaI, which clustered our strains under the same pulsotype. Multiplex PCR targeting the capsule gene cluster and serotype-specific PCR collectively showed that the strains were non-capsulated; thus, they belonged to serotype I. An experimental infection was designed to fulfil Koch's postulates by infecting healthy Pompano with case-driven L. garvieae strains (AOD109-196-2B and AOD110-215-2B) with a cumulative mortality of 70%. Overall, L. garvieae infection in Pompano emphasizes the need for better monitoring and control procedures in aquaculture settings.
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Affiliation(s)
- Sandip Neupane
- International Degree Program of Ornamental Fish Technology and Aquatic Animal Health, International College, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Shreesha Rao
- Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Wei-Xiao Yan
- International Degree Program of Ornamental Fish Technology and Aquatic Animal Health, International College, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Pei-Chi Wang
- 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
- Research Centre for Fish Vaccine and Diseases, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
- Southern Taiwan Fish Diseases Research Centre, 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
- Research Centre for Fish Vaccine and Diseases, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
- Southern Taiwan Fish Diseases Research Centre, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
- Research Centre for Animal Biologics, National Pingtung University of Science and Technology, Pingtung, Taiwan
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Littman EM, Heckman TI, Yazdi Z, Veek T, Mukkatira K, Adkison M, Powell A, Camus A, Soto E. Temperature-associated virulence, species susceptibility and interspecies transmission of a Lactococcus petauri strain from rainbow trout. DISEASES OF AQUATIC ORGANISMS 2023; 155:147-158. [PMID: 37706645 DOI: 10.3354/dao03747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/15/2023]
Abstract
Lactococcus petauri is an important emergent aquaculture pathogen in the USA. To better understand environmental conditions conducive to piscine lactococcosis and the susceptibility of fish species, laboratory-controlled challenges were used as models of infection. Rainbow trout Oncorhynchus mykiss maintained at 13 or 18°C were challenged by intracoelomic (ICe) injection with 101, 103 or 105 colony-forming units per fish (CFU fish-1) and monitored for 21 d. At 13°C, trout experienced mortalities of 7, 7 and 0%, and bacterial persistence of 0, 20 and 0% in survivors, respectively. When exposed to the same bacterial doses, trout maintained at 18°C experienced mortalities of 59, 84 and 91%, and bacterial persistence of 60, 66 and 0% in survivors, confirming a significant role of temperature in the pathogenesis of lactococcosis. Additionally, the susceptibility of rainbow trout, Chinook salmon Oncorhynchus tshawytscha, white sturgeon Acipenser transmontanus, Nile tilapia Oreochromis niloticus, and koi Cyprinus carpio to infection by L. petauri was compared using ICe challenges at 18°C. Trout and salmon experienced 96 and 56% cumulative mortality, respectively, and 17% of surviving salmon remained persistently infected. There were no mortalities in the other fish species, and no culturable bacteria recovered at the end of the challenge. However, when surviving fish were used in further cohabitation trials, naïve trout housed with previously exposed tilapia exhibited 6% mortality, demonstrating that non-salmonids can become sub-clinical carriers of this pathogen. The data obtained provide useful information regarding temperature-associated virulence, fish species susceptibility, and potential carrier transmission of L. petauri that can be used in the development of better management practices to protect against piscine lactococcosis.
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Affiliation(s)
- Eric Maxwell Littman
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
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Abraham T, Yazdi Z, Littman E, Shahin K, Heckman TI, Quijano Cardé EM, Nguyen DT, Hu R, Adkison M, Veek T, Mukkatira K, Richey C, Kwak K, Mohammed HH, Ortega C, Avendaño-Herrera R, Keleher W, LePage V, Gardner I, Welch TJ, Soto E. Detection and virulence of Lactococcus garvieae and L. petauri from four lakes in southern California. JOURNAL OF AQUATIC ANIMAL HEALTH 2023; 35:187-198. [PMID: 37749801 DOI: 10.1002/aah.10188] [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: 10/14/2022] [Revised: 04/24/2023] [Accepted: 04/29/2023] [Indexed: 09/27/2023]
Abstract
OBJECTIVE The first objective of the study aimed to detect the presence of Lactococcus petauri, L. garvieae, and L. formosensis in fish (n = 359) and environmental (n = 161) samples from four lakes near an affected fish farm in California during an outbreak in 2020. The second objective was to compare the virulence of the Lactococcus spp. in Rainbow Trout Oncorhynchus mykiss and Largemouth Bass Micropterus salmoides. METHODS Standard bacterial culture methods were used to isolate Lactococcus spp. from brain and posterior kidney of sampled fish from the four lakes. Quantitative PCR (qPCR) was utilized to detect Lactococcus spp. DNA in fish tissues and environmental samples from the four lakes. Laboratory controlled challenges were conducted by injecting fish intracoelomically with representative isolates of L. petauri (n = 17), L. garvieae (n = 2), or L. formosensis (n = 4), and monitored for 14 days postchallenge (dpc). RESULT Lactococcus garvieae was isolated from the brains of two Largemouth Bass in one of the lakes. Lactococcus spp. were detected in 14 fish (8 Bluegills Lepomis macrochirus and 6 Largemouth Bass) from 3 out of the 4 lakes using a qPCR assay. Of the collected environmental samples, all 4 lakes tested positive for Lactococcus spp. in the soil samples, while 2 of the 4 lakes tested positive in the water samples through qPCR. Challenged Largemouth Bass did not show any signs of infection postinjection throughout the challenge period. Rainbow Trout infected with L. petauri showed clinical signs within 3 dpc and presented a significantly higher cumulative mortality (62.4%; p < 0.0001) at 14 dpc when compared to L. garvieae (0%) and L. formosensis (7.5%) treatments. CONCLUSION The study suggests that qPCR can be used for environmental DNA monitoring of Lactococcus spp. and demonstrates virulence diversity between the etiological agents of piscine lactococcosis.
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Affiliation(s)
- Taylor Abraham
- School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| | - Zeinab Yazdi
- School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| | - Eric Littman
- School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| | - Khalid Shahin
- School of Veterinary Medicine, University of California-Davis, Davis, California, USA
- Aquatic Animals Diseases Laboratory, National Institute of Oceanography and Fisheries, Suez, Egypt
| | - Taylor I Heckman
- School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| | | | - Diem Thu Nguyen
- School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| | - Ruixue Hu
- School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| | - Mark Adkison
- California Department of Fish and Wildlife, Rancho Cordova, California, USA
| | - Tresa Veek
- California Department of Fish and Wildlife, Rancho Cordova, California, USA
| | - Kavery Mukkatira
- California Department of Fish and Wildlife, Rancho Cordova, California, USA
| | - Christine Richey
- California Department of Fish and Wildlife, Rancho Cordova, California, USA
| | - Kevin Kwak
- California Department of Fish and Wildlife, Rancho Cordova, California, USA
| | - Haitham H Mohammed
- Department of Rangeland, Wildlife and Fisheries Management, College of Agriculture and Life Sciences, Texas A&M University, College Station, Texas, USA
| | - Cesar Ortega
- Centro de Investigación y Estudios Avanzados en Salud Animal, Facultad de Medicina Veterinaria y Zootecnia, Universidad Autónoma del Estado de México, Toluca, Mexico
| | - Ruben Avendaño-Herrera
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias de la Vida, Universidad Andrés Bello and Fondo de Financiamiento de Centros de Investigación en Áreas Prioritarias, Centro Interdisciplinario de Investigación en Acuicultura Sustentable, Viña del Mar, Chile
| | | | | | - Ian Gardner
- Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada
| | - Timothy J Welch
- U.S. Department of Agriculture, Agricultural Research Service, National Center for Cool and Coldwater Aquaculture, Leetown, West Virginia, USA
| | - Esteban Soto
- School of Veterinary Medicine, University of California-Davis, Davis, California, USA
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Han Z, Ge L, Wen S, Sun J. Dysfunction of the intestinal physical barrier in the intestinal inflammation of tongue sole, Cynoglossus semilaevis, induced by Shewanella algae infection. FISH & SHELLFISH IMMUNOLOGY 2023:108900. [PMID: 37315911 DOI: 10.1016/j.fsi.2023.108900] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 06/10/2023] [Accepted: 06/12/2023] [Indexed: 06/16/2023]
Abstract
Bacterial intestinal inflammation occurs frequently in cultured fish. However, research on the dysfunction of the intestinal physical barrier in fish intestinal inflammation is scarce. In this study, intestinal inflammation in tongue sole Cynoglossus semilaevis was induced by Shewanella algae and the intestinal permeability was investigated. Gene expression patterns in inflammatory factors, tight junction molecules, and keratins 8 and 18 in the intestines were further explored. Histological examinations of the middle intestines showed that S. algae induced pathological lesions of intestinal inflammation and significantly increased the total number of mucous cells (p < 0.01). Ultrastructural observation in the middle intestines showed that intercellular spaces between epithelial cells were significantly wider in infected fish compared with the control (p < 0.01). The positive result of fluorescence in situ hybridization confirmed the presence of S. algae in the intestine. Enhanced Evans blue exudation and increased levels of serum d-lactate and intestinal fatty acid binding protein were suggestive of increased intestinal barrier permeability. The mRNA levels of four pro-inflammatory cytokines, namely IL-6, IL-8, IL-β, and TNF-α, were significantly increased after S. algae infection at most tested time points (p < 0.01 or p < 0.05), while there was an alternating increasing and decreasing trend in the gene expression patterns of IL-10, TGF-β, TLR-2, AP-1, and CASP-1. The mRNA expression of tight junction molecules (claudin-1, claudin-2, ZO-1, JAM-A, and MarvelD3) and keratins 8 and 18 in the intestines was significantly decreased at 6, 12, 24, 48, or 72 h post infection (p < 0.01 or p < 0.05). In conclusion, S. algae infection induced intestinal inflammation accompanied by increased intestinal permeability in tongue sole, and tight junction molecules and keratins were probably associated with the pathological process.
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Affiliation(s)
- Zhuoran Han
- Tianjin Key Lab of Aqua-ecology and Aquaculture, Fisheries College, Tianjin Agricultural University, Tianjin, 300384, China.
| | - Lunhua Ge
- Tianjin Key Lab of Aqua-ecology and Aquaculture, Fisheries College, Tianjin Agricultural University, Tianjin, 300384, China.
| | - Siyi Wen
- Tianjin Key Lab of Aqua-ecology and Aquaculture, Fisheries College, Tianjin Agricultural University, Tianjin, 300384, China.
| | - Jingfeng Sun
- Tianjin Key Lab of Aqua-ecology and Aquaculture, Fisheries College, Tianjin Agricultural University, Tianjin, 300384, China.
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9
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Meng X, Chen F, Xiong M, Hao H, Wang KJ. A new pathogenic isolate of Kocuria kristinae identified for the first time in the marine fish Larimichthys crocea. Front Microbiol 2023; 14:1129568. [PMID: 37180261 PMCID: PMC10167289 DOI: 10.3389/fmicb.2023.1129568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 04/04/2023] [Indexed: 05/16/2023] Open
Abstract
In recent years, new emerging pathogenic microorganisms have frequently appeared in animals, including marine fish, possibly due to climate change, anthropogenic activities, and even cross-species transmission of pathogenic microorganisms among animals or between animals and humans, which poses a serious issue for preventive medicine. In this study, a bacterium was clearly characterized among 64 isolates from the gills of diseased large yellow croaker Larimichthys crocea that were raised in marine aquaculture. This strain was identified as K. kristinae by biochemical tests with a VITEK 2.0 analysis system and 16S rRNA sequencing and named K. kristinae_LC. The potential genes that might encode virulence-factors were widely screened through sequence analysis of the whole genome of K. kristinae_LC. Many genes involved in the two-component system and drug-resistance were also annotated. In addition, 104 unique genes in K. kristinae_LC were identified by pan genome analysis with the genomes of this strain from five different origins (woodpecker, medical resource, environment, and marine sponge reef) and the analysis results demonstrated that their predicted functions might be associated with adaptation to living conditions such as higher salinity, complex marine biomes, and low temperature. A significant difference in genomic organization was found among the K. kristinae strains that might be related to their hosts living in different environments. The animal regression test for this new bacterial isolate was carried out using L. crocea, and the results showed that this bacterium could cause the death of L. crocea and that the fish mortality was dose-dependent within 5 days post infection, indicating the pathogenicity of K. kristinae_LC to marine fish. Since K. kristinae has been reported as a pathogen for humans and bovines, in our study, we revealed a new isolate of K. kristinae_LC from marine fish for the first time, suggesting the potentiality of cross-species transmission among animals or from marine animals to humans, from which we would gain insight to help in future public prevention strategies for new emerging pathogens.
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Affiliation(s)
- Xiangyu Meng
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, China
| | - Fangyi Chen
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, China
- State-Province Joint Engineering Laboratory of Marine Bioproducts and Technology, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, China
- Fujian Innovation Research Institute for Marine Biological Antimicrobial Peptide Industrial Technology, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, China
| | - Ming Xiong
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, China
- State-Province Joint Engineering Laboratory of Marine Bioproducts and Technology, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, China
- Fujian Innovation Research Institute for Marine Biological Antimicrobial Peptide Industrial Technology, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, China
| | - Hua Hao
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, China
- State-Province Joint Engineering Laboratory of Marine Bioproducts and Technology, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, China
- Fujian Innovation Research Institute for Marine Biological Antimicrobial Peptide Industrial Technology, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, China
| | - Ke-Jian Wang
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, China
- State-Province Joint Engineering Laboratory of Marine Bioproducts and Technology, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, China
- Fujian Innovation Research Institute for Marine Biological Antimicrobial Peptide Industrial Technology, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, China
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10
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de Ruyter T, Littman E, Yazdi Z, Adkison M, Camus A, Yun S, Welch TJ, Keleher WR, Soto E. Comparative Evaluation of Booster Vaccine Efficacy by Intracoelomic Injection and Immersion with a Whole-Cell Killed Vaccine against Lactococcus petauri Infection in Rainbow Trout ( Oncorhynchus mykiss). Pathogens 2023; 12:pathogens12050632. [PMID: 37242302 DOI: 10.3390/pathogens12050632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 04/07/2023] [Accepted: 04/08/2023] [Indexed: 05/28/2023] Open
Abstract
Lactococcus petauri is an important emergent bacterial pathogen of salmonids in the USA. The purpose of this study was to evaluate the protection conferred to rainbow trout (Oncorhynchus mykiss) against L. petauri by formalin-killed vaccines in immersion and injectable forms, as well as the enhanced protection afforded by booster vaccination. In the first challenge, fish were immunized via intracoelomic injection (IC) or immersion (Imm) routes alone. Approximately 418 degree days (Temperature in degree Celsius × days post-immunization) (dd) Imm, or 622 dd IC post-vaccination, fish were challenged via IC with wild-type L. petauri. In the second experiment, initial Imm vaccination was followed by booster vaccination via Imm or IC routes 273 dd post-immunization along with appropriate PBS controls. The various vaccination protocol efficacies were evaluated by challenging fish with L. petauri by cohabitation with diseased fish 399 dd post-booster administration. A relative percent survival (RPS) of 89.5% and 28% was recorded in the IC and Imm single immunization treatments, respectively. In the second study, an RPS of 97.5%, 10.2%, 2.6% and -10.1% plus approximately 0%, 50%, 20%, and 30% bacterial persistence was recorded in the Imm immunized + IC boosted, Imm immunized + mock IC boosted, Imm immunized + Imm boosted, and Imm immunized + mock Imm boosted treatments, respectively. Only the Imm immunized + IC injection boosted treatments provided significant protection when compared to unvaccinated and challenged treatments (p < 0.05). In conclusion, although both Imm and IC vaccines appear safe for trout, the inactivated Imm vaccines seem to provide only mild and temporary protection against lactococcosis; whereas IC immunized trout develop a significantly stronger protective response in both challenges.
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Affiliation(s)
- Tryssa de Ruyter
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA
- School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Eric Littman
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA
| | - Zeinab Yazdi
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA
| | - Mark Adkison
- California Department of Fish and Wildlife, Rancho Cordova, CA 95670, USA
| | - Alvin Camus
- Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
| | - Susan Yun
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA
| | - Timothy J Welch
- National Center for Cool and Coldwater Aquaculture, Kearneysville, WV 25430, USA
| | | | - Esteban Soto
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA
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11
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Design of Lactococcus lactis Strains Producing Garvicin A and/or Garvicin Q, Either Alone or Together with Nisin A or Nisin Z and High Antimicrobial Activity against Lactococcus garvieae. Foods 2023; 12:foods12051063. [PMID: 36900581 PMCID: PMC10000435 DOI: 10.3390/foods12051063] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 02/20/2023] [Accepted: 02/24/2023] [Indexed: 03/06/2023] Open
Abstract
Lactococcus garvieae is a main ichthyopathogen in rainbow trout (Oncorhynchus mykiss, Walbaum) farming, although bacteriocinogenic L. garvieae with antimicrobial activity against virulent strains of this species have also been identified. Some of the bacteriocins characterized, such as garvicin A (GarA) and garvicin Q (GarQ), may show potential for the control of the virulent L. garvieae in food, feed and other biotechnological applications. In this study, we report on the design of Lactococcus lactis strains that produce the bacteriocins GarA and/or GarQ, either alone or together with nisin A (NisA) or nisin Z (NisZ). Synthetic genes encoding the signal peptide of the lactococcal protein Usp45 (SPusp45), fused to mature GarA (lgnA) and/or mature GarQ (garQ) and their associated immunity genes (lgnI and garI, respectively), were cloned into the protein expression vectors pMG36c, which contains the P32 constitutive promoter, and pNZ8048c, which contains the inducible PnisA promoter. The transformation of recombinant vectors into lactococcal cells allowed for the production of GarA and/or GarQ by L. lactis subsp. cremoris NZ9000 and their co-production with NisA by Lactococcus lactis subsp. lactis DPC5598 and L. lactis subsp. lactis BB24. The strains L. lactis subsp. cremoris WA2-67 (pJFQI), a producer of GarQ and NisZ, and L. lactis subsp. cremoris WA2-67 (pJFQIAI), a producer of GarA, GarQ and NisZ, demonstrated the highest antimicrobial activity (5.1- to 10.7-fold and 17.3- to 68.2-fold, respectively) against virulent L. garvieae strains.
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12
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Irshath AA, Rajan AP, Vimal S, Prabhakaran VS, Ganesan R. Bacterial Pathogenesis in Various Fish Diseases: Recent Advances and Specific Challenges in Vaccine Development. Vaccines (Basel) 2023; 11:vaccines11020470. [PMID: 36851346 PMCID: PMC9968037 DOI: 10.3390/vaccines11020470] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 02/08/2023] [Accepted: 02/15/2023] [Indexed: 02/22/2023] Open
Abstract
Aquaculture is a fast-growing food sector but is plagued by a plethora of bacterial pathogens that infect fish. The rearing of fish at high population densities in aquaculture facilities makes them highly susceptible to disease outbreaks, which can cause significant economic loss. Thus, immunity development in fish through vaccination against various pathogens of economically important aquaculture species has been extensively studied and has been largely accepted as a reliable method for preventing infections. Vaccination studies in aquaculture systems are strategically associated with the economically and environmentally sustainable management of aquaculture production worldwide. Historically, most licensed fish vaccines have been developed as inactivated pathogens combined with adjuvants and provided via immersion or injection. In comparison, live vaccines can simulate a whole pathogenic illness and elicit a strong immune response, making them better suited for oral or immersion-based therapy methods to control diseases. Advanced approaches in vaccine development involve targeting specific pathogenic components, including the use of recombinant genes and proteins. Vaccines produced using these techniques, some of which are currently commercially available, appear to elicit and promote higher levels of immunity than conventional fish vaccines. These technological advancements are promising for developing sustainable production processes for commercially important aquatic species. In this review, we explore the multitude of studies on fish bacterial pathogens undertaken in the last decade as well as the recent advances in vaccine development for aquaculture.
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Affiliation(s)
- Aadil Ahmed Irshath
- Department of Biomedical Sciences, School of Bio Sciences and Technology, Vellore Institute of Technology (VIT), Vellore 632 014, Tamil Nadu, India
| | - Anand Prem Rajan
- Department of Biomedical Sciences, School of Bio Sciences and Technology, Vellore Institute of Technology (VIT), Vellore 632 014, Tamil Nadu, India
- Correspondence: (A.P.R.); (R.G.)
| | - Sugumar Vimal
- Department of Biochemistry, Saveetha Medical College & Hospital, Saveetha Institute of Medical and Technical Sciences (SIMATS), Thandalam, Chennai 600 077, Tamilnadu, India
| | - Vasantha-Srinivasan Prabhakaran
- Department of Bioinformatics, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences (SIMATS), Chennai 600 077, Tamilnadu, India
| | - Raja Ganesan
- Institute for Liver and Digestive Diseases, College of Medicine, Hallym University, Chuncheon 24253, Republic of Korea
- Correspondence: (A.P.R.); (R.G.)
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13
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Shahin K, Mukkatira K, Yazdi Z, Richey C, Kwak K, Heckman TI, Mohammed HH, Ortega C, Avendaño-Herrera R, Keleher B, Hyatt MW, Drennan JD, Adkison M, Griffin MJ, Soto E. Development of a quantitative polymerase chain reaction assay for detection of the aetiological agents of piscine lactococcosis. JOURNAL OF FISH DISEASES 2022; 45:847-859. [PMID: 35306674 DOI: 10.1111/jfd.13610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 03/01/2022] [Accepted: 03/04/2022] [Indexed: 06/14/2023]
Abstract
Piscine lactococcosis is an emergent bacterial disease that is associated with high economic losses in many farmed and wild aquatic species worldwide. Early and accurate detection of the causative agent of piscine lactococcosis is essential for management of the disease in fish farms. In this study, a TaqMan quantitative polymerase chain reaction (qPCR) targeting the 16S-23S rRNA internal transcribed spacer region was developed and validated. Validation of the qPCR was performed with DNA of previously typed L. petauri and L. garvieae recovered from different aquatic hosts from distinct geographical locations, closely related bacterial species and common pathogens in trout aquaculture. Further diagnostic sensitivity and specificity was investigated by screening of fish, water and faecal samples. The developed qPCR assay showed high specificity, sensitivity and accuracy in detection of L. petauri and L. garvieae with lack of signals from non-target pathogens, and in screening of rainbow trout (Oncorhynchus mykiss) posterior kidney and environmental samples. The detection limit of the qPCR was four amplicon copies. Moreover, the sensitivity of the qPCR assay was not affected by presence of non-target DNA from either fish or environmental samples. The robustness, specificity and sensitivity of the developed qPCR will facilitate fast and accurate diagnosis of piscine lactococcosis to establish appropriate control measures in fish farms and aquaria.
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Affiliation(s)
- Khalid Shahin
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA
- Aquatic Animal Diseases Laboratory, Aquaculture Department, National Institute of Oceanography and Fisheries, Suez, Egypt
| | | | - Zeinab Yazdi
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Christine Richey
- California Department of Fish and Wildlife, Rancho Cordova, California, USA
| | - Kevin Kwak
- California Department of Fish and Wildlife, Rancho Cordova, California, USA
| | - Taylor I Heckman
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Haitham H Mohammed
- Department of Aquatic Animal Medicine and Management, Faculty of Veterinary Medicine, Assiut University, Assiut, Egypt
| | - Cesar Ortega
- Centro de Investigación y Estudios Avanzados en Salud Animal (CIESA), Facultad de Medicina Veterinaria y Zootecnia (FMVZ), Universidad Autónoma del Estado de México (UAEM), Toluca, Mexico
| | - Ruben Avendaño-Herrera
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Universidad Andrés Bello and Centro FONDAP INCAR, Viña del Mar, Chile
| | - Bill Keleher
- Kennebec River Biosciences, Richmond, Maine, USA
| | - Michael W Hyatt
- Wildlife Conservation Society, New York Aquarium, Brooklyn, New York, USA
| | | | - Mark Adkison
- California Department of Fish and Wildlife, Rancho Cordova, California, USA
| | - Matt J Griffin
- Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Stoneville, Mississippi, USA
| | - Esteban Soto
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California, USA
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14
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Su FJ, Periyasamy T, Chen MM. Comparative Transcriptomic Immune Responses of Mullet (Mugil cephalus) Infected by Planktonic and Biofilm Lactococcus Garvieae. Front Cell Infect Microbiol 2022; 12:887921. [PMID: 35677656 PMCID: PMC9168659 DOI: 10.3389/fcimb.2022.887921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 04/27/2022] [Indexed: 11/13/2022] Open
Abstract
Lactococcus garvieae is an important pathogen of fish, associated with high rates of mortality and infection recurrence in summer or stressful conditions. Chronic infection and disease recurrence have also been reported to be associated with biofilms. However, the impact of biofilm and planktonic bacterial infection on fish immune responses remains unclear. In this study, de novo sequencing was used to compare differences of the spleen transcriptome in planktonic- and biofilm-infected mullets. Among the 181,024 unigenes obtained, 3,392 unigenes were associated with immune response genes. Comparative analysis of the gene expression between infection with the L. garvieae planktonic type and biofilm type identified a total of 3,120 and 3,489 differentially expressed genes in response to planktonic and biofilm infection, respectively, of which 1,366 and 1,458 genes were upregulated, and 1,754 and 1,458 genes were downregulated, respectively. Gene ontology enrichment analysis of immune genes identified genes involved in the complement system, toll-like receptor signaling, and antigen processing, which were further verified by qPCR. Additionally, genes encoding TLR2, IL-1β, TNF-α, C7, and MHC class II peptides were downregulated in response to biofilm infection. Importantly, the results show that biofilm infection induces a different immune pathway response compared with planktonic bacterial infection and, furthermore, illustrates that the prevention of biofilm formation may be a necessary and new strategy for controlling bacterial infection in aquaculture.
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Affiliation(s)
- Feng-Jie Su
- Department of Veterinary Medicine, National Taiwan University, Taipei, Taiwan
| | | | - Meei-Mei Chen
- Department of Veterinary Medicine, National Taiwan University, Taipei, Taiwan
- *Correspondence: Meei-Mei Chen,
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