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Tekedar HC, Patel F, Blom J, Griffin MJ, Waldbieser GC, Kumru S, Abdelhamed H, Dharan V, Hanson LA, Lawrence ML. Tad pili contribute to the virulence and biofilm formation of virulent Aeromonas hydrophila. Front Cell Infect Microbiol 2024; 14:1425624. [PMID: 39145307 PMCID: PMC11322086 DOI: 10.3389/fcimb.2024.1425624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 07/01/2024] [Indexed: 08/16/2024] Open
Abstract
Type IV pili (T4P) are versatile proteinaceous protrusions that mediate diverse bacterial processes, including adhesion, motility, and biofilm formation. Aeromonas hydrophila, a Gram-negative facultative anaerobe, causes disease in a wide range of hosts. Previously, we reported the presence of a unique Type IV class C pilus, known as tight adherence (Tad), in virulent Aeromonas hydrophila (vAh). In the present study, we sought to functionalize the role of Tad pili in the pathogenicity of A. hydrophila ML09-119. Through a comprehensive comparative genomics analysis of 170 A. hydrophila genomes, the conserved presence of the Tad operon in vAh isolates was confirmed, suggesting its potential contribution to pathogenicity. Herein, the entire Tad operon was knocked out from A. hydrophila ML09-119 to elucidate its specific role in A. hydrophila virulence. The absence of the Tad operon did not affect growth kinetics but significantly reduced virulence in catfish fingerlings, highlighting the essential role of the Tad operon during infection. Biofilm formation of A. hydrophila ML09-119 was significantly decreased in the Tad operon deletant. Absence of the Tad operon had no effect on sensitivity to other environmental stressors, including hydrogen peroxide, osmolarity, alkalinity, and temperature; however, it was more sensitive to low pH conditions. Scanning electron microscopy revealed that the Tad mutant had a rougher surface structure during log phase growth than the wildtype strain, indicating the absence of Tad impacts the outer surface of vAh during cell division, of which the biological consequences are unknown. These findings highlight the role of Tad in vAh pathogenesis and biofilm formation, signifying the importance of T4P in bacterial infections.
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Affiliation(s)
- Hasan C. Tekedar
- College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
| | - Fenny Patel
- College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
| | - Jochen Blom
- Bioinformatics & Systems Biology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Matt J. Griffin
- College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
- Thad Cochran National Warmwater Aquaculture Center, Stoneville, MS, United States
| | | | - Salih Kumru
- Faculty of Fisheries, Recep Tayyip Erdogan University, Rize, Türkiye
| | - Hossam Abdelhamed
- College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
| | - Vandana Dharan
- College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
| | - Larry A. Hanson
- College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
| | - Mark L. Lawrence
- College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
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Xu T, Rasmussen-Ivey CR, Moen FS, Fernández-Bravo A, Lamy B, Beaz-Hidalgo R, Khan CD, Castro Escarpulli G, Yasin ISM, Figueras MJ, Azzam-Sayuti M, Karim MM, Alam KMM, Le TTT, Thao NHP, Addo S, Duodu S, Ali S, Latif T, Mey S, Somony T, Liles MR. A Global Survey of Hypervirulent Aeromonas hydrophila (vAh) Identified vAh Strains in the Lower Mekong River Basin and Diverse Opportunistic Pathogens from Farmed Fish and Other Environmental Sources. Microbiol Spectr 2023; 11:e0370522. [PMID: 36815836 PMCID: PMC10101000 DOI: 10.1128/spectrum.03705-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 02/05/2023] [Indexed: 02/24/2023] Open
Abstract
Hypervirulent Aeromonas hydrophila (vAh) has emerged as the etiologic agent of epidemic outbreaks of motile Aeromonas septicemia (MAS) in high-density aquaculture of farmed carp in China and catfish in the United States, which has caused millions of tons of lost fish. We conducted a global survey to better understand the evolution, geographical distribution, and phylogeny of vAh. Aeromonas isolates were isolated from fish that showed clinical symptoms of MAS, and pure cultures were screened for the ability to utilize myo-inositol as the sole carbon source. A total of 113 myo-inositol-utilizing bacterial strains were included in this study, including additional strains obtained from previously published culture collections. Based on a gyrB phylogeny, this collection included 66 A. hydrophila isolates, 48 of which were vAh. This collection also included five new vAh isolates from diseased Pangas catfish (Pangasius pangasius) and striped catfish (Pangasianodon hypophthalmus) obtained in Cambodia and Vietnam, respectively. Genome sequences were generated from representative vAh and non-vAh isolates to evaluate the potential for lateral genetic transfer of the myo-inositol catabolism pathway. Phylogenetic analyses of each of the nine genes required for myo-inositol utilization revealed the close affiliation of vAh strains regardless of geographic origin and suggested lateral genetic transfer of this catabolic pathway from an Enterobacter species. Prediction of virulence factors was conducted to determine differences between vAh and non-vAh strains in terms of virulence and secretion systems. Core genome phylogenetic analyses on vAh isolates and Aeromonas spp. disease isolates (55 in total) were conducted to evaluate the evolutionary relationships among vAh and other Aeromonas sp. isolates, which supported the clonal nature of vAh isolates. IMPORTANCE This global survey of vAh brought together scientists that study fish disease to evaluate the evolution, geographical distribution, phylogeny, and hosts of vAh and other Aeromonas sp. isolates. In addition to vAh isolates from China and the United States, four new vAh isolates were isolated from the lower Mekong River basin in Cambodia and Vietnam, indicating the significant threat of vAh to modern aquaculture and the need for improved biosecurity to prevent vAh spread.
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Affiliation(s)
- Tingbi Xu
- Department of Biological Sciences, Auburn University, Alabama, USA
| | | | | | - Ana Fernández-Bravo
- Unit of Microbiology, Department of Basic Health Sciences, Faculty of Medicine and Health Sciences, IISPV, University Rovira i Virgili, Reus, Spain
| | - Brigitte Lamy
- INSERM U1065, Laboratoire de Bactériologie, CHU Nice, Faculté de Médecine, Université Côte d’Azur, Nice, France
- Centre for Molecular Bacteriology and Infection, Imperial College of London, London, United Kingdom
| | - Roxana Beaz-Hidalgo
- Unit of Microbiology, Department of Basic Health Sciences, Faculty of Medicine and Health Sciences, IISPV, University Rovira i Virgili, Reus, Spain
| | - Chan Dara Khan
- Aquatic Animal Health and Disease Management Office, Department of Aquaculture Development, Fisheries Administration, Ministry of Agriculture Forestry and Fisheries, Phnom Penh, Cambodia
| | - Graciela Castro Escarpulli
- Laboratorio de Investigación Clínica y Ambiental, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad de México, Mexico
| | - Ina Salwany M. Yasin
- Department of Aquaculture, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
| | - Maria J. Figueras
- Unit of Microbiology, Department of Basic Health Sciences, Faculty of Medicine and Health Sciences, IISPV, University Rovira i Virgili, Reus, Spain
| | | | | | | | - Thao Thu Thi Le
- Division of Aquacultural Biotechnology, Biotechnology Center of Ho Chi Minh City, Ho Chi Minh City, Vietnam
| | - Ngo Huynh Phuong Thao
- Division of Aquacultural Biotechnology, Biotechnology Center of Ho Chi Minh City, Ho Chi Minh City, Vietnam
| | - Samuel Addo
- Department of Marine and Fisheries Sciences, University of Ghana, Legon, Ghana
| | - Samuel Duodu
- Department of Biochemistry, Cell, and Molecular Biology, University of Ghana, Legon, Ghana
| | - Shahzad Ali
- Wildlife Epidemiology and Molecular Microbiology Laboratory, Department of Wildlife and Ecology, University of Veterinary and Animal Sciences, Lahore, Pattoki, Pakistan
| | - Tooba Latif
- Wildlife Epidemiology and Molecular Microbiology Laboratory, Department of Wildlife and Ecology, University of Veterinary and Animal Sciences, Lahore, Pattoki, Pakistan
| | - Sothea Mey
- Aquatic Animal Health and Disease Management Office, Department of Aquaculture Development, Fisheries Administration, Ministry of Agriculture Forestry and Fisheries, Phnom Penh, Cambodia
| | - Thay Somony
- Aquatic Animal Health and Disease Management Office, Department of Aquaculture Development, Fisheries Administration, Ministry of Agriculture Forestry and Fisheries, Phnom Penh, Cambodia
| | - Mark R. Liles
- Department of Biological Sciences, Auburn University, Alabama, USA
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Dhanapala PM, Kalupahana RS, Kalupahana AW, Wijesekera D, Kottawatta SA, Jayasekera NK, Silva-Fletcher A, Jagoda SDS. Characterization and Antimicrobial Resistance of Environmental and Clinical Aeromonas Species Isolated from Fresh Water Ornamental Fish and Associated Farming Environment in Sri Lanka. Microorganisms 2021; 9:2106. [PMID: 34683427 PMCID: PMC8537582 DOI: 10.3390/microorganisms9102106] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 09/20/2021] [Indexed: 12/31/2022] Open
Abstract
The aims of this study were to characterize and investigate antimicrobial susceptibility and presence of integrons in 161 Aeromonas spp. isolated from ornamental freshwater fish farming environment, apparently healthy and diseased fish. Phylogenetic analyses of the gyrB gene sequences identified Aeromonas veronii as the most abundant species (75.8%) followed by Aeromonashydrophila (9.3%), Aeromonas caviae (5%), Aeromonas jandaei (4.3%), Aeromonas dhakensis (3.7%), Aeromonas sobria (0.6%), Aeromonas media (0.6%), and Aeromonas popoffii (0.6%). Susceptibility to thirteen antimicrobials was determined and antimicrobial resistance frequencies were: amoxicillin (92.5%), enrofloxacin (67.1%), nalidixic acid (63.4%), erythromycin (26.1%), tetracycline (23.6%), imipenem (18%), trimethoprim-sulfamethoxazole (16.8%), and gentamicin (16.8%). Multi-drug resistance (MDR) was widespread among the isolates (51.6%, 83/161) with 51.6% (63/122) A. veronii isolates being MDR. In addition, 68.3% of isolates had multiple antibiotic resistance (MAR) indexes higher than 0.2, suggesting that they originated from a high-risk source of contamination where antimicrobials are often used. In all, 21.7% isolates carried class 1 integrons, with 97.1% having gene cassettes, while there were 12 isolates carrying class 2 integron gene cassettes. Our findings highlight that the aquatic environment and ornamental fish act as reservoirs of multidrug resistant Aeromonas spp. and underline the need for a judicious use of antimicrobials and timely surveillance of antimicrobial resistance (AMR) in aquaculture.
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Affiliation(s)
- Pavithra M. Dhanapala
- Department of Veterinary Pathobiology, Faculty of Veterinary Medicine and Animal Science, University of Peradeniya, Peradeniya 20400, Sri Lanka; (P.M.D.); (A.W.K.); (D.P.H.W.)
| | - Ruwani S. Kalupahana
- Department of Veterinary Public Health and Pharmacology, Faculty of Veterinary Medicine and Animal Science, University of Peradeniya, Peradeniya 20400, Sri Lanka; (R.S.K.); (S.A.K.)
| | - Anil W. Kalupahana
- Department of Veterinary Pathobiology, Faculty of Veterinary Medicine and Animal Science, University of Peradeniya, Peradeniya 20400, Sri Lanka; (P.M.D.); (A.W.K.); (D.P.H.W.)
| | - D.P.H. Wijesekera
- Department of Veterinary Pathobiology, Faculty of Veterinary Medicine and Animal Science, University of Peradeniya, Peradeniya 20400, Sri Lanka; (P.M.D.); (A.W.K.); (D.P.H.W.)
| | - Sanda A. Kottawatta
- Department of Veterinary Public Health and Pharmacology, Faculty of Veterinary Medicine and Animal Science, University of Peradeniya, Peradeniya 20400, Sri Lanka; (R.S.K.); (S.A.K.)
| | - Niromi K. Jayasekera
- Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine and Animal Science, University of Peradeniya, Peradeniya 20400, Sri Lanka;
| | | | - S.S.S. de S. Jagoda
- Department of Veterinary Pathobiology, Faculty of Veterinary Medicine and Animal Science, University of Peradeniya, Peradeniya 20400, Sri Lanka; (P.M.D.); (A.W.K.); (D.P.H.W.)
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Tekedar HC, Abdelhamed H, Kumru S, Blom J, Karsi A, Lawrence ML. Comparative Genomics of Aeromonas hydrophila Secretion Systems and Mutational Analysis of hcp1 and vgrG1 Genes From T6SS. Front Microbiol 2019; 9:3216. [PMID: 30687246 PMCID: PMC6333679 DOI: 10.3389/fmicb.2018.03216] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 12/11/2018] [Indexed: 12/19/2022] Open
Abstract
Virulent Aeromonas hydrophila causes severe motile Aeromonas septicemia in warmwater fishes. In recent years, channel catfish farming in the U.S.A. and carp farming in China have been affected by virulent A. hydrophila, and genome comparisons revealed that these virulent A. hydrophila strains belong to the same clonal group. Bacterial secretion systems are often important virulence factors; in the current study, we investigated whether secretion systems contribute to the virulent phenotype of these strains. Thus, we conducted comparative secretion system analysis using 55 A. hydrophila genomes, including virulent A. hydrophila strains from U.S.A. and China. Interestingly, tight adherence (TaD) system is consistently encoded in all the vAh strains. The majority of U.S.A. isolates do not possess a complete type VI secretion system, but three core elements [tssD (hcp), tssH, and tssI (vgrG)] are encoded. On the other hand, Chinese isolates have a complete type VI secretion system operon. None of the virulent A. hydrophila isolates have a type III secretion system. Deletion of two genes encoding type VI secretion system proteins (hcp1 and vgrG1) from virulent A. hydrophila isolate ML09-119 reduced virulence 2.24-fold in catfish fingerlings compared to the parent strain ML09-119. By determining the distribution of genes encoding secretion systems in A. hydrophila strains, our study clarifies which systems may contribute to core A. hydrophila functions and which may contribute to more specialized adaptations such as virulence. Our study also clarifies the role of type VI secretion system in A. hydrophila virulence.
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Affiliation(s)
- Hasan C Tekedar
- College of Veterinary Medicine, Mississippi State University, Starkville, MS, United States
| | - Hossam Abdelhamed
- College of Veterinary Medicine, Mississippi State University, Starkville, MS, United States
| | - Salih Kumru
- College of Veterinary Medicine, Mississippi State University, Starkville, MS, United States
| | - Jochen Blom
- Bioinformatics and Systems Biology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Attila Karsi
- College of Veterinary Medicine, Mississippi State University, Starkville, MS, United States
| | - Mark L Lawrence
- College of Veterinary Medicine, Mississippi State University, Starkville, MS, United States
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Awan F, Dong Y, Liu J, Wang N, Mushtaq MH, Lu C, Liu Y. Comparative genome analysis provides deep insights into Aeromonas hydrophila taxonomy and virulence-related factors. BMC Genomics 2018; 19:712. [PMID: 30257645 PMCID: PMC6158803 DOI: 10.1186/s12864-018-5100-4] [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] [Received: 05/21/2018] [Accepted: 09/21/2018] [Indexed: 12/19/2022] Open
Abstract
Background Aeromonas hydrophila is a potential zoonotic pathogen and primary fish pathogen. With overlapping characteristics, multiple isolates are often mislabelled and misclassified. Moreover, the potential pathogenic factors among the publicly available genomes in A. hydrophila strains of different origins have not yet been investigated. Results To identify the valid strains of A. hydrophila and their pathogenic factors, we performed a pan-genomic study. It revealed that there were 13 mislabelled strains and 49 valid strains that were further verified by Average nucleotide identity (ANI), digital DNA-DNA hybridization (dDDH) and in silico multiple locus strain typing (MLST). Multiple numbers of phages were detected among the strains and among them Aeromonas phi 018 was frequently present. The diversity in type III secretion system (T3SS) and conservation of type II and type VI secretion systems (T2SS and T6SS, respectively) among all the strains are important to study for designing future strategies. The most prevalent antibiotic resistances were found to be beta-lactamase, polymyxin and colistin resistances. The comparative analyses of sequence type (ST) 251 and other ST groups revealed that there were higher numbers of virulence factors in ST-251 than in other STs group. Conclusion Publicly available genomes have 13 mislabelled organisms, and there are only 49 valid A. hydrophila strains. This valid pan-genome identifies multiple prophages that can be further utilized. Different A. hydrophila strains harbour multiple virulence factors and antibiotic resistance genes. Identification of such factors is important for designing future treatment regimes. Electronic supplementary material The online version of this article (10.1186/s12864-018-5100-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Furqan Awan
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Yuhao Dong
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Jin Liu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Nannan Wang
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Muhammad Hassan Mushtaq
- Department of Epidemiology and Public Health, University of Veterinary and Animal Sciences, Lahore, Pakistan
| | - Chengping Lu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Yongjie Liu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
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Dang Y, Meng X, Wang S, Li L, Zhang M, Hu M, Xu X, Shen Y, Lv L, Wang R, Li J. Mannose-binding lectin and its roles in immune responses in grass carp (Ctenopharyngodon idella) against Aeromonas hydrophila. FISH & SHELLFISH IMMUNOLOGY 2018; 72:367-376. [PMID: 29129586 DOI: 10.1016/j.fsi.2017.11.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 11/06/2017] [Accepted: 11/07/2017] [Indexed: 06/07/2023]
Abstract
The complement system is a crucial component of the innate immune system that links innate and adaptive immunity via four pathways. Mannose-binding lectin (MBL), the initiating molecule of the lectin pathway, plays a significant role in the innate immune system in mammals and fish. Herein, we identified an MBL homolog (gcMBL) in grass carp (Ctenopharyngodon idella). The full-length 948 bp gcMBL cDNA includes a 741 bp open reading frame encoding a 246 amino acid protein with a signal peptide, collagen triple helix repeat domain, and a C-type lectin-like/link domain. The gcMBL protein shares low similarity with MBL counterparts in other species, and is most closely related to Cyprinus carpio MBL. Transcription of gcMBL was widely distributed in different tissues, and was induced by Aeromonas hydrophila in vivo and in vitro. Expression of gcMBL was also affected by LPS and flagellin stimulation in vitro. In cells over-expressing gcMBL, transcripts of almost all components except gcC5 were up-regulated, and gcMBL, gcIL1β, gcTNF-α, gcIFN, gcCD59, gcC5aR and gcITGβ-2 were significantly up-regulated following exposure to A. hydrophila or stimulation by bacterial PAMPs. Meanwhile, gcMBL deficiency achieved by RNAi down-regulated transcript levels following A. hydrophila challenge, and gcMBL induced NF-κB signalling. These findings indicate a vital role of gcMBL in innate immunity in grass carp.
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Affiliation(s)
- Yunfei Dang
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Shanghai, PR China; Laboratory of Biochemistry and Molecular Biology, Ningbo University, Ningbo, PR China
| | - Xinzhan Meng
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Shanghai, PR China
| | - Shentong Wang
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Shanghai, PR China
| | - Lisen Li
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Shanghai, PR China
| | - Meng Zhang
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Shanghai, PR China
| | - Moyan Hu
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Shanghai, PR China
| | - Xiaoyan Xu
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Shanghai, PR China; Shanghai Engineering Research Centre of Aquaculture, Shanghai Ocean University, Shanghai, PR China; National Demonstration Centre for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, PR China
| | - Yubang Shen
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Shanghai, PR China; Shanghai Engineering Research Centre of Aquaculture, Shanghai Ocean University, Shanghai, PR China; National Demonstration Centre for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, PR China
| | - Liqun Lv
- National Demonstration Centre for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, PR China
| | - Rongquan Wang
- Key Laboratory of Conventional Freshwater Fish Breeding and Health Culture Technology Germplasm Resources, Suzhou Shenhang Eco-technology Development Limited Company, Suzhou, PR China
| | - Jiale Li
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Shanghai, PR China; Shanghai Engineering Research Centre of Aquaculture, Shanghai Ocean University, Shanghai, PR China; National Demonstration Centre for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, PR China.
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Rasmussen-Ivey CR, Hossain MJ, Odom SE, Terhune JS, Hemstreet WG, Shoemaker CA, Zhang D, Xu DH, Griffin MJ, Liu YJ, Figueras MJ, Santos SR, Newton JC, Liles MR. Classification of a Hypervirulent Aeromonas hydrophila Pathotype Responsible for Epidemic Outbreaks in Warm-Water Fishes. Front Microbiol 2016; 7:1615. [PMID: 27803692 PMCID: PMC5067525 DOI: 10.3389/fmicb.2016.01615] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 09/27/2016] [Indexed: 11/24/2022] Open
Abstract
Lineages of hypervirulent Aeromonas hydrophila (vAh) are the cause of persistent outbreaks of motile Aeromonas septicemia in warm-water fishes worldwide. Over the last decade, this virulent lineage of A. hydrophila has resulted in annual losses of millions of tons of farmed carp and catfish in the People's Republic of China and the United States (US). Multiple lines of evidence indicate US catfish and Asian carp isolates of A. hydrophila affiliated with sequence type 251 (ST251) share a recent common ancestor. To address the genomic context for the putative intercontinental transfer and subsequent geographic spread of this pathogen, we conducted a core genome phylogenetic analysis on 61 Aeromonas spp. genomes, of which 40 were affiliated with A. hydrophila, with 26 identified as epidemic strains. Phylogenetic analyses indicate all ST251 strains form a coherent lineage affiliated with A. hydrophila. Within this lineage, conserved genetic loci unique to A. hydrophila were identified, with some genes present in consistently higher copy numbers than in non-epidemic A. hydrophila isolates. In addition, results from analyses of representative ST251 isolates support the conclusion that multiple lineages are present within US vAh isolated from Mississippi, whereas vAh isolated from Alabama appear clonal. This is the first report of genomic heterogeneity within US vAh isolates, with some Mississippi isolates showing closer affiliation with the Asian grass carp isolate ZC1 than other vAh isolated in the US. To evaluate the biological significance of the identified heterogeneity, comparative disease challenges were conducted with representatives of different vAh genotypes. These studies revealed that isolate ZC1 yielded significantly lower mortality in channel catfish, relative to Alabama and Mississippi vAh isolates. Like other Asian vAh isolates, the ZC1 lineage contains all core genes for a complete type VI secretion system (T6SS). In contrast, more virulent US isolates retain only remnants of the T6SS (clpB, hcp, vgrG, and vasH) which may have functional implications. Collectively, these results characterize a hypervirulent A. hydrophila pathotype that affects farmed fish on multiple continents.
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Affiliation(s)
| | | | - Sara E Odom
- Department of Biological Sciences, Auburn University Auburn, AL, USA
| | - Jeffery S Terhune
- School of Fisheries, Aquaculture and Aquatic Sciences Auburn, AL, USA
| | | | - Craig A Shoemaker
- Aquatic Animal Health Research Unit, United States Department of Agriculture-Agricultural Research Service Auburn, AL, USA
| | - Dunhua Zhang
- Aquatic Animal Health Research Unit, United States Department of Agriculture-Agricultural Research Service Auburn, AL, USA
| | - De-Hai Xu
- Aquatic Animal Health Research Unit, United States Department of Agriculture-Agricultural Research Service Auburn, AL, USA
| | - Matt J Griffin
- Thad Cochran National Warmwater Aquaculture Center, College of Veterinary Medicine, Mississippi State University Stoneville, MS, USA
| | - Yong-Jie Liu
- College of Veterinary Medicine, Nanjing Agricultural University Nanjing, China
| | - Maria J Figueras
- Departamento de Ciencias Médicas Básicas, Facultad de Medicina y Ciencias de la Salud, IISPV, Universidad Rovira i Virgili Reus, Spain
| | - Scott R Santos
- Department of Biological Sciences, Auburn University Auburn, AL, USA
| | - Joseph C Newton
- Department of Pathobiology, Auburn University Auburn, AL, USA
| | - Mark R Liles
- Department of Biological Sciences, Auburn University Auburn, AL, USA
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Abstract
We report here the draft genome sequence of Aeromonas sp. strain EERV15 isolated from sand filter. The organism most closely related to Aeromonas sp. EERV15 is Aeromonas veronii B565, with an average 83% amino acid sequence similarity of putatively encoded protein open reading frames.
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Vincent AT, Boyle B, Derome N, Charette SJ. Improvement in the DNA sequencing of genomes bearing long repeated elements. J Microbiol Methods 2014; 107:186-8. [DOI: 10.1016/j.mimet.2014.10.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Revised: 10/29/2014] [Accepted: 10/29/2014] [Indexed: 01/08/2023]
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