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Akgul A, Kalindamar S, Kordon AO, Abdelhamed H, Ibrahim I, Tekedar HC, Karsi A. The RNA chaperone Hfq has a multifaceted role in Edwardsiella ictaluri. Front Cell Infect Microbiol 2024; 14:1394008. [PMID: 39099884 PMCID: PMC11294321 DOI: 10.3389/fcimb.2024.1394008] [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: 02/29/2024] [Accepted: 07/01/2024] [Indexed: 08/06/2024] Open
Abstract
Edwardsiella ictaluri is a Gram-negative, facultative intracellular bacterium that causes enteric septicemia in catfish (ESC). The RNA chaperone Hfq (host factor for phage Qβ replication) facilitates gene regulation via small RNAs (sRNAs) in various pathogenic bacteria. Despite its significance in other bacterial species, the role of hfq in E. ictaluri remains unexplored. This study aimed to elucidate the role of hfq in E. ictaluri by creating an hfq mutant (EiΔhfq) through in-frame gene deletion and characterization. Our findings revealed that the Hfq protein is highly conserved within the genus Edwardsiella. The deletion of hfq resulted in a significantly reduced growth rate during the late exponential phase. Additionally, EiΔhfq displayed a diminished capacity for biofilm formation and exhibited increased motility. Under acidic and oxidative stress conditions, EiΔhfq demonstrated impaired growth, and we observed elevated hfq expression when subjected to in vitro and in vivo stress conditions. EiΔhfq exhibited reduced survival within catfish peritoneal macrophages, although it had no discernible effect on the adherence and invasion of epithelial cells. The infection model revealed that hfq is needed for bacterial persistence in catfish, and its absence caused significant virulence attenuation in catfish. Finally, the EiΔhfq vaccination completely protected catfish against subsequent EiWT infection. In summary, these results underscore the pivotal role of hfq in E. ictaluri, affecting its growth, motility, biofilm formation, stress response, and virulence in macrophages and within catfish host.
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Affiliation(s)
| | | | | | | | | | | | - Attila Karsi
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
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Pinto N, Nissa MU, Yashwanth BS, Sathiyanarayanan A, Pai MGJ, Srivastava S, Goswami M. Proteomics analysis of differentially abundant proteins in the rohu kidney infected with Edwardsiella tarda. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART D, GENOMICS & PROTEOMICS 2024; 50:101221. [PMID: 38430708 DOI: 10.1016/j.cbd.2024.101221] [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: 11/22/2023] [Revised: 02/23/2024] [Accepted: 02/23/2024] [Indexed: 03/05/2024]
Abstract
Edwardsiella tarda (Et) is a zoonotic gram-negative pathogen with a diverse host range, including fish. However, the in-depth molecular mechanisms underlying the response of Labeo rohita (rohu) kidney to Et are poorly understood. A proteomic and histopathological analysis was performed for the rohu kidney after Et infection. The histopathology of the infected rohu kidney showed vacuolation and necrosis. After LC-MS/MS analysis, ~1240 proteins were identified with ≥2 unique peptides. A total of 96 differentially abundant proteins (DAPs) were observed between the control and Et infected group (ET). Metascape and STRING analysis were used for the gene ontology (GO), and protein-protein interaction network (PPI) for the significant pathways of DAPs. In PPI, low-abundant proteins were mapped to metabolic pathways and oxidative phosphorylation (cox5ab, uqcrfs1). High-abundance proteins were mapped to ribosomes (rplp2), protein process in the ER (hspa8), and immune system (ptgdsb.1, muc2). Our label-free proteomic approach in the rohu kidney revealed abundant enriched proteins involved in vesicle coat (ehd4), complement activation (c3a.1, c9, c7a), phagosome (thbs4, mapk1), metabolic reprogramming (hao1, glud1a), wound healing (vim, alox5), and the immune system (psap) after Et infection. A targeted proteomics approach of multiple reaction monitoring (MRM) validated the DAPs (nprl3, ambp, vmo1a, hspg2, muc2, hao1 and glud1a) between control and ET. Overall, the current analysis of histology and proteome in the rohu kidney provides comprehensive data on pathogenicity and the potential immune proteins against Et.
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Affiliation(s)
- Nevil Pinto
- Indian Council of Agricultural Research - Central Institute of Fisheries Education, Versova, Mumbai, Maharashtra 400061, India. https://twitter.com/pintonevil8
| | - Mehar Un Nissa
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - B S Yashwanth
- Indian Council of Agricultural Research - Central Institute of Fisheries Education, Versova, Mumbai, Maharashtra 400061, India
| | - A Sathiyanarayanan
- Indian Council of Agricultural Research - Central Institute of Fisheries Education, Versova, Mumbai, Maharashtra 400061, India
| | - Medha Gayathri J Pai
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Sanjeeva Srivastava
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India. https://twitter.com/Sanjeeva_IITB
| | - Mukunda Goswami
- Indian Council of Agricultural Research - Central Institute of Fisheries Education, Versova, Mumbai, Maharashtra 400061, India.
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Kalindamar S, Abdelhamed H, Kordon AO, Tekedar HC, Pinchuk L, Karsi A. Characterization of Type VI secretion system in Edwardsiella ictaluri. PLoS One 2023; 18:e0296132. [PMID: 38153949 PMCID: PMC10754466 DOI: 10.1371/journal.pone.0296132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 12/06/2023] [Indexed: 12/30/2023] Open
Abstract
Edwardsiella ictaluri is a Gram-negative facultative intracellular fish pathogen causing enteric septicemia of catfish (ESC). While various secretion systems contribute to E. ictaluri virulence, the Type VI secretion system (T6SS) remains poorly understood. In this study, we constructed 13 E. ictaluri T6SS mutants using splicing by overlap extension PCR and characterized them, assessing their uptake and survival in channel catfish (Ictalurus punctatus) peritoneal macrophages, attachment and invasion in channel catfish ovary (CCO) cells, in vitro stress resistance, and virulence and efficacy in channel catfish. Among the mutants, EiΔevpA, EiΔevpH, EiΔevpM, EiΔevpN, and EiΔevpO exhibited reduced replication inside peritoneal macrophages. EiΔevpM, EiΔevpN, and EiΔevpO showed significantly decreased attachment to CCO cells, while EiΔevpN and EiΔevpO also displayed reduced invasion of CCO cells (p < 0.05). Overall, T6SS mutants demonstrated enhanced resistance to oxidative and nitrosative stress in the nutrient-rich medium compared to the minimal medium. However, EiΔevpA, EiΔevpH, EiΔevpM, EiΔevpN, and EiΔevpO were susceptible to oxidative stress in both nutrient-rich and minimal medium. In fish challenges, EiΔevpD, EiΔevpE, EiΔevpG, EiΔevpJ, and EiΔevpK exhibited attenuation and provided effective protection against E. ictaluri wild-type (EiWT) infection in catfish fingerlings. However, their attenuation and protective efficacy were lower in catfish fry. These findings shed light on the role of the T6SS in E. ictaluri pathogenesis, highlighting its significance in intracellular survival, host cell attachment and invasion, stress resistance, and virulence. The attenuated T6SS mutants hold promise as potential candidates for protective immunization strategies in catfish fingerlings.
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Affiliation(s)
- Safak Kalindamar
- Department of Molecular Biology and Genetics, Faculty of Arts and Sciences, Ordu University, Ordu, Türkiye
| | - Hossam Abdelhamed
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States of America
| | - Adef O. Kordon
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States of America
| | - Hasan C. Tekedar
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States of America
| | - Lesya Pinchuk
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States of America
| | - Attila Karsi
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States of America
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Dubytska LP, Koirala R, Sanchez A, Thune R. Edwardsiella ictaluri T3SS Effector EseN Modulates Expression of Host Genes Involved in the Immune Response. Microorganisms 2022; 10:microorganisms10071334. [PMID: 35889053 PMCID: PMC9323599 DOI: 10.3390/microorganisms10071334] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 06/28/2022] [Accepted: 06/29/2022] [Indexed: 12/10/2022] Open
Abstract
The type III secretion system (T3SS) effector EseN is encoded on the Edwardsiella ictaluri chromosome and is homologous to a family of T3SS effector proteins with phosphothreonine lyase activity. Previously we demonstrated that E. ictaluri invasion activates extracellular signal-regulated kinases 1 and 2 (ERK1/2) early in the infection, which are subsequently inactivated by EseN. Comparative transcriptomic analysis showed a total of 753 significant differentially expressed genes in head-kidney-derived macrophages (HKDM) infected with an EseN mutant (∆EseN) compared to HKDM infected with wild-type (WT) strains. This data strongly indicates classical activation of macrophages (the M1 phenotype) in response to E. ictaluri infection and a significant role for EseN in the manipulation of this process. Our data also indicates that E. ictaluri EseN is involved in the modulation of pathways involved in the immune response to infection and expression of several transcription factors, including NF-κβ (c-rel and relB), creb3L4, socs6 and foxo3a. Regulation of transcription factors leads to regulation of proinflammatory interleukins (IL-8, IL-12a, IL-15, IL-6) and cyclooxygenase-2 (COX-2) expression. Inhibition of COX-2 mRNA by WT E. ictaluri leads to decreased production of prostaglandin E2 (PGE2), which is the product of COX-2 activity. Collectively, our results indicate that E. ictaluri EseN is an important player in the modulation of host immune responses to E.ictaluri infection.
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Affiliation(s)
- Lidiya P. Dubytska
- Department of Biology and Chemistry, Southern University and A & M College, Baton Rouge, LA 70813, USA; (R.K.); (A.S.)
- Correspondence: ; Tel.: +1-225-771-33743
| | - Ranjan Koirala
- Department of Biology and Chemistry, Southern University and A & M College, Baton Rouge, LA 70813, USA; (R.K.); (A.S.)
| | - Azhia Sanchez
- Department of Biology and Chemistry, Southern University and A & M College, Baton Rouge, LA 70813, USA; (R.K.); (A.S.)
| | - Ronald Thune
- Department of Pathobiological Sciences, Louisiana State University School of Veterinary Medicine, Baton Rouge, LA 70803, USA;
- School of Animal Science, Louisiana State University Agricultural Experiment Station, Baton Rouge, LA 70803, USA
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Nguyen TT, Xuan TTT, Ngoc TH, Duyen LTM, Vinh TQ, My PDT, Hoang HA, Nga LP. Diverse Bacteriophages Infecting the Bacterial Striped Catfish Pathogen Edwardsiella ictaluri. Microorganisms 2021; 9:microorganisms9091830. [PMID: 34576725 PMCID: PMC8465730 DOI: 10.3390/microorganisms9091830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Revised: 08/17/2021] [Accepted: 08/25/2021] [Indexed: 11/16/2022] Open
Abstract
Bacteriophages infecting Edwardsiella ictaluri have been less investigated, although the host bacterium is one of the most important fish pathogens causing enteric septicemia of catfish (ESC). We present here two distinctly novel bacteriophages vB_EiM_PVN06 and vB_EiA_PVN09 infecting Edwardsiella ictaluri E1, with their geographical origins from the Mekong Delta, Vietnam. Bacteriophage vB_EiM_PVN06 native to a mud sample reveals complete differences of biological properties with the phage vB_EiA_PVN09 originated from a viscus of a healthy catfish (Pangasianodon hypophthalmus) cultured in the same area. Morphological analyses combined with genomic data indicate that phage vB_EiM_PVN06 is classified to Myoviridae family and shares high similarity with E. ictaluri phage PEi21 genome, while vB_EiA_PVN09 is a member of Teseptimavirus genus, Autographiviridae family, and mostly closes to phage vB_EcoP_IME390. The vB_EiA_PVN09 is a T7-like bacteriophage, which has been firstly found infecting to E. ictaluri, and host range analysis also evidences for the cross-infection of this phage to Escherichia coli K12 and Escherichia coli DH5α. Together, our research highlights the diversity of bacteriophages infecting the pathogen E. ictaluri and suggests further explorations of lytic phages in environmental niches, to be exploited in feasible strategies of phage therapy in ESC disease control.
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Affiliation(s)
- Tan-Trung Nguyen
- Faculty of Chemical Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet, District 10, Ho Chi Minh City 700000, Vietnam; (T.-T.N.); (T.T.T.X.); (T.H.N.); (L.T.M.D.); (T.Q.V.); (P.D.T.M.); (H.A.H.)
- Vietnam National University Ho Chi Minh City, Linh Trung Ward, Thu Duc District, Ho Chi Minh City 700000, Vietnam
| | - Tran T. T. Xuan
- Faculty of Chemical Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet, District 10, Ho Chi Minh City 700000, Vietnam; (T.-T.N.); (T.T.T.X.); (T.H.N.); (L.T.M.D.); (T.Q.V.); (P.D.T.M.); (H.A.H.)
- Vietnam National University Ho Chi Minh City, Linh Trung Ward, Thu Duc District, Ho Chi Minh City 700000, Vietnam
| | - To H. Ngoc
- Faculty of Chemical Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet, District 10, Ho Chi Minh City 700000, Vietnam; (T.-T.N.); (T.T.T.X.); (T.H.N.); (L.T.M.D.); (T.Q.V.); (P.D.T.M.); (H.A.H.)
- Vietnam National University Ho Chi Minh City, Linh Trung Ward, Thu Duc District, Ho Chi Minh City 700000, Vietnam
| | - Le T. My Duyen
- Faculty of Chemical Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet, District 10, Ho Chi Minh City 700000, Vietnam; (T.-T.N.); (T.T.T.X.); (T.H.N.); (L.T.M.D.); (T.Q.V.); (P.D.T.M.); (H.A.H.)
- Vietnam National University Ho Chi Minh City, Linh Trung Ward, Thu Duc District, Ho Chi Minh City 700000, Vietnam
| | - Tu Q. Vinh
- Faculty of Chemical Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet, District 10, Ho Chi Minh City 700000, Vietnam; (T.-T.N.); (T.T.T.X.); (T.H.N.); (L.T.M.D.); (T.Q.V.); (P.D.T.M.); (H.A.H.)
- Vietnam National University Ho Chi Minh City, Linh Trung Ward, Thu Duc District, Ho Chi Minh City 700000, Vietnam
| | - Pham D. T. My
- Faculty of Chemical Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet, District 10, Ho Chi Minh City 700000, Vietnam; (T.-T.N.); (T.T.T.X.); (T.H.N.); (L.T.M.D.); (T.Q.V.); (P.D.T.M.); (H.A.H.)
- Vietnam National University Ho Chi Minh City, Linh Trung Ward, Thu Duc District, Ho Chi Minh City 700000, Vietnam
| | - Hoang A. Hoang
- Faculty of Chemical Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet, District 10, Ho Chi Minh City 700000, Vietnam; (T.-T.N.); (T.T.T.X.); (T.H.N.); (L.T.M.D.); (T.Q.V.); (P.D.T.M.); (H.A.H.)
- Vietnam National University Ho Chi Minh City, Linh Trung Ward, Thu Duc District, Ho Chi Minh City 700000, Vietnam
| | - Le P. Nga
- Faculty of Chemical Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet, District 10, Ho Chi Minh City 700000, Vietnam; (T.-T.N.); (T.T.T.X.); (T.H.N.); (L.T.M.D.); (T.Q.V.); (P.D.T.M.); (H.A.H.)
- Vietnam National University Ho Chi Minh City, Linh Trung Ward, Thu Duc District, Ho Chi Minh City 700000, Vietnam
- Correspondence: ; Tel.: +84-902-966166
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Kalindamar S, Abdelhamed H, Kordon AO, Pinchuk LM, Karsi A. Hemolysin Co-regulated Family Proteins Hcp1 and Hcp2 Contribute to Edwardsiella ictaluri Pathogenesis. Front Vet Sci 2021; 8:681609. [PMID: 34150898 PMCID: PMC8207204 DOI: 10.3389/fvets.2021.681609] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 05/07/2021] [Indexed: 01/22/2023] Open
Abstract
Edwardsiella ictaluri is a Gram-negative facultative intracellular pathogen causing enteric septicemia of catfish (ESC), a devastating disease resulting in significant economic losses in the U.S. catfish industry. Bacterial secretion systems are involved in many bacteria's virulence, and Type VI Secretion System (T6SS) is a critical apparatus utilized by several pathogenic Gram-negative bacteria. E. ictaluri strain 93-146 genome has a complete T6SS operon with 16 genes, but the roles of these genes are still not explored. In this research, we aimed to understand the roles of two hemolysin co-regulated family proteins, Hcp1 (EvpC) and Hcp2. To achieve this goal, single and double E. ictaluri mutants (EiΔevpC, EiΔhcp2, and EiΔevpCΔhcp2) were generated and characterized. Catfish peritoneal macrophages were able to kill EiΔhcp2 better than EiΔevpC, EiΔevpCΔhcp2, and E. ictaluri wild-type (EiWT). The attachment of EiΔhcp2 and EiΔevpCΔhcp2 to ovary cells significantly decreased compared to EiWT whereas the cell invasion rates of these mutants were the same as that of EiWT. Mutants exposed to normal catfish serum in vitro showed serum resistance. The fish challenges demonstrated that EiΔevpC and EiΔevpCΔhcp2 were attenuated completely and provided excellent protection against EiWT infection in catfish fingerlings. Interestingly, EiΔhcp2 caused higher mortality than that of EiWT in catfish fingerlings, and severe clinical signs were observed. Although fry were more susceptible to vaccination with EiΔevpC and EiΔevpCΔhcp2, their attenuation and protection were significantly higher compared to EiWT and sham groups, respectively. Taken together, our data indicated that evpC (hcp1) is involved in E. ictaluri virulence in catfish while hcp2 is involved in adhesion to epithelial cells and survival inside catfish macrophages.
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Affiliation(s)
- Safak Kalindamar
- Department of Molecular Biology and Genetics, Faculty of Arts and Sciences, Ordu University, Ordu, Turkey
| | - Hossam Abdelhamed
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
| | - Adef O Kordon
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
| | - Lesya M Pinchuk
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
| | - Attila Karsi
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
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Early Intracellular Trafficking and Subsequent Activity of Programmed Cell Death in Channel Catfish Macrophages Infected with Edwardsiella ictaluri. Microorganisms 2020; 8:microorganisms8111649. [PMID: 33114369 PMCID: PMC7690889 DOI: 10.3390/microorganisms8111649] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 10/16/2020] [Accepted: 10/16/2020] [Indexed: 01/07/2023] Open
Abstract
The development of Edwardsiella-containing-vacuoles (ECV) and the ability of Edwardsiella ictaluri to survive and replicate within macrophages suggests a unique process relative to normal phagosomal/lysosomal maturation and programed cell death. Developing ECV showed that endosomal membrane markers Rab5, EEA1, and Rab7 were all detected in both the wild type (WT) and an E. ictaluri type-3 secretion system (T3SS) mutant, 65ST. Co-localization with Lamp1, however, was significantly lower in the WT. The host cell endoplasmic reticulum marker, calnexin, co-localized to 65ST ECV significantly more than WT ECV, while Golgi vesicle marker, giantin, was recruited to WT ECV significantly more than 65ST. The autophagosomal marker LC3 was significantly lower in WT than in 65ST and Western blotting demonstrated significantly greater induction of the membrane localized, lipidated form, LC3-II, in 65ST ECV than in WT ECV. Activity of the apoptosis initiator caspase-8 increased post-infection in 65ST and was significantly lower in WT-infected cells. Executioner caspase-3/7 activity also increased significantly in 65ST-infected cells compared to WT-infected cells. Repression of apoptosis was further demonstrated with flow cytometry using Alexa Fluor 647-labeled Annexin V and propidium iodide. Results indicate that WT ECV fused with early and late endosomes but that phagosomal/lysosomal fusion did not occur. Additionally, WT-infected cells recruited Golgi vesicles for vacuolar size increase and bacterial growth material, and both autophagy and apoptosis were repressed in the WT. This activity was all based on the function of the E. ictaluri T3SS.
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Tekedar HC, Blom J, Kalindamar S, Nho S, Karsi A, Lawrence ML. Comparative genomics of the fish pathogens Edwardsiella ictaluri 93-146 and Edwardsiella piscicida C07-087. Microb Genom 2020; 6. [PMID: 32108566 PMCID: PMC7067208 DOI: 10.1099/mgen.0.000322] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Edwardsiella ictaluri and Edwardsiella piscicida are important fish pathogens affecting cultured and wild fish worldwide. To investigate the genome-level differences and similarities between catfish-adapted strains in these two species, the complete E. ictaluri 93-146 and E. piscicida C07-087 genomes were evaluated by applying comparative genomics analysis. All available complete (10) and non-complete (19) genomes from five Edwardsiella species were also included in a systematic analysis. Average nucleotide identity and core-genome phylogenetic tree analyses indicated that the five Edwardsiella species were separated from each other. Pan-/core-genome analyses for the 29 strains from the five species showed that genus Edwardsiella members have 9474 genes in their pan genome, while the core genome consists of 1421 genes. Orthology cluster analysis showed that E. ictaluri and E. piscicida genomes have the greatest number of shared clusters. However, E. ictaluri and E. piscicida also have unique features; for example, the E. ictaluri genome encodes urease enzymes and cytochrome o ubiquinol oxidase subunits, whereas E. piscicida genomes encode tetrathionate reductase operons, capsular polysaccharide synthesis enzymes and vibrioferrin-related genes. Additionally, we report for what is believed to be the first time that E. ictaluri 93-146 and three other E. ictaluri genomes encode a type IV secretion system (T4SS), whereas none of the E. piscicida genomes encode this system. Additionally, the E. piscicida C07-087 genome encodes two different type VI secretion systems. E. ictaluri genomes tend to encode more insertion elements, phage regions and genomic islands than E. piscicida. We speculate that the T4SS could contribute to the increased number of mobilome elements in E. ictaluri compared to E. piscicida. Two of the E. piscicida genomes encode full CRISPR-Cas regions, whereas none of the E. ictaluri genomes encode Cas proteins. Overall, comparison of the E. ictaluri and E. piscicida genomes reveals unique features and provides new insights on pathogenicity that may reflect the host adaptation of the two species.
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Affiliation(s)
- Hasan C Tekedar
- College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, USA
| | - Jochen Blom
- Bioinformatics and Systems Biology, Justus-Liebig-University Giessen, 35392 Giessen, Hesse, Germany
| | - Safak Kalindamar
- College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, USA
| | - Seongwon Nho
- Division of Microbiology, National Center for Toxicological Research/FDA, Jefferson, AR, USA
| | - Attila Karsi
- College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, USA
| | - Mark L Lawrence
- College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, USA
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Wang H, Xu L, Wu Z, Chen X. CCR7, CD80/86 and CD83 in yellow catfish (Pelteobagrus fulvidraco): Molecular characteristics and expression patterns with bacterial infection. FISH & SHELLFISH IMMUNOLOGY 2020; 102:228-242. [PMID: 32325216 DOI: 10.1016/j.fsi.2020.04.026] [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: 10/26/2019] [Revised: 03/25/2020] [Accepted: 04/13/2020] [Indexed: 06/11/2023]
Abstract
Dendritic cells (DCs) have a strong ability to stimulate naive T lymphocyte proliferation, so DCs play an important regulatory role in the initiation of the specific immune response. DCs cannot play the role of antigen presentation without the expression of surface molecules. The chemokine receptor CCR7 and the costimulatory molecules CD80/86 and CD83 are not only markers of DC maturation but also important functional molecules in the immune response of DC-T cells. In this study, partial cDNA sequences of CCR7, CD80/86 and CD83 were obtained by rapid amplification of cDNA ends (RACE) technology from yellow catfish. Bioinformatics analysis of deduced amino acid sequences of these three genes showed that CCR7, CD80/86 and CD83 genes in yellow catfish have similar functional domains to the homologs in other vertebrates, which indicated that the functions of these genes may be somewhat conserved during the evolution process. Afterward, the expression characteristics of these three genes in different tissues were detected by q-PCR. This result indicated that CCR7, CD80/86 and CD83 were expressed in all examined tissues, and the highest expression levels of CCR7 and CD80/86 and CD83 were detected in the trunk kidney, muscle and midgut, respectively. Meanwhile, the expression levels of CCR7 and CD80/86 were lowest in the gill, and the expression of CD83 was lowest in the stomach. Finally, healthy yellow catfish were infected with A.hydrophila (1.0 × 107 CFU/mL) or E.ictaluri (1.0 × 106 CFU/mL), q-PCR results indicated that both pathogenic bacteria can induce significant upregulation of CCR7, CD80/86 and CD83 in immune organs, and the expression levels of these genes in the intestine were higher than those in the skin and gill. Our results in this study provide a molecular basis for exploring the role of CCR7, CD80/86 and CD83 in the immune responses induced by bacteria, and can help us to understand the difference of immune responses induced by extracellular and intracellular bacteria.
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Affiliation(s)
- Hui Wang
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China; Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, 430070, China
| | - Lili Xu
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China; Hubei Provincial Engineering Laboratory for Pond Aquaculture, Wuhan, 430070, China
| | - Zhixin Wu
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China; Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, 430070, China
| | - Xiaoxuan Chen
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China; Hubei Provincial Engineering Laboratory for Pond Aquaculture, Wuhan, 430070, China.
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Blackmon LE, Quiniou SMA, Wilson M, Bengtén E. Catfish lymphocytes expressing CC41-reactive leukocyte immune-type receptors (LITRs) proliferate in response to Edwardsiella ictaluri infection in vitro. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2020; 106:103610. [PMID: 31926174 DOI: 10.1016/j.dci.2020.103610] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 12/28/2019] [Accepted: 01/07/2020] [Indexed: 06/10/2023]
Abstract
Monoclonal antibodies (mAbs) CC34 and CC41 recognize overlapping subsets of leukocyte immune-type receptors (LITRs). The mAb CC34 was raised against the clonal TS32.15 cytotoxic T cell line and the mAb CC41 was raised against the clonal NK cell line TS10.1. In this study, an in vitro model was developed to monitor CC34- and CC41-reactive cells in response to Edwardsiella ictaluri infection. Briefly, head kidney leukocytes and peripheral blood lymphocytes (PBL) were isolated from individual catfish and labeled with CellTrace Violet and CellTrace FarRed dye, respectively. Head kidney-derived macrophages were infected with E. ictaluri and then cocultured with autologous PBL. The combined cell cultures were then analyzed using flow cytometry. A significant increase in CC41 staining was observed in the PBL population at 2, 5 and 7 days after culture, which suggest that LITRs are involved in cell-mediated immunity to E. ictaluri.
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Affiliation(s)
- Laura E Blackmon
- Department of Microbiology and Immunology, University of Mississippi Medical Center, 2500 North State St, Jackson, MS, 39216, USA.
| | - Sylvie M A Quiniou
- U.S. Department of Agriculture, Agricultural Research Service, Thad Cochran National Warmwater Aquaculture Center, Warmwater Aquaculture Research Unit, 127 Experiment Station Rd, P. O. Box 38, Stoneville, MS, 38776, USA.
| | - Melanie Wilson
- Department of Microbiology and Immunology, University of Mississippi Medical Center, 2500 North State St, Jackson, MS, 39216, USA.
| | - Eva Bengtén
- Department of Microbiology and Immunology, University of Mississippi Medical Center, 2500 North State St, Jackson, MS, 39216, USA.
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11
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Kalindamar S, Kordon AO, Abdelhamed H, Tan W, Pinchuk LM, Karsi A. Edwardsiella ictaluri evpP is required for colonisation of channel catfish ovary cells and necrosis in anterior kidney macrophages. Cell Microbiol 2019; 22:e13135. [PMID: 31742869 DOI: 10.1111/cmi.13135] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 09/10/2019] [Accepted: 10/23/2019] [Indexed: 12/17/2022]
Abstract
Edwardsiella ictaluri is a Gram-negative facultative anaerobe that can survive inside channel catfish phagocytes. E. ictaluri can orchestrate Type VI Secretion System (T6SS) for survival in catfish macrophages. evpP encodes one of the T6SS translocated effector proteins. However, the role of evpP in E. ictaluri is still unexplored. In this work, we constructed an E. ictaluri evpP mutant (EiΔevpP) and assessed its survival under complement and oxidative stress. Persistence of EiΔevpP in catfish as well as attachment and invasion in catfish macrophage and ovary cells were determined. Further, virulence of EiΔevpP in catfish and apoptosis it caused in macrophages were explored. EiΔevpP behaved same as wild type (EiWT) under complement and oxidative stress in complex media, whereas oxidative stress affected mutant's survival significantly in minimal media (p < .05). Persistence of EiΔevpP in live catfish and uptake and survival inside peritoneal macrophages were similar. The attachment and invasion capabilities of EiΔevpP in catfish ovary cells were significantly less than that of EiWT (p < .05). Although EiΔevpP showed reduced attenuation in catfish, causing decreased catfish mortality compared with EiWT (44.73% vs. 67.53%), this difference was not significant. The apoptosis assay using anterior kidney macrophages indicated that the number of live macrophages exposed to EiΔevpP was significantly higher compared with EiWT exposed macrophages at 24-hr post-treatment (p < .05). However, there were no significant differences in the early and late apoptosis. Remarkably, necrosis in EiΔevpP exposed macrophages was significantly less than that of EiWT exposed macrophages at 24 hr (p < .05). Our results demonstrated that evpP is required for colonisation of catfish ovary cells and increased apoptosis and necrosis in anterior kidney macrophages.
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Affiliation(s)
- Safak Kalindamar
- Department of Molecular Biology and Genetics, Faculty of Arts and Sciences, Ordu University, Ordu, Turkey
| | - Adef O Kordon
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi
| | - Hossam Abdelhamed
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi
| | - Wei Tan
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi
| | - Lesya M Pinchuk
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi
| | - Attila Karsi
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi
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12
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Lewis J, Soto E. Gene expression of putative type VI secretion system (T6SS) genes in the emergent fish pathogen Francisella noatunensis subsp. orientalis in different physiochemical conditions. BMC Microbiol 2019; 19:21. [PMID: 30665355 PMCID: PMC6341738 DOI: 10.1186/s12866-019-1389-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 01/07/2019] [Indexed: 12/27/2022] Open
Abstract
Background Francisella noatunensis subsp. orientalis (Fno) is an emergent fish pathogen and the etiologic agent of piscine francisellosis. Besides persisting in the environment in both biofilm and planktonic forms, Fno is known to infect and replicate inside tilapia macrophages and endothelial-derived cells. However, the mechanism used by this emergent bacterium for intracellular survival is unknown. Additionally, the basis of virulence for Fno is still poorly understood. Several potential virulence determinants have been identified in Fno, including homologues of the recently described F. tularensis Type VI Secretion System (T6SS). In order to gain a better understanding of the role the putative Fno T6SS might play in the pathogenesis of piscine francisellosis, we performed transcriptional analysis of Fno T6SS gene-homologues under temperature, acidic, and oxidative stress conditions. Results Few transcriptional differences were observed at different temperatures, growth stages and pHs; however, a trend towards higher expression of Fno T6SS-homologue genes at 25 °C and under oxidative stress was detected when compared to those quantified at 30 °C and under no H2O2 (p < 0.05). Conclusions Results from this study suggest that several of the F. tularensis T6SS-homologues may play an important role in the virulence of Fno, particularly when the bacterium is exposed to low temperatures and oxidative stress. Electronic supplementary material The online version of this article (10.1186/s12866-019-1389-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jainee Lewis
- Department of Medicine and Epidemiology, University of California-Davis, School of Veterinary Medicine, Davis, CA, 95616, USA
| | - Esteban Soto
- Department of Medicine and Epidemiology, University of California-Davis, School of Veterinary Medicine, Davis, CA, 95616, USA.
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LEE K, KIM HK, PARK SK, SOHN H, CHO Y, CHOI YM, JEONG DG, KIM JH. First report of the occurrence and whole-genome characterization of Edwardsiella tarda in the false killer whale (Pseudorca crassidens). J Vet Med Sci 2018; 80:1041-1046. [PMID: 29695679 PMCID: PMC6021894 DOI: 10.1292/jvms.17-0590] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 04/16/2018] [Indexed: 01/22/2023] Open
Abstract
Although several Edwardsiella tarda infections have been reported, its pathogenic role in marine mammals has not been investigated at the genome level. We investigated the genome of E. tarda strain KC-Pc-HB1, isolated from the false killer whale (Pseudorca crassidens) found bycaught in South Korea. The obtained genome was similar to that of human pathogenic E. tarda strains, but distinct from other Edwardsiella species. Although type III and VI secretion systems, which are essential for the virulence of other Edwardsiella species, were absent, several virulence-related genes involved in the pathogenesis of E. tarda were found in the genome. These results provide important insights into the E. tarda infecting marine mammals and give valuable information on potential virulence factors in this pathogen.
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Affiliation(s)
- Kyunglee LEE
- Cetacean Research Institute (CRI), National Institute of
Fisheries Science (NIFS), Ulsan 44780, Republic of Korea
| | - Hye Kwon KIM
- Infectious Disease Research Center, Korea Research Institute
of Bioscience and Biotechnology, Daejeon 34141, Republic of Korea
| | - Sung-Kyun PARK
- Infectious Disease Research Center, Korea Research Institute
of Bioscience and Biotechnology, Daejeon 34141, Republic of Korea
| | - Hawsun SOHN
- Cetacean Research Institute (CRI), National Institute of
Fisheries Science (NIFS), Ulsan 44780, Republic of Korea
| | - Yuna CHO
- Cetacean Research Institute (CRI), National Institute of
Fisheries Science (NIFS), Ulsan 44780, Republic of Korea
| | - Young-Min CHOI
- Cetacean Research Institute (CRI), National Institute of
Fisheries Science (NIFS), Ulsan 44780, Republic of Korea
| | - Dae Gwin JEONG
- Infectious Disease Research Center, Korea Research Institute
of Bioscience and Biotechnology, Daejeon 34141, Republic of Korea
| | - Ji Hyung KIM
- Infectious Disease Research Center, Korea Research Institute
of Bioscience and Biotechnology, Daejeon 34141, Republic of Korea
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Li MF, Sun L. Edwardsiella tarda Sip2: A Serum-Induced Protein That Is Essential to Serum Survival, Acid Resistance, Intracellular Replication, and Host Infection. Front Microbiol 2018; 9:1084. [PMID: 29887847 PMCID: PMC5980991 DOI: 10.3389/fmicb.2018.01084] [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: 02/25/2018] [Accepted: 05/07/2018] [Indexed: 12/12/2022] Open
Abstract
Edwardsiella tarda is a broad-host pathogen that can infect mammals, reptiles, and fish. E. tarda exhibits a remarkable ability to survive in host serum and replicate in host phagocytes, but the underlining mechanism is unclear. In this study, in order to identify E. tarda proteins involved in serum resistance, iTRAQ proteomic analysis was performed to examine the whole-cell protein profiles of TX01, a pathogenic E. tarda isolate, in response to serum treatment. Of the differentially expressed proteins identified, one (named Sip2) possesses a conserved hydrogenase domain and is homologous to the putative hydrogenase accessory protein HypB. When Sip2 was expressed in Escherichia coli, it significantly enhanced the survival of the host cells in serum. Compared to TX01, the sip2 knockout, TX01Δsip2, was dramatically reduced in the ability of hydrogenase activity, serum resistance, intracellular replication, dissemination in fish tissues, and causing mortality in infected fish. The lost virulence capacities of TX01Δsip2 were restored by complementation with the sip2 gene. Furthermore, TX01Δsip2 was significantly reduced in the capacity to grow under low pHs and iron-depleted conditions, and was unable to maintain its internal pH in acidic environment. Taken together, these results indicate that Sip2 is a novel serum-induced protein that is essential to serum resistance, cellular and tissue infection, and coping with acidic stress via its ability to modulate intracellular pH.
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Affiliation(s)
- Mo-fei Li
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Li Sun
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
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15
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Cheng ZX, Gong QY, Wang Z, Chen ZG, Ye JZ, Li J, Wang J, Yang MJ, Ling XP, Peng B. Edwardsiella tarda Tunes Tricarboxylic Acid Cycle to Evade Complement-Mediated Killing. Front Immunol 2017; 8:1706. [PMID: 29270172 PMCID: PMC5725468 DOI: 10.3389/fimmu.2017.01706] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 11/20/2017] [Indexed: 01/12/2023] Open
Abstract
Evasion of complement-mediated killing is a common phenotype for many different types of pathogens, but the mechanism is still poorly understood. Most of the clinic isolates of Edwardsiella tarda, an important pathogen infecting both of human and fish, are commonly found serum-resistant. To explore the potential mechanisms, we applied gas chromatography-mass spectrometry (GC-MS)-based metabolomics approaches to profile the metabolomes of E. tarda EIB202 in the presence or absence of serum stress. We found that tricarboxylic acid (TCA) cycle was greatly enhanced in the presence of serum. The quantitative real-time PCR (qRT-PCR) and enzyme activity assays validated this result. Furthermore, exogenous succinate that promotes the TCA cycle increased serum resistance, while TCA cycle inhibitors (bromopyruvate and propanedioic acid) that inhibit TCA cycle, attenuated serum resistance. Moreover, the enhanced TCA cycle increased membrane potential, thus decreased the formation of membrane attack complex at cell surface, resulting serum resistance. These evidences suggested a previously unknown membrane potential-dependent mechanism of serum resistance. Therefore, our findings reveal that pathogen mounts a metabolic trick to cope with the serum complement-mediated killing.
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Affiliation(s)
- Zhi-Xue Cheng
- Center for Proteomics and Metabolomics, State Key Laboratory of Bio-Control, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Qi-Yang Gong
- Center for Proteomics and Metabolomics, State Key Laboratory of Bio-Control, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Zhe Wang
- Center for Proteomics and Metabolomics, State Key Laboratory of Bio-Control, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Zhuang-Gui Chen
- Pediatric Intensive Care Unit, Department of Pediatrics, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Jin-Zhou Ye
- Center for Proteomics and Metabolomics, State Key Laboratory of Bio-Control, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Jun Li
- Center for Proteomics and Metabolomics, State Key Laboratory of Bio-Control, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Jie Wang
- Center for Proteomics and Metabolomics, State Key Laboratory of Bio-Control, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Man-Jun Yang
- Center for Proteomics and Metabolomics, State Key Laboratory of Bio-Control, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Xiao-Peng Ling
- Center for Proteomics and Metabolomics, State Key Laboratory of Bio-Control, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Bo Peng
- Center for Proteomics and Metabolomics, State Key Laboratory of Bio-Control, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
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16
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Wang L, Liu Z, Dai S, Yan J, Wise MJ. The Sit-and-Wait Hypothesis in Bacterial Pathogens: A Theoretical Study of Durability and Virulence. Front Microbiol 2017; 8:2167. [PMID: 29209284 PMCID: PMC5701638 DOI: 10.3389/fmicb.2017.02167] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Accepted: 10/23/2017] [Indexed: 12/20/2022] Open
Abstract
The intriguing sit-and-wait hypothesis predicts that bacterial durability in the external environment is positively correlated with their virulence. Since its first proposal in 1987, the hypothesis has been spurring debates in terms of its validity in the field of bacterial virulence. As a special case of the vector-borne transmission versus virulence tradeoff, where vector is now replaced by environmental longevity, there are only sporadic studies over the last three decades showing that environmental durability is possibly linked with virulence. However, no systematic study of these works is currently available and epidemiological analysis has not been updated for the sit-and-wait hypothesis since the publication of Walther and Ewald's (2004) review. In this article, we put experimental evidence, epidemiological data and theoretical analysis together to support the sit-and-wait hypothesis. According to the epidemiological data in terms of gain and loss of virulence (+/-) and durability (+/-) phenotypes, we classify bacteria into four groups, which are: sit-and-wait pathogens (++), vector-borne pathogens (+-), obligate-intracellular bacteria (--), and free-living bacteria (-+). After that, we dive into the abundant bacterial proteomic data with the assistance of bioinformatics techniques in order to investigate the two factors at molecular level thanks to the fast development of high-throughput sequencing technology. Sequences of durability-related genes sourced from Gene Ontology and UniProt databases and virulence factors collected from Virulence Factor Database are used to search 20 corresponding bacterial proteomes in batch mode for homologous sequences via the HMMER software package. Statistical analysis only identified a modest, and not statistically significant correlation between mortality and survival time for eight non-vector-borne bacteria with sit-and-wait potentials. Meanwhile, through between-group comparisons, bacteria with higher host-mortality are significantly more durable in the external environment. The results of bioinformatics analysis correspond well with epidemiological data, that is, non-vector-borne pathogens with sit-and-wait potentials have higher number of virulence and durability genes compared with other bacterial groups. However, the conclusions are constrained by the relatively small bacterial sample size and non-standardized experimental data.
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Affiliation(s)
- Liang Wang
- School of Medical Informatics, Xuzhou Medical University, Xuzhou, China
| | - Zhanzhong Liu
- Department of Clinical Pharmacology, Xuzhou Infectious Diseases Hospital, Xuzhou, China
| | - Shiyun Dai
- School of Anaesthesia, Xuzhou Medical University, Xuzhou, China
| | - Jiawei Yan
- Clinical Laboratory of Tuberculosis, Xuzhou Infectious Diseases Hospital, Xuzhou, China
| | - Michael J. Wise
- School of Computer Science and Software Engineering, University of Western Australia, Perth, WA, Australia
- The Marshall Centre for Infectious Diseases Research and Training, University of Western Australia, Perth, WA, Australia
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Regulation of Type III Secretion of Translocon and Effector Proteins by the EsaB/EsaL/EsaM Complex in Edwardsiella tarda. Infect Immun 2017. [PMID: 28630070 DOI: 10.1128/iai.00322-17] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The type III secretion system (T3SS) plays a crucial role in the pathogenesis of many Gram-negative bacteria, including Edwardsiella tarda, an important fish pathogen. Within the E. tarda T3SS, there are three proteins (EsaB/EsaL/EsaM) that are homologous to proteins present in many other bacteria, including SpiC/SsaL/SsaM in Salmonella, SepD/SepL/CesL in enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC), and YscB/YopN/SycN in Yersinia EsaL was found to interact with both EsaB and EsaM within the bacterial cell, as revealed by a coimmunoprecipitation assay. Moreover, EsaM is required for EsaB stability, and the two proteins interact with each other. EsaB, EsaL, and EsaM are all indispensable for the secretion of the T3SS translocon protein EseC into supernatants under pH 5.5 and pH 7.2 conditions. Unlike EseC, EseG is a T3SS effector whose secretion is suppressed by EsaL at pH 7.2 while it is promoted at pH 5.5 condition. Despite this finding, mutant strains lacking EsaB, EsaL, or EsaM (i.e., the ΔesaB, ΔesaL, or ΔesaM strain, respectively) were all outcompeted by wild-type E. tarda during a coinfection model. These results demonstrate that EsaB/EsaL/EsaM form a ternary complex controlling the secretion of T3SS translocon and effector proteins and contributing to E. tarda pathogenesis.
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18
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Chen Q, Chen J, Chen J, Lu XJ. Molecular and functional characterization of liver X receptor in ayu, Plecoglossus altivelis: Regulator of inflammation and efferocytosis. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2016; 65:358-368. [PMID: 27539204 DOI: 10.1016/j.dci.2016.08.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 08/14/2016] [Accepted: 08/14/2016] [Indexed: 06/06/2023]
Abstract
Liver X receptors (LXR) are modulators of metabolic processes and inflammation in mammals as nuclear receptors. However, the precise function of LXR in teleosts remains unclear. Here, we characterized a LXR gene (PaLXR) from ayu, Plecoglossus altivelis. The PaLXR transcript was expressed widely in all tissues studied, and changes in expression were observed in tissues and monocytes/macrophages (MO/MΦ) upon infection with the bacterium Edwardsiella ictaluri. PaLXR activation decreased the mRNA expression of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and IL-10 upon E. ictaluri infection, while their expression was increased following the knockdown of PaLXR by siRNA. Moreover, E. ictaluri infection induced the apoptosis of ayu neutrophils and PaLXR activation enhanced the internalization of E. ictaluri-infected apoptotic neutrophils by MO/MΦ (efferocytosis), while PaLXR knockdown led to decreased efferocytosis. Furthermore, PaLXR activation inhibited intracellular bacterial survival during efferocytosis, while PaLXR knockdown enhanced survival. In conclusion, our results indicate that PaLXR plays a role in the modulation of innate immune responses in ayu MO/MФ.
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Affiliation(s)
- Qiang Chen
- Laboratory of Biochemistry and Molecular Biology, School of Marine Sciences, Ningbo University, Ningbo 315211, China; The Donghai Sea Collaborative Innovation Center for Industrial Upgrading Mariculture, Ningbo University, Ningbo 315211, China
| | - Jie Chen
- Laboratory of Biochemistry and Molecular Biology, School of Marine Sciences, Ningbo University, Ningbo 315211, China; The Donghai Sea Collaborative Innovation Center for Industrial Upgrading Mariculture, Ningbo University, Ningbo 315211, China
| | - Jiong Chen
- Laboratory of Biochemistry and Molecular Biology, School of Marine Sciences, Ningbo University, Ningbo 315211, China; The Donghai Sea Collaborative Innovation Center for Industrial Upgrading Mariculture, Ningbo University, Ningbo 315211, China.
| | - Xin-Jiang Lu
- Laboratory of Biochemistry and Molecular Biology, School of Marine Sciences, Ningbo University, Ningbo 315211, China.
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Ucko M, Colorni A, Dubytska L, Thune RL. Edwardsiella piscicida-like pathogen in cultured grouper. DISEASES OF AQUATIC ORGANISMS 2016; 121:141-148. [PMID: 27667811 DOI: 10.3354/dao03051] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
An Edwardsiella sp. was isolated from the kidney of diseased groupers (Epinephelus aeneus and E. marginatus) cultured in Eilat (Israel, Red Sea). Affected fish presented a severe suppurative nephritis with large abscesses occasionally spreading into the surrounding musculature. Biochemical profiles and phenotypic comparisons failed to provide a clear identification to the species level, and genetic analysis of the 16S subunit failed to discriminate between Edwardsiella piscicida, E. tarda and E. ictaluri. Analysis of the gyrB gene, however, placed the grouper isolates into the E. piscicida-like group, a newly recognized taxon which also encompasses the non-motile strains previously classified as atypical E. tarda. Initial genomic analysis revealed the presence of the Edwardsiella type 3 secretion system (T3SS) but also revealed a pathogenicity island encoding a second T3SS with homology to the locus of enterocyte effacement of Escherichia coli. Further analysis revealed 3 different type 6 secretion systems that were also present in all sequenced isolates of Edwardsiella piscicida-like strains. Based on estimated DNA-DNA hybridization values and the average nucleotide index, the grouper strain fits into the E. piscicida-like phylogroup described as E. anguillarum sp. nov. The peculiarities associated with this isolate and the association of other conspecific piscine isolates from multiple marine and brackish water species suggest a link of the entire E. piscicida-like phylogroup to the marine environment.
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Affiliation(s)
- Michal Ucko
- Israel Oceanographic and Limnological Research, National Center for Mariculture, PO Box 1212, Eilat 88112, Israel
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Identification and Characterization of Putative Translocated Effector Proteins of the Edwardsiella ictaluri Type III Secretion System. mSphere 2016; 1:mSphere00039-16. [PMID: 27303737 PMCID: PMC4888880 DOI: 10.1128/msphere.00039-16] [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: 02/12/2016] [Accepted: 03/25/2016] [Indexed: 01/12/2023] Open
Abstract
The bacterial pathogen Edwardsiella ictaluri causes enteric septicemia of catfish (ESC), an economically significant disease of farm-raised channel catfish. Commercial catfish production accounts for the majority of the total fin fish aquaculture in the United States, with almost 300,000 tons produced annually, and ESC is the leading cause of disease loss in the industry. We have demonstrated the survival and replication of E. ictaluri within channel catfish cells and identified a secretion system that is essential for E. ictaluri intracellular replication and virulence. We have also identified nine proteins encoded in the E. ictaluri genome that we believe are actively transferred from the bacterium to the cytoplasm of the host cell and act to manipulate host cell physiology to the advantage of the bacterium. The data presented here confirm that the proteins are actually transferred during an infection, which will lead to further work on approaches to preventing or controlling ESC. Edwardsiella ictaluri, a major pathogen in channel catfish aquaculture, encodes a type III secretion system (T3SS) that is essential for intracellular replication and virulence. Previous work identified three putative T3SS effectors in E. ictaluri, and in silico analysis of the E. ictaluri genome identified six additional putative effectors, all located on the chromosome outside the T3SS pathogenicity island. To establish active translocation by the T3SS, we constructed translational fusions of each effector to the amino-terminal adenylate cyclase (AC) domain of the Bordetella pertussis adenylate cyclase toxin CyaA. When translocated through the membrane of the Edwardsiella-containing vacuole (ECV), the cyclic AMP produced by the AC domain in the presence of calmodulin in the host cell cytoplasm can be measured. Results showed that all nine effectors were translocated from E. ictaluri in the ECV to the cytoplasm of the host cells in the wild-type strain but not in a T3SS mutant, indicating that translocation is dependent on the T3SS machinery. This confirms that the E. ictaluri T3SS is similar to the Salmonella pathogenicity island 2 T3SS in that it translocates effectors through the membrane of the bacterial vacuole directly into the host cell cytoplasm. Additional work demonstrated that both initial acidification and subsequent neutralization of the ECV were necessary for effector translocation, except for two of them that did not require neutralization. Single-gene mutants constructed for seven of the individual effectors were all attenuated for replication in CCO cells, but only three were replication deficient in head kidney-derived macrophages (HKDM). IMPORTANCE The bacterial pathogen Edwardsiella ictaluri causes enteric septicemia of catfish (ESC), an economically significant disease of farm-raised channel catfish. Commercial catfish production accounts for the majority of the total fin fish aquaculture in the United States, with almost 300,000 tons produced annually, and ESC is the leading cause of disease loss in the industry. We have demonstrated the survival and replication of E. ictaluri within channel catfish cells and identified a secretion system that is essential for E. ictaluri intracellular replication and virulence. We have also identified nine proteins encoded in the E. ictaluri genome that we believe are actively transferred from the bacterium to the cytoplasm of the host cell and act to manipulate host cell physiology to the advantage of the bacterium. The data presented here confirm that the proteins are actually transferred during an infection, which will lead to further work on approaches to preventing or controlling ESC.
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21
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Population-specific renal proteomes of marine and freshwater three-spined sticklebacks. J Proteomics 2016; 135:112-131. [DOI: 10.1016/j.jprot.2015.10.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Revised: 09/16/2015] [Accepted: 10/02/2015] [Indexed: 12/20/2022]
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Li C, Beck BH, Peatman E. Nutritional impacts on gene expression in the surface mucosa of blue catfish (Ictalurus furcatus). DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2014; 44:226-234. [PMID: 24378224 DOI: 10.1016/j.dci.2013.12.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 12/20/2013] [Accepted: 12/21/2013] [Indexed: 06/03/2023]
Abstract
Short-term feed deprivation is a common occurrence in both wild and farmed fish species, due to reproductive processes, seasonal variations in temperature, or in response to a disease outbreak. Fasting can have dramatic physiological and biological consequences for fish, including impacts on mucosal immunity which can, in turn, change host susceptibility to pathogens. Culture and selection of blue catfish (Ictalurus furcatus) has gained importance as the production of a channel catfish×blue catfish (Ictalurus punctatus×I. furcatus) hybrid has increased in the Southeast US. Following a recent examination of fasting-induced impacts on mucosal immunity in channel catfish, here we utilized Illumina-based RNA-seq expression profiling to compare changes in blue catfish gill and skin after a brief (7 day) period of fasting. Transcriptome sequencing and de novo assembly of over 194 million 100 base-pair transcript reads was followed by differential expression analysis. Fasting altered a total of 530 genes in the surface mucosa, including genes regulating the immune response, energy metabolism, mucus production, cellular cytoskeletal structure, cell proliferation, and antioxidant responses. In particular, fasting perturbed arginine synthesis and metabolism pathways in a manner likely altering macrophage activation states and immune readiness. Our findings highlight key mediators of the critical interaction between nutrition and immunity at points of pathogen adherence and entry.
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Affiliation(s)
- Chao Li
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL 36849, USA
| | - Benjamin H Beck
- United States Department of Agriculture, Agricultural Research Service, Stuttgart National Aquaculture Research Center, Stuttgart, AR 72160, USA
| | - Eric Peatman
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL 36849, USA.
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23
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Suanyuk N, Rogge M, Thune R, Watthanaphiromsakul M, Champhat N, Wiangkum W. Mortality and pathology of hybrid catfish, Clarias macrocephalus (Günther) × Clarias gariepinus (Burchell), associated with Edwardsiella ictaluri infection in southern Thailand. JOURNAL OF FISH DISEASES 2014; 37:385-395. [PMID: 23763374 DOI: 10.1111/jfd.12127] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 04/11/2013] [Accepted: 04/18/2013] [Indexed: 06/02/2023]
Abstract
Enteric septicaemia of catfish (ESC) caused by Edwardsiella ictaluri is becoming an increasing problem in aquaculture and has been reported worldwide in a variety of fish species. This study reports ESC in hybrid catfish, Clarias macrocephalus (Günther) × Clarias gariepinus (Burchell), cultured in southern Thailand. The bacteria were identified as E. ictaluri by conventional and rapid identification systems, as well as by genetic and phylogenetic characterization. Analysis of 16S rRNA indicated 100% homology to the 16S rRNA sequence of several E. ictaluri strains in GenBank. Plasmid profiles demonstrated 4.0- and 5.6-kb plasmids, compared with the 4.8- and 5.6-kb plasmids in the US isolates, and representative genes of three of the four known pathogenicity islands of US isolates were present. Serologically, lipopolysaccharide (LPS) purified from the Thai isolates was not recognized by a monoclonal antibody against the LPS of US isolates. Fish experimentally infected with E. ictaluri showed 23-100% mortality within 14 days with a 168-h LD50 of 6.92 × 10(7) CFU mL(-1) by immersion and a 96-h LD50 of 1.58 × 10(6) CFU fish(-1) by intraperitoneal injection. Examination of tissue sections obtained from both naturally and experimentally infected fish indicated that infection of hybrid catfish with E. ictaluri produced lesions in several organs including liver, kidney, spleen, heart and brain. Histopathology findings included cellular necrosis, focal haemorrhage, infiltration of lymphocytes and multifocal granulomatous inflammation in the infected organs.
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Affiliation(s)
- N Suanyuk
- Kidchakan Supamattaya Aquatic Animal Health Research Center, Department of Aquatic Science, Faculty of Natural Resources, Prince of Songkla University, Hat Yai, Songkhla, Thailand
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24
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Modulation of vacuolar pH is required for replication of Edwardsiella ictaluri in channel catfish macrophages. Infect Immun 2014; 82:2329-36. [PMID: 24664505 DOI: 10.1128/iai.01616-13] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Previous in vitro work demonstrated that Edwardsiella ictaluri produces an acid-activated urease that can modulate environmental pH through the production of ammonia from urea. Additional work revealed that expression of the E. ictaluri type III secretion system (T3SS) is upregulated by acidic pH. Both the urease and the T3SS were previously shown to be essential to intracellular replication. In this work, fluorescence microscopy with LysoTracker Red DND-99 (LTR) indicated that E. ictaluri-containing vacuoles (ECV) became acidified following ingestion by head kidney-derived macrophages (HKDM). In vivo ratiometric imaging demonstrated a lowered ECV pH, which fell to as low as pH 4 but subsequently increased to pH 6 or greater. Inhibition of vacuolar H(+)-ATPases by use of the specific inhibitor bafilomycin A1 abrogated both ECV acidification and intracellular replication in HKDM. Failure of an E. ictaluri urease knockout mutant to increase the ECV pH in the in vivo ratiometric assay suggests that ammonia produced by the urease reaction mediates the pH increase. Additionally, when the specific arginase inhibitor l-norvaline was used to treat E. ictaluri-infected HKDM, the ECV failed to neutralize and E. ictaluri was unable to replicate. This indicates that the HKDM-encoded arginase enzyme produces the urea used by the E. ictaluri urease enzyme. Failure of the ECV to acidify would prevent both upregulation of the T3SS and activation of the urease enzyme, either of which would prevent E. ictaluri from replicating in HKDM. Failure of the ECV to neutralize would result in a vacuolar pH too low to support E. ictaluri replication.
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25
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Mao Z, Ye J, Li M, Xu H, Chen J. Vaccination efficiency of surface antigens and killed whole cell of Pseudomonas putida in large yellow croaker (Pseudosciaena crocea). FISH & SHELLFISH IMMUNOLOGY 2013; 35:375-381. [PMID: 23659996 DOI: 10.1016/j.fsi.2013.04.030] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2013] [Revised: 04/18/2013] [Accepted: 04/25/2013] [Indexed: 06/02/2023]
Abstract
Large yellow croaker (Pseudosciaena crocea), a major marine fish aquacultured in the southeastern coastal region of China, has become endangered by the pathogen Pseudomonas putida in recent years. P. putida infections occur in low water temperatures when fish reduce food intake, thus oral antibiotic administration is not practical. Therefore, vaccination may be the only method to prevent the infection. In the present study, main surface antigens of P. putida, including lipopolysaccharide (LPS), outer membrane proteins (OMP), extracellular biofilm polysaccharide (EPS), and formalin-killed cell (FKC) bacterin, were prepared and the fish vaccinated. On post-immunization day 28, serum antibody titers, phagocytic responses of leukocytes, and lysozyme activities of the fish were evaluated. The efficiency of vaccination was tested by artificial challenge via intraperitoneal injection of live bacteria on post-immunization day 28 and 35, respectively. The results showed that although significant humoral and innate immune responses were elicited in all vaccination groups, the challenge produced similar poor protection in both tests, with a relative percent survival (RPS) of 0-40%. Although the EPS group showed a complete lack of protection, LPS reached the highest RPS value (40%), suggesting that LPS may be involved in protection immunity against the pathogen. Further analysis of the ultra-structures of tissues from infected fish via TEM revealed macrophage survival and intracellular replication ability of the pathogen. New strategies for development might put more emphasis on efficient clearance of intracellular bacteria. The present study is the first to report vaccination against the fish pathogen P. putida and the first investigation of intracellular survival of this pathogen in host macrophages.
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Affiliation(s)
- Zhijuan Mao
- Biological and Environmental College, Zhejiang Wanli University, No. 8, South Qianhu Road, Ningbo 315100, China.
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26
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Santander J, Martin T, Loh A, Pohlenz C, Gatlin DM, Curtiss R. Mechanisms of intrinsic resistance to antimicrobial peptides of Edwardsiella ictaluri and its influence on fish gut inflammation and virulence. MICROBIOLOGY (READING, ENGLAND) 2013; 159:1471-1486. [PMID: 23676433 PMCID: PMC4085987 DOI: 10.1099/mic.0.066639-0] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 05/10/2013] [Indexed: 11/18/2022]
Abstract
The genus Edwardsiella comprises a genetically distinct taxon related to other members of the family Enterobacteriaceae. It consists of bacteria differing strongly in their biochemical and physiological features, natural habitats, and pathogenic properties. Intrinsic resistance to cationic antimicrobial peptides (CAMPs) is a specific property of the genus Edwardsiella. In particular, Edwardsiella ictaluri, an important pathogen of the catfish (Ictalurus punctatus) aquaculture and the causative agent of a fatal systemic infection, is highly resistant to CAMPs. E. ictaluri mechanisms of resistance to CAMPs are unknown. We hypothesized that E. ictaluri lipopolysaccharide (LPS) plays a role in both virulence and resistance to CAMPs. The putative genes related to LPS oligo-polysaccharide (O-PS) synthesis were in-frame deleted. Individual deletions of wibT, gne and ugd eliminated synthesis of the O-PS, causing auto-agglutination, rough colonies, biofilm-like formation and motility defects. Deletion of ugd, the gene that encodes the UDP-glucose dehydrogenase enzyme responsible for synthesis of UDP-glucuronic acid, causes sensitivity to CAMPs, indicating that UDP-glucuronic acid and its derivatives are related to CAMP intrinsic resistance. E. ictaluri OP-S mutants showed different levels of attenuation, colonization of lymphoid tissues and immune protection in zebrafish (Danio rerio) and catfish. Orally inoculated catfish with O-PS mutant strains presented different degrees of gut inflammation and colonization of lymphoid tissues. Here we conclude that intrinsic resistance to CAMPs is mediated by Ugd enzyme, which has a pleiotropic effect in E. ictaluri influencing LPS synthesis, motility, agglutination, fish gut inflammation and virulence.
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Affiliation(s)
- Javier Santander
- Biodesign Institute, Center for Infectious Diseases and Vaccinology, Arizona State University, Tempe, AZ 85287, USA
| | - Taylor Martin
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Amanda Loh
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Camilo Pohlenz
- Department of Wildlife and Fisheries Sciences, Texas A&M University System, College Station, TX 77843, USA
| | - Delbert M. Gatlin
- Department of Wildlife and Fisheries Sciences, Texas A&M University System, College Station, TX 77843, USA
- Intercollegiate Faculty of Nutrition, Texas A&M University System, College Station, TX 77843, USA
| | - Roy Curtiss
- Biodesign Institute, Center for Infectious Diseases and Vaccinology, Arizona State University, Tempe, AZ 85287, USA
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
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Pohlenz C, Buentello A, Mwangi W, Gatlin DM. Arginine and glutamine supplementation to culture media improves the performance of various channel catfish immune cells. FISH & SHELLFISH IMMUNOLOGY 2012; 32:762-768. [PMID: 22326940 DOI: 10.1016/j.fsi.2012.01.029] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Revised: 01/20/2012] [Accepted: 01/29/2012] [Indexed: 05/31/2023]
Abstract
Specific components of both the innate and adaptive immune systems of channel catfish were evaluated after supplementation of culture media with arginine (ARG) and/or glutamine (GLN). Primary cell cultures of head-kidney macrophages (MØ) were used for phagocytic and bactericidal assays against Edwardsiella ictaluri. Additionally, proliferation assays were conducted with naïve peripheral blood lymphocytes (PBL) exposed to non-specific mitogens. To indirectly assess amino acid utilization of both MØ and PBL, amino acid levels, with emphasis on ARG and GLN, were evaluated in the basal medium before and after activation or mitogenic exposure. After bactericidal and proliferation assays, the sum of the media free amino acid pool significantly (P < 0.05) decreased 23% and 45%, respectively. Glutamine levels in medium decreased by 38% and ARG by 18% during the bactericidal assay. Also, decreases of 52 and 46% from initial values were found after the proliferation assay for GLN and ARG, respectively. Macrophage phagocytosis and killing ability was significantly (P < 0.05) enhanced by ARG supplementation to culture media regardless of GLN supplementation. Proliferation of naïve T- and B-lymphocytes upon mitogenic exposure was significantly (P < 0.05) enhanced by supplementing ARG and GLN to the media, but limited synergistic effects were observed. These results suggest that in vitro, ARG and GLN are important substrates and immunomodulators of both innate and adaptive responses in fish leukocytes, and further highlights the potential use of ARG and GLN as immunonutrients in aquafeeds.
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Affiliation(s)
- Camilo Pohlenz
- Department of Wildlife and Fisheries Sciences and Intercollegiate Faculty of Nutrition, Texas A&M University System, College Station, TX 77843, USA
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28
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Li C, Zhang Y, Wang R, Lu J, Nandi S, Mohanty S, Terhune J, Liu Z, Peatman E. RNA-seq analysis of mucosal immune responses reveals signatures of intestinal barrier disruption and pathogen entry following Edwardsiella ictaluri infection in channel catfish, Ictalurus punctatus. FISH & SHELLFISH IMMUNOLOGY 2012; 32:816-827. [PMID: 22366064 DOI: 10.1016/j.fsi.2012.02.004] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Revised: 02/02/2012] [Accepted: 02/03/2012] [Indexed: 05/31/2023]
Abstract
The mucosal surfaces of fish (gill, skin, gastrointestinal tract) are important sites of bacterial exposure and host defense mechanisms. In mammalian systems, the intestinal epithelium is well characterized as both a selectively permeable barrier regulated by junctional proteins and as a primary site of infection for a number of enteric pathogens including viruses, bacteria, and parasites. The causative bacterium of enteric septicemia of catfish, Edwardsiella ictaluri, is believed to gain entry through the intestinal epithelium, with previous research using a rat intestinal epithelial cell line (IEC-6) indicating actin polymerization and receptor-mediated endocytosis as potential mechanisms of uptake. Here, we utilized high-throughput RNA-seq to characterize the role of the intestinal epithelial barrier following E. ictaluri challenge. A total of 197.6 million reads were obtained and assembled into 176,481 contigs with an average length of 893.7 bp and N50 of 1676 bp. The assembled contigs contained 14,457 known unigenes, including 2719 genes not previously identified in other catfish transcriptome studies. Comparison of digital gene expression between challenged and control samples revealed 1633 differentially expressed genes at 3 h, 24 h, and 3 day following exposure. Gene pathway analysis of the differentially expressed gene set indicated the centrality of actin cytoskeletal polymerization/remodelling and junctional regulation in pathogen entry and subsequent inflammatory responses. The expression patterns of fifteen differentially expressed genes related to intestinal epithelial barrier dysfunction were validated by quantitative real-time RT-PCR (average correlation coeff. 0.92, p < 0.001). Our results set a foundation for future studies comparing mechanisms of pathogen entry and mucosal immunity across several important catfish pathogens including E. ictaluri, Edwardsiellatarda, Flavobacterium columnare, and virulent atypical Aeromonas hydrophila. Understanding of molecular mechanisms of pathogen entry during infection will provide insight into strategies for selection of resistant catfish brood stocks against various diseases.
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Affiliation(s)
- Chao Li
- Department of Fisheries and Allied Aquacultures, Aquatic Genomics Unit, Auburn University, Auburn, AL 36849, USA
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29
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Early interactions of Edwardsiella ictaluri, with Pangasianodon catfish and its invasive ability in cell lines. Vet Res Commun 2012; 36:119-27. [DOI: 10.1007/s11259-012-9521-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/03/2012] [Indexed: 11/25/2022]
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30
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Wang YM, Wang QY, Xiao JF, Liu Q, Wu HZ, Zhang YX. Genetic relationships of Edwardsiella strains isolated in China aquaculture revealed by rep-PCR genomic fingerprinting and investigation of Edwardsiella virulence genes. J Appl Microbiol 2011; 111:1337-48. [DOI: 10.1111/j.1365-2672.2011.05166.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Regulation of the Edwardsiella ictaluri type III secretion system by pH and phosphate concentration through EsrA, EsrB, and EsrC. Appl Environ Microbiol 2011; 77:4293-302. [PMID: 21551284 DOI: 10.1128/aem.00195-11] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A recently described Edwardsiella ictaluri type III secretion system (T3SS) with functional similarity to the Salmonella pathogenicity island 2 T3SS is required for replication in channel catfish head-kidney-derived macrophages (HKDM) and virulence in channel catfish. Quantitative PCR and Western blotting identified low pH and phosphate limitation as conducive to expression of the E. ictaluri T3SS, growth conditions that mimic the phagosomal environment. Mutagenesis studies demonstrated that expression is under the control of the EsrAB two-component regulatory system. EsrB also induces upregulation of the AraC-type regulatory protein EsrC, which enhances expression of the EscB/EseG chaperone/effector operon in concert with EsrB and induces expression of the pEI1-encoded effector, EseH. EsrC also induces expression of a putative type VI secretion system translocon protein, EvpC, which is secreted under the same low-pH conditions as the T3SS translocon proteins. The pEI2-encoded effector, EseI, was upregulated under low-pH and low-phosphate conditions but not in an EsrB- or EsrC-dependent manner. Mutations of EsrA and EsrB both resulted in loss of the ability to replicate in HKDM and full attenuation in the channel catfish host. Mutation of EsrC did not affect intracellular replication but did result in attenuation in catfish. Although EsrB is the primary transcriptional regulator for E. ictaluri genes within the T3SS pathogenicity island, EsrC regulates expression of the plasmid-carried effector eseH and appears to mediate coordinated expression of the T6SS with the T3SS.
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