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Lin J, Yang J, Cheng J, Zhang W, Yang X, Ding W, Zhang H, Wang Y, Shen X. Pseudomonas aeruginosa H3-T6SS Combats H 2O 2 Stress by Diminishing the Amount of Intracellular Unincorporated Iron in a Dps-Dependent Manner and Inhibiting the Synthesis of PQS. Int J Mol Sci 2023; 24:1614. [PMID: 36675127 PMCID: PMC9866239 DOI: 10.3390/ijms24021614] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/28/2022] [Accepted: 01/10/2023] [Indexed: 01/17/2023] Open
Abstract
The type VI secretion system (T6SS), a protein translocation nanomachine, is widely distributed in Gram-negative bacteria and delivers effectors directly into target cells or the extracellular environment to help the bacteria gain a competitive fitness advantage and promote bacterial survival in harmful environments. In this study, we demonstrated that the synthesis of the Pseudomonas quinolone signal (PQS) in Pseudomonas aeruginosa PAO1 was inhibited by the H3-T6SS gene cluster under iron-rich conditions, and that this inhibition was relieved under iron starvation conditions. Conversely, PQS differentially regulated the expression of the H3-T6SS structural genes and the effector protein gene tseF. The expression of tseF was inhibited by PQS, while the expressions of the H3-T6SS structural genes were positively regulated by PQS. Further studies showed that the H3-T6SS was involved in the resistance of P. aeruginosa to oxidative stress caused by hydrogen peroxide (H2O2). Interestingly, H3-T6SS expression was neither induced by H2O2 stress nor regulated by OxyR (a global anti-oxidative transcriptional regulator) but was positively regulated by RpoS (a major transcription regulator of the stress response). In addition, we found that the clpV3 (a structural gene of H3-T6SS) mutation resulted in upregulation of two proteins related to PQS synthesis and many proteins related to oxidative stress resistance, while the expression of some iron storage proteins, especially Dps, were significantly downregulated. Furthermore, the clpV3 mutation led to an increase in the intracellular free Fe2+ content of P. aeruginosa. Further studies showed that both the PQS deficient mutation and overexpression of dps effectively restored the H2O2 sensitive phenotype of the H3-T6SS mutant. Finally, we proposed the following model of H3-T6SS-mediated resistance to H2O2 stress in P. aeruginosa. H3-T6SS not only reduces the intracellular free Fe2+ level by upregulating the expression of ferritin Dps, but also inhibits the synthesis of PQS to mediate the resistance of P. aeruginosa to H2O2 stress. This study highlights the important role of H3-T6SS in the ability of P. aeruginosa to combat H2O2 stress and provides a perspective for understanding the stress response mechanism of bacteria.
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Affiliation(s)
- Jinshui Lin
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan’an University, Yan’an 716000, China
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling 712100, China
| | - Jianshe Yang
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan’an University, Yan’an 716000, China
| | - Juanli Cheng
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan’an University, Yan’an 716000, China
| | - Weipeng Zhang
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Xu Yang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling 712100, China
| | - Wei Ding
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Heng Zhang
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan’an University, Yan’an 716000, China
| | - Yao Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling 712100, China
| | - Xihui Shen
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling 712100, China
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Oliveira TF, Quieróz GA, Leibowitz MP, Gomes Leal CA. Development of an inactivated whole cell vaccine through immersion for immunoprophylaxis of Francisella orientalis infections in Nile tilapia (Oreochromis niloticus L.) fingerlings and juveniles. FISH & SHELLFISH IMMUNOLOGY 2022; 127:405-411. [PMID: 35772679 DOI: 10.1016/j.fsi.2022.06.040] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 06/03/2022] [Accepted: 06/23/2022] [Indexed: 06/15/2023]
Abstract
Francisella orientalis infections, known as francisellosis, are one of the most important diseases affecting the production of Nile tilapia, causing high mortality rates in the most susceptible fish stages: fingerlings and juveniles. Antibiotic therapy is the method of choice for treating the disease, as there are no commercially available vaccines. In this study, we developed an inactivated whole-cell vaccine using an isolate of F. orientalis in combination with the aqueous adjuvant Montanide IMS 1312 VG, which was administered to Nile tilapia through immersion. Two immunization trials (1 and 2) were conducted with fish at the fingerling and juvenile stages. For each trial, five different experimental groups were established: a complete vaccine (bacterin in combination with aqueous adjuvant), bacterin, aqueous adjuvant, and positive and negative controls. Thirty days after vaccination, an experimental challenge was performed through intraperitoneal injection of the same F. orientalis isolate. As a result, the vaccinated fingerlings were the only group in which mortality and progression of clinical signs of francisellosis were statistically significantly reduced, although relative percentage of survival (RPS) was low at 50%. In the juvenile group, RPS was higher at 63%, but not statistically significant. Nevertheless, an RPS of only 50% is acceptable for using vaccines in the field. The bacterin and adjuvant treatments alone were not effective, showing an RPS of 37% and 0%, respectively. Post-vaccination mortality was observed in the group exposed only to the adjuvant, which may indicate excessive immune stimulation at this stage. Interestingly, the immune response elicited by the vaccine was unable to eliminate the pathogen from the host; therefore, the surviving animals became carriers. Although the immune response elicited by the vaccine was unable to eliminate the pathogen from the host, this vaccine formulation could be a viable alternative for use in the field and serve as another means of controlling the mortality caused by the pathogen. Our study provides the first report of vaccination, using immersion, against francisellosis at the most susceptible stages of farmed Nile tilapia. Future studies should address the efficiency of immersion vaccines under field conditions.
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Affiliation(s)
- Thaís F Oliveira
- Department of Preventive Veterinary Medicine, Veterinary School, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Guilherme A Quieróz
- Department of Preventive Veterinary Medicine, Veterinary School, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Marcia P Leibowitz
- Department of Preventive Veterinary Medicine, Veterinary School, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Carlos Augusto Gomes Leal
- Department of Preventive Veterinary Medicine, Veterinary School, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil.
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de Oliveira AL, Barbieri NL, Newman DM, Young MM, Nolan LK, Logue CM. Characterizing the Type 6 Secretion System (T6SS) and its role in the virulence of avian pathogenic Escherichia coli strain APECO18. PeerJ 2021; 9:e12631. [PMID: 35003930 PMCID: PMC8686734 DOI: 10.7717/peerj.12631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 11/22/2021] [Indexed: 11/22/2022] Open
Abstract
Avian pathogenic E. coli is the causative agent of extra-intestinal infections in birds known as colibacillosis, which can manifest as localized or systemic infections. The disease affects all stages of poultry production, resulting in economic losses that occur due to morbidity, carcass condemnation and increased mortality of the birds. APEC strains have a diverse virulence trait repertoire, which includes virulence factors involved in adherence to and invasion of the host cells, serum resistance factors, and toxins. However, the pathogenesis of APEC infections remains to be fully elucidated. The Type 6 secretion (T6SS) system has recently gained attention due to its role in the infection process and protection of bacteria from host defenses in human and animal pathogens. Previous work has shown that T6SS components are involved in the adherence to and invasion of host cells, as well as in the formation of biofilm, and intramacrophage bacterial replication. Here, we analyzed the frequency of T6SS genes hcp, impK, evpB, vasK and icmF in a collection of APEC strains and their potential role in virulence-associated phenotypes of APECO18. The T6SS genes were found to be significantly more prevalent in APEC than in fecal E. coli isolates from healthy birds. Expression of T6SS genes was analyzed in culture media and upon contact with host cells. Mutants were generated for hcp, impK, evpB, and icmF and characterized for their impact on virulence-associated phenotypes, including adherence to and invasion of host model cells, and resistance to predation by Dictyostelium discoideum. Deletion of the aforementioned genes did not significantly affect adherence and invasion capabilities of APECO18. Deletion of hcp reduced resistance of APECO18 to predation by D. discoideum, suggesting that T6SS is involved in the virulence of APECO18.
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Affiliation(s)
- Aline L. de Oliveira
- Department of Population Health, University of Georgia, Athens, GA, United States of America
- Department of Microbiology, University of Georgia, Athens, GA, United States of America
| | - Nicolle L. Barbieri
- Department of Population Health, University of Georgia, Athens, GA, United States of America
| | - Darby M. Newman
- Department of Population Health, University of Georgia, Athens, GA, United States of America
| | - Meaghan M. Young
- Department of Population Health, University of Georgia, Athens, GA, United States of America
| | - Lisa K. Nolan
- Department of Infectious Diseases, University of Georgia, Athens, GA, United States of America
| | - Catherine M. Logue
- Department of Population Health, University of Georgia, Athens, GA, United States of America
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Lin J, Xu L, Yang J, Wang Z, Shen X. Beyond dueling: roles of the type VI secretion system in microbiome modulation, pathogenesis and stress resistance. STRESS BIOLOGY 2021; 1:11. [PMID: 37676535 PMCID: PMC10441901 DOI: 10.1007/s44154-021-00008-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Accepted: 08/09/2021] [Indexed: 09/08/2023]
Abstract
Bacteria inhabit diverse and dynamic environments, where nutrients may be limited and toxic chemicals can be prevalent. To adapt to these stressful conditions, bacteria have evolved specialized protein secretion systems, such as the type VI secretion system (T6SS) to facilitate their survival. As a molecular syringe, the T6SS expels various effectors into neighboring bacterial cells, eukaryotic cells, or the extracellular environment. These effectors improve the competitive fitness and environmental adaption of bacterial cells. Although primarily recognized as antibacterial weapons, recent studies have demonstrated that T6SSs have functions beyond interspecies competition. Here, we summarize recent research on the role of T6SSs in microbiome modulation, pathogenesis, and stress resistance.
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Affiliation(s)
- Jinshui Lin
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan'an University, Yan'an, Shaanxi, 716000, People's Republic of China
| | - Lei Xu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, People's Republic of China
| | - Jianshe Yang
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan'an University, Yan'an, Shaanxi, 716000, People's Republic of China
| | - Zhuo Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, People's Republic of China
| | - Xihui Shen
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, People's Republic of China.
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Hoare R, Leigh W, Limakom T, Wongwaradechkul R, Metselaar M, Shinn AP, Ngo TPH, Thompson KD, Adams A. Oral vaccination of Nile tilapia (Oreochromis niloticus) against francisellosis elevates specific antibody titres in serum and mucus. FISH & SHELLFISH IMMUNOLOGY 2021; 113:86-88. [PMID: 33826937 DOI: 10.1016/j.fsi.2021.03.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 03/22/2021] [Accepted: 03/29/2021] [Indexed: 06/12/2023]
Abstract
Although Nile tilapia (Oreochromis niloticus) is a well-established aquaculture species globally, there are a limited number of commercial vaccines available or are used for this species. The majority of diseases affecting farmed tilapia are bacterial, with antibiotics frequently used to treat fish. The current study was performed to optimise the use of mucosal vaccines for tilapia by adapting an existing bacterin vaccine against Francisella noatunensis subsp. orientalis (Fno) as a proof of concept. This vaccine has previously provided excellent protection by injection, however, the preference for tilapia farmers would be to vaccinate fish by immersion or orally, due to the lower cost and ease of application. These vaccination routes, however, are often less efficacious probably due to the lack of adjuvants in immersion and oral vaccines. The aims of this study, therefore, were to optimise the formulation and dose of the Fno vaccine with mucosal adjuvants for oral and immersion delivery. Tilapia fry (av. 6 g) were given three concentrations (high, medium, low; i.e. 1×109, 1×108 and 1×107 CFU mL-1) of antigen combined with the oral adjuvant by oral gavage, to optimise the dose needed to induce an immune response to Fno, and the immune response obtained compared with fish vaccinated by immersion (with and without an immersion adjuvant). Fry were boosted by the same route at 420 degree days (DD), and samples (serum, mucus ) taken at 840 DD for specific antibody responses measured by ELISA and western blotting. Specific IgM titres were significantly elevated in serum and mucus of fish given the high dose adjuvanted vaccine by gavage. In addition, by western blotting with serum, a significant immunogenic reaction was evident between 20 and 37 kDa in the fish given the high dose oral vaccine by gavage. As protection against Fno provided by the injection vaccine was correlated with specific antibody responses these findings suggest the oral vaccine also has potential to provide protection. Further studies are needed to optimise delivery of the vaccine via feed.
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Affiliation(s)
- R Hoare
- Institute of Aquaculture, University of Stirling, Stirling, UK.
| | - W Leigh
- Institute of Aquaculture, University of Stirling, Stirling, UK
| | - T Limakom
- Benchmark R&D (Thailand) Ltd., Saensook, Chonburi, 20000, Thailand
| | | | - M Metselaar
- Benchmark Animal Health, Bush House, Edinburgh Technopole, Edinburgh, UK
| | - A P Shinn
- Benchmark R&D (Thailand) Ltd., Saensook, Chonburi, 20000, Thailand
| | - T P H Ngo
- Aquacultural Biotechnology Division, Biotechnology Centre of Ho Chi Minh City, Viet Nam
| | - K D Thompson
- Moredun Research Institute, Pentland Science Park, Penicuik, UK
| | - A Adams
- Institute of Aquaculture, University of Stirling, Stirling, UK
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Larva of greater wax moth Galleria mellonella is a suitable alternative host for the fish pathogen Francisella noatunensis subsp. orientalis. BMC Microbiol 2020; 20:8. [PMID: 31918661 PMCID: PMC6953311 DOI: 10.1186/s12866-020-1695-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 12/31/2019] [Indexed: 12/26/2022] Open
Abstract
Background Francisella noatunensis subsp. orientalis (Fno) is the etiological agent of francisellosis in cultured warm water fish, such as tilapia. Antibiotics are administered to treat the disease but a better understanding of Fno infection biology will inform improved treatment and prevention measures. However, studies with native hosts are costly and considerable benefits would derive from access to a practical alternative host. Here, larvae of Galleria mellonella were assessed for suitability to study Fno virulence. Results Larvae were killed by Fno in a dose-dependent manner but the insects could be rescued from lethal doses of bacteria by antibiotic therapy. Infection progression was assessed by histopathology (haematoxylin and eosin staining, Gram Twort and immunohistochemistry) and enumeration of bacteria recovered from the larval haemolymph on selective agar. Fno was phagocytosed and could survive intracellularly, which is consistent with observations in fish. Virulence of five Fno isolates showed strong agreement between G. mellonella and red Nile tilapia hosts. Conclusions This study shows that an alternative host, G. mellonella, can be applied to understand Fno infections, which will assist efforts to identify solutions to piscine francisellosis thus securing the livelihoods of tilapia farmers worldwide and ensuring the production of this important food source.
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Pereira FL, Tavares GC, de Carvalho AF, Rosa JCC, Rezende CP, Leal CAG, Figueiredo HCP. Effects of temperature changes in the transcriptional profile of the emerging fish pathogen Francisella noatunensis subsp. orientalis. Microb Pathog 2019; 133:103548. [PMID: 31112771 DOI: 10.1016/j.micpath.2019.103548] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 05/16/2019] [Accepted: 05/17/2019] [Indexed: 01/05/2023]
Abstract
One of the major challenges in Nile tilapia (Oreochromis niloticus L.) farming is the occurrence of bacterial infections, and the Francisella noatunensis subsp. orientalis (FNO) is an important pathogen that has emerged in last decades. Francisellosis outbreaks have been reported in the literature as occurring seasonally when water temperature is below 24 °C. The aim of this study was to quantify the median lethal doses (LD50) of FNO in experimental challenges at 28 °C and 22 °C, and to investigate the impact of temperature changes in whole genome expression using microarray technology. The LD50 for Nile tilapia at 28 °C was ∼105.7, whereas at 22 °C, the LD50 was ∼102.2, showing that the decrease in temperature enhanced disease outcome. Out of 1917 genes screened, a total of 31 and 19 genes were down- and up-regulated at 22 °C, respectively. These genes were grouped by orthology into functional categories of: amino acid, inorganic ion, and carbohydrate transport and metabolism; transcription; and posttranslational modification, protein turnover, and chaperones. Expression of genes related to metabolism, oxidative stress, and thermal shock were regulated by temperature changes, reflecting an ability of FNO to adapt to the environment. Expression of virulence genes usually required for the Francisella genus was not changed between tested temperatures, including that of genes located on the Francisella Pathogenicity Island.
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Affiliation(s)
- Felipe Luiz Pereira
- AQUACEN, National Reference Laboratory for Aquatic Animal Diseases, Ministry of Agriculture, Livestock and Food Supply, Federal University of Minas Gerais, Brazil.
| | - Guilherme Campos Tavares
- AQUACEN, National Reference Laboratory for Aquatic Animal Diseases, Ministry of Agriculture, Livestock and Food Supply, Federal University of Minas Gerais, Brazil.
| | - Alex Fiorini de Carvalho
- AQUACEN, National Reference Laboratory for Aquatic Animal Diseases, Ministry of Agriculture, Livestock and Food Supply, Federal University of Minas Gerais, Brazil.
| | - Júlio César Camara Rosa
- AQUACEN, National Reference Laboratory for Aquatic Animal Diseases, Ministry of Agriculture, Livestock and Food Supply, Federal University of Minas Gerais, Brazil.
| | - Cristiana Perdigão Rezende
- AQUACEN, National Reference Laboratory for Aquatic Animal Diseases, Ministry of Agriculture, Livestock and Food Supply, Federal University of Minas Gerais, Brazil.
| | - Carlos Augusto Gomes Leal
- AQUACEN, National Reference Laboratory for Aquatic Animal Diseases, Ministry of Agriculture, Livestock and Food Supply, Federal University of Minas Gerais, Brazil.
| | - Henrique César Pereira Figueiredo
- AQUACEN, National Reference Laboratory for Aquatic Animal Diseases, Ministry of Agriculture, Livestock and Food Supply, Federal University of Minas Gerais, Brazil. http://www.vet.ufmg.br/
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