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Sun XN, Wang Q, Wang YF, Tao Y, Zheng CL, Wang MH, Che MY, Cui ZH, Li XL, Zhang Q, Xu MX, Wang S, Nie P, Sun YL. Isolation and identification of vapA-absent Aeromonas salmonicida in diseased snakehead Channa argus in China. Int Microbiol 2024; 27:1137-1150. [PMID: 38062211 DOI: 10.1007/s10123-023-00455-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 11/10/2023] [Accepted: 11/13/2023] [Indexed: 08/06/2024]
Abstract
Aeromonas salmonicida is the typical pathogen causing furunculosis, reported widely in salmonids. Because of multiple serotypes, the control of A. salmonicida-caused disease has increasingly received much attention. Recently, A. salmonicida infection was reported in non-salmonid fish species. Here, a pathogenic A. salmonicida, named as As-s, was isolated from cultured snakehead (Channa argus) in a local fish farm in Shandong, China. As-s displayed clear hemolysis, amylase, and positive catalase activities, and grew at a wide range of temperatures (10-37 °C) and pH values (5.5-8.5). As-s was highly sensitive to cefuroxime sodium, ceftriaxone, ceftazidime, piperacillin, and cefoperazone and also apparently sensitive to chloramphenicol, erythromycin, and 25% cinnamaldehyde. The Virulence array protein gene cloning' results suggested that As-s has this gene compared with the other two vapA-containing strains, despite a close relationship of these strains via phylogenetic analysis. Severe ulcers on skin, muscle, and abnormal liver, and hemorrhage in pectoral/ventral fins and anal region were observed, and exophthalmos were also noticed in infected juvenile snakehead, as well as necrosis and infiltration of blood cells emerged in the internal organs using pathological section. In addition, As-s caused high mortality in snakehead, consistently with its immune gene response. This study reports the first isolation of vapA-absent A. salmonicida in snakehead.
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Affiliation(s)
- Xin Na Sun
- School of Marine Science and Engineering, Qingdao Agricultural University, 266237, Qingdao, Shandong, China
| | - Qing Wang
- School of Marine Science and Engineering, Qingdao Agricultural University, 266237, Qingdao, Shandong, China
| | - Ying Fei Wang
- School of Marine Science and Engineering, Qingdao Agricultural University, 266237, Qingdao, Shandong, China
| | - Ye Tao
- School of Marine Science and Engineering, Qingdao Agricultural University, 266237, Qingdao, Shandong, China
| | - Chao Li Zheng
- School of Marine Science and Engineering, Qingdao Agricultural University, 266237, Qingdao, Shandong, China
| | - Ming Hao Wang
- School of Marine Science and Engineering, Qingdao Agricultural University, 266237, Qingdao, Shandong, China
| | - Ming Yue Che
- School of Marine Science and Engineering, Qingdao Agricultural University, 266237, Qingdao, Shandong, China
| | - Zhen Hao Cui
- School of Marine Sciences, Ningbo University, 315832, Ningbo, Zhejiang, China
| | - Xin Long Li
- School of Marine Science and Engineering, Qingdao Agricultural University, 266237, Qingdao, Shandong, China
| | - Qian Zhang
- School of Marine Science and Engineering, Qingdao Agricultural University, 266237, Qingdao, Shandong, China
| | - Meng Xi Xu
- School of Marine Science and Engineering, Qingdao Agricultural University, 266237, Qingdao, Shandong, China
| | - Su Wang
- School of Marine Science and Engineering, Qingdao Agricultural University, 266237, Qingdao, Shandong, China
| | - Pin Nie
- School of Marine Science and Engineering, Qingdao Agricultural University, 266237, Qingdao, Shandong, China
| | - Yan Ling Sun
- School of Marine Science and Engineering, Qingdao Agricultural University, 266237, Qingdao, Shandong, China.
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Tomioka N, Tran P T, Aoki M, Takemura Y, Syutsubo K. Escherichia coli removal in down-flow hanging sponge reactors: insights from laboratory reactor studies. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2024; 59:295-304. [PMID: 39091064 DOI: 10.1080/10934529.2024.2384205] [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: 05/10/2024] [Revised: 07/18/2024] [Accepted: 07/20/2024] [Indexed: 08/04/2024]
Abstract
Down-flow hanging sponge (DHS) reactors, employed in domestic wastewater treatment, have demonstrated efficacy in eliminating Escherichia coli and other potentially pathogenic bacteria. The aim of this study was to elucidate the mechanism of removal of E. coli by employing a cube-shaped polyurethane sponge carrier within a compact hanging reactor. An E. coli removal experiment was conducted on this prepared sponge. Escherichia. coli level was found to decrease by more than 2 logs after passing through five nutrient-restricted DHS sponges. Conversely, a newly introduced sponge did not exhibit a comparable reduction in E. coli level. Furthermore, under conditions of optimal nutritional status, the reduction in E. coli level was limited to 0.5 logs, underscoring the crucial role of nutrient restriction in achieving effective elimination. Analysis of the sponge-associated bacterial community revealed the presence of a type VI secretion system (T6SS), a competitive mechanism observed in bacteria. This finding suggests that T6SS might play a pivotal role in contributing to the observed decline in E. coli level.
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Affiliation(s)
- Noriko Tomioka
- Regional Environment Conservation Division, National Institute for Environmental Studies, Tsukuba, Japan
| | - Thao Tran P
- Regional Environment Conservation Division, National Institute for Environmental Studies, Tsukuba, Japan
- School of Chemistry and Life Science, Hanoi University of Science and Technology, Hanoi, Vietnam
| | - Masataka Aoki
- Regional Environment Conservation Division, National Institute for Environmental Studies, Tsukuba, Japan
| | - Yasuyuki Takemura
- Department of Civil Engineering, National Institute of Technology (KOSEN), Wakayama College, Gobo, Japan
| | - Kazuaki Syutsubo
- Regional Environment Conservation Division, National Institute for Environmental Studies, Tsukuba, Japan
- Research Center of Water Environment Technology, School of Engineering, The University of Tokyo, Bunkyo-ku, Japan
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He L, Huang R, Chen H, Zhao L, Zhang Z. Discovery and characterization of a novel pathogen Erwinia pyri sp. nov. associated with pear dieback: taxonomic insights and genomic analysis. Front Microbiol 2024; 15:1365685. [PMID: 38784818 PMCID: PMC11111954 DOI: 10.3389/fmicb.2024.1365685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 04/08/2024] [Indexed: 05/25/2024] Open
Abstract
In 2022, a novel disease similar to pear fire blight was found in a pear orchard in Zhangye City, Gansu Province, China. The disease mainly damages the branches, leaves, and fruits of the plant. To identify the pathogen, tissue isolation and pathogenicity testing (inoculating the potential pathogen on healthy plant tissues) were conducted. Furthermore, a comprehensive analysis encompassing the pathogen's morphological, physiological, and biochemical characteristics and whole-genome sequencing was conducted. The results showed that among the eight isolates, the symptoms on the detached leaves and fruits inoculated with isolate DE2 were identical to those observed in the field. Verifying Koch's postulates confirmed that DE2 was the pathogenic bacterium that causes the disease. Based on a 16S rRNA phylogenetic tree, isolate DE2 belongs to the genus Erwinia. Biolog and API 20E results also indicated that isolate DE2 is an undescribed species of Erwinia. Isolate DE2 was negative for oxidase. Subsequently, the complete genome sequence of isolate DE2 was determined and compared to the complete genome sequences of 29 other Erwinia species based on digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) analyses. The ANI and dDDH values between strain DE2 and Erwinia species were both below the species thresholds (ANI < 95-96%, dDDH<70%), suggesting that isolate DE2 is a new species of Erwinia. We will temporarily name strain DE2 as Erwinia pyri sp. nov. There were 548 predicted virulence factors in the genome of strain DE2, comprising 534 on the chromosome and 5 in the plasmids. The whole genome sequence of strain DE2 has been submitted to the NCBI database (ASM3075845v1) with accession number GCA_030758455.1. The strain DE2 has been preserved at the China Center for Type Culture Collection (CCTCC) under the deposit number CCTCC AB 2024080. This study represents the initial report of a potentially new bacterial species in the genus Erwinia that causes a novel pear dieback disease. The findings provide a valuable strain resource for the study of the genus Erwinia and establish a robust theoretical foundation for the prevention and control of emerging pear dieback diseases.
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Affiliation(s)
| | | | | | | | - Zhenfen Zhang
- Key Laboratory of Grassland Ecosystem, Ministry of Education, Sino-U.S. Centers for Grazing Land Ecosystem Sustainability, Ministry of Science and Technology, Pratacultural College, Gansu Agricultural University, Lanzhou, China
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Lu L, Qi Z, Chen Z, Wang H, Wei X, Zhao B, Wang Z, Shao Y, Tu J, Song X. Avian pathogenic Escherichia coli T6SS effector protein Hcp2a causes mitochondrial dysfunction through interaction with LETM1 protein in DF-1 cells. Poult Sci 2024; 103:103514. [PMID: 38367471 PMCID: PMC10879833 DOI: 10.1016/j.psj.2024.103514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/25/2024] [Accepted: 01/25/2024] [Indexed: 02/19/2024] Open
Abstract
The type VI secretion system (T6SS) of avian pathogenic Escherichia coli (APEC) can affect the functions of eukaryotic cells by secreting or injecting effectors. Hemolysin co-regulatory protein (Hcp), one of the markers of the T6SS, is both a structural protein and an effector protein of the T6SS. According to previous studies, mitochondria in eukaryotic cells are targeted by pathogenic bacteria. However, little is known about the regulation of mitochondria in eukaryotic host cells by the T6SS effector protein Hcp of APEC. In our study, DF-1 cells co-incubated with Hcp2a protein for 6 h showed decreased mitochondrial membrane potential, increased Ca2+ concentration, and increased cellular reactive oxygen species (ROS) levels. We therefore conclude that Hcp2a protein causes dysfunction to mitochondria in DF-1 cells. To explain the mechanism that causes mitochondrial dysfunction, we reanalyzed the Hcp2a interaction protein dataset in DF-1 cells, and the Leucine zipper EF-hand-containing transmembrane protein 1 (LETM1), which is associated with mitochondria, was screened. The protein and molecular docking results showed that Hcp2a protein and LETM1 protein have better binding. Finally, subcellular localization results showed that Hcp2a was localized to mitochondria. In summary, Hcp2a effector proteins caused dysfunction to DF-1 cellular mitochondria, and we hypothesize that the interaction of Hcp2a protein with LETM1 protein induces mitochondrial dysfunction and promotes mitochondrial localization of Hcp2a in DF-1 cells.
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Affiliation(s)
- Liting Lu
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China; Anhui Province Engineering Laboratory for Animal Food Quality and Bio-Safety, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China
| | - Zhao Qi
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China; Anhui Province Engineering Laboratory for Animal Food Quality and Bio-Safety, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China
| | - Zhe Chen
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China; Anhui Province Engineering Laboratory for Animal Food Quality and Bio-Safety, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China
| | - Haiyang Wang
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China; Anhui Province Engineering Laboratory for Animal Food Quality and Bio-Safety, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China
| | - Xiyang Wei
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China; Anhui Province Engineering Laboratory for Animal Food Quality and Bio-Safety, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China
| | - Bingyu Zhao
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China; Anhui Province Engineering Laboratory for Animal Food Quality and Bio-Safety, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China
| | - Zhenyu Wang
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China; Anhui Province Engineering Laboratory for Animal Food Quality and Bio-Safety, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China
| | - Ying Shao
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China; Anhui Province Engineering Laboratory for Animal Food Quality and Bio-Safety, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China
| | - Jian Tu
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China; Anhui Province Engineering Laboratory for Animal Food Quality and Bio-Safety, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China; Joint Research Center for Food Nutrition and Health of IHM, Anhui Agricultural University, Hefei, PR China
| | - Xiangjun Song
- Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China; Anhui Province Engineering Laboratory for Animal Food Quality and Bio-Safety, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China; Joint Research Center for Food Nutrition and Health of IHM, Anhui Agricultural University, Hefei, PR China.
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5
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Neil B, Cheney GL, Rosenzweig JA, Sha J, Chopra AK. Antimicrobial resistance in aeromonads and new therapies targeting quorum sensing. Appl Microbiol Biotechnol 2024; 108:205. [PMID: 38349402 PMCID: PMC10864486 DOI: 10.1007/s00253-024-13055-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 01/31/2024] [Accepted: 02/05/2024] [Indexed: 02/15/2024]
Abstract
Aeromonas species (spp.) are well-known fish pathogens, several of which have been recognized as emerging human pathogens. The organism is capable of causing a wide spectrum of diseases in humans, ranging from gastroenteritis, wound infections, and septicemia to devastating necrotizing fasciitis. The systemic form of infection is often fatal, particularly in patients with underlying chronic diseases. Indeed, recent trends demonstrate rising numbers of hospital-acquired Aeromonas infections, especially in immuno-compromised individuals. Additionally, Aeromonas-associated antibiotic resistance is an increasing challenge in combating both fish and human infections. The acquisition of antibiotic resistance is related to Aeromonas' innate transformative properties including its ability to share plasmids and integron-related gene cassettes between species and with the environment. As a result, alternatives to antibiotic treatments are desperately needed. In that vein, many treatments have been proposed and studied extensively in the fish-farming industry, including treatments that target Aeromonas quorum sensing. In this review, we discuss current strategies targeting quorum sensing inhibition and propose that such studies empower the development of novel chemotherapeutic approaches to combat drug-resistant Aeromonas spp. infections in humans. KEY POINTS: • Aeromonas notoriously acquires and maintains antimicrobial resistance, making treatment options limited. • Quorum sensing is an essential virulence mechanism in Aeromonas infections. • Inhibiting quorum sensing can be an effective strategy in combating Aeromonas infections in animals and humans.
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Affiliation(s)
- Blake Neil
- Department of Microbiology and Immunology, Medical Branch, University of Texas, Galveston, TX, 77555, USA
| | - Gabrielle L Cheney
- John Sealy School of Medicine, Medical Branch, University of Texas, Galveston, TX, 77555, USA
| | - Jason A Rosenzweig
- Department of Biology, Texas Southern University, Houston, TX, 77004, USA
| | - Jian Sha
- Department of Microbiology and Immunology, Medical Branch, University of Texas, Galveston, TX, 77555, USA
| | - Ashok K Chopra
- Department of Microbiology and Immunology, Medical Branch, University of Texas, Galveston, TX, 77555, USA.
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Kjellin J, Lee D, Steinsland H, Dwane R, Barth Vedoy O, Hanevik K, Koskiniemi S. Colicins and T6SS-based competition systems enhance enterotoxigenic E. coli (ETEC) competitiveness. Gut Microbes 2024; 16:2295891. [PMID: 38149626 PMCID: PMC10761095 DOI: 10.1080/19490976.2023.2295891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 12/13/2023] [Indexed: 12/28/2023] Open
Abstract
Diarrheal diseases are still a significant problem for humankind, causing approximately half a million deaths annually. To cause diarrhea, enteric bacterial pathogens must first colonize the gut, which is a niche occupied by the normal bacterial microbiota. Therefore, the ability of pathogenic bacteria to inhibit the growth of other bacteria can facilitate the colonization process. Although enterotoxigenic Escherichia coli (ETEC) is one of the major causative agents of diarrheal diseases, little is known about the competition systems found in and used by ETEC and how they contribute to the ability of ETEC to colonize a host. Here, we collected a set of 94 fully assembled ETEC genomes by performing whole-genome sequencing and mining the NCBI RefSeq database. Using this set, we performed a comprehensive search for delivered bacterial toxins and investigated how these toxins contribute to ETEC competitiveness in vitro. We found that type VI secretion systems (T6SS) were widespread among ETEC (n = 47). In addition, several closely related ETEC strains were found to encode Colicin Ia and T6SS (n = 8). These toxins provide ETEC competitive advantages during in vitro competition against other E. coli, suggesting that the role of T6SS as well as colicins in ETEC biology has until now been underappreciated.
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Affiliation(s)
- Jonas Kjellin
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Danna Lee
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Hans Steinsland
- CISMAC, Centre for International Health, Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Rachel Dwane
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Oda Barth Vedoy
- Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Kurt Hanevik
- Department of Clinical Science, University of Bergen, Bergen, Norway
- National centre for Tropical Infectious Diseases, Department of Medicine, Haukeland University Hospital, Bergen, Norway
| | - Sanna Koskiniemi
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
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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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Hespanhol JT, Nóbrega-Silva L, Bayer-Santos E. Regulation of type VI secretion systems at the transcriptional, posttranscriptional and posttranslational level. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001376. [PMID: 37552221 PMCID: PMC10482370 DOI: 10.1099/mic.0.001376] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 07/25/2023] [Indexed: 08/09/2023]
Abstract
Bacteria live in complex polymicrobial communities and are constantly competing for resources. The type VI secretion system (T6SS) is a widespread antagonistic mechanism used by Gram-negative bacteria to gain an advantage over competitors. T6SSs translocate toxic effector proteins inside target prokaryotic cells in a contact-dependent manner. In addition, some T6SS effectors can be secreted extracellularly and contribute to the scavenging scarce metal ions. Bacteria deploy their T6SSs in different situations, categorizing these systems into offensive, defensive and exploitative. The great variety of bacterial species and environments occupied by such species reflect the complexity of regulatory signals and networks that control the expression and activation of the T6SSs. Such regulation is tightly controlled at the transcriptional, posttranscriptional and posttranslational level by abiotic (e.g. pH, iron) or biotic (e.g. quorum-sensing) cues. In this review, we provide an update on the current knowledge about the regulatory networks that modulate the expression and activity of T6SSs across several species, focusing on systems used for interbacterial competition.
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Affiliation(s)
- Julia Takuno Hespanhol
- Department of Microbiology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo 05508-900, Brazil
| | - Luize Nóbrega-Silva
- Department of Microbiology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo 05508-900, Brazil
| | - Ethel Bayer-Santos
- Department of Microbiology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo 05508-900, Brazil
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Lee HJ, Storesund JE, Lunestad BT, Hoel S, Lerfall J, Jakobsen AN. Whole genome sequence analysis of Aeromonas spp. isolated from ready-to-eat seafood: antimicrobial resistance and virulence factors. Front Microbiol 2023; 14:1175304. [PMID: 37455746 PMCID: PMC10348363 DOI: 10.3389/fmicb.2023.1175304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 06/08/2023] [Indexed: 07/18/2023] Open
Abstract
Aeromonas are widespread in aquatic environments and are considered emerging pathogens in humans and animals. Multidrug resistant (MDR) Aeromonas circulating in the aquatic environment and food production chain can potentially disseminate antimicrobial resistance (AMR) to humans via the foodborne route. In this study, we aimed to investigate AMR and virulence factors of 22 Aeromonas strains isolated from ready-to-eat (RTE) seafood. A multilocus phylogenetic analysis (MLPA) using the concatenated sequences of six housekeeping genes (gyrB, rpoD, gyrA, recA, dnaJ, and dnaX) in the 22 Aeromonas genomes and average nucleotide identity (ANI) analysis revealed eight different species; A. caviae, A. dhakensis, A. hydrophila, A. media, A. rivipollensis, A. salmonicida, A. bestiarum, and A. piscicola. The presence of virulence genes, AMR genes and mobile genetic elements (MGEs) in the Aeromonas genomes was predicted using different databases. Our data showed that the genes responsible for adherence and motility (Msh type IV pili, tap type IV pili, polar flagella), type II secretion system (T2SS) and hemolysins were present in all strains, while the genes encoding enterotoxins and type VI secretion system (T6SS) including major effectors were highly prevalent. Multiple AMR genes encoding β-lactamases such as cphA and blaOXA were detected, and the distribution of those genes was species-specific. In addition, the quinolone resistance gene, qnrS2 was found in a IncQ type plasmid of the A. rivopollensis strain A539. Furthermore, we observed the co-localization of a class I integron (intl1) with two AMR genes (sul1 and aadA1), and a Tn521 transposon carrying a mercury operon in A. caviae strain SU4-2. Various MGEs including other transposons and insertion sequence (IS) elements were identified without strongly associating with detected AMR genes or virulence genes. In conclusion, Aeromonas strains in RTE seafood were potentially pathogenic, carrying several virulence-related genes. Aeromonas carrying multiple AMR genes and MGEs could potentially be involved in the dissemination and spread of AMR genes to other bacterial species residing in the same environment and possibly to humans. Considering a One-Health approach, we highlight the significance of monitoring AMR caused by Aeromonas circulating in the food chain.
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Affiliation(s)
- Hye-Jeong Lee
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology, Trondheim, Norway
| | - Julia E. Storesund
- Section for Contaminants and Biohazards, Institute of Marine Research, Bergen, Norway
| | - Bjørn-Tore Lunestad
- Section for Contaminants and Biohazards, Institute of Marine Research, Bergen, Norway
| | - Sunniva Hoel
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology, Trondheim, Norway
| | - Jørgen Lerfall
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology, Trondheim, Norway
| | - Anita Nordeng Jakobsen
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology, Trondheim, Norway
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Chi Y, Jiao H, Ran J, Xiong C, Wei J, Ozdemir E, Wu R. Construction and efficacy of Aeromonas veronii mutant Δhcp as a live attenuated vaccine for the largemouth bass (Micropterus salmoides). FISH & SHELLFISH IMMUNOLOGY 2023; 136:108694. [PMID: 36944414 DOI: 10.1016/j.fsi.2023.108694] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 03/13/2023] [Accepted: 03/15/2023] [Indexed: 06/18/2023]
Abstract
Aeromonas veronii is a human and animal co-pathogenic bacterium that could have a significant negative impact on both human health and aquaculture. In this study, a mutant strain of A. veronii with deletion of the hemolysin co-regulated protein (hcp) gene was constructed (Δhcp-AV). Compared with the wild strain, Δhcp-AV showed significantly reduced growth capacity and biofilm formation ability. Motility tests showed that the hcp gene had no significant effect on the swimming and swarming ability. In addition, the pathogenicity was also reduced. To evaluate the efficacy of Δhcp-AV as a live attenuated vaccine for prevention of Aeromonas veronii infection, we compared the immune response of largemouth bass (Micropterus salmoides) after immunization with 500 μL of 1.47 × 105 CFU/mL of Δhcp-AV and 4 × 108 CFU/mL of inactivated A. veronii. Obvious increases of serum immune related enzyme activity were observed in immunization groups. Expression levels of immune-related genes in Δhcp-AV group were up-regulated, and higher than those in inactivated A. veronii group. After challenging with live A. veronii, the relative percent survival (RPS) was 100% in Δhcp- AV group, whereas the RPS was 76.67% in inactivated A. veronii group. Our data suggest that the live attenuated vaccine Δhcp- AV could elicit a stronger immune response and provide a higher RPS than inactivated A. veronii. These data suggest that hcp gene is an important virulence factor of A. veronii, and the live attenuated vaccine Δhcp-AV is safe and effective for prevention A. veronii infection in M. salmoides farming.
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Affiliation(s)
- Yuyu Chi
- College of Fisheries, Southwest University, Chongqing, 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development, Minister of Education, Southwest University, Chongqing, 400715, China.
| | - Hanyang Jiao
- College of Fisheries, Southwest University, Chongqing, 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development, Minister of Education, Southwest University, Chongqing, 400715, China.
| | - Jiayan Ran
- College of Fisheries, Southwest University, Chongqing, 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development, Minister of Education, Southwest University, Chongqing, 400715, China.
| | - Chuanyu Xiong
- College of Fisheries, Southwest University, Chongqing, 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development, Minister of Education, Southwest University, Chongqing, 400715, China.
| | - Jinming Wei
- College of Fisheries, Southwest University, Chongqing, 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development, Minister of Education, Southwest University, Chongqing, 400715, China.
| | - Eda Ozdemir
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, 39762, USA.
| | - Ronghua Wu
- College of Fisheries, Southwest University, Chongqing, 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development, Minister of Education, Southwest University, Chongqing, 400715, China.
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11
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Singh RP, Kumari K. Bacterial type VI secretion system (T6SS): an evolved molecular weapon with diverse functionality. Biotechnol Lett 2023; 45:309-331. [PMID: 36683130 DOI: 10.1007/s10529-023-03354-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 12/14/2022] [Accepted: 01/05/2023] [Indexed: 01/24/2023]
Abstract
Bacterial secretion systems are nanomolecular complexes that release a diverse set of virulence factors/or proteins into its surrounding or translocate to their target host cells. Among these systems, type VI secretion system 'T6SS' is a recently discovered molecular secretion system which is widely distributed in Gram-negative (-ve) bacteria, and shares structural similarity with the puncturing device of bacteriophages. The presence of T6SS is an advantage to many bacteria as it delivers toxins to its neighbour pathogens for competitive survival, and also translocates protein effectors to the host cells, leading to disruption of lipid membranes, cell walls, and cytoskeletons etc. Recent studies have characterized both anti-prokaryotic and anti-eukaryotic effectors, where T6SS is involved in diverse cellular functions including favouring colonization, enhancing the survival, adhesive modifications, internalization, and evasion of the immune system. With the evolution of advanced genomics and proteomics tools, there has been an increase in the number of characterized T6SS effector arsenals and also more clear information about the adaptive significance of this complex system. The functions of T6SS are generally regulated at the transcription, post-transcription and post-translational levels through diverse mechanisms. In the present review, we aimed to provide information about the distribution of T6SS in diverse bacteria, any structural similarity/or dissimilarity, effectors proteins, functional significance, and regulatory mechanisms. We also tried to provide information about the diverse roles played by T6SS in its natural environments and hosts, and further any changes in the microbiome.
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Affiliation(s)
- Rajnish Prakash Singh
- Department of Bioengineering and Biotechnology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand, 835215, India.
| | - Kiran Kumari
- Department of Bioengineering and Biotechnology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand, 835215, India
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12
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VgrG Spike Dictates PAAR Requirement for the Assembly of the Type VI Secretion System. J Bacteriol 2023; 205:e0035622. [PMID: 36655996 PMCID: PMC9945574 DOI: 10.1128/jb.00356-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Widely employed by Gram-negative pathogens for competition and pathogenesis, the type six protein secretion system (T6SS) can inject toxic effectors into neighboring cells through the penetration of a spear-like structure comprising a long Hcp tube and a VgrG-PAAR spike complex. The cone-shaped PAAR is believed to sharpen the T6SS spear for penetration but it remains unclear why PAAR is required for T6SS functions in some bacteria but dispensable in others. Here, we report the conditional requirement of PAAR for T6SS functions in Aeromonas dhakensis, an emerging human pathogen that may cause severe bacteremia. By deleting the two PAAR paralogs, we show that PAAR is not required for T6SS secretion, bacterial killing, or specific effector delivery in A. dhakensis. By constructing combinatorial PAAR and vgrG deletions, we demonstrate that deletion of individual PAAR moderately reduced T6SS functions but double or triple deletions of PAAR in the vgrG deletion mutants severely impaired T6SS functions. Notably, the auxiliary-cluster-encoded PAAR2 and VgrG3 are less critical than the main-cluster-encoded PAAR1 and VgrG1&2 proteins to T6SS functions. In addition, PAAR1 but not PAAR2 contributes to antieukaryotic virulence in amoeba. Our data suggest that, for a multi-PAAR T6SS, the variable role of PAAR paralogs correlates with the VgrG-spike composition that collectively dictates T6SS assembly. IMPORTANCE Gram-negative bacteria often encode multiple paralogs of the cone-shaped PAAR that sits atop the VgrG-spike and is thought to sharpen the spear-like T6SS puncturing device. However, it is unclear why PAAR is required for the assembly of some but not all T6SSs and why there are multiple PAARs if they are not required. Our data delineate a VgrG-mediated conditional requirement for PAAR and suggest a core-auxiliary relationship among different PAAR-VgrG modules that may have been acquired sequentially by the T6SS during evolution.
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13
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Song L, Yang H, Meng X, Su R, Cheng S, Wang H, Bai X, Guo D, Lü X, Xia X, Shi C. Inhibitory Effects of Trans-Cinnamaldehyde Against Pseudomonas aeruginosa Biofilm Formation. Foodborne Pathog Dis 2023; 20:47-58. [PMID: 36779942 DOI: 10.1089/fpd.2022.0073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023] Open
Abstract
Pseudomonas aeruginosa biofilm formation has been considered to be an important determinant of its pathogenicity in most infections. The antibiofilm activity of trans-cinnamaldehyde (TC) against P. aeruginosa was investigated in this study. Results demonstrated that the minimum inhibitory concentration (MIC) of TC against P. aeruginosa was 0.8 mg/mL, and subinhibitory concentrations (SICs) was 0.2 mg/mL and below. Crystal violet staining showed that TC at 0.05-0.2 mg/mL reduced biofilm biomass in 48 h in a concentration-dependent mode. The formation area of TC-treated biofilms was significantly declined (p < 0.01) on the glass slides observed by light microscopy. Field-emission scanning electron microscopy further demonstrated that TC destroyed the biofilm morphology and structure. Confocal laser scanning microscopic observed the dispersion of biofilms and the reduction of exopolysaccharides after TC treatment stained with concanavalin A (Con-A)-fluorescein isothiocyanate conjugate and Hoechst 33258. Meanwhile, TC caused a significant decrease (p < 0.01) in the component of polysaccharides, proteins, and DNA in extracellular polymeric substance. The swimming and swarming motility and quorum sensing of P. aeruginosa was also found to be significantly inhibited (p < 0.01) by TC at SICs. Furthermore, SICs of TC repressed the several genes transcription associated with biofilm formation as determined by real-time quantitative polymerase chain reaction. Overall, our findings suggest that TC could be applied as natural and safe antibiofilm agent to inhibit the biofilm formation of P. aeruginosa.
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Affiliation(s)
- Luyi Song
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Hui Yang
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Xinru Meng
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Ruiying Su
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Shuai Cheng
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Haoran Wang
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Xiangyang Bai
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Du Guo
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Xin Lü
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Xiaodong Xia
- School of Food Science and Technology, National Engineering Research Center of Seafood, Dalian Polytechnic University, Dalian, China
| | - Chao Shi
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
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14
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Wang Y, Zeng M, Xia L, Valerie Olovo C, Su Z, Zhang Y. Bacterial strategies for immune systems - Role of the type VI secretion system. Int Immunopharmacol 2023; 114:109550. [PMID: 36525796 DOI: 10.1016/j.intimp.2022.109550] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 11/09/2022] [Accepted: 12/02/2022] [Indexed: 12/15/2022]
Abstract
The process of host infection by bacteria is complicated. Bacterial infections strongly induce the host immune system, which necessitates a robust clearance of the infection. However, bacteria have over time developed strategies that enable their evasion of attacks by the host immune system. One such strategy is the type VI secretion system (T6SS), a special needle-like secretion system that is widespread in Gram-negative bacteria and is responsible for delivering effector proteins into the external bacterial environment or directly into the host cell cytosol. Bacterial T6SS and its secreted effector proteins play an important role in the interaction between bacteria and host immune system. They also serve as antigens that are employed in the development of vaccines for clinical trials as well as future vaccine candidates. This review focuses mainly on aspects of T6SS effectors that impact the strength of the host immune system, including inflammation, autophagy, and apoptosis (silent programmed cell death). The T6SS-based vaccines are also described.
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Affiliation(s)
- Yurou Wang
- Institute for Medical Immunology of Jiangsu University, Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu 212013, China; Department of Biochemistry and Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China
| | - Minmin Zeng
- Department of Biochemistry and Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China
| | - Lin Xia
- Department of Laboratory Medicine, Affiliated Hospital of Jiangsu University, Zhenjiang 212001, China; International Genome Center, Jiangsu University, Zhenjiang 212013, China
| | - Chinasa Valerie Olovo
- Department of Biochemistry and Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China
| | - Zhaoliang Su
- Institute for Medical Immunology of Jiangsu University, Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu 212013, China; International Genome Center, Jiangsu University, Zhenjiang 212013, China
| | - Ying Zhang
- Institute for Medical Immunology of Jiangsu University, Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu 212013, China; Department of Biochemistry and Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China.
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15
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Effector protein Hcp2a of avian pathogenic Escherichia coli interacts with the endoplasmatic reticulum associated RPL23 protein of chicken DF-1 fibroblasts. Vet Res 2023; 54:6. [PMID: 36717947 PMCID: PMC9885592 DOI: 10.1186/s13567-023-01138-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 01/06/2023] [Indexed: 01/31/2023] Open
Abstract
The type VI secretion system (T6SS) is a secretion apparatus widely found in pathogenic Gram-negative bacteria and is important for competition among various bacteria and host cell pathogenesis. Hcp is a core component of functional T6SS and transports toxic effectors into target cells by assembling to form tube-like structures. Studies have shown that Hcp simultaneously acts as an effector to influence cellular physiological activities; however, the mechanism of its activity in host cells remains unclear. To investigate the target of effector protein Hcp2a in a chicken fibroblast cell line, we first detected the subcellular localization of Hcp2a in DF-1 cells by indirect immunofluorescence assay. The results showed that Hcp2a protein was localized in the endoplasmic reticulum of DF-1 cells. We also used a streptavidin-biotin affinity pull-down assay combined with LC-MS/MS to screen DF-1 cell lysates for proteins that interact with Hcp2a and analyze the cellular functional pathways affected by them. The results showed that Hcp2a interacted with 52 DF-1 cellular proteins that are involved in multiple intracellular pathways. To further explore the mechanism of Hcp2a protein targeting the endoplasmic reticulum of DF-1 cells, we screened three endoplasmic reticulum-associated proteins (RSL1D1, RPS3A, and RPL23) from 52 prey proteins of Hcp2a for protein-protein molecular docking analysis. The docking analysis showed that the effector protein Hcp2a and the RPL23 protein had good complementarity. Overall, we propose that Hcp2a has strong binding activity to the RPL23 protein in DF-1 cells and this may help Hcp2a anchor to the endoplasmic reticulum in DF-1 cells.
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16
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Dubey S, Ager-Wick E, Peng B, Evensen Ø, Sørum H, Munang’andu HM. Characterization of virulence and antimicrobial resistance genes of Aeromonas media strain SD/21-15 from marine sediments in comparison with other Aeromonas spp. Front Microbiol 2022; 13:1022639. [PMID: 36532448 PMCID: PMC9752117 DOI: 10.3389/fmicb.2022.1022639] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 10/06/2022] [Indexed: 10/03/2023] Open
Abstract
Aeromonas media is a Gram-negative bacterium ubiquitously found in aquatic environments. It is a foodborne pathogen associated with diarrhea in humans and skin ulceration in fish. In this study, we used whole genome sequencing to profile all antimicrobial resistance (AMR) and virulence genes found in A. media strain SD/21-15 isolated from marine sediments in Denmark. To gain a better understanding of virulence and AMR genes found in several A. media strains, we included 24 whole genomes retrieved from the public databanks whose isolates originate from different host species and environmental samples from Asia, Europe, and North America. We also compared the virulence genes of strain SD/21-15 with A. hydrophila, A. veronii, and A. salmonicida reference strains. We detected Msh pili, tap IV pili, and lateral flagella genes responsible for expression of motility and adherence proteins in all isolates. We also found hylA, hylIII, and TSH hemolysin genes in all isolates responsible for virulence in all isolates while the aerA gene was not detected in all A. media isolates but was present in A. hydrophila, A. veronii, and A. salmonicida reference strains. In addition, we detected LuxS and mshA-Q responsible for quorum sensing and biofilm formation as well as the ferric uptake regulator (Fur), heme and siderophore genes responsible for iron acquisition in all A. media isolates. As for the secretory systems, we found all genes that form the T2SS in all isolates while only the vgrG1, vrgG3, hcp, and ats genes that form parts of the T6SS were detected in some isolates. Presence of bla MOX-9 and bla OXA-427 β-lactamases as well as crp and mcr genes in all isolates is suggestive that these genes were intrinsically encoded in the genomes of all A. media isolates. Finally, the presence of various transposases, integrases, recombinases, virulence, and AMR genes in the plasmids examined in this study is suggestive that A. media has the potential to transfer virulence and AMR genes to other bacteria. Overall, we anticipate these data will pave way for further studies on virulence mechanisms and the role of A. media in the spread of AMR genes.
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Affiliation(s)
- Saurabh Dubey
- Section for Experimental Biomedicine, Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Eirill Ager-Wick
- Section for Experimental Biomedicine, Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Bo Peng
- State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, School of Life Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Higher Education Mega Center, Guangzhou, China
| | - Øystein Evensen
- Department of Paraclinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Henning Sørum
- Department of Paraclinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
| | - Hetron Mweemba Munang’andu
- Section for Experimental Biomedicine, Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Ås, Norway
- Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
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17
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Song L, Wu J, Weng K, Yao F, Vongsangnak W, Zhu G, Chen G, Zhang Y, Xu Q. The salmonella effector Hcp modulates infection response, and affects salmonella adhesion and egg contamination incidences in ducks. Front Cell Infect Microbiol 2022; 12:948237. [PMID: 36262184 PMCID: PMC9575552 DOI: 10.3389/fcimb.2022.948237] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 07/05/2022] [Indexed: 11/17/2022] Open
Abstract
Salmonella Entertidis (SE) often causes persistent infections and egg contamination in laying ducks. Hcp, the core structural and effector proteins of the Type VI Secretion System (T6SS) in SE, contributes to bacterial invasion, adhesion and virulence. However, little is known about the effect of Hcp on the host’s infection responses and egg contamination incidences in duck. Herein, we generated an hcp deletion mutant SE MY1△hcp and detected its ability to invade duck granulosa cells (dGCs) and contaminate eggs. In comparison with MY1-infected group, the SE adhesion decreased by 15.96% in MY1△hcp-infected dGCs, and the apoptosis in MY1△hcp-infected dGCs decreased by 26.58% and 30.99% at 3 and 6 hours postinfection, respectively. However, the expression levels of immunogenic genes TLR4, NOD1, TNFα, IL-1β and proinflammatory cytokines IL-6, IL-1β, TNF-α release were markedly lower in the dGCs inoculated with MY1△hcp than that of the wild type. Besides, the laying ducks were challenged with MY1 or MY1△hcp in vivo, respectively. The lower egg production and higher egg contamination were observed in MY1-infected ducks in comparison with MY1△hcp-infected birds. Furthermore, the host’s infection response of differentially abundant proteins (DAPs) to Salmonella effector Hcp was identified using quantitative proteomics. A total of 164 DAPs were identified between the MY1- and MY1△hcp-infected cells, which were mainly engaged in the immune, hormone synthesis, cell proliferation and cell apoptotic process. Among them, STAT3, AKT1, MAPK9, MAPK14, and CREBBP were the center of the regulatory network, which might serve as key host response regulators to bacterial Hcp. In conclusion, we demonstrated that effector Hcp contributed to not only SE invasion, induction of dGCs apoptosis, and trigger of immune responses, but also enhanced contamination incidences. Also, the STAT3, AKT1, MAPK9, MAPK14, and CREBBP were identified as host’s infection response regulators of bacterial Hcp in duck. Overall, these results not only offered a novel evidence of SE ovarian transmission but also identified some promising candidate regulators during SE infection.
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Affiliation(s)
- Lina Song
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
| | - Jia Wu
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
| | - Kaiqi Weng
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
| | - Fenghua Yao
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
| | - Wanwipa Vongsangnak
- Department of Zoology, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - Guoqiang Zhu
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
| | - Guohong Chen
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
| | - Yu Zhang
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
- *Correspondence: Yu Zhang,
| | - Qi Xu
- Joint International Research Laboratory of Agriculture & Agri-Product Safety of Ministry of Education, Yangzhou University, Yangzhou, China
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
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18
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Heterologous Assembly of the Type VI Secretion System Empowers Laboratory Escherichia coli with Antimicrobial and Cell Penetration Capabilities. Appl Environ Microbiol 2022; 88:e0130522. [PMID: 36154120 DOI: 10.1128/aem.01305-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The synthetic biology toolbox has amassed a vast number of diverse functional modules, but protein translocation modules for cell penetration and cytosol-to-cytosol delivery remain relatively scarce. The type VI secretion system (T6SS), commonly found in many Gram-negative pathogens, functions as a contractile device to translocate protein toxins to prokaryotic and eukaryotic cells. Here, we have assembled the T6SS of Aeromonas dhakensis, an opportunistic waterborne pathogen, in the common laboratory strain Escherichia coli BL21(DE3). We constructed a series of plasmids (pT6S) carrying the T6SS structural and effector genes under native or tetracycline-inducible promoters, the latter for controlled expression. Using fluorescence microscopy and biochemical analyses, we demonstrate a functional T6SS in E. coli capable of secreting proteins directly into the cytosol of neighboring bacteria and outcompeting a number of drug-resistant pathogens. The heterologous assembly of T6SS not only confers the lab workhorse E. coli with the cytosol-to-cytosol protein delivery capability but also demonstrates the potential for harnessing the T6SS of various pathogens for general protein delivery and antibacterial applications. IMPORTANCE The T6SS is a powerful and versatile protein delivery system. However, the complexity of its macromolecular structure and gene regulation makes it not a trivial task to reconstitute the T6SSs of pathogens in a nonpathogenic host. In this study, we have assembled an inducible T6SS in E. coli BL21(DE3) and demonstrated its functions in protein delivery and antimicrobial activities. The engineered T6SS empowers E. coli to deliver protein cargos into a wide range of prokaryotic and eukaryotic cells.
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19
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Tena-Garitaonaindia M, Ceacero-Heras D, Montoro MDMM, de Medina FS, Martínez-Augustin O, Daddaoua A. A Standardized Extract of Lentinula edodes Cultured Mycelium Inhibits Pseudomonas aeruginosa Infectivity Mechanisms. Front Microbiol 2022; 13:814448. [PMID: 35369436 PMCID: PMC8966770 DOI: 10.3389/fmicb.2022.814448] [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: 11/13/2021] [Accepted: 02/14/2022] [Indexed: 12/03/2022] Open
Abstract
The priority pathogen list of the World Health Organization classified Pseudomonas aeruginosa as the second top critical pathogen. Hence, the development of novel antibacterial strategies to tackle this bacterium is highly necessary. Herein we explore the potential antibacterial effect of a standardized extract of cultured mycelium of Lentinula edodes (AHCC®) on P. aeruginosa. AHCC® was found to inhibit the growth rate and biofilm formation of strain PAO1. No change in swarming was observed, but AHCC® hampered swimming and twitching motility. In accordance, a decreased expression of metabolism, growth, and biofilm formation genes was shown. AHCC® also diminished the levels of exotoxin A and bacteria inside IEC18 cells and the secretion of IL-6, IL-10 and TNF by infected macrophages. This effect was related to a reduced phosphorylation of MAPKs and to bacteria internalization. Taken together, our data suggest that AHCC® has a potential role to prevent P. aeruginosa infections and may lead to the development of new therapies.
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Affiliation(s)
- Mireia Tena-Garitaonaindia
- Department of Biochemistry and Molecular Biology II, Pharmacy School, University of Granada, Granada, Spain
| | - Diego Ceacero-Heras
- Department of Biochemistry and Molecular Biology II, Pharmacy School, University of Granada, Granada, Spain
| | - María Del Mar Maldonado Montoro
- Clinical Analysis Service, Hospital Campus de la Salud, Granada, Spain.,Instituto de Investigación Biosanitaria (IBS), Granada, Spain
| | - Fermín Sánchez de Medina
- Department of Pharmacology, School of Pharmacy, University of Granada, Granada, Spain.,Department of Pharmacology, Pharmacy School, University of Granada, Granada, Spain
| | - Olga Martínez-Augustin
- Department of Biochemistry and Molecular Biology II, Pharmacy School, University of Granada, Granada, Spain.,Instituto de Investigación Biosanitaria (IBS), Granada, Spain.,Department of Pharmacology, Pharmacy School, University of Granada, Granada, Spain.,Institute of Nutrition and Food Technology "José Mataix," Center of Biomedical Research, University of Granada, Granada, Spain
| | - Abdelali Daddaoua
- Department of Biochemistry and Molecular Biology II, Pharmacy School, University of Granada, Granada, Spain.,Instituto de Investigación Biosanitaria (IBS), Granada, Spain.,Institute of Nutrition and Food Technology "José Mataix," Center of Biomedical Research, University of Granada, Granada, Spain
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20
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Zhao Y, Liu Y, Li N, Muhammad M, Gong S, Ju J, Cai T, Wang J, Zhao B, Liu D. Significance of broad-spectrum racemases for the viability and pathogenicity of Aeromonas hydrophila. Future Microbiol 2022; 17:251-265. [PMID: 35152710 DOI: 10.2217/fmb-2021-0112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aim: To investigate the function of broad-spectrum racemases in Aeromonas hydrophila (BsrA). Results: The A. hydrophila gene encoding BsrA (bsr) mutants (AHΔbsr) exhibited a significant decrease in growth, motility, extracellular protease production and biofilm formation compared with the wild-type. Furthermore, bsr gene knockout instigated cell wall damage compared with the wild-type strains. The survival rate and replication capability in the blood and organs of the AHΔbsr-infected mice were significantly decreased. The degree of tissue injury in the AHΔbsr-infected group was lower than that of the wild-type-infected group. Moreover, there was a significant decrease in the expression of 12 AHΔbsr virulence genes. Conclusion: The bsr gene is essential for the viability and virulence of A. hydrophila.
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Affiliation(s)
- Yi Zhao
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Yaoyao Liu
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Na Li
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Murtala Muhammad
- Department of Biochemistry, Kano University of Science and Technology, Wudil, 713281, Nigeria
| | - Siyu Gong
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Jiansong Ju
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Tongxuan Cai
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Jialu Wang
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Baohua Zhao
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Dong Liu
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
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21
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Li J, Wu Z, Wu C, Chen DD, Zhou Y, Zhang YA. VasH Contributes to Virulence of Aeromonas hydrophila and Is Necessary to the T6SS-mediated Bactericidal Effect. Front Vet Sci 2021; 8:793458. [PMID: 34966816 PMCID: PMC8710571 DOI: 10.3389/fvets.2021.793458] [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: 10/26/2021] [Accepted: 11/09/2021] [Indexed: 11/16/2022] Open
Abstract
Aeromonas hydrophila is a Gram-negative bacterium that is commonly distributed in aquatic surroundings and has been considered as a pathogen of fish, amphibians, reptiles, and mammals. In this study, a virulent strain A. hydrophila GD18, isolated from grass carp (Ctenopharyngodon idella), was characterized to belong to a new sequence type ST656. Whole-genome sequencing and phylogenetic analysis showed that GD18 was closer to environmental isolates, however distantly away from the epidemic ST251 clonal group. The type VI secretion system (T6SS) was known to target both eukaryotic and prokaryotic cells by delivering various effector proteins in diverse niches by Gram-negative bacteria. Genome-wide searching and hemolysin co-regulated protein (Hcp) expression test showed that GD18 possessed a functional T6SS and is conditionally regulated. Further analysis revealed that VasH, a σ54-transcriptional activator, was strictly required for the functionality of T6SS in A. hydrophila GD18. Mutation of vasH gene by homologous recombination significantly abolished the bactericidal property. Then the virulence contribution of VasH was characterized in both in vitro and in vivo models. The results supported that VasH not only contributed to the bacterial cytotoxicity and resistance against host immune cleaning, but also was required for virulence and systemic dissemination of A. hydrophila GD18. Taken together, these findings provide a perspective for understanding the VasH-mediated regulation mechanism and T6SS-mediated virulence and bactericidal effect of A. hydrophila.
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Affiliation(s)
- Jihong Li
- Institute of Hydrobiology, Chinese Academy of Sciences (CAS), Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Zhihao Wu
- State Key Laboratory of Agricultural Microbiology, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Changsong Wu
- State Key Laboratory of Agricultural Microbiology, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Dan-Dan Chen
- Institute of Hydrobiology, Chinese Academy of Sciences (CAS), Wuhan, China
| | - Yang Zhou
- State Key Laboratory of Agricultural Microbiology, College of Fisheries, Huazhong Agricultural University, Wuhan, China.,Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, Wuhan, China.,Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Yong-An Zhang
- Institute of Hydrobiology, Chinese Academy of Sciences (CAS), Wuhan, China.,State Key Laboratory of Agricultural Microbiology, College of Fisheries, Huazhong Agricultural University, Wuhan, China.,Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, Wuhan, China.,Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
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22
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da Silva Filho AC, Marchaukoski JN, Raittz RT, De Pierri CR, de Jesus Soares Machado D, Fadel-Picheth CMT, Picheth G. Prediction and Analysis in silico of Genomic Islands in Aeromonas hydrophila. Front Microbiol 2021; 12:769380. [PMID: 34912316 PMCID: PMC8667584 DOI: 10.3389/fmicb.2021.769380] [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: 09/01/2021] [Accepted: 11/01/2021] [Indexed: 11/13/2022] Open
Abstract
Aeromonas are Gram-negative rods widely distributed in the environment. They can cause severe infections in fish related to financial losses in the fish industry, and are considered opportunistic pathogens of humans causing infections ranging from diarrhea to septicemia. The objective of this study was to determine in silico the contribution of genomic islands to A. hydrophila. The complete genomes of 17 A. hydrophila isolates, which were separated into two phylogenetic groups, were analyzed using a genomic island (GI) predictor. The number of predicted GIs and their characteristics varied among strains. Strains from group 1, which contains mainly fish pathogens, generally have a higher number of predicted GIs, and with larger size, than strains from group 2 constituted by strains recovered from distinct sources. Only a few predicted GIs were shared among them and contained mostly genes from the core genome. Features related to virulence, metabolism, and resistance were found in the predicted GIs, but strains varied in relation to their gene content. In strains from group 1, O Ag biosynthesis clusters OX1 and OX6 were identified, while strains from group 2 each had unique clusters. Metabolic pathways for myo-inositol, L-fucose, sialic acid, and a cluster encoding QueDEC, tgtA5, and proteins related to DNA metabolism were identified in strains of group 1, which share a high number of predicted GIs. No distinctive features of group 2 strains were identified in their predicted GIs, which are more diverse and possibly better represent GIs in this species. However, some strains have several resistance attributes encoded by their predicted GIs. Several predicted GIs encode hypothetical proteins and phage proteins whose functions have not been identified but may contribute to Aeromonas fitness. In summary, features with functions identified on predicted GIs may confer advantages to host colonization and competitiveness in the environment.
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Affiliation(s)
| | - Jeroniza Nunes Marchaukoski
- Department of Bioinformatics, Professional and Technical Education Sector, Federal University of Parana, Curitiba, Brazil
| | - Roberto Tadeu Raittz
- Department of Bioinformatics, Professional and Technical Education Sector, Federal University of Parana, Curitiba, Brazil
| | | | - Diogo de Jesus Soares Machado
- Department of Bioinformatics, Professional and Technical Education Sector, Federal University of Parana, Curitiba, Brazil
| | | | - Geraldo Picheth
- Department of Clinical Analysis, Federal University of Parana, Curitiba, Brazil
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23
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Liang X, Pei TT, Li H, Zheng HY, Luo H, Cui Y, Tang MX, Zhao YJ, Xu P, Dong T. VgrG-dependent effectors and chaperones modulate the assembly of the type VI secretion system. PLoS Pathog 2021; 17:e1010116. [PMID: 34852023 PMCID: PMC8668125 DOI: 10.1371/journal.ppat.1010116] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 12/13/2021] [Accepted: 11/15/2021] [Indexed: 11/19/2022] Open
Abstract
The type VI secretion system (T6SS) is a spear-like nanomachine found in gram-negative pathogens for delivery of toxic effectors to neighboring bacterial and host cells. Its assembly requires a tip spike complex consisting of a VgrG-trimer, a PAAR protein, and the interacting effectors. However, how the spike controls T6SS assembly remains elusive. Here we investigated the role of three VgrG-effector pairs in Aeromonas dhakensis strain SSU, a clinical isolate with a constitutively active T6SS. By swapping VgrG tail sequences, we demonstrate that the C-terminal ~30 amino-acid tail dictates effector specificity. Double deletion of vgrG1&2 genes (VgrG3+) abolished T6SS secretion, which can be rescued by ectopically expressing chimeric VgrG3 with a VgrG1/2-tail but not the wild type VgrG3. In addition, deletion of effector-specific chaperones also severely impaired T6SS secretion, despite the presence of intact VgrG and effector proteins, in both SSU and Vibrio cholerae V52. We further show that SSU could deliver a V. cholerae effector VasX when expressing a plasmid-borne chimeric VgrG with VasX-specific VgrG tail and chaperone sequences. Pull-down analyses show that two SSU effectors, TseP and TseC, could interact with their cognate VgrGs, the baseplate protein TssK, and the key assembly chaperone TssA. Effectors TseL and VasX could interact with TssF, TssK and TssA in V. cholerae. Collectively, we demonstrate that chimeric VgrG-effector pairs could bypass the requirement of heterologous VgrG complex and propose that effector-stuffing inside the baseplate complex, facilitated by chaperones and the interaction with structural proteins, serves as a crucial structural determinant for T6SS assembly. Effectors of bacterial secretion systems are generally considered as secreted proteins for interspecies interactions rather than components of the secretion apparatus. Our results reveal the complex interactions of effectors, chaperones, and structural proteins are crucial for T6SS assembly, suggesting an integral role of effectors as parts of the apparatus and distinctive from other secretion systems.
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Affiliation(s)
- Xiaoye Liang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Tong-Tong Pei
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Hao Li
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Hao-Yu Zheng
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Han Luo
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Yang Cui
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Ming-Xuan Tang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Ya-Jie Zhao
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Ping Xu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Tao Dong
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
- * E-mail:
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24
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Abstract
Genetic editing has revolutionized biotechnology, but delivery of endonuclease genes as DNA can lead to aberrant integration or overexpression, leading to off-target effects. Here, we develop a mechanism to deliver Cre recombinase as a protein by engineering the bacterial type six secretion system (T6SS). Using multiple T6SS fusion proteins, Aeromonas dhakensis or attenuated Vibrio cholerae donor strains, and a gain-of-function cassette for detecting Cre recombination, we demonstrate successful delivery of active Cre directly into recipient cells. The most efficient transfer was achieved using a truncated version of PAAR2 from V. cholerae, resulting in a relatively small (118-amino-acid) delivery tag. We further demonstrate the versatility of this system by delivering an exogenous effector, TseC, enabling V. cholerae to kill Pseudomonas aeruginosa. This implies that P. aeruginosa is naturally resistant to all native effectors of V. cholerae and that the TseC chaperone protein is not required for its activity. Moreover, it demonstrates that the engineered system can improve T6SS efficacy against specific pathogens, proposing future application in microbiome manipulation or as a next-generation antimicrobial. Inexpensive and easy to produce, this protein delivery system has many potential applications, ranging from studying T6SS effectors to genetic editing.
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25
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Sensing of intracellular Hcp levels controls T6SS expression in Vibrio cholerae. Proc Natl Acad Sci U S A 2021; 118:2104813118. [PMID: 34161288 DOI: 10.1073/pnas.2104813118] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The type 6 secretion system (T6SS) is a bacterial weapon broadly distributed in gram-negative bacteria and used to kill competitors and predators. Featuring a long and double-tubular structure, this molecular machine is energetically costly to produce and thus is likely subject to diverse regulation strategies that are largely ill defined. In this study, we report a quantity-sensing control of the T6SS that down-regulates the expression of secreted components when they accumulate in the cytosol due to T6SS inactivation. Using Vibrio cholerae strains that constitutively express an active T6SS, we demonstrate that mRNA levels of secreted components, including the inner-tube protein component Hcp, were down-regulated in T6SS structural gene mutants while expression of the main structural genes remained unchanged. Deletion of both hcp gene copies restored expression from their promoters, while Hcp overexpression negatively impacted expression. We show that Hcp directly interacts with the RpoN-dependent T6SS regulator VasH, and deleting the N-terminal regulator domain of VasH abolishes this interaction as well as the expression difference of hcp operons between T6SS-active and inactive strains. We find that negative regulation of hcp also occurs in other V. cholerae strains and the pathogens Aeromonas dhakensis and Pseudomonas aeruginosa This Hcp-dependent sensing control is likely an important energy-conserving mechanism that enables T6SS-encoding organisms to quickly adjust T6SS expression and prevent wasteful build-up of its major secreted components in the absence of their efficient export out of the bacterial cell.
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26
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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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27
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Characterization of Lysozyme-Like Effector TseP Reveals the Dependence of Type VI Secretion System (T6SS) Secretion on Effectors in Aeromonas dhakensis Strain SSU. Appl Environ Microbiol 2021; 87:e0043521. [PMID: 33837015 DOI: 10.1128/aem.00435-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The type VI secretion system (T6SS) is a widespread weapon employed by Gram-negative bacteria for interspecies interaction in complex communities. Analogous to a contractile phage tail, the double-tubular T6SS injects toxic effectors into prokaryotic and eukaryotic neighboring cells. Although effectors dictate T6SS functions, their identities remain elusive in many pathogens. Here, we report the lysozyme-like effector TseP in Aeromonas dhakensis, a waterborne pathogen that can cause severe gastroenteritis and systemic infection. Using secretion, competition, and enzymatic assays, we demonstrate that TseP is a T6SS-dependent effector with cell wall-lysing activities, and TsiP is its cognate immunity protein. Triple deletion of tseP and two known effector genes, tseI and tseC, abolished T6SS-mediated secretion, while complementation with any single effector gene partially restored bacterial killing and Hcp secretion. In contrast to whole-gene deletions, the triple-effector inactivation in the 3effc mutant abolished antibacterial killing but not T6SS secretion. We further demonstrate that the 3effc mutation abolished T6SS-mediated toxicity of SSU to Dictyostelium discoideum amoebae, suggesting that the T6SS physical puncture is nontoxic to eukaryotic cells. These data highlight not only the necessity of possessing functionally diverse effectors for survival in multispecies communities but also that effector inactivation would be an efficient strategy to detoxify the T6SS while preserving its delivery efficiency, converting the T6SS to a platform for protein delivery to a variety of recipient cells. IMPORTANCE Delivery of cargo proteins via protein secretion systems has been shown to be a promising tool in various applications. However, secretion systems are often used by pathogens to cause disease. Thus, strategies are needed to detoxify secretion systems while preserving their efficiency. The T6SS can translocate proteins through physical puncture of target cells without specific surface receptors and can target a broad range of recipients. In this study, we identified a cell wall-lysing effector, and by inactivating it and the other two known effectors, we have built a detoxified T6SS-active strain that may be used for protein delivery to prokaryotic and eukaryotic recipient cells.
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28
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Moriel B, de Campos Prediger K, de Souza EM, Pedrosa FO, Fadel-Picheth CMT, Cruz LM. In silico comparative analysis of Aeromonas Type VI Secretion System. Braz J Microbiol 2021; 52:229-243. [PMID: 33410103 DOI: 10.1007/s42770-020-00405-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 11/12/2020] [Indexed: 12/29/2022] Open
Abstract
Aeromonas are bacteria broadly spread in the environment, particularly in aquatic habitats and can induce human infections. Several virulence factors have been described associated with bacterial pathogenicity, such as the Type VI Secretion System (T6SS). This system translocates effector proteins into target cells through a bacteriophage-like contractile structure encoded by tss genes. Here, a total of 446 Aeromonas genome sequences were screened for T6SS and the proteins subjected to in silico analysis. The T6SS-encoding locus was detected in 243 genomes and its genes are encoded in a cluster containing 13 core and 5 accessory genes, in highly conserved synteny. The amino acid residues identity of T6SS proteins ranges from 78 to 98.8%. In most strains, a pair of tssD and tssI is located upstream the cluster (tssD-2, tssI-2) and another pair was detected distant from the cluster (tssD-1, tssI-1). Significant variability was seen in TssI (VgrG) C-terminal region, which was sorted in four groups based on its sequence length and protein domains. TssI containing ADP-ribosyltransferase domain are associated exclusively with TssI-1, while genes coding proteins carrying DUF4123 (a conserved domain of unknown function) were observed downstream tssI-1 or tssI-2 and escort of possible effector proteins. Genes coding proteins containing DUF1910 and DUF1911 domains were located only downstream tssI-2 and might represent a pair of toxin/immunity proteins. Nearly all strains display downstream tssI-3, that codes for a lysozyme family domain protein. These data reveal that Aeromonas T6SS cluster synteny is conserved and the low identity observed for some genes might be due to species heterogeneity or its niche/functionality.
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Affiliation(s)
- Barbara Moriel
- Department of Clinical Analysis, Setor de Ciências da Saúde, Curitiba, Brazil
| | | | - Emanuel M de Souza
- Department of Biochemistry and Molecular Biology, Setor de Ciências Biológicas, Curitiba, PR, Brazil
| | - Fábio O Pedrosa
- Department of Biochemistry and Molecular Biology, Setor de Ciências Biológicas, Curitiba, PR, Brazil
| | | | - Leonardo M Cruz
- Department of Biochemistry and Molecular Biology, Setor de Ciências Biológicas, Curitiba, PR, Brazil.
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29
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Mahmud AKMF, Nilsson K, Fahlgren A, Navais R, Choudhury R, Avican K, Fällman M. Genome-Scale Mapping Reveals Complex Regulatory Activities of RpoN in Yersinia pseudotuberculosis. mSystems 2020; 5:e01006-20. [PMID: 33172972 PMCID: PMC7657599 DOI: 10.1128/msystems.01006-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 10/20/2020] [Indexed: 11/26/2022] Open
Abstract
RpoN, an alternative sigma factor commonly known as σ54, is implicated in persistent stages of Yersinia pseudotuberculosis infections in which genes associated with this regulator are upregulated. We here combined phenotypic and genomic assays to provide insight into its role and function in this pathogen. RpoN was found essential for Y. pseudotuberculosis virulence in mice, and in vitro functional assays showed that it controls biofilm formation and motility. Mapping genome-wide associations of Y. pseudotuberculosis RpoN using chromatin immunoprecipitation coupled with next-generation sequencing identified an RpoN binding motif located at 103 inter- and intragenic sites on both sense and antisense strands. Deletion of rpoN had a large impact on gene expression, including downregulation of genes encoding proteins involved in flagellar assembly, chemotaxis, and quorum sensing. There were also clear indications of cross talk with other sigma factors, together with indirect effects due to altered expression of other regulators. Matching differential gene expression with locations of the binding sites implicated around 130 genes or operons potentially activated or repressed by RpoN. Mutagenesis of selected intergenic binding sites confirmed both positive and negative regulatory effects of RpoN binding. Corresponding mutations of intragenic sense sites had less impact on associated gene expression. Surprisingly, mutating intragenic sites on the antisense strand commonly reduced expression of genes carried by the corresponding sense strand.IMPORTANCE The alternative sigma factor RpoN (σ54), which is widely distributed in eubacteria, has been implicated in controlling gene expression of importance for numerous functions including virulence. Proper responses to host environments are crucial for bacteria to establish infection, and regulatory mechanisms involved are therefore of high interest for development of future therapeutics. Little is known about the function of RpoN in the intestinal pathogen Y. pseudotuberculosis, and we therefore investigated its regulatory role in this pathogen. This regulator was indeed found to be critical for establishment of infection in mice, likely involving its requirement for motility and biofilm formation. The RpoN regulon involved both activating and suppressive effects on gene expression which could be confirmed with mutagenesis of identified binding sites. This is the first study of its kind of RpoN in Y. pseudotuberculosis, revealing complex regulation of gene expression involving both productive and silent effects of its binding to DNA, providing important information about RpoN regulation in enterobacteria.
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Affiliation(s)
- A K M Firoj Mahmud
- Department of Molecular Biology, Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Kristina Nilsson
- Department of Molecular Biology, Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Anna Fahlgren
- Department of Molecular Biology, Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Roberto Navais
- Department of Molecular Biology, Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Rajdeep Choudhury
- Department of Molecular Biology, Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Kemal Avican
- Department of Molecular Biology, Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Maria Fällman
- Department of Molecular Biology, Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
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30
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Liu L, Song L, Deng R, Lan R, Jin W, Tran Van Nhieu G, Cao H, Liu Q, Xiao Y, Li X, Meng G, Ren Z. Citrobacter freundii Activation of NLRP3 Inflammasome via the Type VI Secretion System. J Infect Dis 2020; 223:2174-2185. [PMID: 33151309 DOI: 10.1093/infdis/jiaa692] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 11/03/2020] [Indexed: 12/27/2022] Open
Abstract
Citrobacter freundii is a significant cause of human infections, responsible for food poisoning, diarrhea, and urinary tract infections. We previously identified a highly cytotoxic and adhesive C. freundii strain CF74 expressing a type VI secretion system (T6SS). In this study, we showed that in mice-derived macrophages, C. freundii CF74 activated the Nucleotide Oligomerization Domain -Like Receptor Family, Pyrin Domain Containing 3(NLRP3) inflammasomes in a T6SS-dependent manner. The C. freundii T6SS activated the inflammasomes mainly through caspase 1 and mediated pyroptosis of macrophages by releasing the cleaved gasdermin-N domain. The CF74 T6SS was required for flagellin-induced interleukin 1β release by macrophages. We further show that the T6SS tail component and effector, hemolysin co-regulation protein-2 (Hcp-2), was necessary and sufficient to trigger NLRP3 inflammasome activation. In vivo, the T6SS played a key role in mediating interleukin 1β secretion and the survival of mice during C. freundii infection in mice. These findings provide novel insights into the role of T6SS in the pathogenesis of C. freundii.
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Affiliation(s)
- Liyun Liu
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Research Units of Discovery of Unknown Bacteria and Function (2018RU010), Chinese Academy of Medical Sciences, Beijing, China
| | - Liqiong Song
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Research Units of Discovery of Unknown Bacteria and Function (2018RU010), Chinese Academy of Medical Sciences, Beijing, China
| | - Rong Deng
- The Center for Microbes, Development and Health, CAS Key Laboratory of Molecular Virology & Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
| | - Ruiting Lan
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Wenjie Jin
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Research Units of Discovery of Unknown Bacteria and Function (2018RU010), Chinese Academy of Medical Sciences, Beijing, China
| | - Guy Tran Van Nhieu
- Calcium Signaling and Microbial Infections, Inserm U1282, Laboratoire de Biologie et Pharmacologie Appliquée, UMR 8113, Ecole Normale Supérieure Paris Saclay, Gif-sur-Yvette, France
| | - Huifang Cao
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Qin Liu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Yuchun Xiao
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Research Units of Discovery of Unknown Bacteria and Function (2018RU010), Chinese Academy of Medical Sciences, Beijing, China
| | - Xianping Li
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Research Units of Discovery of Unknown Bacteria and Function (2018RU010), Chinese Academy of Medical Sciences, Beijing, China
| | - Guangxun Meng
- The Center for Microbes, Development and Health, CAS Key Laboratory of Molecular Virology & Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
| | - Zhihong Ren
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Research Units of Discovery of Unknown Bacteria and Function (2018RU010), Chinese Academy of Medical Sciences, Beijing, China
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Soria-Bustos J, Ares MA, Gómez-Aldapa CA, González-Y-Merchand JA, Girón JA, De la Cruz MA. Two Type VI Secretion Systems of Enterobacter cloacae Are Required for Bacterial Competition, Cell Adherence, and Intestinal Colonization. Front Microbiol 2020; 11:560488. [PMID: 33072020 PMCID: PMC7541819 DOI: 10.3389/fmicb.2020.560488] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 08/12/2020] [Indexed: 12/22/2022] Open
Abstract
Enterobacter cloacae has emerged as an opportunistic pathogen in healthcare-associated infections. Analysis of the genomic sequences of several E. cloacae strains revealed the presence of genes that code for expression of at least one type VI secretion system (T6SS). Here, we report that E. cloacae strain ATCC 13047 codes for two functional T6SS named T6SS-1 and T6SS-2. T6SS-1 and T6SS-2 were preferentially expressed in tryptic soy broth and tissue culture medium (DMEM), respectively. Mutants in T6SS-1-associated genes clpV1 and hcp1 significantly affected their ability of inter- and intra-bacterial killing indicating that T6SS-1 is required for bacterial competition. In addition, the Hcp effector protein was detected in supernatants of E. cloacae cultures and a functional T6SS-1 was required for the secretion of this protein. A clpV2 mutant was impaired in both biofilm formation and adherence to epithelial cells, supporting the notion that these phenotypes are T6SS-2 dependent. In vivo data strongly suggest that both T6SSs are required for intestinal colonization because single and double mutants in clpV1 and clpV2 genes were defective in gut colonization in mice. We conclude that the two T6SSs are involved in the pathogenesis scheme of E. cloacae with specialized functions in the interaction with other bacteria and with host cells.
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Affiliation(s)
- Jorge Soria-Bustos
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, Mexico.,Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Miguel A Ares
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, Mexico
| | - Carlos A Gómez-Aldapa
- Instituto de Ciencias Básicas e Ingeniería, Universidad Autónoma del Estado de Hidalgo, Carretera Pachuca-Tulancingo Km 4.5 Mineral de la Reforma, Hidalgo, Mexico
| | - Jorge A González-Y-Merchand
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Jorge A Girón
- Centro de Detección Biomolecular, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Miguel A De la Cruz
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, Mexico
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Horizontal Gene Transfer Clarifies Taxonomic Confusion and Promotes the Genetic Diversity and Pathogenicity of Plesiomonas shigelloides. mSystems 2020; 5:5/5/e00448-20. [PMID: 32934114 PMCID: PMC7498682 DOI: 10.1128/msystems.00448-20] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The taxonomic position of P. shigelloides has been the subject of debate for a long time, and until now, the evolutionary dynamics and pathogenesis of P. shigelloides were unclear. In this study, pan-genome analysis indicated extensive genetic diversity and the presence of large and variable gene repertoires. Our results revealed that horizontal gene transfer was the focal driving force for the genetic diversity of the P. shigelloides pan-genome and might have contributed to the emergence of novel properties. Vibrionaceae and Aeromonadaceae were found to be the predominant donor taxa for horizontal genes, which might have caused the taxonomic confusion historically. Comparative genomic analysis revealed the potential of P. shigelloides to cause intestinal and invasive diseases. Our results could advance the understanding of the evolution and pathogenesis of P. shigelloides, particularly in elucidating the role of horizontal gene transfer and investigating virulence-related elements. Plesiomonas shigelloides is an emerging pathogen that has been shown to be involved in gastrointestinal diseases and extraintestinal infections in humans. However, the taxonomic position, evolutionary dynamics, and pathogenesis of P. shigelloides remain unclear. We reported the draft genome sequences of 12 P. shigelloides strains representing different serogroups. We were able to determine a clear distinction between P. shigelloides and other members of Enterobacterales via core genome phylogeny, Neighbor-Net network, and average genome identity analysis. The pan-genome analysis of P. shigelloides revealed extensive genetic diversity and presented large flexible gene repertoires, while the core genome phylogeny exhibited a low level of clonality. The discordance between the core genome phylogeny and the pan-genome phylogeny indicated that flexible accessory genomes account for an important proportion of the evolution of P. shigelloides, which was subsequently characterized by determinations of hundreds of horizontally transferred genes (horizontal genes), massive gene expansions and contractions, and diverse mobile genetic elements (MGEs). The apparently high levels of horizontal gene transfer (HGT) in P. shigelloides were conferred from bacteria with novel properties from other taxa (mainly Vibrionaceae and Aeromonadaceae), which caused the historical taxonomic confusion and shaped the virulence gene pools. Furthermore, P. shigelloides genomes contain many macromolecular secretion system genes, virulence factor genes, and resistance genes, indicating its potential to cause intestinal and invasive infections. Collectively, our work provides insights into the phylogenetic position, evolutionary dynamic, and pathogenesis of P. shigelloides at the genomic level, which could facilitate the observation and research of this important pathogen. IMPORTANCE The taxonomic position of P. shigelloides has been the subject of debate for a long time, and until now, the evolutionary dynamics and pathogenesis of P. shigelloides were unclear. In this study, pan-genome analysis indicated extensive genetic diversity and the presence of large and variable gene repertoires. Our results revealed that horizontal gene transfer was the focal driving force for the genetic diversity of the P. shigelloides pan-genome and might have contributed to the emergence of novel properties. Vibrionaceae and Aeromonadaceae were found to be the predominant donor taxa for horizontal genes, which might have caused the taxonomic confusion historically. Comparative genomic analysis revealed the potential of P. shigelloides to cause intestinal and invasive diseases. Our results could advance the understanding of the evolution and pathogenesis of P. shigelloides, particularly in elucidating the role of horizontal gene transfer and investigating virulence-related elements.
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Radisic V, Nimje PS, Bienfait AM, Marathe NP. Marine Plastics from Norwegian West Coast Carry Potentially Virulent Fish Pathogens and Opportunistic Human Pathogens Harboring New Variants of Antibiotic Resistance Genes. Microorganisms 2020; 8:microorganisms8081200. [PMID: 32784594 PMCID: PMC7464100 DOI: 10.3390/microorganisms8081200] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 07/30/2020] [Accepted: 08/04/2020] [Indexed: 12/16/2022] Open
Abstract
To our best knowledge this is the first study characterizing fish pathogens isolated from marine plastics from the West coast of Norway for their potential for pathogenicity using whole genome sequencing. Marine plastic polymers identified as polyethylene, polyethylene/ethylene vinyl acetate copolymer and polypropylene, yielded a total of 37 bacterial isolates dominated by Pseudomonas spp. (70%). Six isolates representing either fish pathogens or opportunistic human pathogens were selected for whole genome sequencing (WGS). These included four isolates belonging to Aeromonas spp., one Acinetobacter beijerinckii isolate and one Morganella morganii isolate. Three Aeromonas salmonicida isolates were potentially virulent and carried virulence factors involved in attachment, type II and type VI secretion systems as well as toxins such as aerA/act, ahh1, ast, hlyA, rtxA and toxA. A. salmonicida and Acinetobacter beijerinckii carried new variants of antibiotic resistance genes (ARGs) such as β-lactamases and chloramphenicol acetyltransferase (catB), whereas Morganella morganii carried several clinically relevant ARGs. Our study shows that marine plastics carry not only potentially virulent fish pathogens but also multidrug resistant opportunistic human pathogens like M. morganii and may serve as vectors for transport of these pathogens in the marine environment.
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Affiliation(s)
- Vera Radisic
- Institute of Marine Research, 5005 Bergen, Norway; (V.R.); (P.S.N.); (A.M.B.)
- Department of Biological Sciences, University of Bergen, 5006 Bergen, Norway
| | - Priyank S. Nimje
- Institute of Marine Research, 5005 Bergen, Norway; (V.R.); (P.S.N.); (A.M.B.)
| | | | - Nachiket P. Marathe
- Institute of Marine Research, 5005 Bergen, Norway; (V.R.); (P.S.N.); (A.M.B.)
- Correspondence:
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Chien CF, Liu CY, Lu YY, Sung YH, Chen KY, Lin NC. HSI-II Gene Cluster of Pseudomonas syringae pv. tomato DC3000 Encodes a Functional Type VI Secretion System Required for Interbacterial Competition. Front Microbiol 2020; 11:1118. [PMID: 32582082 PMCID: PMC7283901 DOI: 10.3389/fmicb.2020.01118] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 05/05/2020] [Indexed: 11/13/2022] Open
Abstract
The type VI secretion system (T6SS) is a widespread bacterial nanoweapon used for delivery of toxic proteins into cell targets and contributes to virulence, anti-inflammatory processes, and interbacterial competition. In the model phytopathogenic bacterium Pseudomonas syringae pv. tomato (Pst) DC3000, two T6SS gene clusters, HSI-I and HSI-II, were identified, but their functions remain unclear. We previously reported that hcp2, located in HSI-II, is involved in competition with enterobacteria and yeast. Here, we demonstrated that interbacterial competition of Pst DC3000 against several Gram-negative plant-associated bacteria requires mainly HSI-II activity. By means of a systematic approach using in-frame deletion mutants for each gene in the HSI-II cluster, we identified genes indispensable for Hcp2 expression, Hcp2 secretion and interbacterial competition ability. Deletion of PSPTO_5413 only affected growth in interbacterial competition assays but not Hcp2 secretion, which suggests that PSPTO_5413 might be a putative effector. Moreover, PSPTO_5424, encoding a putative σ54-dependent transcriptional regulator, positively regulated the expression of all three operons in HSI-II. Our discovery that the HSI-II gene cluster gives Pst DC3000 the ability to compete with other plant-associated bacteria could help in understanding a possible mechanism of how phytopathogenic bacteria maintain their ecological niches.
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Affiliation(s)
- Ching-Fang Chien
- Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan
| | - Cheng-Ying Liu
- Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan
| | - Yew-Yee Lu
- Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan
| | - You-Hsing Sung
- Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan
| | - Kuo-Yau Chen
- Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan
| | - Nai-Chun Lin
- Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan
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Zhang M, Kang J, Wu B, Qin Y, Huang L, Zhao L, Mao L, Wang S, Yan Q. Comparative transcriptome and phenotype analysis revealed the role and mechanism of ompR in the virulence of fish pathogenic Aeromonas hydrophila. Microbiologyopen 2020; 9:e1041. [PMID: 32282134 PMCID: PMC7349151 DOI: 10.1002/mbo3.1041] [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: 10/31/2019] [Revised: 03/18/2020] [Accepted: 03/18/2020] [Indexed: 12/16/2022] Open
Abstract
Aeromonas hydrophila B11 strain was isolated from diseased Anguilla japonica, which had caused severe gill ulcers in farmed eel, causing huge economic losses. EnvZ‐OmpR is a model two‐component system in the bacteria and is widely used in the research of signal transduction and gene transcription regulation. In this study, the ompR of A. hydrophila B11 strain was first silenced by RNAi technology. The role of ompR in the pathogenicity of A. hydrophila B11 was investigated by analyzing both the bacterial comparative transcriptome and phenotype. The qRT‐PCR results showed that the expression of ompR in the ompR‐RNAi strain decreased by 97% compared with the wild‐type strain. The virulence test showed that after inhibition of the ompR expression, the LD50 of A. hydrophila B11 decreased by an order of magnitude, suggesting that ompR is involved in the regulation of bacterial virulence. Comparative transcriptome analysis showed that the expression of ompR can directly regulate the expression of several important virulence‐related genes, such as the bacterial type II secretion system; moreover, ompR expression also regulates the expression of multiple genes related to bacterial chemotaxis, motility, adhesion, and biofilm formation. Further studies on the phenotype of A. hydrophila B11 and ompR‐RNAi also confirmed that the downregulation of ompR expression can decrease bacterial chemotaxis, adhesion, and biofilm formation.
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Affiliation(s)
- Mengmeng Zhang
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Jianping Kang
- Fujian Fisheries Technology Extension Center, Fuzhou, China
| | - Bin Wu
- Fujian Fisheries Technology Extension Center, Fuzhou, China
| | - Yingxue Qin
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China.,Fujian Province Key Laboratory of Special Aquatic Formula Feed, Fujian Tianma Science and Technology Group Co., Ltd., Fuqing, China
| | - Lixing Huang
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Lingmin Zhao
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Leilei Mao
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Suyun Wang
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Qingpi Yan
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China
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36
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Gut Microbiota, Antibiotic Therapy and Antimicrobial Resistance: A Narrative Review. Microorganisms 2020; 8:microorganisms8020269. [PMID: 32079318 PMCID: PMC7074698 DOI: 10.3390/microorganisms8020269] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Revised: 02/08/2020] [Accepted: 02/08/2020] [Indexed: 12/13/2022] Open
Abstract
Antimicrobial resistance is a major concern. Epidemiological studies have demonstrated direct relationships between antibiotic consumption and emergence/dissemination of resistant strains. Within the last decade, authors confounded spectrum activity and ecological effects and did not take into account several other factors playing important roles, such as impact on anaerobic flora, biliary elimination and sub-inhibitory concentration. The ecological impact of antibiotics on the gut microbiota by direct or indirect mechanisms reflects the breaking of the resistance barrier to colonization. To limit the impact of antibiotic therapy on gut microbiota, consideration of the spectrum of activity and route of elimination must be integrated into the decision. Various strategies to prevent (antimicrobial stewardship, action on residual antibiotics at colonic level) or cure dysbiosis (prebiotic, probiotic and fecal microbiota transplantation) have been introduced or are currently being developed.
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37
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Fernández-Bravo A, Figueras MJ. An Update on the Genus Aeromonas: Taxonomy, Epidemiology, and Pathogenicity. Microorganisms 2020; 8:microorganisms8010129. [PMID: 31963469 PMCID: PMC7022790 DOI: 10.3390/microorganisms8010129] [Citation(s) in RCA: 249] [Impact Index Per Article: 62.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 01/10/2020] [Accepted: 01/14/2020] [Indexed: 02/07/2023] Open
Abstract
The genus Aeromonas belongs to the Aeromonadaceae family and comprises a group of Gram-negative bacteria widely distributed in aquatic environments, with some species able to cause disease in humans, fish, and other aquatic animals. However, bacteria of this genus are isolated from many other habitats, environments, and food products. The taxonomy of this genus is complex when phenotypic identification methods are used because such methods might not correctly identify all the species. On the other hand, molecular methods have proven very reliable, such as using the sequences of concatenated housekeeping genes like gyrB and rpoD or comparing the genomes with the type strains using a genomic index, such as the average nucleotide identity (ANI) or in silico DNA–DNA hybridization (isDDH). So far, 36 species have been described in the genus Aeromonas of which at least 19 are considered emerging pathogens to humans, causing a broad spectrum of infections. Having said that, when classifying 1852 strains that have been reported in various recent clinical cases, 95.4% were identified as only four species: Aeromonas caviae (37.26%), Aeromonas dhakensis (23.49%), Aeromonas veronii (21.54%), and Aeromonas hydrophila (13.07%). Since aeromonads were first associated with human disease, gastroenteritis, bacteremia, and wound infections have dominated. The literature shows that the pathogenic potential of Aeromonas is considered multifactorial and the presence of several virulence factors allows these bacteria to adhere, invade, and destroy the host cells, overcoming the immune host response. Based on current information about the ecology, epidemiology, and pathogenicity of the genus Aeromonas, we should assume that the infections these bacteria produce will remain a great health problem in the future. The ubiquitous distribution of these bacteria and the increasing elderly population, to whom these bacteria are an opportunistic pathogen, will facilitate this problem. In addition, using data from outbreak studies, it has been recognized that in cases of diarrhea, the infective dose of Aeromonas is relatively low. These poorly known bacteria should therefore be considered similarly as enteropathogens like Salmonella and Campylobacter.
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Fernández-Bravo A, Kilgore PB, Andersson JA, Blears E, Figueras MJ, Hasan NA, Colwell RR, Sha J, Chopra AK. T6SS and ExoA of flesh-eating Aeromonas hydrophila in peritonitis and necrotizing fasciitis during mono- and polymicrobial infections. Proc Natl Acad Sci U S A 2019; 116:24084-24092. [PMID: 31712444 PMCID: PMC6883842 DOI: 10.1073/pnas.1914395116] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
An earlier report described a human case of necrotizing fasciitis (NF) caused by mixed infection with 4 Aeromonas hydrophila strains (NF1-NF4). While the NF2, NF3, and NF4 strains were clonal and possessed exotoxin A (ExoA), the NF1 strain was determined to be phylogenetically distinct, harboring a unique type 6 secretion system (T6SS) effector (TseC). During NF1 and NF2 mixed infection, only NF1 disseminated, while NF2 was rapidly killed by a contact-dependent mechanism and macrophage phagocytosis, as was demonstrated by using in vitro models. To confirm these findings, we developed 2 NF1 mutants (NF1ΔtseC and NF1ΔvasK); vasK encodes an essential T6SS structural component. NF1 VasK and TseC were proven to be involved in contact-dependent killing of NF2 in vitro, as well as in its elimination at the intramuscular injection site in vivo during mixed infection, with overall reduced mouse mortality. ExoA was shown to have an important role in NF by both NF1-exoA (with cis exoA) and NF2 during monomicrobial infection. However, the contribution of ExoA was more important for NF2 than NF1 in the murine peritonitis model. The NF2∆exoA mutant did not significantly alter animal mortality or NF1 dissemination during mixed infection in the NF model, suggesting that the ExoA activity was significant at the injection site. Immunization of mice to ExoA protected animals from NF2 monomicrobial challenge, but not from polymicrobial infection because of NF2 clearance. This study clarified the roles of T6SS and ExoA in pathogenesis caused by A. hydrophila NF strains in both mouse peritonitis and NF models in monomicrobial and polymicrobial infections.
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Affiliation(s)
- Ana Fernández-Bravo
- Unidad de Microbiología, Departamento de Ciencias Médicas Básicas, Facultad de Medicina y Ciencias de la Salud, Instituto de Investigación Sanitaria Pere Virgili, Universidad Rovira i Virgili, 43201 Reus, Spain
| | - Paul B Kilgore
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, 77555
| | - Jourdan A Andersson
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, 77555
- Department of Pathology and Immunology and Texas Children's Microbiome Center, Baylor College of Medicine, Houston, TX, 77030
| | - Elizabeth Blears
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, 77555
| | - Maria José Figueras
- Unidad de Microbiología, Departamento de Ciencias Médicas Básicas, Facultad de Medicina y Ciencias de la Salud, Instituto de Investigación Sanitaria Pere Virgili, Universidad Rovira i Virgili, 43201 Reus, Spain
| | - Nur A Hasan
- Research and Development Department, CosmosID Inc., Rockville, MD 20850
- Center for Bioinformatics and Computational Biology, University of Maryland Institute for Advanced Computer Studies, University of Maryland, College Park, MD 20742
| | - Rita R Colwell
- Research and Development Department, CosmosID Inc., Rockville, MD 20850
- Center for Bioinformatics and Computational Biology, University of Maryland Institute for Advanced Computer Studies, University of Maryland, College Park, MD 20742
- Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, MD 21205
| | - Jian Sha
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, 77555;
| | - Ashok K Chopra
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, 77555;
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Prediger KDC, Dallagassa CB, Moriel B, Vizzotto BS, Volanski W, Souza EM, Pedrosa FO, Weiss V, Alberton D, Guizelini D, Fadel-Picheth CMT. Virulence characteristics and antimicrobial resistance of Aeromonas veronii biovar sobria 312M, a clinical isolate. Braz J Microbiol 2019; 51:511-518. [PMID: 31707718 DOI: 10.1007/s42770-019-00180-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 10/21/2019] [Indexed: 01/17/2023] Open
Abstract
Aeromonas are bacteria widely distributed in the environment, and some species are able to cause infections in humans, of which diarrhea is the most common. The objective of this study was to evaluate the presence of virulence and antimicrobial resistance associated characteristics in A. veronii biovar sobria strain 312M isolated from diarrheal stools. For this, the genome sequencing and phenotypical tests were performed. The draft genome annotation revealed several complete pathways associated with carbon metabolism and a mucin-desulfating sulfatase which may contribute to intestine colonization, and a large number of virulence-associated genes encoding structures associated with adhesion, toxins, and secretion systems. The strain exhibited swimming and swarming motility, biofilm formation, and hemolytic activity. It was resistant to ampicillin, ampicillin/sulbactam, and amoxicillin-clavulanic acid. Although a cphA gene encoding a narrow-spectrum carbapenase was identified in the strain genome, no carbapenemase activity was detected in the antimicrobial susceptibility test. When compared with other A. veronii with complete genomes, the main differences in virulence characteristics are related to lateral flagella and type III and VI secretion systems; the antimicrobial resistance spectrum also varied among strains. The results indicated that A. veronii biovar sobria 312M presents high virulence potential and resistance to limited classes of antimicrobials.
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Affiliation(s)
- Karoline de C Prediger
- Departamento de Análises Clínicas, Universidade Federal do Paraná, Av. Prefeito Lothário Meisner 635, Curitiba, Paraná, CEP 80.210-170, Brazil
| | - Cibelle B Dallagassa
- Departamento de Análises Clínicas, Universidade Federal do Paraná, Av. Prefeito Lothário Meisner 635, Curitiba, Paraná, CEP 80.210-170, Brazil
| | - Bárbara Moriel
- Departamento de Análises Clínicas, Universidade Federal do Paraná, Av. Prefeito Lothário Meisner 635, Curitiba, Paraná, CEP 80.210-170, Brazil
| | - Bruno Stefanello Vizzotto
- Departamento de Análises Clínicas, Universidade Federal do Paraná, Av. Prefeito Lothário Meisner 635, Curitiba, Paraná, CEP 80.210-170, Brazil.,Universidade Franciscana, Santa Maria, Rio Grande do Sul, Brazil
| | - Waldemar Volanski
- Departamento de Análises Clínicas, Universidade Federal do Paraná, Av. Prefeito Lothário Meisner 635, Curitiba, Paraná, CEP 80.210-170, Brazil
| | - Emanuel M Souza
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná, Av. Coronel Francisco H. dos Santos 100, Curitiba, Paraná, CEP 81.531-980, Brazil
| | - Fábio O Pedrosa
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná, Av. Coronel Francisco H. dos Santos 100, Curitiba, Paraná, CEP 81.531-980, Brazil
| | - Vinícius Weiss
- Programa de Pós-Graduação em Bioinformática, Universidade Federal do Paraná, Rua Alcides Vieira Arcoverde 1225, Curitiba, Paraná, CEP 81.520-260, Brazil
| | - Dayane Alberton
- Departamento de Análises Clínicas, Universidade Federal do Paraná, Av. Prefeito Lothário Meisner 635, Curitiba, Paraná, CEP 80.210-170, Brazil
| | - Dieval Guizelini
- Programa de Pós-Graduação em Bioinformática, Universidade Federal do Paraná, Rua Alcides Vieira Arcoverde 1225, Curitiba, Paraná, CEP 81.520-260, Brazil
| | - Cyntia M T Fadel-Picheth
- Departamento de Análises Clínicas, Universidade Federal do Paraná, Av. Prefeito Lothário Meisner 635, Curitiba, Paraná, CEP 80.210-170, Brazil.
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40
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Comprehensive Analysis Reveals the Evolution and Pathogenicity of Aeromonas, Viewed from Both Single Isolated Species and Microbial Communities. mSystems 2019; 4:4/5/e00252-19. [PMID: 31641046 PMCID: PMC6811364 DOI: 10.1128/msystems.00252-19] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The genus Aeromonas is a common gastrointestinal pathogen associated with human and animal infections. Due to the high level of cross-species similarity, their evolutionary dynamics and genetic diversity are still fragmented. Hereby, we investigated the pan-genomes of 29 Aeromonas species, as well as Aeromonas species in microbial communities, to clarify their evolutionary dynamics and genetic diversity, with special focus on virulence factors and horizontal gene transfer events. Our study revealed an open pan-genome of Aeromonas containing 10,144 gene families. These Aeromonas species exhibited different functional constraints, with the single-copy core genes and most accessory genes experiencing purifying selection. The significant congruence between core genome and pan-genome trees revealed that core genes mainly affected evolutionary divergences of Aeromonas species. Gene gains and losses revealed a high level of genome plasticity, exhibited by hundreds of gene expansions and contractions, horizontally transferred genes, and mobile genetic elements. The selective constraints shaped virulence gene pools of these Aeromonas strains, where genes encoding hemolysin were ubiquitous. Of these strains, Aeromonas aquatica MX16A seemed to be more resistant, as it harbored most resistance genes. Finally, the virulence factors of Aeromonas in microbial communities were quite dynamic in response to environment changes. For example, the virulence diversity of Aeromonas in microbial communities could reach levels that match some of the most virulent Aeromonas species (such as A. hydrophila) in penetrated-air and modified-air packaging. Our work shed some light onto genetic diversity, evolutionary history, and functional features of Aeromonas, which could facilitate the detection and prevention of infections.IMPORTANCE Aeromonas has long been known as a gastrointestinal pathogen, yet it has many species whose evolutionary dynamics and genetic diversity had been unclear until now. We have conducted pan-genome analysis for 29 Aeromonas species and revealed a high level of genome plasticity exhibited by hundreds of gene expansions and contractions, horizontally transferred genes, and mobile genetic elements. These species also contained many virulence factors both identified from single isolated species and microbial community. This pan-genome study could elevate the level for detection and prevention of Aeromonas infections.
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Liu J, Dong Y, Wang N, Ma S, Lu C, Liu Y. Diverse effects of nitric oxide reductase NorV on Aeromonas hydrophila virulence-associated traits under aerobic and anaerobic conditions. Vet Res 2019; 50:67. [PMID: 31547881 PMCID: PMC6755692 DOI: 10.1186/s13567-019-0683-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 08/23/2019] [Indexed: 11/10/2022] Open
Abstract
NorV has been known to be an anaerobic nitric oxide reductase associated with nitric oxide (NO) detoxification. Recently, we showed that the norV gene of Aeromonas hydrophila was highly upregulated after co-culturing with Tetrahymena thermophila. Here, we demonstrated that the transcription and expression levels of norV were upregulated in a dose-dependent manner after exposure to NO under aerobic and anaerobic conditions. To investigate the roles of norV in resisting predatory protists and virulence of A. hydrophila, we constructed the norV gene-deletion mutant (ΔnorV). Compared to the wild type, the ΔnorV mutant showed no significant difference in growth at various NO concentrations under aerobic conditions but significantly stronger NO-mediated growth inhibition under anaerobic conditions. The deletion of norV exhibited markedly decreased cytotoxicity, hemolytic and protease activities under aerobic and anaerobic conditions. Also, the hemolysin co-regulated protein (Hcp) in the ΔnorV mutant showed increased secretion under aerobic conditions but decreased secretion under anaerobic conditions as compared to the wild-type. Moreover, the inactivation of norV led to reduced resistance to predation by T. thermophila, decreased survival within macrophages and highly attenuated virulence in zebrafish. Our data indicate a diverse role for norV in the expression of A. hydrophila virulence-associated traits that is not completely dependent on its function as a nitric oxide reductase. This study provides insights into an unexplored area of NorV, which will contribute to our understanding of bacterial pathogenesis and the development of new control strategies for A. hydrophila infection.
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Affiliation(s)
- Jin Liu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yuhao Dong
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Nannan Wang
- College of Animal Science and Technology, Jinling Institute of Technology, Nanjing, 211169, China
| | - Shuiyan Ma
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Chengping Lu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yongjie Liu
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China.
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Navarro-Garcia F, Ruiz-Perez F, Cataldi Á, Larzábal M. Type VI Secretion System in Pathogenic Escherichia coli: Structure, Role in Virulence, and Acquisition. Front Microbiol 2019; 10:1965. [PMID: 31543869 PMCID: PMC6730261 DOI: 10.3389/fmicb.2019.01965] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 08/09/2019] [Indexed: 12/18/2022] Open
Abstract
Bacterial pathogens utilize a myriad of mechanisms to invade mammalian hosts, damage tissue sites, and evade the immune system. One essential strategy of Gram-negative bacteria is the secretion of virulence factors through both inner and outer membranes to reach a potential target. Most secretion systems are harbored in mobile elements including transposons, plasmids, pathogenicity islands, and phages, and Escherichia coli is one of the more versatile bacteria adopting this genetic information by horizontal gene transfer. Additionally, E. coli is a bacterial species with members of the commensal intestinal microbiota and pathogens associated with numerous types of infections such as intestinal, urinary, and systemic in humans and other animals. T6SS cluster plasticity suggests evolutionarily divergent systems were acquired horizontally. T6SS is a secretion nanomachine that is extended through the bacterial double membrane; from this apparatus, substrates are conveyed straight from the cytoplasm of the bacterium into a target cell or to the extracellular space. This nanomachine consists of three main complexes: proteins in the inner membrane that are T4SS component-like, the baseplate complex, and the tail complex, which are formed by components evolutionarily related to contractile bacteriophage tails. Advances in the T6SS understanding include the functional and structural characterization of at least 13 subunits (so-called core components), which are thought to comprise the minimal apparatus. So far, the main role of T6SS is on bacterial competition by using it to kill neighboring non-immune bacteria for which antibacterial proteins are secreted directly into the periplasm of the bacterial target after cell-cell contact. Interestingly, a few T6SSs have been associated directly to pathogenesis, e.g., roles in biofilm formation and macrophage survival. Here, we focus on the advances on T6SS from the perspective of E. coli pathotypes with emphasis in the secretion apparatus architecture, the mechanisms of pathogenicity of effector proteins, and the events of lateral gene transfer that led to its spread.
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Affiliation(s)
- Fernando Navarro-Garcia
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV-IPN), Mexico City, Mexico
| | - Fernando Ruiz-Perez
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, VA, United States
| | - Ángel Cataldi
- Laboratorio de Escherichia coli, Instituto de Agrobiotecnología y Biología Molecular (IABIMO) INTA-CONICET, Buenos Aires, Argentina
| | - Mariano Larzábal
- Laboratorio de Escherichia coli, Instituto de Agrobiotecnología y Biología Molecular (IABIMO) INTA-CONICET, Buenos Aires, Argentina
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Tekedar HC, Kumru S, Blom J, Perkins AD, Griffin MJ, Abdelhamed H, Karsi A, Lawrence ML. Comparative genomics of Aeromonas veronii: Identification of a pathotype impacting aquaculture globally. PLoS One 2019; 14:e0221018. [PMID: 31465454 PMCID: PMC6715197 DOI: 10.1371/journal.pone.0221018] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 07/29/2019] [Indexed: 12/30/2022] Open
Abstract
Aeromonas veronii is a gram-negative species abundant in aquatic environments that causes disease in humans as well as terrestrial and aquatic animals. In the current study, 41 publicly available A. veronii genomes were compared to investigate distribution of putative virulence genes, global dissemination of pathotypes, and potential mechanisms of virulence. The complete genome of A. veronii strain ML09-123 from an outbreak of motile aeromonas septicemia in farm-raised catfish in the southeastern United States was included. Dissemination of A. veronii strain types was discovered in dispersed geographical locations. Isolate ML09-123 is highly similar to Chinese isolate TH0426, suggesting the two strains have a common origin and may represent a pathotype impacting aquaculture in both countries. Virulence of strain ML09-123 in catfish in a dose-dependent manner was confirmed experimentally. Subsystem category disposition showed the majority of genomes exhibit similar distribution of genomic elements. The type I secretion system (T1SS), type II secretion system (T2SS), type 4 pilus (T4P), and flagellum core elements are conserved in all A. veronii genomes, whereas the type III secretion system (T3SS), type V secretion system (T5SS), type VI secretion system (T6SS), and tight adherence (TAD) system demonstrate variable dispersal. Distribution of mobile elements is dependent on host and geographic origin, suggesting this species has undergone considerable genetic exchange. The data presented here lends insight into the genomic variation of A. veronii and identifies a pathotype impacting aquaculture globally.
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Affiliation(s)
- Hasan C. Tekedar
- College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, United States of America
| | - Salih Kumru
- College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, United States of America
| | - Jochen Blom
- Bioinformatics & Systems Biology, Justus-Liebig-University Giessen, Giessen, Hesse, Germany
| | - Andy D. Perkins
- Department of Computer Science and Engineering, Mississippi State University, Mississippi State, Mississippi, United States of America
| | - Matt J. Griffin
- College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, United States of America
- Thad Cochran National Warmwater Aquaculture Center, Stoneville, Mississippi State, United States of America
| | - Hossam Abdelhamed
- College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, United States of America
| | - Attila Karsi
- College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, United States of America
| | - Mark L. Lawrence
- College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, United States of America
- * E-mail:
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Crisan CV, Chande AT, Williams K, Raghuram V, Rishishwar L, Steinbach G, Watve SS, Yunker P, Jordan IK, Hammer BK. Analysis of Vibrio cholerae genomes identifies new type VI secretion system gene clusters. Genome Biol 2019; 20:163. [PMID: 31405375 PMCID: PMC6691524 DOI: 10.1186/s13059-019-1765-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 07/18/2019] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Like many bacteria, Vibrio cholerae deploys a harpoon-like type VI secretion system (T6SS) to compete against other microbes in environmental and host settings. The T6SS punctures adjacent cells and delivers toxic effector proteins that are harmless to bacteria carrying cognate immunity factors. Only four effector/immunity pairs encoded on one large and three auxiliary gene clusters have been characterized from largely clonal, patient-derived strains of V. cholerae. RESULTS We sequence two dozen V. cholerae strain genomes from diverse sources and develop a novel and adaptable bioinformatics tool based on hidden Markov models. We identify two new T6SS auxiliary gene clusters and describe Aux 5 here. Four Aux 5 loci are present in the host strain, each with an atypical effector/immunity gene organization. Structural prediction of the putative effector indicates it is a lipase, which we name TleV1 (type VI lipase effector Vibrio). Ectopic TleV1 expression induces toxicity in Escherichia coli, which is rescued by co-expression of the TliV1a immunity factor. A clinical V. cholerae reference strain expressing the Aux 5 cluster uses TleV1 to lyse its parental strain upon contact via its T6SS but is unable to kill parental cells expressing the TliV1a immunity factor. CONCLUSION We develop a novel bioinformatics method and identify new T6SS gene clusters in V. cholerae. We also show the TleV1 toxin is delivered in a T6SS manner by V. cholerae and can lyse other bacterial cells. Our web-based tool can be modified to identify additional novel T6SS genomic loci in diverse bacterial species.
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Affiliation(s)
- Cristian V Crisan
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA, 30332-0230, USA
- Institute for Bioengineering and Biosciences, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA, 30332-0230, USA
- School of Biological Sciences, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA, 30332-0230, USA
| | - Aroon T Chande
- Institute for Bioengineering and Biosciences, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA, 30332-0230, USA
- School of Biological Sciences, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA, 30332-0230, USA
- Applied Bioinformatics Laboratory, Atlanta, GA, USA
- PanAmerican Bioinformatics Institute, Cali, Valle del Cauca, Colombia
| | - Kenneth Williams
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA, 30332-0230, USA
- Institute for Bioengineering and Biosciences, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA, 30332-0230, USA
- School of Biological Sciences, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA, 30332-0230, USA
| | - Vishnu Raghuram
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA, 30332-0230, USA
- Institute for Bioengineering and Biosciences, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA, 30332-0230, USA
- School of Biological Sciences, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA, 30332-0230, USA
| | - Lavanya Rishishwar
- Institute for Bioengineering and Biosciences, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA, 30332-0230, USA
- School of Biological Sciences, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA, 30332-0230, USA
- Applied Bioinformatics Laboratory, Atlanta, GA, USA
- PanAmerican Bioinformatics Institute, Cali, Valle del Cauca, Colombia
| | - Gabi Steinbach
- Institute for Bioengineering and Biosciences, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA, 30332-0230, USA
- Applied Bioinformatics Laboratory, Atlanta, GA, USA
- School of Physics, Georgia Institute of Technology, Atlanta, GA, USA
| | - Samit S Watve
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA
| | - Peter Yunker
- Institute for Bioengineering and Biosciences, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA, 30332-0230, USA
- Applied Bioinformatics Laboratory, Atlanta, GA, USA
- School of Physics, Georgia Institute of Technology, Atlanta, GA, USA
| | - I King Jordan
- Institute for Bioengineering and Biosciences, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA, 30332-0230, USA
- School of Biological Sciences, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA, 30332-0230, USA
- Applied Bioinformatics Laboratory, Atlanta, GA, USA
- PanAmerican Bioinformatics Institute, Cali, Valle del Cauca, Colombia
| | - Brian K Hammer
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA, 30332-0230, USA.
- Institute for Bioengineering and Biosciences, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA, 30332-0230, USA.
- School of Biological Sciences, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA, 30332-0230, USA.
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Zhou CB, Fang JY. The role of pyroptosis in gastrointestinal cancer and immune responses to intestinal microbial infection. Biochim Biophys Acta Rev Cancer 2019; 1872:1-10. [DOI: 10.1016/j.bbcan.2019.05.001] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Revised: 04/18/2019] [Accepted: 05/01/2019] [Indexed: 01/04/2023]
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Sen R, Nayak L, De RK. PyPredT6: A python-based prediction tool for identification of Type VI effector proteins. J Bioinform Comput Biol 2019; 17:1950019. [DOI: 10.1142/s0219720019500197] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Prediction of effector proteins is of paramount importance due to their crucial role as first-line invaders while establishing a pathogen-host interaction, often leading to infection of the host. Prediction of T6 effector proteins is a new challenge since the discovery of T6 Secretion System and the unique nature of the particular secretion system. In this paper, we have first designed a Python-based standalone tool, called PyPredT6, to predict T6 effector proteins. A total of 873 unique features has been extracted from the peptide and nucleotide sequences of the experimentally verified effector proteins. Based on these features and using machine learning algorithms, we have performed in silico prediction of T6 effector proteins in Vibrio cholerae and Yersinia pestis to establish the applicability of PyPredT6. PyPredT6 is available at http://projectphd.droppages.com/PyPredT6.html .
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Affiliation(s)
- Rishika Sen
- Machine Intelligence Unit, Indian Statistical Institute, 103 B.T. Road, Kolkata-700108, India
| | - Losiana Nayak
- Machine Intelligence Unit, Indian Statistical Institute, 103 B.T. Road, Kolkata-700108, India
| | - Rajat K. De
- Machine Intelligence Unit, Indian Statistical Institute, 103 B.T. Road, Kolkata-700108, India
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Immunogenicity and protective efficacy of mucosal delivery of recombinant hcp of Campylobacter jejuni Type VI secretion system (T6SS) in chickens. Mol Immunol 2019; 111:182-197. [PMID: 31078054 DOI: 10.1016/j.molimm.2019.04.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 02/05/2019] [Accepted: 04/23/2019] [Indexed: 12/30/2022]
Abstract
The type VI secretion system (T6SS) has recently emerged as a new pattern of protein secretions in Campylobacter jejuni (C. jejuni). Within the T6SS cluster, hemolysin co-regulated protein (hcp) is considered as a hallmark of functional T6SS and holds key role in bacterial virulence. As poultry is the primary reservoir of C. jejuni and the major sources for human infection, we evaluated the capacity of recombinant hcp (rhcp) immunization in blocking C. jejuni colonization in chickens with an aim to control bacterial transmission to humans via poultry food chain. Considering the mucosal route is the primary portal for C. jejuni entry and gut mucosa offers the apposite site for C. jejuni adherence, we investigated the immune-protective potential of intra-gastric administration of rhcp using chitosan-based nanoparticles. To achieve this goal, full length coding sequence of hcp gene from C. jejuni was cloned and expressed in E. coli. Purified rhcp was entrapped in chitosan-Sodium tripolyphosphate nanoparticles (CS-TPP NPs) and orally gavaged in chickens. Our results suggest that intra-gastric immunization of CS-TPP-rhcp induces consistent and steady increase in intestinal (sIgA) and systemic antibody (IgY) response against rhcp with significant reduction in cecal load of C. jejuni. The protection afforded by rhcp associated cellular responses with Th1 and Th17 profile in terms of increased expression of NFkB, IL-1β, IL-8, IL-6, IFN-γ and IL-17 A genes. Though systemic immunization of rhcp with IFA resulting in a robust systemic (IgY) and local (sIgA) antibody response, mucosal administration of rhcp loaded CS-TPP NPs was found to be superior in terms of bacterial clearance. Altogether, present study suggests that chitosan based intra-gastric delivery of rhcp have several advantages over the injectable composition and could be a promising vaccine approach to effectively control C. jejuni colonization in chickens.
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Liu D, Zhang T, Wang Y, Muhammad M, Xue W, Ju J, Zhao B. Knockout of alanine racemase gene attenuates the pathogenicity of Aeromonas hydrophila. BMC Microbiol 2019; 19:72. [PMID: 30940083 PMCID: PMC6444436 DOI: 10.1186/s12866-019-1437-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 03/17/2019] [Indexed: 11/10/2022] Open
Abstract
Background Aeromonas hydrophila is an opportunistic pathogen of poikilothermic and homoeothermic animals, including humans. In the present study, we described the role of Alanine racemase (alr-2) in the virulence of A. hydrophila using an alr-2 knockout mutant (A.H.Δalr). Results In mouse and common carp models, the survival of animals challenged with A.H.Δalr was significantly increased compared with the wild-type (WT), and the mutant was also impaired in its ability to replicate in the organs and blood of infected mice and fish. The A.H.Δalr significantly increased phagocytosis by macrophages of the mice and fish. These attenuation effects of alr-2 could be complemented by the addition of D-alanine to the A.H.Δalr strain. The histopathology results indicated that the extent of tissue injury in the WT-infected animals was more severe than in the A.H.Δalr-infected groups. The expression of 9 virulence genes was significantly down-regulated, and 3 outer membrane genes were significantly up-regulated in A.H.Δalr. Conclusions Our data suggest that alr-2 is essential for the virulence of A. hydrophila. Our findings suggested alanine racemase could be applied in the development of new antibiotics against A. hydrophila.
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Affiliation(s)
- Dong Liu
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Ting Zhang
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Yaping Wang
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Murtala Muhammad
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Wen Xue
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Jiansong Ju
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China
| | - Baohua Zhao
- College of Life Science, Hebei Normal University, Shijiazhuang, 050024, China.
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Tekedar HC, Abdelhamed H, Kumru S, Blom J, Karsi A, Lawrence ML. Comparative Genomics of Aeromonas hydrophila Secretion Systems and Mutational Analysis of hcp1 and vgrG1 Genes From T6SS. Front Microbiol 2019; 9:3216. [PMID: 30687246 PMCID: PMC6333679 DOI: 10.3389/fmicb.2018.03216] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 12/11/2018] [Indexed: 12/19/2022] Open
Abstract
Virulent Aeromonas hydrophila causes severe motile Aeromonas septicemia in warmwater fishes. In recent years, channel catfish farming in the U.S.A. and carp farming in China have been affected by virulent A. hydrophila, and genome comparisons revealed that these virulent A. hydrophila strains belong to the same clonal group. Bacterial secretion systems are often important virulence factors; in the current study, we investigated whether secretion systems contribute to the virulent phenotype of these strains. Thus, we conducted comparative secretion system analysis using 55 A. hydrophila genomes, including virulent A. hydrophila strains from U.S.A. and China. Interestingly, tight adherence (TaD) system is consistently encoded in all the vAh strains. The majority of U.S.A. isolates do not possess a complete type VI secretion system, but three core elements [tssD (hcp), tssH, and tssI (vgrG)] are encoded. On the other hand, Chinese isolates have a complete type VI secretion system operon. None of the virulent A. hydrophila isolates have a type III secretion system. Deletion of two genes encoding type VI secretion system proteins (hcp1 and vgrG1) from virulent A. hydrophila isolate ML09-119 reduced virulence 2.24-fold in catfish fingerlings compared to the parent strain ML09-119. By determining the distribution of genes encoding secretion systems in A. hydrophila strains, our study clarifies which systems may contribute to core A. hydrophila functions and which may contribute to more specialized adaptations such as virulence. Our study also clarifies the role of type VI secretion system in A. hydrophila virulence.
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Affiliation(s)
- Hasan C Tekedar
- College of Veterinary Medicine, Mississippi State University, Starkville, MS, United States
| | - Hossam Abdelhamed
- College of Veterinary Medicine, Mississippi State University, Starkville, MS, United States
| | - Salih Kumru
- College of Veterinary Medicine, Mississippi State University, Starkville, MS, United States
| | - Jochen Blom
- Bioinformatics and Systems Biology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Attila Karsi
- College of Veterinary Medicine, Mississippi State University, Starkville, MS, United States
| | - Mark L Lawrence
- College of Veterinary Medicine, Mississippi State University, Starkville, MS, United States
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Ugarte-Torres A, Perry S, Franko A, Church DL. Multidrug-resistant Aeromonas hydrophila causing fatal bilateral necrotizing fasciitis in an immunocompromised patient: a case report. J Med Case Rep 2018; 12:326. [PMID: 30382899 PMCID: PMC6211551 DOI: 10.1186/s13256-018-1854-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Accepted: 09/21/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Aeromonas hydrophila is a water-dwelling, gram-negative rod-shaped bacterium, associated with diarrheal illness and, less commonly, necrotizing skin and soft tissue infections, especially among immunocompromised patients. Necrotizing fasciitis is associated with a high mortality rate, especially when caused by Aeromonas spp. Our patient was infected with an extremely aggressive form of multidrug-resistant Aeromonas spp. that produced both an extended-spectrum β-lactamase and an AmpC enzyme. Aeromonads are being recognized as important emerging pathogens because of their inherent antibiotic resistance profiles compounded by other virulence factors. These difficult-to-treat organisms can have significant implications in both clinical and public health settings. CASE PRESENTATION A 37-year-old Caucasian male with immunosuppression due to aplastic anemia being treated with cyclosporine, presented to hospital with relapsed disease. While in hospital, he subsequently developed overwhelming sepsis secondary to bilateral lower extremity necrotizing fasciitis. The necrotizing fasciitis was caused by a multidrug-resistant strain of A. hydrophila. Despite broad-spectrum antibiotics and aggressive surgical debridement, he succumbed to this severe invasive infection. CONCLUSIONS Necrotizing fasciitis caused by Aeromonas spp. is a rare infection that may have a poor clinical outcome, particularly if the diagnosis is delayed and/or the organism is highly virulent and multidrug resistant. Enhanced education of clinicians and microbiologists is required to prevent unnecessary complications and improve survival.
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Affiliation(s)
- Alejandra Ugarte-Torres
- Department of Medicine, University of Calgary, 9-3535 Research Rd NW, Calgary, AB, T2L 2K8, Canada
| | - Sarah Perry
- Department of Medicine, University of Calgary, 9-3535 Research Rd NW, Calgary, AB, T2L 2K8, Canada
| | - Angela Franko
- Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, Canada
| | - Deirdre L Church
- Department of Medicine, University of Calgary, 9-3535 Research Rd NW, Calgary, AB, T2L 2K8, Canada. .,Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, Canada. .,Department of Medicine, Snyder Institute for Chronic Diseases, Cummings School of Medicine, University of Calgary, Calgary, Canada.
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