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Lucidi M, Visaggio D, Migliaccio A, Capecchi G, Visca P, Imperi F, Zarrilli R. Pathogenicity and virulence of Acinetobacter baumannii: Factors contributing to the fitness in healthcare settings and the infected host. Virulence 2024; 15:2289769. [PMID: 38054753 PMCID: PMC10732645 DOI: 10.1080/21505594.2023.2289769] [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: 05/17/2023] [Accepted: 11/27/2023] [Indexed: 12/07/2023] Open
Abstract
Acinetobacter baumannii is a common cause of healthcare-associated infections and hospital outbreaks, particularly in intensive care units. Much of the success of A. baumannii relies on its genomic plasticity, which allows rapid adaptation to adversity and stress. The capacity to acquire novel antibiotic resistance determinants and the tolerance to stresses encountered in the hospital environment promote A. baumannii spread among patients and long-term contamination of the healthcare setting. This review explores virulence factors and physiological traits contributing to A. baumannii infection and adaptation to the hospital environment. Several cell-associated and secreted virulence factors involved in A. baumannii biofilm formation, cell adhesion, invasion, and persistence in the host, as well as resistance to xeric stress imposed by the healthcare settings, are illustrated to give reasons for the success of A. baumannii as a hospital pathogen.
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Affiliation(s)
- Massimiliano Lucidi
- Department of Science, Roma Tre University, Rome, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
| | - Daniela Visaggio
- Department of Science, Roma Tre University, Rome, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
- Santa Lucia Foundation IRCCS, Rome, Italy
| | | | | | - Paolo Visca
- Department of Science, Roma Tre University, Rome, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
- Santa Lucia Foundation IRCCS, Rome, Italy
| | - Francesco Imperi
- Department of Science, Roma Tre University, Rome, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
- Santa Lucia Foundation IRCCS, Rome, Italy
| | - Raffaele Zarrilli
- Department of Public Health, University of Naples Federico II, Naples, Italy
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2
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Lau YT, Tan HS. Acinetobacter baumannii subunit vaccines: recent progress and challenges. Crit Rev Microbiol 2024; 50:434-449. [PMID: 37211625 DOI: 10.1080/1040841x.2023.2215303] [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: 01/16/2023] [Revised: 03/28/2023] [Accepted: 05/12/2023] [Indexed: 05/23/2023]
Abstract
Acinetobacter baumannii is a Gram-negative, opportunistic pathogen that causes nosocomial infection with a high mortality rate in immunocompromised individuals. With the frequent emergence of multidrug-resistant A. baumannii strains that have rapidly gained resistance to most antibiotics, an extensive search for an effective A. baumannii vaccine is ongoing. Over the decade, many subunit vaccine candidates were identified using reverse vaccinology and in vivo animal studies for validation. Nineteen subunit vaccine candidates with a wide range of efficacy, from 14% to 100% preclinical survival rates, were included in this review. This article provides an updated review of several outer membrane proteins (Omp) that emerged as vaccine candidates with great potential, including OmpA, Omp34, Omp22 and BamA, based on their high conservancy, antigenicity, and immune protection against A. baumannii infection. However, there is still no licenced A. baumannii vaccine currently due to several practical issues that have yet to be resolved, such as inconsistencies between validation studies, antigen variability and insolubility. Moving forward, much investigation and innovation are still required to tackle these challenges for the regulatory approval of an A. baumannii subunit vaccine, including standardisation of immunisation study parameters, improving antigen solubility and the incorporation of nucleic acid vaccine technology.
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Affiliation(s)
- Yi Teng Lau
- School of Science, Monash University Malaysia, Bandar Sunway, Malaysia
| | - Hock Siew Tan
- School of Science, Monash University Malaysia, Bandar Sunway, Malaysia
- Tropical Medicine and Biology Multidisciplinary Platform, Monash University Malaysia, Bandar Sunway, Malaysia
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3
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Li Y, Cui Y, Song K, Shen L, Xiao L, Jin J, Zhao Y, Yan Y, Zhao S, Yao W, Wang S, Du Z, Yang R, Yi B, Song Y. TagP, a PAAR-domain containing protein, plays roles in the fitness and virulence of Acinetobacter baumannii. Front Cell Infect Microbiol 2024; 14:1379106. [PMID: 39193505 PMCID: PMC11348943 DOI: 10.3389/fcimb.2024.1379106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Accepted: 07/03/2024] [Indexed: 08/29/2024] Open
Abstract
Background Type VI secretion system (T6SS) is widely present in Gram-negative bacteria and directly mediates antagonistic prokaryote interactions. PAAR (proline-alanine-alanine-arginine repeats) proteins have been proven essential for T6SS-mediated secretion and target cell killing. Although PAAR proteins are commonly found in A. baumannii, their biological functions are not fully disclosed yet. In this study, we investigated the functions of a PAAR protein termed TagP (T6SS-associated-gene PAAR), encoded by the gene ACX60_RS09070 outside the core T6SS locus of A. baumannii strain ATCC 17978. Methods In this study, tagP null and complement A. baumannii ATCC 17978 strains were constructed. The influence of TagP on T6SS function was investigated through Hcp detection and bacterial competition assay; the influence on environmental fitness was studied through in vitro growth, biofilm formation assay, surface motility assay, survivability in various simulated environmental conditions; the influence on pathogenicity was explored through cell adhesion and invasion assays, intramacrophage survival assay, serum survival assay, and G. melonella Killing assays. Quantitative transcriptomic and proteomic analyses were utilized to observe the global impact of TagP on bacterial status. Results Compared with the wildtype strain, the tagP null mutant was impaired in several tested phenotypes such as surface motility, biofilm formation, tolerance to adverse environments, adherence to eukaryotic cells, endurance to serum complement killing, and virulence to Galleria melonella. Notably, although RNA-Seq and proteomics analysis revealed that many genes were significantly down-regulated in the tagP null mutant compared to the wildtype strain, there is no significant difference in their antagonistic abilities. We also found that Histone-like nucleoid structuring protein (H-NS) was significantly upregulated in the tagP null mutant at both mRNA and protein levels. Conclusions This study enriches our understanding of the biofunction of PAAR proteins in A. baumannii. The results indicates that TagP involved in a unique modulation of fitness and virulence control in A. baumannii, it is more than a classic PAAR protein involved in T6SS, while how TagP play roles in the fitness and virulence of A. baumannii needs further investigation to clarify.
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Affiliation(s)
- Yanbing Li
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- Department of Clinical Laboratory, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Yiming Cui
- School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Kai Song
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Leiming Shen
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Liting Xiao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Junyan Jin
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yanting Zhao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yanfeng Yan
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Shengyuan Zhao
- Department of Clinical Laboratory, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Wenwu Yao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Shihua Wang
- School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Zongmin Du
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Ruifu Yang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Bin Yi
- Department of Clinical Laboratory, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Yajun Song
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
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4
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Maure A, Robino E, Van der Henst C. The intracellular life of Acinetobacter baumannii. Trends Microbiol 2023; 31:1238-1250. [PMID: 37487768 DOI: 10.1016/j.tim.2023.06.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 06/16/2023] [Accepted: 06/23/2023] [Indexed: 07/26/2023]
Abstract
Acinetobacter baumannii is a Gram-negative opportunistic bacterium responsible for nosocomial and community-acquired infections. This pathogen is globally disseminated and associated with high levels of antibiotic resistance, which makes it an important threat to human health. Recently, new evidence showed that several A. baumannii isolates can survive and proliferate within eukaryotic professional and/or nonprofessional phagocytic cells, with in vivo consequences. This review provides updated information and describes the tools that A. baumannii possesses to adhere, colonize, and replicate in host cells. Additionally, we emphasize the high genetic and phenotypic heterogeneity detected amongst A. baumannii isolates and its impact on the bacterial intracellular features. We also discuss the need for standardized methods to characterize this pathogen robustly and consequently consider some strains as facultative intracellular bacteria.
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Affiliation(s)
- Alexandra Maure
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium; Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Etienne Robino
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium; Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Charles Van der Henst
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium; Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium.
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5
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Vaca DJ, Frenzel F, Ballhorn W, Torres SG, Leisegang MS, Günther S, Bender D, Kraiczy P, Göttig S, Kempf VAJ. Adhesion of human pathogenic bacteria to endothelial cells is facilitated by fibronectin interaction. Microbes Infect 2023; 25:105172. [PMID: 37343664 DOI: 10.1016/j.micinf.2023.105172] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 06/07/2023] [Accepted: 06/10/2023] [Indexed: 06/23/2023]
Abstract
Human pathogenic bacteria circulating in the bloodstream need to find a way to interact with endothelial cells (ECs) lining the blood vessels to infect and colonise the host. The extracellular matrix (ECM) of ECs might represent an attractive initial target for bacterial interaction, as many bacterial adhesins have reported affinities to ECM proteins, in particular to fibronectin (Fn). Here, we analysed the general role of EC-expressed Fn for bacterial adhesion. For this, we evaluated the expression levels of ECM coding genes in different ECs, revealing that Fn is the highest expressed gene and thereby, it is highly abundant in the ECM environment of ECs. The role of Fn as a mediator in bacterial cell-host adhesion was evaluated in adhesion assays of Acinetobacter baumannii, Bartonella henselae, Borrelia burgdorferi, and Staphylococcus aureus to ECs. The assays demonstrated that bacteria colocalised with Fn fibres, as observed by confocal laser scanning microscopy. Fn removal from the ECM environment (FN1 knockout ECs) diminished bacterial adherence to ECs in both static and dynamic adhesion assays to varying extents, as evaluated via absolute quantification using qPCR. Interactions between adhesins and Fn might represent the crucial step for the adhesion of human-pathogenic Gram-negative and Gram-positive bacteria targeting the ECs as a niche of infection.
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Affiliation(s)
- Diana J Vaca
- Institute of Medical Microbiology and Infection Control, Goethe University, Paul Ehrlich Straße 40, 60596, Frankfurt, Germany.
| | - Fabienne Frenzel
- Institute of Medical Microbiology and Infection Control, Goethe University, Paul Ehrlich Straße 40, 60596, Frankfurt, Germany.
| | - Wibke Ballhorn
- Institute of Medical Microbiology and Infection Control, Goethe University, Paul Ehrlich Straße 40, 60596, Frankfurt, Germany.
| | - Sara Garcia Torres
- Institute of Medical Microbiology and Infection Control, Goethe University, Paul Ehrlich Straße 40, 60596, Frankfurt, Germany.
| | - Matthias S Leisegang
- Institute for Cardiovascular Physiology, Goethe University, Theodor-Stern-Kai 7, 60590, Frankfurt, Germany; German Center of Cardiovascular Research (DZHK), Partner Site RheinMain, Theodor-Stern-Kai 7, 60590, Frankfurt, Germany.
| | - Stefan Günther
- Max Planck Institute for Heart and Lung Research, Parkstraße 1, 61231, Bad Nauheim, Germany.
| | - Daniela Bender
- Federal Institute for Vaccines and Biomedicines, Department of Virology, Paul Ehrlich Institute, Paul-Ehrlich-Straße 51-59, 63225, Langen, Germany.
| | - Peter Kraiczy
- Institute of Medical Microbiology and Infection Control, Goethe University, Paul Ehrlich Straße 40, 60596, Frankfurt, Germany.
| | - Stephan Göttig
- Institute of Medical Microbiology and Infection Control, Goethe University, Paul Ehrlich Straße 40, 60596, Frankfurt, Germany.
| | - Volkhard A J Kempf
- Institute of Medical Microbiology and Infection Control, Goethe University, Paul Ehrlich Straße 40, 60596, Frankfurt, Germany.
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6
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Solanki V, Tiwari M, Tiwari V. Investigation of Peptidoglycan-Associated Lipoprotein of Acinetobacter baumannii and Its Interaction with Fibronectin To Find Its Therapeutic Potential. Infect Immun 2023; 91:e0002323. [PMID: 37017535 PMCID: PMC10187120 DOI: 10.1128/iai.00023-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 03/07/2023] [Indexed: 04/06/2023] Open
Abstract
Acinetobacter baumannii causes hospital-acquired infections and is responsible for high mortality and morbidity. The interaction of this bacterium with the host is critical in bacterial pathogenesis and infection. Here, we report the interaction of peptidoglycan-associated lipoprotein (PAL) of A. baumannii with host fibronectin (FN) to find its therapeutic potential. The proteome of A. baumannii was explored in the host-pathogen interaction database to filter out the PAL of the bacterial outer membrane that interacts with the host's FN protein. This interaction was confirmed experimentally using purified recombinant PAL and pure FN protein. To investigate the pleiotropic role of PAL protein, different biochemical assays using wild-type PAL and PAL mutants were performed. The result showed that PAL mediates bacterial pathogenesis, adherence, and invasion in host pulmonary epithelial cells and has a role in the biofilm formation, bacterial motility, and membrane integrity of bacteria. All of the results suggest that PAL's interaction with FN plays a vital role in host-cell interaction. In addition, the PAL protein also interacts with Toll-like receptor 2 and MARCO receptor, which suggests the role of PAL protein in innate immune responses. We have also investigated the therapeutic potential of this protein for vaccine and therapeutic design. Using reverse vaccinology, PAL's potential epitopes were filtered out that exhibit binding potential with host major histocompatibility complex class I (MHC-I), MHC-II, and B cells, suggesting that PAL protein is a potential vaccine target. The immune simulation showed that PAL protein could elevate innate and adaptive immune response with the generation of memory cells and would have subsequent potential to eliminate bacterial infection. Therefore, the present study highlights the interaction ability of a novel host-pathogen interacting partner (PAL-FN) and uncovers its therapeutic potential to combat infection caused by A. baumannii.
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Affiliation(s)
- Vandana Solanki
- Department of Biochemistry, Central University of Rajasthan, Ajmer, Rajasthan, India
| | - Monalisa Tiwari
- Department of Biochemistry, Central University of Rajasthan, Ajmer, Rajasthan, India
| | - Vishvanath Tiwari
- Department of Biochemistry, Central University of Rajasthan, Ajmer, Rajasthan, India
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7
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Ishikawa M, Nakatani H, Hori K. Growth phase-dependent production of the adhesive nanofiber protein AtaA in Acinetobacter sp. Tol 5. J Biosci Bioeng 2023; 135:224-231. [PMID: 36653269 DOI: 10.1016/j.jbiosc.2022.12.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 11/30/2022] [Accepted: 12/24/2022] [Indexed: 01/18/2023]
Abstract
AtaA, the sticky, long, and peritrichate nanofiber protein from Acinetobacter sp. Tol 5, mediates autoagglutination and is highly adhesive to various material surfaces, resulting in a biofilm. Although the production of the adhesive nanofiber protein is likely to require a large amount of energy and material sources, the relationship between AtaA fiber production and cell growth remains unknown. Here, we report the growth phase-dependent AtaA fiber production in Tol 5. We examined the ataA gene expression in different growth phases using a reporter gene assay with an originally developed reporter plasmid and using reverse transcription-quantitative polymerase chain reaction. Bacterial cells with surface-displayed AtaA at different growth phases were immunostained and analyzed using fluorescence flow cytometry and confocal laser scanning microscopy. The results indicate that Tol 5 modulated the amount of surface-displayed AtaA at the transcriptional level. AtaA production was low in the early growth phase but remarkably increased in the late growth phase, covering the whole bacterial cell with AtaA fibers in the stationary phase. Tol 5 displayed AtaA fibers poorly in the early growth phase and showed less autoagglutination and adhesiveness than those in the stationary phase. Although Tol 5 grew as fast as its ataA-deficient mutant in the early growth phase, the optical density of Tol 5 culture was slightly lower than that of the ataA-deficient mutant in the late growth phase. Based on these experimental results, we propose the growth-phase-dependent production of AtaA fiber for efficient and fast cell growth.
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Affiliation(s)
- Masahito Ishikawa
- Department of Frontier Bioscience, Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura-cho, Nagahama, Shiga 526-0829, Japan; PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Hajime Nakatani
- Department of Biomolecular Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Katsutoshi Hori
- Department of Biomolecular Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
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Shadan A, Pathak A, Ma Y, Pathania R, Singh RP. Deciphering the virulence factors, regulation, and immune response to Acinetobacter baumannii infection. Front Cell Infect Microbiol 2023; 13:1053968. [PMID: 36968113 PMCID: PMC10038080 DOI: 10.3389/fcimb.2023.1053968] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 02/06/2023] [Indexed: 02/25/2023] Open
Abstract
Deciphering the virulence factors, regulation, and immune response to Acinetobacter baumannii infectionAcinetobacter baumannii is a gram-negative multidrug-resistant nosocomial pathogen and a major cause of hospital acquired infetions. Carbapenem resistant A. baumannii has been categorised as a Priority1 critial pathogen by the World Health Organisation. A. baumannii is responsible for infections in hospital settings, clinical sectors, ventilator-associated pneumonia, and bloodstream infections with a mortality rates up to 35%. With the development of advanced genome sequencing, molecular mechanisms of manipulating bacterial genomes, and animal infection studies, it has become more convenient to identify the factors that play a major role in A. baumannii infection and its persistence. In the present review, we have explored the mechanism of infection, virulence factors, and various other factors associated with the pathogenesis of this organism. Additionally, the role of the innate and adaptive immune response, and the current progress in the development of innovative strategies to combat this multidrug-resistant pathogen is also discussed.
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Affiliation(s)
- Afreen Shadan
- Department of Microbiology, Dr. Shyama Prasad Mukherjee University, Ranchi, Jharkhand, India
| | - Avik Pathak
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Roorkee, India
| | - Ying Ma
- College of Resources and Environment, Southwest University, Chongqing, China
- *Correspondence: Ying Ma, ; Ranjana Pathania, ; Rajnish Prakash Singh,
| | - Ranjana Pathania
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Roorkee, India
- *Correspondence: Ying Ma, ; Ranjana Pathania, ; Rajnish Prakash Singh,
| | - Rajnish Prakash Singh
- Department of Bioengineering and Biotechnology, Birla Institute of Technology, Ranchi, Jharkhand, India
- *Correspondence: Ying Ma, ; Ranjana Pathania, ; Rajnish Prakash Singh,
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9
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Tamadonfar KO, Di Venanzio G, Pinkner JS, Dodson KW, Kalas V, Zimmerman MI, Bazan Villicana J, Bowman GR, Feldman MF, Hultgren SJ. Structure-function correlates of fibrinogen binding by Acinetobacter adhesins critical in catheter-associated urinary tract infections. Proc Natl Acad Sci U S A 2023; 120:e2212694120. [PMID: 36652481 PMCID: PMC9942807 DOI: 10.1073/pnas.2212694120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 11/17/2022] [Indexed: 01/19/2023] Open
Abstract
Multidrug-resistant Acinetobacter baumannii infections are an urgent clinical problem and can cause difficult-to-treat nosocomial infections. During such infections, like catheter-associated urinary tract infections (CAUTI), A. baumannii rely on adhesive, extracellular fibers, called chaperone-usher pathway (CUP) pili for critical binding interactions. The A. baumannii uropathogenic strain, UPAB1, and the pan-European subclone II isolate, ACICU, use the CUP pili Abp1 and Abp2 (previously termed Cup and Prp, respectively) in tandem to establish CAUTIs, specifically to facilitate bacterial adherence and biofilm formation on the implanted catheter. Abp1 and Abp2 pili are tipped with two domain tip adhesins, Abp1D and Abp2D, respectively. We discovered that both adhesins bind fibrinogen, a critical host wound response protein that is released into the bladder upon catheterization and is subsequently deposited on the catheter. The crystal structures of the Abp1D and Abp2D receptor-binding domains were determined and revealed that they both contain a large, distally oriented pocket, which mediates binding to fibrinogen and other glycoproteins. Genetic, biochemical, and biophysical studies revealed that interactions with host proteins are governed by several critical residues in and along the edge of the binding pocket, one of which regulates the structural stability of an anterior loop motif. K34, located outside of the pocket but interacting with the anterior loop, also regulates the binding affinity of the protein. This study illuminates the mechanistic basis of the critical fibrinogen-coated catheter colonization step in A. baumannii CAUTI pathogenesis.
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Affiliation(s)
- Kevin O. Tamadonfar
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO63110
- Center for Women’s Infectious Disease Research, Washington University School of Medicine, St Louis, MO63110
| | - Gisela Di Venanzio
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO63110
| | - Jerome S. Pinkner
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO63110
- Center for Women’s Infectious Disease Research, Washington University School of Medicine, St Louis, MO63110
| | - Karen W. Dodson
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO63110
- Center for Women’s Infectious Disease Research, Washington University School of Medicine, St Louis, MO63110
| | - Vasilios Kalas
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO63110
- Center for Women’s Infectious Disease Research, Washington University School of Medicine, St Louis, MO63110
- Department of Medicine, McGaw Medical Center of Northwestern University, Chicago, IL60611
| | - Maxwell I. Zimmerman
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO63110
| | - Jesus Bazan Villicana
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO63110
- Center for Women’s Infectious Disease Research, Washington University School of Medicine, St Louis, MO63110
| | - Gregory R. Bowman
- Department of Biochemistry & Molecular Biophysics, Washington University School of Medicine, St. Louis, MO63110
- Department of Biomedical Engineering and Center for Biological Systems Engineering, Washington University School of Medicine, St. Louis, MO63110
| | - Mario F. Feldman
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO63110
| | - Scott J. Hultgren
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO63110
- Center for Women’s Infectious Disease Research, Washington University School of Medicine, St Louis, MO63110
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10
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Li P, Zhang S, Wang J, Al-Shamiri MM, Han B, Chen Y, Han S, Han L. Uncovering the Secretion Systems of Acinetobacter baumannii: Structures and Functions in Pathogenicity and Antibiotic Resistance. Antibiotics (Basel) 2023; 12:antibiotics12020195. [PMID: 36830106 PMCID: PMC9952577 DOI: 10.3390/antibiotics12020195] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 01/06/2023] [Accepted: 01/16/2023] [Indexed: 01/19/2023] Open
Abstract
Infections led by Acinetobacter baumannii strains are of great concern in healthcare environments due to the strong ability of the bacteria to spread through different apparatuses and develop drug resistance. Severe diseases can be caused by A. baumannii in critically ill patients, but its biological process and mechanism are not well understood. Secretion systems have recently been demonstrated to be involved in the pathogenic process, and five types of secretion systems out of the currently known six from Gram-negative bacteria have been found in A. baumannii. They can promote the fitness and pathogenesis of the bacteria by releasing a variety of effectors. Additionally, antibiotic resistance is found to be related to some types of secretion systems. In this review, we describe the genetic and structural compositions of the five secretion systems that exist in Acinetobacter. In addition, the function and molecular mechanism of each secretion system are summarized to explain how they enable these critical pathogens to overcome eukaryotic hosts and prokaryotic competitors to cause diseases.
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Affiliation(s)
- Pu Li
- School of Public Health, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
| | - Sirui Zhang
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
| | - Jingdan Wang
- School of Public Health, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
| | - Mona Mohamed Al-Shamiri
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
| | - Bei Han
- School of Public Health, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
| | - Yanjiong Chen
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
| | - Shaoshan Han
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an 710061, China
| | - Lei Han
- Department of Microbiology and Immunology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an 710061, China
- Correspondence:
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11
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Yang N, Jin X, Zhu C, Gao F, Weng Z, Du X, Feng G. Subunit vaccines for Acinetobacter baumannii. Front Immunol 2023; 13:1088130. [PMID: 36713441 PMCID: PMC9878323 DOI: 10.3389/fimmu.2022.1088130] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 12/22/2022] [Indexed: 01/15/2023] Open
Abstract
Acinetobacter baumannii is a gram-negative bacterium and a crucial opportunistic pathogen in hospitals. A. baumannii infection has become a challenging problem in clinical practice due to the increasing number of multidrug-resistant strains and their prevalence worldwide. Vaccines are effective tools to prevent and control A. baumannii infection. Many researchers are studying subunit vaccines against A. baumannii. Subunit vaccines have the advantages of high purity, safety, and stability, ease of production, and highly targeted induced immune responses. To date, no A. baumannii subunit vaccine candidate has entered clinical trials. This may be related to the easy degradation of subunit vaccines in vivo and weak immunogenicity. Using adjuvants or delivery vehicles to prepare subunit vaccines can slow down degradation and improve immunogenicity. The common immunization routes include intramuscular injection, subcutaneous injection, intraperitoneal injection and mucosal vaccination. The appropriate immunization method can also enhance the immune effect of subunit vaccines. Therefore, selecting an appropriate adjuvant and immunization method is essential for subunit vaccine research. This review summarizes the past exploration of A. baumannii subunit vaccines, hoping to guide current and future research on these vaccines.
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Affiliation(s)
- Ning Yang
- Department of Respiratory and Critical Care Medicine, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Xiao Jin
- Department of Respiratory and Critical Care Medicine, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Chenghua Zhu
- Department of Respiratory and Critical Care Medicine, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Fenglin Gao
- Department of Respiratory and Critical Care Medicine, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Zheqi Weng
- The Second Clinical Medical School of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Xingran Du
- Department of Infectious Disease, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China,*Correspondence: Xingran Du, ; Ganzhu Feng,
| | - Ganzhu Feng
- Department of Respiratory and Critical Care Medicine, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China,*Correspondence: Xingran Du, ; Ganzhu Feng,
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12
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Jeffreys S, Chambers JP, Yu JJ, Hung CY, Forsthuber T, Arulanandam BP. Insights into Acinetobacter baumannii protective immunity. Front Immunol 2022; 13:1070424. [PMID: 36466845 PMCID: PMC9716351 DOI: 10.3389/fimmu.2022.1070424] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 11/07/2022] [Indexed: 11/19/2022] Open
Abstract
Acinetobacter baumannii is a nosocomic opportunistic Gram-negative bacteria known for its extensive drug-resistant phenotype. A. baumannii hospital-acquired infections are major contributors to increased costs and mortality observed during the COVID-19 pandemic. With few effective antimicrobials available for treatment of this pathogen, immune-based therapy becomes an attractive strategy to combat multi-drug resistant Acinetobacter infection. Immunotherapeutics is a field of growing interest with advances in vaccines and monoclonal antibodies providing insight into the protective immune response required to successfully combat this pathogen. This review focuses on current knowledge describing the adaptive immune response to A. baumannii, the importance of antibody-mediated protection, developments in cell-mediated protection, and their respective therapeutic application going forward. With A. baumannii’s increasing resistance to most current antimicrobials, elucidating an effective host adaptive immune response is paramount in the guidance of future immunotherapeutic development.
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Affiliation(s)
- Sean Jeffreys
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX, United States
| | - James P. Chambers
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX, United States
| | - Jieh-Juen Yu
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX, United States
| | - Chiung-Yu Hung
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX, United States
| | - Thomas Forsthuber
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX, United States
| | - Bernard P. Arulanandam
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX, United States
- Department of Immunology, Tufts University School of Medicine, Boston, MA, United States
- *Correspondence: Bernard P. Arulanandam,
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13
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InvL, an Invasin-Like Adhesin, Is a Type II Secretion System Substrate Required for Acinetobacter baumannii Uropathogenesis. mBio 2022; 13:e0025822. [PMID: 35638734 PMCID: PMC9245377 DOI: 10.1128/mbio.00258-22] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Acinetobacter baumannii is an opportunistic pathogen of growing concern, as isolates are commonly multidrug resistant. While A. baumannii is most frequently associated with pulmonary infections, a significant proportion of clinical isolates come from urinary sources, highlighting its uropathogenic potential. The type II secretion system (T2SS) of commonly used model Acinetobacter strains is important for virulence in various animal models, but the potential role of the T2SS in urinary tract infection (UTI) remains unknown. Here, we used a catheter-associated UTI (CAUTI) model to demonstrate that a modern urinary isolate, UPAB1, requires the T2SS for full virulence. A proteomic screen to identify putative UPAB1 T2SS effectors revealed an uncharacterized lipoprotein with structural similarity to the intimin-invasin family, which serve as type V secretion system (T5SS) adhesins required for the pathogenesis of several bacteria. This protein, designated InvL, lacked the β-barrel domain associated with T5SSs but was confirmed to require the T2SS for both surface localization and secretion. This makes InvL the first identified T2SS effector belonging to the intimin-invasin family. InvL was confirmed to be an adhesin, as the protein bound to extracellular matrix components and mediated adhesion to urinary tract cell lines in vitro. Additionally, the invL mutant was attenuated in the CAUTI model, indicating a role in Acinetobacter uropathogenesis. Finally, bioinformatic analyses revealed that InvL is present in nearly all clinical isolates belonging to international clone 2, a lineage of significant clinical importance. In all, we conclude that the T2SS substrate InvL is an adhesin required for A. baumannii uropathogenesis. IMPORTANCE While pathogenic Acinetobacter can cause various infections, we recently found that 20% of clinical isolates come from urinary sources. Despite the clinical relevance of Acinetobacter as a uropathogen, few virulence factors involved in urinary tract colonization have been defined. Here, we identify a novel type II secretion system effector, InvL, which is required for full uropathogenesis by a modern urinary isolate. Although InvL has predicted structural similarity to the intimin-invasin family of autotransporter adhesins, InvL is predicted to be anchored to the membrane as a lipoprotein. Similar to other invasin homologs, however, we demonstrate that InvL is a bona fide adhesin capable of binding extracellular matrix components and mediating adhesion to urinary tract cell lines. In all, this work establishes InvL as an adhesin important for Acinetobacter's urinary tract virulence and represents the first report of a type II secretion system effector belonging to the intimin-invasin family.
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14
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Interaction of Bartonella henselae with Fibronectin Represents the Molecular Basis for Adhesion to Host Cells. Microbiol Spectr 2022; 10:e0059822. [PMID: 35435766 PMCID: PMC9241615 DOI: 10.1128/spectrum.00598-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Deciphering the mechanisms of bacterial host cell adhesion is a clue for preventing infections. We describe the underestimated role that the extracellular matrix protein fibronectin plays in the adhesion of human-pathogenic
Bartonella henselae
to host cells.
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15
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Sun P, Li X, Pan C, Liu Z, Wu J, Wang H, Zhu L. A Short Peptide of Autotransporter Ata Is a Promising Protective Antigen for Vaccination Against Acinetobacter baumannii. Front Immunol 2022; 13:884555. [PMID: 35493470 PMCID: PMC9043751 DOI: 10.3389/fimmu.2022.884555] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 03/21/2022] [Indexed: 11/25/2022] Open
Abstract
With the emergence of multidrug-resistant strains, Acinetobacter baumannii infection is becoming a thorny health problem in hospitals. However, there are no licensed vaccines against A. baumannii. Acinetobacter trimeric autotransporter (Ata) is an important known virulence factor located on the outer membrane of bacteria. Herein, we carried out a series of experiments to test the immunogenicity of a short C-terminal extracellular region of Ata (Ataα, only containing 39 amino acids) in a murine model. The short peptide Ataα was fused with the cholera toxin B subunit (CTB), which has been reported to have immunoadjuvant activity. The fusion protein showed no inflammation and organ damages, and have the ability to elicit both Th1 and Th2 immune responses in mice. The bactericidal activities against A. baumannii and prophylactic effects of the fusion protein were further evidenced by a significant reduction in the bacterial load in the organs and blood. In addition, the candidate vaccine could provide broad protection against lethal challenges with a variety of A. baumannii strains. Moreover, when CpG was added on the basis of aluminum adjuvant, the immune response, especially cellular immunity, could be further strengthened. Overall, these results revealed that the Ataα is a promising vaccine target against A. baumannii infection.
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Affiliation(s)
- Peng Sun
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Biotechnology, Beijing, China
- School of Medicine, Tsinghua University, Beijing, China
| | - Xin Li
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Biotechnology, Beijing, China
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China
| | - Chao Pan
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Biotechnology, Beijing, China
| | - Zhicheng Liu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Biotechnology, Beijing, China
| | - Jun Wu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Biotechnology, Beijing, China
| | - Hengliang Wang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Biotechnology, Beijing, China
- School of Medicine, Tsinghua University, Beijing, China
| | - Li Zhu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Biotechnology, Beijing, China
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16
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Li X, Pan C, Liu Z, Sun P, Hua X, Feng E, Yu Y, Wu J, Zhu L, Wang H. Safety and immunogenicity of a new glycoengineered vaccine against Acinetobacter baumannii in mice. Microb Biotechnol 2022; 15:703-716. [PMID: 33755314 PMCID: PMC8867989 DOI: 10.1111/1751-7915.13770] [Citation(s) in RCA: 10] [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: 08/25/2020] [Revised: 01/27/2021] [Accepted: 01/28/2021] [Indexed: 12/03/2022] Open
Abstract
Acinetobacter baumannii poses a serious threat to human health, mainly because of its widespread distribution and severe drug resistance. However, no licensed vaccines exist for this pathogen. In this study, we created a conjugate vaccine against A. baumannii by introducing an O-linked glycosylation system into the host strain. After demonstrating the ability of the vaccine to elicit Th1 and Th2 immune responses and observing its good safety in mouse a model, the strong in vitro bactericidal activity and prophylactic effects of the conjugate vaccine against infection were further demonstrated by evaluating post-infection tissue bacterial loads, observing suppressed serum pro-inflammatory cytokine levels. Additionally, the broad protection from the vaccine was further proved via lethal challenge with A. baumannii. Overall, these results indicated that the conjugate vaccine could elicit an efficient immune response and provide good protection against A. baumannii infection in murine sepsis models. Thus, the conjugate vaccine can be considered as a promising candidate vaccine for preventing A. baumannii infection.
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Affiliation(s)
- Xin Li
- State Key Laboratory of Pathogen and BiosecurityBeijing Institute of Biotechnology20 Dongdajie Street, Fengtai DistrictBeijing100071China
| | - Chao Pan
- State Key Laboratory of Pathogen and BiosecurityBeijing Institute of Biotechnology20 Dongdajie Street, Fengtai DistrictBeijing100071China
| | - Zhicheng Liu
- State Key Laboratory of Pathogen and BiosecurityBeijing Institute of Biotechnology20 Dongdajie Street, Fengtai DistrictBeijing100071China
| | - Peng Sun
- State Key Laboratory of Pathogen and BiosecurityBeijing Institute of Biotechnology20 Dongdajie Street, Fengtai DistrictBeijing100071China
| | - Xiaoting Hua
- Department of Infectious DiseasesSir Run Run Shaw HospitalCollege of MedicineZhejiang UniversityHangzhouChina
| | - Erling Feng
- State Key Laboratory of Pathogen and BiosecurityBeijing Institute of Biotechnology20 Dongdajie Street, Fengtai DistrictBeijing100071China
| | - Yunsong Yu
- Department of Infectious DiseasesSir Run Run Shaw HospitalCollege of MedicineZhejiang UniversityHangzhouChina
| | - Jun Wu
- State Key Laboratory of Pathogen and BiosecurityBeijing Institute of Biotechnology20 Dongdajie Street, Fengtai DistrictBeijing100071China
| | - Li Zhu
- State Key Laboratory of Pathogen and BiosecurityBeijing Institute of Biotechnology20 Dongdajie Street, Fengtai DistrictBeijing100071China
| | - Hengliang Wang
- State Key Laboratory of Pathogen and BiosecurityBeijing Institute of Biotechnology20 Dongdajie Street, Fengtai DistrictBeijing100071China
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17
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Virulence of Acinetobacter baumannii in proteins moonlighting. Arch Microbiol 2021; 204:96. [DOI: 10.1007/s00203-021-02721-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 12/10/2021] [Accepted: 12/10/2021] [Indexed: 10/19/2022]
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18
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Tram G, Poole J, Adams FG, Jennings MP, Eijkelkamp BA, Atack JM. The Acinetobacter baumannii Autotransporter Adhesin Ata Recognizes Host Glycans as High-Affinity Receptors. ACS Infect Dis 2021; 7:2352-2361. [PMID: 34339169 DOI: 10.1021/acsinfecdis.1c00021] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Acinetobacter baumannii is a significant opportunistic pathogen responsible for infections of the lung, blood, skin, urinary tract, and soft tissues, with some strains exhibiting almost complete resistance to commonly used antibiotics. This multidrug resistance, together with a dearth of new antibiotic development, mean novel methods of treatment and prevention are urgently needed. Although many A. baumannii factors required to colonize the host have been identified, little is known about the specific host molecules recognized by these factors. A. baumannii produces a trimeric autotransporter adhesin known as Ata that has been previously demonstrated to bind components of the host cell's extracellular matrix, which are often heavily glycosylated. We hypothesized that Ata would exhibit lectin activity which would play a role in adherence to the host cell surface. Our biophysical analysis using glycan arrays and surface plasmon resonance demonstrated that Ata binds galactose, N-acetylglucosamine, and galactose (β1-3/4) N-acetylglucosamine with high-affinity. These structures are present on many of the proteins which were previously reported to be bound by Ata. We also demonstrated that the recognition of human plasma fibronectin by Ata requires this ability to bind glycans, as the interaction between Ata and fibronectin does not occur when fibronectin is deglycosylated. This strongly suggests a key role for Ata lectin activity during host adherence. This information will assist in directing the development of new and effective treatments to block host interactions using glycans and/or novel compounds in multidrug resistant A. baumannii infections.
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Affiliation(s)
- Greg Tram
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4215, Australia
| | - Jessica Poole
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4215, Australia
| | - Felise G. Adams
- Molecular Sciences & Technology, College of Science and Engineering, Flinders University, Sturt Road, Bedford Park, South Australia 5042, Australia
| | - Michael P. Jennings
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4215, Australia
| | - Bart A. Eijkelkamp
- Molecular Sciences & Technology, College of Science and Engineering, Flinders University, Sturt Road, Bedford Park, South Australia 5042, Australia
| | - John M. Atack
- Institute for Glycomics, Griffith University, Gold Coast, Queensland 4215, Australia
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19
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Kamuyu G, Suen Cheng Y, Willcocks S, Kewcharoenwong C, Kiratisin P, Taylor PW, Wren BW, Lertmemongkolchai G, Stabler RA, Brown J. Sequential Vaccination With Heterologous Acinetobacter baumannii Strains Induces Broadly Reactive Antibody Responses. Front Immunol 2021; 12:705533. [PMID: 34394105 PMCID: PMC8363311 DOI: 10.3389/fimmu.2021.705533] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 07/08/2021] [Indexed: 12/11/2022] Open
Abstract
Antibody therapy may be an alternative treatment option for infections caused by the multi-drug resistant (MDR) bacterium Acinetobacter baumannii. As A. baumannii has multiple capsular serotypes, a universal antibody therapy would need to target conserved protein antigens rather than the capsular polysaccharides. We have immunized mice with single or multiple A. baumannii strains to induce antibody responses to protein antigens, and then assessed whether these responses provide cross-protection against a collection of genetically diverse clinical A. baumannii isolates. Immunized mice developed antibody responses to multiple protein antigens. Flow cytometry IgG binding assays and immunoblots demonstrated improved recognition of both homologous and heterologous clinical strains in sera from mice immunized with multiple strains compared to a single strain. The capsule partially inhibited bacterial recognition by IgG and the promotion of phagocytosis by human neutrophils. However, after immunization with multiple strains, serum antibodies to protein antigens promoted neutrophil phagocytosis of heterologous A. baumannii strains. In an infection model, mice immunized with multiple strains had lower bacterial counts in the spleen and liver following challenge with a heterologous strain. These data demonstrate that antibodies targeting protein antigens can improve immune recognition and protection against diverse A. baumannii strains, providing support for their use as an antibody therapy.
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Affiliation(s)
- Gathoni Kamuyu
- Centre for Inflammation and Tissue Repair, University College London (UCL) Respiratory, London, United Kingdom
| | - Yat Suen Cheng
- Centre for Inflammation and Tissue Repair, University College London (UCL) Respiratory, London, United Kingdom
| | - Sam Willcocks
- London School of Hygiene and Tropical Medicine, Infectious and Tropical Disease, Department of Infection Biology, London, United Kingdom
| | - Chidchamai Kewcharoenwong
- Cellular and Molecular Immunology Unit, Centre for Research and Development of Medical Diagnostic Laboratories (CMDL), Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
| | - Pattarachai Kiratisin
- Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok-Noi, Bangkok, Thailand
| | - Peter W Taylor
- School of Pharmacy, University College London, London, United Kingdom
| | - Brendan W Wren
- London School of Hygiene and Tropical Medicine, Infectious and Tropical Disease, Department of Infection Biology, London, United Kingdom
| | - Ganjana Lertmemongkolchai
- Cellular and Molecular Immunology Unit, Centre for Research and Development of Medical Diagnostic Laboratories (CMDL), Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand.,Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand
| | - Richard A Stabler
- London School of Hygiene and Tropical Medicine, Infectious and Tropical Disease, Department of Infection Biology, London, United Kingdom
| | - Jeremy Brown
- Centre for Inflammation and Tissue Repair, University College London (UCL) Respiratory, London, United Kingdom
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20
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Shhadeh A, Galaski J, Alon-Maimon T, Fahoum J, Wiener R, Slade DJ, Mandelboim O, Bachrach G. CEACAM1 Activation by CbpF-Expressing E. coli. Front Cell Infect Microbiol 2021; 11:699015. [PMID: 34395310 PMCID: PMC8358318 DOI: 10.3389/fcimb.2021.699015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 07/13/2021] [Indexed: 01/04/2023] Open
Abstract
Recent studies on the oral, anaerobic, gram-negative bacterium Fusobacterium nucleatum revealed its presence and involvement in colorectal, esophageal and breast cancer. We previously demonstrated that F. nucleatum binds and activates the human inhibitory receptors TIGIT and CEACAM1 leading to inhibition of T and NK cell anti-tumor immunity. CEACAM1 was found to be bound and activated by the fusobacterial trimeric autotransporter adhesin CbpF. Here we report the generation of a recombinant E. coli expressing full-length CbpF that efficiently binds and activates CEACAM1.
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Affiliation(s)
- Amjad Shhadeh
- The Institute of Dental Sciences, The Hebrew University-Hadassah School of Dental Medicine, Jerusalem, Israel
| | - Johanna Galaski
- The Concern Foundation Laboratories at the Lautenberg Center for General and Tumor Immunology, Department of Immunology and Cancer Research, Institute for Medical Research Israel Canada (IMRIC), Faculty of Medicine, The Hebrew University Medical School, Jerusalem, Israel.,I. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Tamar Alon-Maimon
- The Institute of Dental Sciences, The Hebrew University-Hadassah School of Dental Medicine, Jerusalem, Israel
| | - Jamal Fahoum
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel Canada (IMRIC), Faculty of Medicine, The Hebrew University Medical School, Jerusalem, Israel
| | - Reuven Wiener
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel Canada (IMRIC), Faculty of Medicine, The Hebrew University Medical School, Jerusalem, Israel
| | - Daniel J Slade
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Ofer Mandelboim
- The Concern Foundation Laboratories at the Lautenberg Center for General and Tumor Immunology, Department of Immunology and Cancer Research, Institute for Medical Research Israel Canada (IMRIC), Faculty of Medicine, The Hebrew University Medical School, Jerusalem, Israel
| | - Gilad Bachrach
- The Institute of Dental Sciences, The Hebrew University-Hadassah School of Dental Medicine, Jerusalem, Israel
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21
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Pompilio A, Scribano D, Sarshar M, Di Bonaventura G, Palamara AT, Ambrosi C. Gram-Negative Bacteria Holding Together in a Biofilm: The Acinetobacter baumannii Way. Microorganisms 2021; 9:1353. [PMID: 34206680 PMCID: PMC8304980 DOI: 10.3390/microorganisms9071353] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/14/2021] [Accepted: 06/18/2021] [Indexed: 12/24/2022] Open
Abstract
Bacterial biofilms are a serious public-health problem worldwide. In recent years, the rates of antibiotic-resistant Gram-negative bacteria associated with biofilm-forming activity have increased worrisomely, particularly among healthcare-associated pathogens. Acinetobacter baumannii is a critically opportunistic pathogen, due to the high rates of antibiotic resistant strains causing healthcare-acquired infections (HAIs). The clinical isolates of A. baumannii can form biofilms on both biotic and abiotic surfaces; hospital settings and medical devices are the ideal environments for A. baumannii biofilms, thereby representing the main source of patient infections. However, the paucity of therapeutic options poses major concerns for human health infections caused by A. baumannii strains. The increasing number of multidrug-resistant A. baumannii biofilm-forming isolates in association with the limited number of biofilm-eradicating treatments intensify the need for effective antibiofilm approaches. This review discusses the mechanisms used by this opportunistic pathogen to form biofilms, describes their clinical impact, and summarizes the current and emerging treatment options available, both to prevent their formation and to disrupt preformed A. baumannii biofilms.
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Affiliation(s)
- Arianna Pompilio
- Center for Advanced Studies and Technology (CAST), Department of Medical, Oral and Biotechnological Sciences, Service of Clinical Microbiology, “G. d’Annunzio” University of Chieti-Pescara, 66100 Chieti, Italy; (A.P.); (G.D.B.)
| | - Daniela Scribano
- Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Rome, Italy;
- Dani Di Giò Foundation-Onlus, 00193 Rome, Italy
| | - Meysam Sarshar
- Research Laboratories, Bambino Gesù Children’s Hospital, IRCCS, 00146 Rome, Italy;
| | - Giovanni Di Bonaventura
- Center for Advanced Studies and Technology (CAST), Department of Medical, Oral and Biotechnological Sciences, Service of Clinical Microbiology, “G. d’Annunzio” University of Chieti-Pescara, 66100 Chieti, Italy; (A.P.); (G.D.B.)
| | - Anna Teresa Palamara
- Department of Infectious Diseases, Istituto Superiore di Sanità, 00161 Rome, Italy;
- Laboratory Affiliated to Institute Pasteur Italia-Cenci Bolognetti Foundation, Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Rome, Italy
| | - Cecilia Ambrosi
- Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Open University, IRCCS, 00166 Rome, Italy
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22
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Ma C, McClean S. Mapping Global Prevalence of Acinetobacter baumannii and Recent Vaccine Development to Tackle It. Vaccines (Basel) 2021; 9:vaccines9060570. [PMID: 34205838 PMCID: PMC8226933 DOI: 10.3390/vaccines9060570] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/16/2021] [Accepted: 05/22/2021] [Indexed: 12/23/2022] Open
Abstract
Acinetobacter baumannii is a leading cause of nosocomial infections that severely threaten public health. The formidable adaptability and resistance of this opportunistic pathogen have hampered the development of antimicrobial therapies which consequently leads to very limited treatment options. We mapped the global prevalence of multidrug-resistant A. baumannii and showed that carbapenem-resistant A. baumannii is widespread throughout Asia and the Americas. Moreover, when antimicrobial resistance rates of Acinetobacter spp. exceed a threshold level, the proportion of A. baumannii isolates from clinical samples surges. Therefore, vaccines represent a realistic alternative strategy to tackle this pathogen. Research into anti-A. baumannii vaccines have enhanced in the past decade and multiple antigens have been investigated preclinically with varying results. This review summarises the current knowledge of virulence factors relating to A. baumannii–host interactions and its implication in vaccine design, with a view to understanding the current state of A. baumannii vaccine development and the direction of future efforts.
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23
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López-Siles M, Corral-Lugo A, McConnell MJ. Vaccines for multidrug resistant Gram negative bacteria: lessons from the past for guiding future success. FEMS Microbiol Rev 2021; 45:fuaa054. [PMID: 33289833 DOI: 10.1093/femsre/fuaa054] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 10/18/2020] [Indexed: 02/07/2023] Open
Abstract
Antimicrobial resistance is a major threat to global public health. Vaccination is an effective approach for preventing bacterial infections, however it has not been successfully applied to infections caused by some of the most problematic multidrug resistant pathogens. In this review, the potential for vaccines to contribute to reducing the burden of disease of infections caused by multidrug resistant Gram negative bacteria is presented. Technical, logistical and societal hurdles that have limited successful vaccine development for these infections in the past are identified, and recent advances that can contribute to overcoming these challenges are assessed. A synthesis of vaccine technologies that have been employed in the development of vaccines for key multidrug resistant Gram negative bacteria is included, and emerging technologies that may contribute to future successes are discussed. Finally, a comprehensive review of vaccine development efforts over the last 40 years for three of the most worrisome multidrug resistant Gram negative pathogens, Acinetobacter baumannii, Klebsiella pneumoniae and Pseudomonas aeruginosa is presented, with a focus on recent and ongoing studies. Finally, future directions for the vaccine development field are highlighted.
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Affiliation(s)
- Mireia López-Siles
- Intrahospital Infections Laboratory, National Centre for Microbiology, Instituto de Salud Carlos III (ISCIII), Madrid, Spain
| | - Andrés Corral-Lugo
- Intrahospital Infections Laboratory, National Centre for Microbiology, Instituto de Salud Carlos III (ISCIII), Madrid, Spain
| | - Michael J McConnell
- Intrahospital Infections Laboratory, National Centre for Microbiology, Instituto de Salud Carlos III (ISCIII), Madrid, Spain
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Hatefi Oskuei R, Darvish Alipour Astaneh S, Rasooli I. A conserved region of Acinetobacter trimeric autotransporter adhesion, Ata, provokes suppression of Acinetobacter baumannii virulence. Arch Microbiol 2021; 203:3483-3493. [PMID: 33907866 DOI: 10.1007/s00203-021-02343-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 04/17/2021] [Accepted: 04/21/2021] [Indexed: 01/02/2023]
Abstract
The Acinetobacter trimeric autotransporter adhesin (Ata) is an important virulence factor. The conserved region from the genomic sequence of a 6777bp/2258 amino acid of Acinetobacter baumannii ATCC®19606™ ata was explored. A 263aa of the C-terminal of Ata (rcAta263) was expressed. The effect of rcAta263 on A. baumannii virulence was studied in a murine model. IgG and IgA were elicited and the mice groups challenged with A. baumannii showed significant survival rates from 66 to 100%. The bacterial loads were determined in the spleens, livers, and lungs of both control and test groups. The adhesion rate of A. baumannii to A549 cells in the presence of serum, cytotoxicity, mutagenicity, and biofilm disruption potential of rcAta263 were determined. Intraperitoneally challenged groups showed a significantly reduced bacterial load in the organs of the immunized mice. Intranasal challenge reduced 4 logs of bacterial CFU/g in the test group. The immunized mice sera reduced adherence of A. baumannii to A549 cells to 80%. No cytotoxic or mutagenic effect was detected. Biofilm disruption was significantly increased in the presence of immunized mice sera. Immunization with the conserved region of Ata significantly combats the virulence of A. baumannii which could be considered as a therapeutic strategy to control A. baumannii infections.
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Affiliation(s)
- Ramin Hatefi Oskuei
- Department of Biology, Shahed University, Tehran-Qom Express way, Tehran, 3319118651, Iran
| | - Shakiba Darvish Alipour Astaneh
- Department of Biotechnology, Semnan University, Central Administration of Semnan University, Campus 1, Semnan, 35131-19111, I. R. of Iran
| | - Iraj Rasooli
- Department of Biology, Shahed University, Tehran-Qom Express way, Tehran, 3319118651, Iran.
- Molecular Microbiology Research Center and Department of Biology, Shahed University, Tehran, Iran.
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25
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Okaro U, George S, Anderson B. What Is in a Cat Scratch? Growth of Bartonella henselae in a Biofilm. Microorganisms 2021; 9:835. [PMID: 33919891 PMCID: PMC8070961 DOI: 10.3390/microorganisms9040835] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/02/2021] [Accepted: 04/07/2021] [Indexed: 01/04/2023] Open
Abstract
Bartonella henselae (B. henselae) is a gram-negative bacterium that causes cat scratch disease, bacteremia, and endocarditis, as well as other clinical presentations. B. henselae has been shown to form a biofilm in vitro that likely plays a role in the establishment and persistence of the bacterium in the host. Biofilms are also known to form in the cat flea vector; hence, the ability of this bacterium to form a biofilm has broad biological significance. The release of B. henselae from a biofilm niche appears to be important in disease persistence and relapse in the vertebrate host but also in transmission by the cat flea vector. It has been shown that the BadA adhesin of B. henselae is critical for adherence and biofilm formation. Thus, the upregulation of badA is important in initiating biofilm formation, and down-regulation is important in the release of the bacterium from the biofilm. We summarize the current knowledge of biofilm formation in Bartonella species and the role of BadA in biofilm formation. We discuss the evidence that defines possible mechanisms for the regulation of the genes required for biofilm formation. We further describe the regulation of those genes in the conditions that mimic both the arthropod vector and the mammalian host for B. henselae. The treatment for persistent B. henselae infection remains a challenge; hence, a better understanding of the mechanisms by which this bacterium persists in its host is critical to inform future efforts to develop drugs to treat such infections.
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Affiliation(s)
- Udoka Okaro
- Foundational Sciences Directorate, Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702, USA;
| | - Sierra George
- Department of Molecular Medicine, MDC7, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., Tampa, FL 33612, USA;
| | - Burt Anderson
- Department of Molecular Medicine, MDC7, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., Tampa, FL 33612, USA;
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Acinetobacter baumannii: An Ancient Commensal with Weapons of a Pathogen. Pathogens 2021; 10:pathogens10040387. [PMID: 33804894 PMCID: PMC8063835 DOI: 10.3390/pathogens10040387] [Citation(s) in RCA: 85] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/19/2021] [Accepted: 03/23/2021] [Indexed: 12/22/2022] Open
Abstract
Acinetobacter baumannii is regarded as a life-threatening pathogen associated with community-acquired and nosocomial infections, mainly pneumonia. The rise in the number of A. baumannii antibiotic-resistant strains reduces effective therapies and increases mortality. Bacterial comparative genomic studies have unraveled the innate and acquired virulence factors of A. baumannii. These virulence factors are involved in antibiotic resistance, environmental persistence, host-pathogen interactions, and immune evasion. Studies on host–pathogen interactions revealed that A. baumannii evolved different mechanisms to adhere to in order to invade host respiratory cells as well as evade the host immune system. In this review, we discuss current data on A. baumannii genetic features and virulence factors. An emphasis is given to the players in host–pathogen interaction in the respiratory tract. In addition, we report recent investigations into host defense systems using in vitro and in vivo models, providing new insights into the innate immune response to A. baumannii infections. Increasing our knowledge of A. baumannii pathogenesis may help the development of novel therapeutic strategies based on anti-adhesive, anti-virulence, and anti-cell to cell signaling pathways drugs.
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27
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López-Martín M, Dubern JF, Alexander MR, Williams P. AbaM Regulates Quorum Sensing, Biofilm Formation, and Virulence in Acinetobacter baumannii. J Bacteriol 2021; 203:e00635-20. [PMID: 33495249 PMCID: PMC8088503 DOI: 10.1128/jb.00635-20] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 01/08/2021] [Indexed: 12/31/2022] Open
Abstract
Acinetobacter baumannii possesses a single divergent luxR/luxRI-type quorum-sensing (QS) locus named abaR/abaI This locus also contains a third gene located between abaR and abaI, which we term abaM, that codes for an uncharacterized member of the RsaM protein family known to regulate N-acylhomoserine lactone (AHL)-dependent QS in other beta- and gammaproteobacteria. Here, we show that disruption of abaM via a T26 insertion in A. baumannii strain AB5075 resulted in increased production of N-(3-hydroxydodecanoyl)-l-homoserine lactone and enhanced surface motility and biofilm formation. In contrast to the wild type and the abaI::T26 mutant, the virulence of the abaM::T26 mutant was completely attenuated in a Galleria mellonella infection model. Transcriptomic analysis of the abaM::T26 mutant revealed that AbaM differentially regulates at least 76 genes, including the csu pilus operon and the acinetin 505 lipopeptide biosynthetic operon, that are involved in surface adherence, biofilm formation and virulence. A comparison of the wild type, abaM::T26 and abaI::T26 transcriptomes, indicates that AbaM regulates ∼21% of the QS regulon including the csu operon. Moreover, the QS genes (abaI and abaR) were among the most upregulated in the abaM::T26 mutant. A. baumanniilux-based abaM reporter gene fusions revealed that abaM expression is positively regulated by QS but negatively autoregulated. Overall, the data presented in this work demonstrates that AbaM plays a central role in regulating A. baumannii QS, virulence, surface motility, and biofilm formation.IMPORTANCEAcinetobacter baumannii is a multiantibiotic-resistant pathogen of global health care importance. Understanding Acinetobacter virulence gene regulation could aid the development of novel anti-infective strategies. In A. baumannii, the abaR and abaI genes that code for the receptor and synthase components of an N-acylhomoserine (AHL) lactone-dependent quorum sensing system (QS) are separated by abaM Here, we show that although mutation of abaM increased AHL production, surface motility, and biofilm development, it resulted in the attenuation of virulence. AbaM was found to control both QS-dependent and QS-independent genes. The significance of this work lies in the identification of AbaM, an RsaM ortholog known to control virulence in plant pathogens, as a modulator of virulence in a human pathogen.
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Affiliation(s)
- Mario López-Martín
- Biodiscovery Institute, National Biofilms Innovation Centre, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Jean-Frédéric Dubern
- Biodiscovery Institute, National Biofilms Innovation Centre, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Morgan R Alexander
- Advanced Materials and Healthcare Technologies, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
| | - Paul Williams
- Biodiscovery Institute, National Biofilms Innovation Centre, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
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28
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Belisario JC, Lee HH, Luknauth H, Rigel NW, Martinez LR. Acinetobacter baumannii Strains Deficient in the Clp Chaperone-Protease Genes Have Reduced Virulence in a Murine Model of Pneumonia. Pathogens 2021; 10:pathogens10020204. [PMID: 33668542 PMCID: PMC7917692 DOI: 10.3390/pathogens10020204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 01/05/2023] Open
Abstract
Acinetobacter baumannii has emerged as a significant opportunistic Gram-negative pathogen and causative agent of nosocomial pneumonia especially in immunocompromised individuals in intensive care units. Recent advances to understand the contribution and function of A. baumannii virulence factors in its pathogenesis have begun to elucidate how this bacterium interacts with immune cells and its interesting mechanisms for multi-antibiotic resistance. Taking advantage of the availability of the A. baumannii AB5075 transposon mutant library, we investigated the impact of the A. baumannii Clp genes, which encode for a chaperone-protease responsible for the degradation of misfolded proteins, on bacterial virulence in a model of pneumonia using C57BL/6 mice and survival within J774.16 macrophage-like cells. Clp-protease A. baumannii mutants exhibit decreased virulence in rodents, high phagocytic cell-mediated killing and reduced biofilm formation. Capsular staining showed evidence of encapsulation in A. baumannii AB5075 and Clp-mutant strains. Surprisingly, clpA and clpS mutants displayed irregular cell morphology, which may be important in the biofilm structural deficiencies observed in these strains. Interestingly, clpA showed apical-like growth, proliferation normally observed in filamentous fungi. These findings provide new information regarding A. baumannii pathogenesis and may be important for the development of therapies intended at reducing morbidity and mortality associated with this remarkable pathogen.
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Affiliation(s)
- J Christian Belisario
- Department of Physical Medicine and Rehabilitation, University of Pennsylvania, Philadelphia, PA 19146, USA;
- Department of Biomedical Sciences, NYIT College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568, USA;
| | - Hiu Ham Lee
- Department of Biomedical Sciences, NYIT College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568, USA;
| | - Harshani Luknauth
- Department of Biology, Hofstra University, Hempstead, NY 11549, USA; (H.L.); (N.W.R.)
| | - Nathan W. Rigel
- Department of Biology, Hofstra University, Hempstead, NY 11549, USA; (H.L.); (N.W.R.)
| | - Luis R. Martinez
- Department of Biomedical Sciences, NYIT College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568, USA;
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL 32610, USA
- Correspondence:
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29
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Mea HJ, Yong PVC, Wong EH. An overview of Acinetobacter baumannii pathogenesis: Motility, adherence and biofilm formation. Microbiol Res 2021; 247:126722. [PMID: 33618061 DOI: 10.1016/j.micres.2021.126722] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 12/13/2022]
Abstract
The Gram-negative opportunistic pathogen Acinetobacter baumannii has gain notoriety in recent decades, primarily due to its propensity to cause nosocomial infections in critically ill patients. Its global spread, multi-drug resistance features and plethora of virulence factors make it a serious threat to public health worldwide. Though much effort has been expended in uncovering its successes, it continues to confound researchers due to its highly adaptive nature, mutating to meet the needs of a given environment. Its persistence in the clinical setting allows it to be in close proximity to a potential host, where contact can be made facilitating infection and colonization. In this article, we aim to provide a current overview of the bacterial virulence factors, specifically focusing on factors involved in the initial stages of infection, highlighting the role of adaptation facilitated by two-component systems and biofilm formation. Finally, the study of host-pathogen interactions using available animal models, their suitability, notable findings and some perspectives moving forward are also discussed.
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Affiliation(s)
- Hing Jian Mea
- School of Biosciences, Faculty of Health and Medical Sciences, Taylor's University Lakeside Campus, 47500, Subang Jaya, Selangor Darul Ehsan, Malaysia
| | - Phelim Voon Chen Yong
- School of Biosciences, Faculty of Health and Medical Sciences, Taylor's University Lakeside Campus, 47500, Subang Jaya, Selangor Darul Ehsan, Malaysia
| | - Eng Hwa Wong
- School of Medicine, Faculty of Health and Medical Sciences, Taylor's University Lakeside Campus, 47500, Subang Jaya, Selangor Darul Ehsan, Malaysia.
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30
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Ramezanalizadeh F, Rasooli I, Owlia P. Protective response against Acinetobacter baumannii with ferric iron receptors HemTR-BauA in a murine sepsis model. Future Microbiol 2021; 16:143-157. [PMID: 33528272 DOI: 10.2217/fmb-2020-0133] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Aim: Iron uptake and metabolism pathways are promising targets in vaccine development as an alternative strategy for antibiotics. Methods & methods: HemTR, a putative heme receptor of Acinetobacter baumannii, was expressed and its protectivity against A. baumannii was determined singly or in combination with the siderophore receptor, BauA, in mice. Results: High level of IgG was elicited. There was a delay in mice mortality with reduced bacterial loads in internal organs in the sublethal challenge. Protection was better in the HemTR-BauA group in both lethal and sublethal challenges. Passive transfer of anti-HemTR and anti-BauA partially protected mice against A. baumannii infection. Conclusion: HemTR in combination with other iron receptors could contribute to the development of protective vaccines against A. baumannii.
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Affiliation(s)
| | - Iraj Rasooli
- Department of Biology, Molecular Microbiology Research Center, Shahed University, Tehran, 3319118651, Iran
| | - Parviz Owlia
- Department of Microbiology, Molecular Microbiology Research Center, School of Medicine, Shahed University, Tehran, 3319118651, Iran
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31
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Niu T, Guo L, Luo Q, Zhou K, Yu W, Chen Y, Huang C, Xiao Y. Wza gene knockout decreases Acinetobacter baumannii virulence and affects Wzy-dependent capsular polysaccharide synthesis. Virulence 2021; 11:1-13. [PMID: 31878839 PMCID: PMC6961727 DOI: 10.1080/21505594.2019.1700659] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
To investigate the virulence of capsular polysaccharide export protein (Wza) in carbapenem-resistant Acinetobacter baumannii and its effect on capsule formation. wza gene knockout and complementation strains were constructed, and changes in bacterial virulence were observed using in vitro adhesion, antiserum complement killing, anti-oxidation experiments, and infections in Galleria mellonella and mice. The effect of wza knockout on the genes wzb and wzc and wzi were assessed by RT-PCR. We successfully constructed wza knockout and complementation strains. Compared with wild-type (WT) strains, wza knockout strains displayed lower adhesion to A549 cells (p = 0.044), lower antiserum complement killing ability (p = 0.001), and lower mortality of G. mellonella (p = 0.010) and mice (p = 0.033). Expression levels of wzb, wzc and wzi were decreased in wza knockout strains. The antioxidant capacity of Wza knockout bacteria was only slightly decreased. Complementation of the wza gene returned the adhesion ability, antiserum complement killing ability, and mortality of G. mellonella and mice to WT levels. Expression of wzb, wzc and wzi was also returned to WT levels following wza complementation. The results clearly demonstrate that Wza is toxic. Wza affects the expression of other proteins of the Wzy capsule polysaccharide synthesis pathway, which affects the assembly, export, and extracellular fixation of capsular polysaccharide, resulting in synergistic effects that decrease bacterial virulence.
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Affiliation(s)
- Tianshui Niu
- Collaborative Initiative Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis & Treatment of Infectious Diseases, the First Affiliated Hospital, college of Medicine, Zhejiang University, Hangzhou, China.,Hangzhou Red Cross Hospital/Zhe Jiang Chinese Medcine and Western Medcine Integrated Hospital, Hangzhou, China
| | - Lihua Guo
- Collaborative Initiative Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis & Treatment of Infectious Diseases, the First Affiliated Hospital, college of Medicine, Zhejiang University, Hangzhou, China
| | - Qixia Luo
- Collaborative Initiative Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis & Treatment of Infectious Diseases, the First Affiliated Hospital, college of Medicine, Zhejiang University, Hangzhou, China
| | - Kai Zhou
- Collaborative Initiative Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis & Treatment of Infectious Diseases, the First Affiliated Hospital, college of Medicine, Zhejiang University, Hangzhou, China
| | - Wei Yu
- Zhejiang Provincial People's Hospital, People's Hospital of Hangzhou Medical College, Hangzhou, China
| | - Yunbo Chen
- Collaborative Initiative Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis & Treatment of Infectious Diseases, the First Affiliated Hospital, college of Medicine, Zhejiang University, Hangzhou, China
| | - Chen Huang
- Collaborative Initiative Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis & Treatment of Infectious Diseases, the First Affiliated Hospital, college of Medicine, Zhejiang University, Hangzhou, China
| | - Yonghong Xiao
- Collaborative Initiative Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis & Treatment of Infectious Diseases, the First Affiliated Hospital, college of Medicine, Zhejiang University, Hangzhou, China
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32
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Microscale communication between bacterial pathogens and the host epithelium. Genes Immun 2021; 22:247-254. [PMID: 34588625 PMCID: PMC8497271 DOI: 10.1038/s41435-021-00149-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 08/18/2021] [Accepted: 08/23/2021] [Indexed: 02/01/2023]
Abstract
Pathogenic bacteria have evolved a variety of highly selective adhesins allowing these microbes to engage specific surface determinants of their eukaryotic host cells. Receptor clustering induced by the multivalent microorganisms will not only anchor the bacteria to the tissue, but will inevitably trigger host cell signaling. It has become clear, that these bacteria-initiated signaling events can be seen as a form of localized communication with host epithelial cells. Such a microscale communication can have immediate consequences in the form of changes in host cell membrane morphology or cytoskeletal organization, but can also lead to transcriptional responses and medium- and long-term alterations in cellular physiology. In this review, we will discuss several examples of this form of microscale communication between bacterial pathogens and mammalian host cells and try to delineate their downstream ramifications in the infection process. Furthermore, we will highlight recent findings that specialized pathogenic bacteria utilize the adhesin-based interaction to diffuse the short-range messenger molecule nitric oxide into the host tissue. While anti-adhesive strategies to disrupt the initial bacterial attachment have not yet translated into medical applications, the ability to interfere with the microscale communication emanating on the host side provides an unconventional approach for preventing infectious diseases.
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33
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Acinetobacter baumannii Targets Human Carcinoembryonic Antigen-Related Cell Adhesion Molecules (CEACAMs) for Invasion of Pneumocytes. mSystems 2020; 5:5/6/e00604-20. [PMID: 33361319 PMCID: PMC7762790 DOI: 10.1128/msystems.00604-20] [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
Multidrug-resistant Acinetobacter baumannii is regarded as a life-threatening pathogen mainly associated with nosocomial and community-acquired pneumonia. Here, we show that A. baumannii can bind the human carcinoembryonic antigen-related cell adhesion molecule (CEACAM) receptors CEACAM1, CEACAM5, and CEACAM6. This specific interaction enhances A. baumannii internalization in membrane-bound vacuoles, promptly decorated with Rab5, Rab7, and lipidated microtubule-associated protein light chain 3 (LC3). Dissecting intracellular signaling pathways revealed that infected pneumocytes trigger interleukin-8 (IL-8) secretion via the extracellular signal-regulated kinase (ERK)1/2 and nuclear factor-kappa B (NF-κB) signaling pathways for A. baumannii clearance. However, in CEACAM1-L-expressing cells, IL-8 secretion lasts only 24 h, possibly due to an A. baumannii-dependent effect on the CEACAM1-L intracellular domain. Conversely, the glycosylphosphatidylinositol-anchored CEACAM5 and CEACAM6 activate the c-Jun NH2-terminal kinase (JNK)1/2-Rubicon-NOX2 pathway, suggestive of LC3-associated phagocytosis. Overall, our data show for the first time novel mechanisms of adhesion to and invasion of pneumocytes by A. baumannii via CEACAM-dependent signaling pathways that eventually lead to bacterial killing. These findings suggest that CEACAM upregulation could put patients at increased risk of lower respiratory tract infection by A. baumannii IMPORTANCE This work shows for the first time that Acinetobacter baumannii binds to carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1), CEACAM5, and CEACAM6. This binding significantly enhances A. baumannii internalization within alveolar host cell epithelia. Intracellular trafficking involves typical Rab5 and Rab7 vacuolar proteins as well as light chain 3 (LC3) and slowly progresses to bacterial killing by endosome acidification. CEACAM engagement by A. baumannii leads to distinct and specific downstream signaling pathways. The CEACAM1 pathway finely tunes interleukin-8 (IL-8) secretion, whereas CEACAM5 and CEACAM6 mediate LC3-associated phagocytosis. The present study provides new insights into A. baumannii-host interactions and could represent a promising therapeutic strategy to reduce pulmonary infections caused by this pathogen.
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34
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Recent Advances in the Pursuit of an Effective Acinetobacter baumannii Vaccine. Pathogens 2020; 9:pathogens9121066. [PMID: 33352688 PMCID: PMC7766458 DOI: 10.3390/pathogens9121066] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 12/15/2020] [Accepted: 12/17/2020] [Indexed: 12/22/2022] Open
Abstract
Acinetobacter baumannii has been a major cause of nosocomial infections for decades. The absence of an available vaccine coupled with emerging multidrug resistance has prevented the medical community from effectively controlling this human pathogen. Furthermore, the ongoing pandemic caused by SARS-CoV-2 has increased the risk of hospitalized patients developing ventilator-associated pneumonia caused by bacterial opportunists including A. baumannii. The shortage of antibiotics in the development pipeline prompted the World Health Organization to designate A. baumannii a top priority for the development of new medical countermeasures, such as a vaccine. There are a number of important considerations associated with the development of an A. baumannii vaccine, including strain characteristics, diverse disease manifestations, and target population. In the past decade, research efforts have revealed a number of promising new immunization strategies that could culminate in a safe and protective vaccine against A. baumannii. In this review, we highlight the recent progress in the development of A. baumannii vaccines, discuss potential challenges, and propose future directions to achieve an effective intervention against this human pathogen.
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35
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Liu W, Wu Z, Mao C, Guo G, Zeng Z, Fei Y, Wan S, Peng J, Wu J. Antimicrobial Peptide Cec4 Eradicates the Bacteria of Clinical Carbapenem-Resistant Acinetobacter baumannii Biofilm. Front Microbiol 2020; 11:1532. [PMID: 32849322 PMCID: PMC7431629 DOI: 10.3389/fmicb.2020.01532] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Accepted: 06/12/2020] [Indexed: 11/25/2022] Open
Abstract
The drug resistance rate of Acinetobacter baumannii increases year on year, and the drugs available for the treatment of carbapenem-resistant A. baumannii (CRAB) infection are extremely limited. A. baumannii, which forms biofilms, protects itself by secreting substrates such as exopolysaccharides, allowing it to survive under adverse conditions and increasing drug resistance. Antimicrobial peptides are small molecular peptides with broad-spectrum antibacterial activity and immunomodulatory function. Previous studies have shown that the antimicrobial peptide Cec4 has a strong effect on A. baumannii, but the antibacterial and biofilm inhibition of this antimicrobial peptide on clinical carbapenem resistance A. baumannii is not thoroughly understood. In this study, it was indicated that most of the 200 strains of CRAB were susceptible to Cec4 with a MIC of 4 μg/ml. Cec4 has a strong inhibitory and eradication effect on the CRAB biofilm; the minimum biofilm inhibition concentration (MBIC) was 64–128 μg/ml, and the minimum biofilm eradication concentration (MBEC) was 256–512 μg/ml. It was observed that Cec4 disrupted the structure of the biofilm using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). A comparative transcriptome analysis of the effects of the antimicrobial peptide Cec4 on CRAB biofilm, identified 185 differentially expressed genes, including membrane proteins, bacterial resistance genes, and pilus-related genes. The results show that multiple metabolic pathways, two-component regulation systems, quorum sensing, and antibiotic synthesis-related pathways in A. baumannii biofilms were affected after Cec4 treatment. In conclusion, Cec4 may represent a new choice for the prevention and treatment of clinical infections, and may also provide a theoretical basis for the development of antimicrobial peptide drugs.
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Affiliation(s)
- Weiwei Liu
- Immune Cells and Antibody Engineering Research Center of Guizhou Province, Guizhou Medical University, Guiyang, China.,Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guiyang, China.,The Key and Characteristic Laboratory of Modern Pathogen Biology, Basic Medical College, Guizhou Medical University, Guiyang, China
| | - Zhaoying Wu
- Immune Cells and Antibody Engineering Research Center of Guizhou Province, Guizhou Medical University, Guiyang, China.,Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guiyang, China.,The Key and Characteristic Laboratory of Modern Pathogen Biology, Basic Medical College, Guizhou Medical University, Guiyang, China
| | - Chengju Mao
- Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guiyang, China.,The Key and Characteristic Laboratory of Modern Pathogen Biology, Basic Medical College, Guizhou Medical University, Guiyang, China
| | - Guo Guo
- The Key and Characteristic Laboratory of Modern Pathogen Biology, Basic Medical College, Guizhou Medical University, Guiyang, China
| | - Zhu Zeng
- Immune Cells and Antibody Engineering Research Center of Guizhou Province, Guizhou Medical University, Guiyang, China.,The Key and Characteristic Laboratory of Modern Pathogen Biology, Basic Medical College, Guizhou Medical University, Guiyang, China
| | - Ying Fei
- The Center for Clinical Laboratories, The Affiliated Hospital of Guizhou Medical University, Guiyang, China
| | - Shan Wan
- The Center for Clinical Laboratories, The Affiliated Hospital of Guizhou Medical University, Guiyang, China
| | - Jian Peng
- Immune Cells and Antibody Engineering Research Center of Guizhou Province, Guizhou Medical University, Guiyang, China.,Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guiyang, China.,The Key and Characteristic Laboratory of Modern Pathogen Biology, Basic Medical College, Guizhou Medical University, Guiyang, China
| | - Jianwei Wu
- The Key and Characteristic Laboratory of Modern Pathogen Biology, Basic Medical College, Guizhou Medical University, Guiyang, China
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36
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Weidensdorfer M, Ishikawa M, Hori K, Linke D, Djahanschiri B, Iruegas R, Ebersberger I, Riedel-Christ S, Enders G, Leukert L, Kraiczy P, Rothweiler F, Cinatl J, Berger J, Hipp K, Kempf VAJ, Göttig S. The Acinetobacter trimeric autotransporter adhesin Ata controls key virulence traits of Acinetobacter baumannii. Virulence 2020; 10:68-81. [PMID: 31874074 PMCID: PMC6363060 DOI: 10.1080/21505594.2018.1558693] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Acinetobacter baumannii is a Gram-negative pathogen that causes a multitude of nosocomial infections. The Acinetobacter trimeric autotransporter adhesin (Ata) belongs to the superfamily of trimeric autotransporter adhesins which are important virulence factors in many Gram-negative species. Phylogenetic profiling revealed that ata is present in 78% of all sequenced A. baumannii isolates but only in 2% of the closely related species A. calcoaceticus and A. pittii. Employing a markerless ata deletion mutant of A. baumannii ATCC 19606 we show that adhesion to and invasion into human endothelial and epithelial cells depend on Ata. Infection of primary human umbilical cord vein endothelial cells (HUVECs) with A. baumannii led to the secretion of interleukin (IL)-6 and IL-8 in a time- and Ata-dependent manner. Furthermore, infection of HUVECs by WT A. baumannii was associated with higher rates of apoptosis via activation of caspases-3 and caspase-7, but not necrosis, in comparison to ∆ata. Ata deletion mutants were furthermore attenuated in their ability to kill larvae of Galleria mellonella and to survive in larvae when injected at sublethal doses. This indicates that Ata is an important multifunctional virulence factor in A. baumannii that mediates adhesion and invasion, induces apoptosis and contributes to pathogenicity in vivo.
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Affiliation(s)
- Marko Weidensdorfer
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe University, Frankfurt, Germany
| | - Masahito Ishikawa
- Department of Biotechnology, Graduate School of Engineering, Nagoya University, Nagoya, Japan
| | - Katsutoshi Hori
- Department of Biotechnology, Graduate School of Engineering, Nagoya University, Nagoya, Japan
| | - Dirk Linke
- Department of Biosciences, Section for Genetics and Evolutionary Biology, University of Oslo, Oslo, Norway
| | - Bardya Djahanschiri
- Department for Applied Bioinformatics, Institute of Cell Biology and Neuroscience, Goethe University, Frankfurt, Germany
| | - Ruben Iruegas
- Department for Applied Bioinformatics, Institute of Cell Biology and Neuroscience, Goethe University, Frankfurt, Germany
| | - Ingo Ebersberger
- Department for Applied Bioinformatics, Institute of Cell Biology and Neuroscience, Goethe University, Frankfurt, Germany.,Senckenberg Biodiversity and Climate Research Centre Frankfurt (BIK-F), Frankfurt, Germany
| | - Sara Riedel-Christ
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe University, Frankfurt, Germany
| | - Giulia Enders
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe University, Frankfurt, Germany
| | - Laura Leukert
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe University, Frankfurt, Germany
| | - Peter Kraiczy
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe University, Frankfurt, Germany
| | - Florian Rothweiler
- Institute of Medical Virology, University Hospital, Goethe University, Frankfurt, Germany
| | - Jindrich Cinatl
- Institute of Medical Virology, University Hospital, Goethe University, Frankfurt, Germany
| | - Jürgen Berger
- Electron Microscopy Facility, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Katharina Hipp
- Electron Microscopy Facility, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Volkhard A J Kempf
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe University, Frankfurt, Germany
| | - Stephan Göttig
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe University, Frankfurt, Germany
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37
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Monem S, Furmanek-Blaszk B, Łupkowska A, Kuczyńska-Wiśnik D, Stojowska-Swędrzyńska K, Laskowska E. Mechanisms Protecting Acinetobacter baumannii against Multiple Stresses Triggered by the Host Immune Response, Antibiotics and Outside-Host Environment. Int J Mol Sci 2020; 21:E5498. [PMID: 32752093 PMCID: PMC7432025 DOI: 10.3390/ijms21155498] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/29/2020] [Accepted: 07/30/2020] [Indexed: 02/06/2023] Open
Abstract
Acinetobacter baumannii is considered one of the most persistent pathogens responsible for nosocomial infections. Due to the emergence of multidrug resistant strains, as well as high morbidity and mortality caused by this pathogen, A. baumannii was placed on the World Health Organization (WHO) drug-resistant bacteria and antimicrobial resistance research priority list. This review summarizes current studies on mechanisms that protect A. baumannii against multiple stresses caused by the host immune response, outside host environment, and antibiotic treatment. We particularly focus on the ability of A. baumannii to survive long-term desiccation on abiotic surfaces and the population heterogeneity in A. baumannii biofilms. Insight into these protective mechanisms may provide clues for the development of new strategies to fight multidrug resistant strains of A. baumannii.
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Affiliation(s)
- Soroosh Monem
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland; (S.M.); (A.Ł.); (D.K.-W.); (K.S.-S.)
| | - Beata Furmanek-Blaszk
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland;
| | - Adrianna Łupkowska
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland; (S.M.); (A.Ł.); (D.K.-W.); (K.S.-S.)
| | - Dorota Kuczyńska-Wiśnik
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland; (S.M.); (A.Ł.); (D.K.-W.); (K.S.-S.)
| | - Karolina Stojowska-Swędrzyńska
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland; (S.M.); (A.Ł.); (D.K.-W.); (K.S.-S.)
| | - Ewa Laskowska
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland; (S.M.); (A.Ł.); (D.K.-W.); (K.S.-S.)
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38
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Thibau A, Dichter AA, Vaca DJ, Linke D, Goldman A, Kempf VAJ. Immunogenicity of trimeric autotransporter adhesins and their potential as vaccine targets. Med Microbiol Immunol 2020; 209:243-263. [PMID: 31788746 PMCID: PMC7247748 DOI: 10.1007/s00430-019-00649-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 11/19/2019] [Indexed: 12/15/2022]
Abstract
The current problem of increasing antibiotic resistance and the resurgence of numerous infections indicate the need for novel vaccination strategies more than ever. In vaccine development, the search for and the selection of adequate vaccine antigens is the first important step. In recent years, bacterial outer membrane proteins have become of major interest, as they are the main proteins interacting with the extracellular environment. Trimeric autotransporter adhesins (TAAs) are important virulence factors in many Gram-negative bacteria, are localised on the bacterial surface, and mediate the first adherence to host cells in the course of infection. One example is the Neisseria adhesin A (NadA), which is currently used as a subunit in a licensed vaccine against Neisseria meningitidis. Other TAAs that seem promising vaccine candidates are the Acinetobacter trimeric autotransporter (Ata), the Haemophilus influenzae adhesin (Hia), and TAAs of the genus Bartonella. Here, we review the suitability of various TAAs as vaccine candidates.
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Affiliation(s)
- Arno Thibau
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe-University, Paul-Ehrlich-Str. 40, 60596 Frankfurt am Main, Germany
| | - Alexander A. Dichter
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe-University, Paul-Ehrlich-Str. 40, 60596 Frankfurt am Main, Germany
| | - Diana J. Vaca
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe-University, Paul-Ehrlich-Str. 40, 60596 Frankfurt am Main, Germany
| | - Dirk Linke
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Oslo, Norway
| | - Adrian Goldman
- Astbury Centre for Structural Molecular Biology, School of Biomedical Sciences, University of Leeds, Leeds, UK
- Molecular and Integrative Biosciences Program, University of Helsinki, Helsinki, Finland
| | - Volkhard A. J. Kempf
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe-University, Paul-Ehrlich-Str. 40, 60596 Frankfurt am Main, Germany
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39
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M Campos JC, Antunes LCM, Ferreira RBR. Global priority pathogens: virulence, antimicrobial resistance and prospective treatment options. Future Microbiol 2020; 15:649-677. [DOI: 10.2217/fmb-2019-0333] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp. and Salmonella spp. are part of a group of pathogens that pose a major threat to human health due to the emergence of multidrug-resistant strains. Moreover, these bacteria have several virulence factors that allow them to successfully colonize their hosts, such as toxins and the ability to produce biofilms, resulting in an urgent need to develop new strategies to fight these pathogens. In this review, we compile the most up-to-date information on the epidemiology, virulence and resistance of these clinically important microorganisms. Additionally, we address new therapeutic alternatives, with a focus on molecules with antivirulence activity, which are considered promising to combat multidrug-resistant bacteria.
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Affiliation(s)
- Juliana C de M Campos
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Luis CM Antunes
- Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
- Instituto Nacional de Ciência e Tecnologia de Inovação em Doenças de Populações Negligenciadas, Centro de Desenvolvimento Tecnológico em Saúde, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Rosana BR Ferreira
- Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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40
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Kishii K, Hamada M, Aoki K, Ito K, Onodera J, Ishii Y, Tateda K. Differences in biofilm formation and transcription of biofilm-associated genes among Acinetobacter baumannii clinical strains belonging to the international clone II lineage. J Infect Chemother 2020; 26:693-698. [PMID: 32249162 DOI: 10.1016/j.jiac.2020.02.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 02/14/2020] [Accepted: 02/28/2020] [Indexed: 10/24/2022]
Abstract
Acinetobacter baumannii isolates belonging to international clonal lineage (IC) II are often multidrug-resistant and are the predominant cause of nosocomial outbreaks. While many studies have investigated the genetic and functional basis of antimicrobial resistance of these strains, few have examined specific virulence characteristics such as biofilm formation or overall pathogenic potential. Here, we analyzed biofilm formation and the associated mechanisms in A. baumannii clinical isolates from Japan belonging to the IC II lineage. Draft whole-genome sequence data for each of the isolates was analyzed to detect biofilm-associated genes, including csu (pili) and bfmS/R (two-component regulatory system), and transcription of these genes was evaluated using reverse transcription quantitative PCR. Biofilm formation was measured by crystal violet staining assay. csu operon genes showed some variation in prevalence among the isolates, with an overall prevalence of 73.7% (14/19). The biofilms formed by csu operon-positive isolates were significantly more mature than those of csu operon-negative isolates, supporting the importance of the csu operon in biofilm formation by A. baumannii. However, there was substantial variation among the csu operon-positive isolates, indicating the influence of other factors in biofilm formation. Furthermore, transcriptional levels of csu operon genes were highly divergent, with comprehensive analysis indicating that regulatory factors other than bfmS/R were involved. Our findings are a first step towards understanding the mechanisms of biofilm formation by A. baumannii IC II strains.
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Affiliation(s)
- Kozue Kishii
- Department of Health Sciences, Saitama Prefectural University, 820, Sannomiya, Koshigaya-shi, Saitama, 343-8540, Japan; Department of Microbiology and Infectious Diseases, Toho University School of Medicine, 5-21-16, Omori-nishi, Ota-ku, Tokyo, 143-8540, Japan.
| | - Masakaze Hamada
- Department of Microbiology and Infectious Diseases, Toho University School of Medicine, 5-21-16, Omori-nishi, Ota-ku, Tokyo, 143-8540, Japan.
| | - Kotaro Aoki
- Department of Microbiology and Infectious Diseases, Toho University School of Medicine, 5-21-16, Omori-nishi, Ota-ku, Tokyo, 143-8540, Japan.
| | - Kengo Ito
- Department of Microbiology and Infectious Diseases, Toho University School of Medicine, 5-21-16, Omori-nishi, Ota-ku, Tokyo, 143-8540, Japan.
| | - Joh Onodera
- Department of Microbiology and Infectious Diseases, Toho University School of Medicine, 5-21-16, Omori-nishi, Ota-ku, Tokyo, 143-8540, Japan.
| | - Yoshikazu Ishii
- Department of Microbiology and Infectious Diseases, Toho University School of Medicine, 5-21-16, Omori-nishi, Ota-ku, Tokyo, 143-8540, Japan.
| | - Kazuhiro Tateda
- Department of Microbiology and Infectious Diseases, Toho University School of Medicine, 5-21-16, Omori-nishi, Ota-ku, Tokyo, 143-8540, Japan.
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41
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Ayoub Moubareck C, Hammoudi Halat D. Insights into Acinetobacter baumannii: A Review of Microbiological, Virulence, and Resistance Traits in a Threatening Nosocomial Pathogen. Antibiotics (Basel) 2020; 9:antibiotics9030119. [PMID: 32178356 PMCID: PMC7148516 DOI: 10.3390/antibiotics9030119] [Citation(s) in RCA: 201] [Impact Index Per Article: 50.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 03/01/2020] [Accepted: 03/02/2020] [Indexed: 12/12/2022] Open
Abstract
Being a multidrug-resistant and an invasive pathogen, Acinetobacter baumannii is one of the major causes of nosocomial infections in the current healthcare system. It has been recognized as an agent of pneumonia, septicemia, meningitis, urinary tract and wound infections, and is associated with high mortality. Pathogenesis in A. baumannii infections is an outcome of multiple virulence factors, including porins, capsules, and cell wall lipopolysaccharide, enzymes, biofilm production, motility, and iron-acquisition systems, among others. Such virulence factors help the organism to resist stressful environmental conditions and enable development of severe infections. Parallel to increased prevalence of infections caused by A. baumannii, challenging and diverse resistance mechanisms in this pathogen are well recognized, with major classes of antibiotics becoming minimally effective. Through a wide array of antibiotic-hydrolyzing enzymes, efflux pump changes, impermeability, and antibiotic target mutations, A. baumannii models a unique ability to maintain a multidrug-resistant phenotype, further complicating treatment. Understanding mechanisms behind diseases, virulence, and resistance acquisition are central to infectious disease knowledge about A. baumannii. The aims of this review are to highlight infections and disease-producing factors in A. baumannii and to touch base on mechanisms of resistance to various antibiotic classes.
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Affiliation(s)
- Carole Ayoub Moubareck
- College of Natural and Health Sciences, Zayed University, Dubai P.O. Box 144534, UAE
- Correspondence: ; Tel.: +971-4-402-1745
| | - Dalal Hammoudi Halat
- Department of Pharmaceutical Sciences, School of Pharmacy, Lebanese International University, Beirut, Bekaa Campuses 1103, Lebanon;
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42
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Geesink P, Wegner CE, Probst AJ, Herrmann M, Dam HT, Kaster AK, Küsel K. Genome-inferred spatio-temporal resolution of an uncultivated Roizmanbacterium reveals its ecological preferences in groundwater. Environ Microbiol 2019; 22:726-737. [PMID: 31742865 DOI: 10.1111/1462-2920.14865] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 11/15/2019] [Accepted: 11/15/2019] [Indexed: 11/27/2022]
Abstract
Subsurface ecosystems like groundwater harbour diverse microbial communities, including small-sized, putatively symbiotic organisms of the Candidate Phyla Radiation, yet little is known about their ecological preferences and potential microbial partners. Here, we investigated a member of the superphylum Microgenomates (Cand. Roizmanbacterium ADI133) from oligotrophic groundwater using mini-metagenomics and monitored its spatio-temporal distribution using 16S rRNA gene analyses. A Roizmanbacteria-specific quantitative PCR assay allowed us to track its abundance over the course of 1 year within eight groundwater wells along a 5.4 km hillslope transect, where Roizmanbacteria reached maximum relative abundances of 2.3%. In-depth genomic analyses suggested that Cand. Roizmanbacterium ADI133 is a lactic acid fermenter, potentially able to utilize a range of complex carbon substrates, including cellulose. We hypothesize that it attaches to host cells using a trimeric autotransporter adhesin and inhibits their cell wall biosynthesis using a toxin-antitoxin system. Network analyses based on correlating Cand. Roizmanbacterium ADI133 abundances with amplicon sequencing-derived microbial community profiles suggested one potential host organism, classified as a member of the class Thermodesulfovibrionia (Nitrospirae). By providing lactate as an electron donor Cand. Roizmanbacterium ADI133 potentially mediates the transfer of carbon to other microorganisms and thereby is an important connector in the microbial community.
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Affiliation(s)
- Patricia Geesink
- Institute of Biodiversity, Friedrich Schiller University Jena, Jena, Germany
| | - Carl-Eric Wegner
- Institute of Biodiversity, Friedrich Schiller University Jena, Jena, Germany
| | - Alexander J Probst
- Department for Chemistry, Biofilm Centre, Group for Aquatic Microbial Ecology (GAME), University Duisburg-Essen, Essen, Germany
| | - Martina Herrmann
- Institute of Biodiversity, Friedrich Schiller University Jena, Jena, Germany.,German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
| | - Hang T Dam
- Institute for Biological Interfaces (IGB 5), Karlsruhe Institute of Technology (KIT), Karlsruhe, Eggenstein-Leopoldshafen, Germany.,DSMZ, Braunschweig, Germany
| | - Anne-Kristin Kaster
- Institute for Biological Interfaces (IGB 5), Karlsruhe Institute of Technology (KIT), Karlsruhe, Eggenstein-Leopoldshafen, Germany.,DSMZ, Braunschweig, Germany
| | - Kirsten Küsel
- Institute of Biodiversity, Friedrich Schiller University Jena, Jena, Germany.,German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
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43
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Vaca DJ, Thibau A, Schütz M, Kraiczy P, Happonen L, Malmström J, Kempf VAJ. Interaction with the host: the role of fibronectin and extracellular matrix proteins in the adhesion of Gram-negative bacteria. Med Microbiol Immunol 2019; 209:277-299. [PMID: 31784893 PMCID: PMC7248048 DOI: 10.1007/s00430-019-00644-3] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 11/14/2019] [Indexed: 01/03/2023]
Abstract
The capacity of pathogenic microorganisms to adhere to host cells and avoid clearance by the host immune system is the initial and most decisive step leading to infections. Bacteria have developed different strategies to attach to diverse host surface structures. One important strategy is the adhesion to extracellular matrix (ECM) proteins (e.g., collagen, fibronectin, laminin) that are highly abundant in connective tissue and basement membranes. Gram-negative bacteria express variable outer membrane proteins (adhesins) to attach to the host and to initiate the process of infection. Understanding the underlying molecular mechanisms of bacterial adhesion is a prerequisite for targeting this interaction by “anti-ligands” to prevent colonization or infection of the host. Future development of such “anti-ligands” (specifically interfering with bacteria-host matrix interactions) might result in the development of a new class of anti-infective drugs for the therapy of infections caused by multidrug-resistant Gram-negative bacteria. This review summarizes our current knowledge about the manifold interactions of adhesins expressed by Gram-negative bacteria with ECM proteins and the use of this information for the generation of novel therapeutic antivirulence strategies.
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Affiliation(s)
- Diana J Vaca
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe University Frankfurt am Main, Paul-Ehrlich-Str. 40, 60596, Frankfurt, Germany
| | - Arno Thibau
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe University Frankfurt am Main, Paul-Ehrlich-Str. 40, 60596, Frankfurt, Germany
| | - Monika Schütz
- Institute for Medical Microbiology and Infection Control, University Hospital, Eberhard Karls-University, Tübingen, Germany
| | - Peter Kraiczy
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe University Frankfurt am Main, Paul-Ehrlich-Str. 40, 60596, Frankfurt, Germany
| | - Lotta Happonen
- Division of Infection Medicine, Department of Clinical Sciences, Faculty of Medicine, Lund University, Lund, Sweden
| | - Johan Malmström
- Division of Infection Medicine, Department of Clinical Sciences, Faculty of Medicine, Lund University, Lund, Sweden
| | - Volkhard A J Kempf
- Institute for Medical Microbiology and Infection Control, University Hospital, Goethe University Frankfurt am Main, Paul-Ehrlich-Str. 40, 60596, Frankfurt, Germany.
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44
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Pierce into the Native Structure of Ata, a Trimeric Autotransporter of Acinetobacter baumannii ATCC 17978. Int J Pept Res Ther 2019. [DOI: 10.1007/s10989-019-09920-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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45
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Morris FC, Dexter C, Kostoulias X, Uddin MI, Peleg AY. The Mechanisms of Disease Caused by Acinetobacter baumannii. Front Microbiol 2019; 10:1601. [PMID: 31379771 PMCID: PMC6650576 DOI: 10.3389/fmicb.2019.01601] [Citation(s) in RCA: 155] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 06/26/2019] [Indexed: 01/29/2023] Open
Abstract
Acinetobacter baumannii is a Gram negative opportunistic pathogen that has demonstrated a significant insurgence in the prevalence of infections over recent decades. With only a limited number of “traditional” virulence factors, the mechanisms underlying the success of this pathogen remain of great interest. Major advances have been made in the tools, reagents, and models to study A. baumannii pathogenesis, and this has resulted in a substantial increase in knowledge. This article provides a comprehensive review of the bacterial virulence factors, the host immune responses, and animal models applicable for the study of this important human pathogen. Collating the most recent evidence characterizing bacterial virulence factors, their cellular targets and genetic regulation, we have encompassed numerous aspects important to the success of this pathogen, including membrane proteins and cell surface adaptations promoting immune evasion, mechanisms for nutrient acquisition and community interactions. The role of innate and adaptive immune responses is reviewed and areas of paucity in our understanding are highlighted. Finally, with the vast expansion of available animal models over recent years, we have evaluated those suitable for use in the study of Acinetobacter disease, discussing their advantages and limitations.
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Affiliation(s)
- Faye C Morris
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Carina Dexter
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Xenia Kostoulias
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Muhammad Ikhtear Uddin
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Anton Y Peleg
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia.,Department of Infectious Diseases, The Alfred Hospital and Central Clinical School, Monash University, Melbourne, VIC, Australia
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46
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Different Virulence Capabilities and ompA Expressions in ST2 and ST513 of Multidrug-Resistant Acinetobacter baumannii. Curr Microbiol 2019; 76:723-731. [DOI: 10.1007/s00284-019-01686-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Accepted: 04/08/2019] [Indexed: 10/27/2022]
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47
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Rahbar MR, Zarei M, Jahangiri A, Khalili S, Nezafat N, Negahdaripour M, Fattahian Y, Ghasemi Y. Trimeric autotransporter adhesins in Acinetobacter baumannii, coincidental evolution at work. INFECTION GENETICS AND EVOLUTION 2019; 71:116-127. [PMID: 30922803 DOI: 10.1016/j.meegid.2019.03.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 02/27/2019] [Accepted: 03/23/2019] [Indexed: 12/20/2022]
Abstract
Trimeric autotransporter (TAA), also known as type Vc secretion system, is expressed by many strains of Acinetobacter baumannii, an opportunistic pathogen, which is responsible for nosocomial infections worldwide. TAAs, are modular homotrimeric virulence factors, containing a signal peptide, complex stalk, and conserved membrane anchoring domain. The evolutionary mechanisms underlying the evolvement of these adhesins are not clear. Here, we showed that TAA genes were laterally acquired and underwent gene duplication and recombination. The heterogeneity of TAA nucleotide sequences, GC content, codon usage, and the probability of recombination and duplication events were assessed by MEGA7. Given the heterogeneity of sequences, we used all-against-all BLAST for clustering the TAAs. The pattern of distribution of TAAs are highly scattered; GC content and codon usage for these genes are variable. Multiple events of lateral gene transfer from the early history of Acinetobacter and the occurrence of gene duplication, gene loss, and recombination after acquiring the alien genes may explain the scattered pattern of distribution of TAAs. Additionally, this gene is not present in many clinical isolates of A. baumannii, thus is not a single virulence factor attributing to the infection. The advantage of harboring such genes might be adopting to different environments by developing the biofilm communities. We suggested that TAA genes were laterally acquired in the environmental context and incidentally provided some benefits at the infection site. Thus, coincidental evolution theory may be better suited for describing the evolution of TAA genes in A. baumannii genomes.
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Affiliation(s)
- Mohammad Reza Rahbar
- Pharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mahboubeh Zarei
- Pharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Abolfazl Jahangiri
- Applied Microbiology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Saeed Khalili
- Department of Biology Sciences, Shahid Rajaee Teacher Training University, Tehran, Iran
| | - Navid Nezafat
- Pharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz, Iran; Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Manica Negahdaripour
- Pharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz, Iran; Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Yaser Fattahian
- Department of Biotechnology, Institute of Science and High Technology and Environmental Sciences, Graduate University of Advanced Technology, Kerman, Iran
| | - Younes Ghasemi
- Pharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz, Iran; Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran.
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48
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Emergence of High-Level Colistin Resistance in an Acinetobacter baumannii Clinical Isolate Mediated by Inactivation of the Global Regulator H-NS. Antimicrob Agents Chemother 2018; 62:AAC.02442-17. [PMID: 29712662 DOI: 10.1128/aac.02442-17] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 03/01/2018] [Indexed: 12/31/2022] Open
Abstract
Colistin is a crucial last-line drug used for the treatment of life-threatening infections caused by multidrug-resistant strains of the Gram-negative bacterium Acinetobacter baumannii However, colistin-resistant A. baumannii isolates can still be isolated following failed colistin therapy. Resistance is most often mediated by the addition of phosphoethanolamine (pEtN) to lipid A by PmrC, following missense mutations in the pmrCAB operon encoding PmrC and the two-component signal transduction system PmrA/PmrB. We recovered a pair of A. baumannii isolates from a single patient before (6009-1) and after (6009-2) failed colistin treatment. These strains displayed low and very high levels of colistin resistance (MICs, 8 to 16 μg/ml and 128 μg/ml), respectively. To understand how increased colistin resistance arose, we sequenced the genome of each isolate, which revealed that 6009-2 had an extra copy of the insertion sequence element ISAba125 within a gene encoding an H-NS family transcriptional regulator. To confirm the role of H-NS in colistin resistance, we generated an hns deletion mutant in 6009-1 and showed that colistin resistance increased upon the deletion of hns We also provided 6009-2 with an intact copy of hns and showed that the strain was no longer resistant to high concentrations of colistin. Transcriptomic analysis of the clinical isolates identified more than 150 genes as being differentially expressed in the colistin-resistant hns mutant 6009-2. Importantly, the expression of eptA, encoding a second lipid A-specific pEtN transferase but not pmrC, was increased in the hns mutant. This is the first time an H-NS family transcriptional regulator has been associated with a pEtN transferase and colistin resistance.
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Elhosseiny NM, Attia AS. Acinetobacter: an emerging pathogen with a versatile secretome. Emerg Microbes Infect 2018; 7:33. [PMID: 29559620 PMCID: PMC5861075 DOI: 10.1038/s41426-018-0030-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 12/08/2017] [Accepted: 01/09/2018] [Indexed: 02/06/2023]
Abstract
Acinetobacter baumannii is a notorious pathogen that has emerged as a healthcare nightmare in recent years because it causes serious infections that are associated with high morbidity and mortality rates. Due to its exceptional ability to acquire resistance to almost all available antibiotics, A. baumannii is currently ranked as the first pathogen on the World Health Organization’s priority list for the development of new antibiotics. The versatile range of effectors secreted by A. baumannii represents a large proportion of the virulence arsenal identified in this bacterium to date. Thus, these factors, together with the secretory machinery responsible for their extrusion into the extracellular milieu, are key targets for novel therapeutics that are greatly needed to combat this deadly pathogen. In this review, we provide a comprehensive, up-to-date overview of the organization and regulatory aspects of the Acinetobacter secretion systems, with a special emphasis on their versatile substrates that could be targeted to fight the deadly infections caused by this elusive pathogen.
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Affiliation(s)
- Noha M Elhosseiny
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, 11562, Egypt
| | - Ahmed S Attia
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, 11562, Egypt.
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50
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Harding CM, Hennon SW, Feldman MF. Uncovering the mechanisms of Acinetobacter baumannii virulence. Nat Rev Microbiol 2017; 16:91-102. [PMID: 29249812 DOI: 10.1038/nrmicro.2017.148] [Citation(s) in RCA: 547] [Impact Index Per Article: 78.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Acinetobacter baumannii is a nosocomial pathogen that causes ventilator-associated as well as bloodstream infections in critically ill patients, and the spread of multidrug-resistant Acinetobacter strains is cause for concern. Much of the success of A. baumannii can be directly attributed to its plastic genome, which rapidly mutates when faced with adversity and stress. However, fundamental virulence mechanisms beyond canonical drug resistance were recently uncovered that enable A. baumannii and, to a limited extent, other medically relevant Acinetobacter species to successfully thrive in the health-care environment. In this Review, we explore the molecular features that promote environmental persistence, including desiccation resistance, biofilm formation and motility, and we discuss the most recently identified virulence factors, such as secretion systems, surface glycoconjugates and micronutrient acquisition systems that collectively enable these pathogens to successfully infect their hosts.
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Affiliation(s)
- Christian M Harding
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri 63110, USA.,VaxNewMo LLC, St. Louis, Missouri 63108, USA
| | - Seth W Hennon
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri 63110, USA
| | - Mario F Feldman
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri 63110, USA.,VaxNewMo LLC, St. Louis, Missouri 63108, USA
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