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Bento CM, van Calster K, Piller T, Oliveira GS, de Vooght L, Cappoen D, Cos P, Gomes MS, Silva T. Characterization of novel double-reporter strains of Mycobacterium abscessus for drug discovery: a study in mScarlet. Microbiol Spectr 2024; 12:e0036224. [PMID: 39189762 DOI: 10.1128/spectrum.00362-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 07/26/2024] [Indexed: 08/28/2024] Open
Abstract
Mycobacterium abscessus (Mab) is an emerging pathogen that poses a severe health threat, especially in people with cystic fibrosis and other chronic lung diseases. Available drugs are largely ineffective due to an exquisite intrinsic resistance, making Mab infections only comparable to multidrug-resistant tuberculosis. Current treatment is based on lengthy multidrug therapy, complicated by poor outcomes and high rates of treatment failure, recurrence, and mortality. Thus, finding new and more efficient drugs to combat this pathogen is urgent. However, drug discovery efforts targeting Mab have been limited, and traditional drug screening methods are labor-intensive, low-throughput, and do not reflect clinical effectiveness. Therefore, this work aimed to develop a new, efficient, and reliable tool for drug screening against Mab that can be used in vitro for identifying hits in a high-throughput manner and in vivo to select drug candidates for future clinical trials. We engineered two stable double-reporter strains of Mab capable of emitting strong fluorescent and luminescent signals. This is due to the expression of mScarlet protein and luciferase enzyme or the entire lux operon. Importantly, these strains maintain the same ground characteristics as the non-transformed Mab strain. We show that these new strains can be applied to various setups, from MIC determination in broth cultures and macrophage infection assays to in vivo infection (using the Galleria mellonella model). Using these strains enhances the potential for high-throughput screening of thousands of compounds in a fast and reliable way. IMPORTANCE Mycobacterium abscessus (Mab) is currently considered an "incurable nightmare." Its intrinsic resistance, high toxicity, long duration, and low cure rates of available therapies often lead to the clinical decision not to treat. Moreover, one of the significant drawbacks of anti-Mab drug development is the lack of correlation between in vitro susceptibility and clinical efficacy. Most drug screening assays are performed on Mab growing in liquid cultures. But being an intracellular pathogen, inducing granulomas and biofilm formation, the broth culture is far from ideal as in vitro drug-testing setup. This study presents new double-reporter Mab strains that allow direct real-time bacterial detection and quantification in a non-invasive way. These strains can be applied to an extensive range of experimental settings, far surpassing the utility of single-reporter bacteria. They can be used in all steps of the pre-clinical anti-Mab drug development pipeline, constituting a highly valuable tool to increase its success.
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Affiliation(s)
- Clara M Bento
- i3S-Instituto de Investigação e Inovação e Saúde, Universidade do Porto, Porto, Portugal
- IBMC-Instituto de Biologia Celular e Molecular, Universidade do Porto, Porto, Portugal
- Programa Doutoral em Biologia Molecular e Celular (MCBiology), Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto, Porto, Portugal
| | - Kevin van Calster
- Laboratory for Microbiology, Parasitology and Hygiene (LMPH), Wilrijk, Belgium
| | - Tatiana Piller
- Laboratory for Microbiology, Parasitology and Hygiene (LMPH), Wilrijk, Belgium
| | - Gabriel S Oliveira
- i3S-Instituto de Investigação e Inovação e Saúde, Universidade do Porto, Porto, Portugal
- ICBAS-Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto, Porto, Portugal
| | - Linda de Vooght
- Laboratory for Microbiology, Parasitology and Hygiene (LMPH), Wilrijk, Belgium
| | - Davie Cappoen
- Laboratory for Microbiology, Parasitology and Hygiene (LMPH), Wilrijk, Belgium
| | - Paul Cos
- Laboratory for Microbiology, Parasitology and Hygiene (LMPH), Wilrijk, Belgium
| | - M Salomé Gomes
- i3S-Instituto de Investigação e Inovação e Saúde, Universidade do Porto, Porto, Portugal
- ICBAS-Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto, Porto, Portugal
| | - Tânia Silva
- i3S-Instituto de Investigação e Inovação e Saúde, Universidade do Porto, Porto, Portugal
- ICBAS-Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto, Porto, Portugal
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2
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Longo BM, Trunfio M, Calcagno A. Dual β-lactams for the treatment of Mycobacterium abscessus: a review of the evidence and a call to act against an antibiotic nightmare. J Antimicrob Chemother 2024:dkae288. [PMID: 39150384 DOI: 10.1093/jac/dkae288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/17/2024] Open
Abstract
Mycobacterium abscessus complex is a group of rapidly growing non-tuberculous mycobacteria (NTM), increasingly emerging as opportunistic pathogens. Current treatment options for these microorganisms are limited and associated with a high rate of treatment failure, toxicity and recurrence. In search of new therapeutic strategies, interest has grown in dual β-lactam (DBL) therapy, as research recently discovered that M. abscessus cell wall synthesis is mainly regulated by two types of enzymes (d,d-transpeptidases and l,d-transpeptidases) differently susceptible to inhibition by distinct β-lactams. In vitro studies testing several DBL combinations have shown synergy in extracellular broth cultures as well as in the intracellular setting: cefoxitin/imipenem, ceftaroline/imipenem, ceftazidime/ceftaroline and ceftazidime/imipenem. The addition of specific β-lactamase inhibitors (BLIs) targeting M. abscessus β-lactamase did not significantly enhance the activity of DBL combinations. However, in vivo data are lacking. We reviewed the literature on DBL/DBL-BLI-based therapies for M. abscessus infections to raise greater attention on this promising yet overlooked treatment option and to guide future preclinical and clinical studies.
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Affiliation(s)
- Bianca Maria Longo
- Department of Medical Sciences, Unit of Infectious Diseases, Amedeo di Savoia Hospital, University of Turin, 10149 Turin, Italy
| | - Mattia Trunfio
- Department of Medical Sciences, Unit of Infectious Diseases, Amedeo di Savoia Hospital, University of Turin, 10149 Turin, Italy
- Department of Medicine, Division of Infectious Diseases and Global Public Health, University of California San Diego, La Jolla, CA 92037, USA
| | - Andrea Calcagno
- Department of Medical Sciences, Unit of Infectious Diseases, Amedeo di Savoia Hospital, University of Turin, 10149 Turin, Italy
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Jones BS, Pareek V, Hu DD, Weaver SD, Syska C, Galfano G, Champion MM, Champion PA. N - acetyl-transferases required for iron uptake and aminoglycoside resistance promote virulence lipid production in M. marinum. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.05.602253. [PMID: 39005365 PMCID: PMC11245092 DOI: 10.1101/2024.07.05.602253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
Phagosomal lysis is a key aspect of mycobacterial infection of host macrophages. Acetylation is a protein modification mediated enzymatically by N-acetyltransferases (NATs) that impacts bacterial pathogenesis and physiology. To identify NATs required for lytic activity, we leveraged Mycobacterium marinum, a nontubercular pathogen and an established model for M. tuberculosis. M. marinum hemolysis is a proxy for phagolytic activity. We generated M. marinum strains with deletions in conserved NAT genes and screened for hemolytic activity. Several conserved lysine acetyltransferases (KATs) contributed to hemolysis. Hemolysis is mediated by the ESX-1 secretion system and by phthiocerol dimycocerosate (PDIM), a virulence lipid. For several strains, the hemolytic activity was restored by the addition of second copy of the ESX-1 locus. Using thin-layer chromatography (TLC), we found a single NAT required for PDIM and phenolic glycolipid (PGL) production. MbtK is a conserved KAT required for mycobactin siderophore synthesis and virulence. Mycobactin J exogenously complemented PDIM/PGL production in the Δ mbtK strain. The Δ mbtK M. marinum strain was attenuated in macrophage and Galleria mellonella infection models. Constitutive expression of either eis or papA5, which encode a KAT required for aminoglycoside resistance and a PDIM/PGL biosynthetic enzyme, rescued PDIM/PGL production and virulence of the Δ mbtK strain. Eis N-terminally acetylated PapA5 in vitro , supporting a mechanism for restored lipid production. Overall, our study establishes connections between the MbtK and Eis NATs, and between iron uptake and PDIM and PGL synthesis in M. marinum . Our findings underscore the multifunctional nature of mycobacterial NATs and their connection to key virulence pathways. Significance Statement Acetylation is a modification of protein N-termini, lysine residues, antibiotics and lipids. Many of the enzymes that promote acetylation belong to the GNAT family of proteins. M. marinum is a well-established as a model to understand how M. tuberculosis causes tuberculosis. In this study we sought to identify conserved GNAT proteins required for early stages of mycobacterial infection. Using M. marinum, we determined that several GNAT proteins are required for the lytic activity of M. marinum. We uncovered previously unknown connections between acetyl-transferases required for iron uptake and antimicrobial resistance, and the production of the unique mycobacterial lipids, PDIM and PGLOur data support that acetyl-transferases from the GNAT family are interconnected, and have activities beyond those previously reported.
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Dartois V, Bonfield TL, Boyce JP, Daley CL, Dick T, Gonzalez-Juarrero M, Gupta S, Kramnik I, Lamichhane G, Laughon BE, Lorè NI, Malcolm KC, Olivier KN, Tuggle KL, Jackson M. Preclinical murine models for the testing of antimicrobials against Mycobacterium abscessus pulmonary infections: Current practices and recommendations. Tuberculosis (Edinb) 2024; 147:102503. [PMID: 38729070 PMCID: PMC11168888 DOI: 10.1016/j.tube.2024.102503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 03/08/2024] [Accepted: 03/17/2024] [Indexed: 05/12/2024]
Abstract
Mycobacterium abscessus, a rapidly growing nontuberculous mycobacterium, is increasingly recognized as an important pathogen of the human lung, disproportionally affecting people with cystic fibrosis (CF) and other susceptible individuals with non-CF bronchiectasis and compromised immune functions. M. abscessus infections are extremely difficult to treat due to intrinsic resistance to many antibiotics, including most anti-tuberculous drugs. Current standard-of-care chemotherapy is long, includes multiple oral and parenteral repurposed drugs, and is associated with significant toxicity. The development of more effective oral antibiotics to treat M. abscessus infections has thus emerged as a high priority. While murine models have proven instrumental in predicting the efficacy of therapeutic treatments for M. tuberculosis infections, the preclinical evaluation of drugs against M. abscessus infections has proven more challenging due to the difficulty of establishing a progressive, sustained, pulmonary infection with this pathogen in mice. To address this issue, a series of three workshops were hosted in 2023 by the Cystic Fibrosis Foundation (CFF) and the National Institute of Allergy and Infectious Diseases (NIAID) to review the current murine models of M. abscessus infections, discuss current challenges and identify priorities toward establishing validated and globally harmonized preclinical models. This paper summarizes the key points from these workshops. The hope is that the recommendations that emerged from this exercise will facilitate the implementation of informative murine models of therapeutic efficacy testing across laboratories, improve reproducibility from lab-to-lab and accelerate preclinical-to-clinical translation.
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Affiliation(s)
- Véronique Dartois
- Center for Discovery and Innovation & Department of Medical Sciences, Hackensack Meridian School of Medicine, Hackensack Meridian Health, Nutley, NJ, USA.
| | - Tracey L Bonfield
- Genetics and Genome Sciences and National Center for Regenerative Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Jim P Boyce
- Division of Microbiology and Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Charles L Daley
- Department of Medicine, National Jewish Health, Denver, CO, USA; Department of Medicine, University of Colorado School of Medicine, Aurora, CO, USA
| | - Thomas Dick
- Center for Discovery and Innovation & Department of Medical Sciences, Hackensack Meridian School of Medicine, Hackensack Meridian Health, Nutley, NJ, USA; Department of Microbiology and Immunology, Georgetown University, Washington, DC, USA
| | - Mercedes Gonzalez-Juarrero
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, 80523-1682, USA
| | - Shashank Gupta
- Laboratory of Chronic Airway Infection, Pulmonary Branch, National Heart, Lung, and Blood Institute, Bethesda, MD, USA; Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Igor Kramnik
- National Emerging Infectious Diseases Laboratories, Boston University, Boston, MA, 02215, USA; Department of Medicine, Boston University School of Medicine, Boston, MA, 02118, USA
| | - Gyanu Lamichhane
- Division of Infectious Diseases, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Barbara E Laughon
- Division of Microbiology and Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Nicola I Lorè
- Emerging Bacterial Pathogens Unit, Division of Immunology, Transplantation and Infectious Diseases, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Kenneth C Malcolm
- Department of Medicine, National Jewish Health, Denver, CO, USA; Department of Medicine, University of Colorado School of Medicine, Aurora, CO, USA
| | - Kenneth N Olivier
- Department of Medicine, Division of Pulmonary Diseases and Critical Care Medicine, University of North Carolina, USA; Marsico Lung Institute, Chapel Hill, 27599-7248, NC, USA
| | | | - Mary Jackson
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, 80523-1682, USA.
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Rakovitsky N, Temkin E, Hameir A, Lurie-Weinberger M, Keren-Paz A, Carmeli Y. Zophobas morio larvae as a novel model for the study of Acinetobacter virulence and antimicrobial resistance. Front Microbiol 2024; 15:1375787. [PMID: 38476953 PMCID: PMC10927975 DOI: 10.3389/fmicb.2024.1375787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Accepted: 02/12/2024] [Indexed: 03/14/2024] Open
Abstract
The use of mammalian models for in vivo testing of bacterial virulence raises ethical concerns and is expensive and time-consuming. As an alternative, non-mammalian models are sought. Galleria mellonella larvae have been used as a model to study several bacterial pathogens. However, their maintenance is challenging, and commercial supply is low. In this study, we aimed to establish the Zophobas morio larvae as an alternative non-mammalian model for the evaluation of the pathogenicity and antimicrobial susceptibility of Acinetobacter baumannii. We infected Z. morio with Acinetobacter strains and determined the optimal temperature and inoculum. To visualize the bacterial distribution within the larvae, hematoxylin and eosin (H&E) staining was performed. Next, a survival model of infected larvae was established, and virulence was compared between strains. The effect of antimicrobial treatment in relation to antibiotic susceptibility was studied. Our results demonstrate that Z. morio can be used as a model system for in vivo studies of A. baumannii.
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Affiliation(s)
- Nadya Rakovitsky
- National Institute for Antibiotic Resistance and Infection Control, Israel Ministry of Health, Tel Aviv, Israel
| | - Elizabeth Temkin
- National Institute for Antibiotic Resistance and Infection Control, Israel Ministry of Health, Tel Aviv, Israel
| | - Amichay Hameir
- National Institute for Antibiotic Resistance and Infection Control, Israel Ministry of Health, Tel Aviv, Israel
| | - Mor Lurie-Weinberger
- National Institute for Antibiotic Resistance and Infection Control, Israel Ministry of Health, Tel Aviv, Israel
| | - Alona Keren-Paz
- National Institute for Antibiotic Resistance and Infection Control, Israel Ministry of Health, Tel Aviv, Israel
| | - Yehuda Carmeli
- National Institute for Antibiotic Resistance and Infection Control, Israel Ministry of Health, Tel Aviv, Israel
- School of Medicine, Tel Aviv University, Tel Aviv, Israel
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6
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Piller T, De Vooght L, Gansemans Y, Van Nieuwerburgh F, Cos P. Mycothione reductase as a potential target in the fight against Mycobacterium abscessus infections. mSphere 2024; 9:e0066923. [PMID: 38085034 PMCID: PMC10826361 DOI: 10.1128/msphere.00669-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 11/06/2023] [Indexed: 01/31/2024] Open
Abstract
While infections caused by Mycobacterium abscessus complex (MABC) are rising worldwide, the current treatment of these infections is far from ideal due to its numerous shortcomings thereby increasing the urge for novel drug targets. In this study, mycothione reductase (Mtr) was evaluated for its potential as a drug target for MABC infections since it is a key enzyme needed in the recycling of mycothiol, the main low-molecular-weight thiol protecting the bacteria against reactive oxygen species and other reactive intermediates. First, a Mab∆mtr mutant strain was generated, lacking mtr expression. Next, the in vitro sensitivity of Mab∆mtr to oxidative stress and antimycobacterial drugs was determined. Finally, we evaluated the intramacrophage survival and the virulence of Mab∆mtr in Galleria mellonella larvae. Mab∆mtr demonstrated a 39.5-fold reduction in IC90 when exposed to bedaquiline in vitro. Furthermore, the Mab∆mtr mutant showed a decreased ability to proliferate inside macrophages and larvae, suggesting that Mtr plays an important role during MABC infection. Altogether, these findings support the assumption of Mtr being a potential target for antimycobacterial drugs.IMPORTANCEMycobacterium abscessus complex (MABC) is a group of bacteria causing a serious public health problem worldwide due to its ability to cause progressive disease, its highly resistant profile against various antibiotics, and its lengthy treatment. Therefore, new drugs are needed to alleviate antibiotic resistance and reduce the length of the current treatment. A potential new target for new antibiotics is mycothione reductase (Mtr), an important enzyme belonging to a pathway that protects the bacteria against harmful conditions. Our research created a bacterium deficient of mtr by using advanced genetic techniques and demonstrated that mtr-deficient bacteria have a decreased ability to multiply during infection. Furthermore, we show evidence that currently used antibiotics combined with mtr deficiency can lead to a better treatment of MABC infection. Altogether, our results validate Mtr as a potential new target and suggest that Mtr plays a role during MABC infection.
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Affiliation(s)
- T. Piller
- Department of Pharmaceutical Sciences, Laboratory of Microbiology, Parasitology and Hygiene (LMPH), University of Antwerp, Wilrijk, Belgium
| | - L. De Vooght
- Department of Pharmaceutical Sciences, Laboratory of Microbiology, Parasitology and Hygiene (LMPH), University of Antwerp, Wilrijk, Belgium
| | - Y. Gansemans
- Laboratory of Pharmaceutical Biotechnology, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
| | - F. Van Nieuwerburgh
- Laboratory of Pharmaceutical Biotechnology, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
| | - P. Cos
- Department of Pharmaceutical Sciences, Laboratory of Microbiology, Parasitology and Hygiene (LMPH), University of Antwerp, Wilrijk, Belgium
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Admella J, Torrents E. Investigating bacterial infections in Galleria mellonella larvae: Insights into pathogen dissemination and behavior. J Invertebr Pathol 2023; 200:107975. [PMID: 37541571 DOI: 10.1016/j.jip.2023.107975] [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: 05/16/2023] [Revised: 07/04/2023] [Accepted: 07/30/2023] [Indexed: 08/06/2023]
Abstract
The insect Galleria mellonella is an alternative animal model widely used for studying bacterial infections. It presents a wide range of advantages, including its low cost, easy maintenance and lack of ethical constraints. Among other features, their innate immune system is very similar to that of mammals. In this study, we dissected several larvae infected with important human pathogens: Mycobacterium abscessus, Staphylococcus aureus and Pseudomonas aeruginosa. By observing the fat body, gut, trachea, and hemolymph under the microscope, we were able to describe where bacteria tend to disseminate. We also quantified the number of bacteria in the hemolymph throughout the infection course and found significant differences between the different pathogens. With this work, we aimed to better understand the behavior and dissemination of bacteria in the infected larvae.
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Affiliation(s)
- Joana Admella
- Bacterial Infections and Antimicrobial Therapies Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 15-21, 08028 Barcelona, Spain; Microbiology Section, Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, 643 Diagonal Ave., 08028 Barcelona, Spain
| | - Eduard Torrents
- Bacterial Infections and Antimicrobial Therapies Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 15-21, 08028 Barcelona, Spain; Microbiology Section, Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, 643 Diagonal Ave., 08028 Barcelona, Spain.
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8
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Bar-Oz M, Martini MC, Alonso MN, Meir M, Lore NI, Miotto P, Riva C, Angala SK, Xiao J, Masiello CS, Misiakou MA, Sun H, Moy JK, Jackson M, Johansen HK, Cirillo DM, Shell SS, Barkan D. The small non-coding RNA B11 regulates multiple facets of Mycobacterium abscessus virulence. PLoS Pathog 2023; 19:e1011575. [PMID: 37603560 PMCID: PMC10470900 DOI: 10.1371/journal.ppat.1011575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 08/31/2023] [Accepted: 07/24/2023] [Indexed: 08/23/2023] Open
Abstract
Mycobacterium abscessus causes severe disease in patients with cystic fibrosis. Little is known in M. abscessus about the roles of small regulatory RNAs (sRNA) in gene regulation. We show that the sRNA B11 controls gene expression and virulence-associated phenotypes in this pathogen. B11 deletion from the smooth strain ATCC_19977 produced a rough strain, increased pro-inflammatory signaling and virulence in multiple infection models, and increased resistance to antibiotics. Examination of clinical isolate cohorts identified isolates with B11 mutations or reduced expression. We used RNAseq and proteomics to investigate the effects of B11 on gene expression and test the impact of mutations found in clinical isolates. Over 200 genes were differentially expressed in the deletion mutant. Strains with the clinical B11 mutations showed expression trends similar to the deletion mutant, suggesting partial loss of function. Among genes upregulated in the B11 mutant, there was a strong enrichment for genes with B11-complementary sequences in their predicted ribosome binding sites (RBS), consistent with B11 functioning as a negative regulator that represses translation via base-pairing to RBSs. Comparing the proteomes similarly revealed that upregulated proteins were strongly enriched for B11-complementary sequences. Intriguingly, genes upregulated in the absence of B11 included components of the ESX-4 secretion system, critical for M. abscessus virulence. Many of these genes had B11-complementary sequences at their RBSs, which we show is sufficient to mediate repression by B11 through direct binding. Altogether, our data show that B11 acts as a direct negative regulator and mediates (likely indirect) positive regulation with pleiotropic effects on gene expression and clinically important phenotypes in M. abscessus. The presence of hypomorphic B11 mutations in clinical strains is consistent with the idea that lower B11 activity may be advantageous for M. abscessus in some clinical contexts. This is the first report on an sRNA role in M. abscessus.
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Affiliation(s)
- Michal Bar-Oz
- Koret School of Veterinary Medicine, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Maria Carla Martini
- Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
| | - Maria Natalia Alonso
- Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
| | | | | | - Paolo Miotto
- IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Camilla Riva
- IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Shiva K Angala
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Junpei Xiao
- Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
| | - Catherine S Masiello
- Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
| | - Maria-Anna Misiakou
- Center for Genomic Medicine, Copenhagen University Hospital-Rigshospitalet, Copenhagen, Denmark
| | - Huaming Sun
- Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
| | - Justin K Moy
- Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
| | - Mary Jackson
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | | | | | - Scarlet S Shell
- Worcester Polytechnic Institute, Worcester, Massachusetts, United States of America
| | - Daniel Barkan
- Koret School of Veterinary Medicine, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
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9
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Bugyna L, Kendra S, Bujdáková H. Galleria mellonella-A Model for the Study of aPDT-Prospects and Drawbacks. Microorganisms 2023; 11:1455. [PMID: 37374956 PMCID: PMC10301295 DOI: 10.3390/microorganisms11061455] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 05/29/2023] [Accepted: 05/30/2023] [Indexed: 06/29/2023] Open
Abstract
Galleria mellonella is a promising in vivo model insect used for microbiological, medical, and pharmacological research. It provides a platform for testing the biocompatibility of various compounds and the kinetics of survival after an infection followed by subsequent treatment, and for the evaluation of various parameters during treatment, including the host-pathogen interaction. There are some similarities in the development of pathologies with mammals. However, a limitation is the lack of adaptive immune response. Antimicrobial photodynamic therapy (aPDT) is an alternative approach for combating microbial infections, including biofilm-associated ones. aPDT is effective against Gram-positive and Gram-negative bacteria, viruses, fungi, and parasites, regardless of whether they are resistant to conventional treatment. The main idea of this comprehensive review was to collect information on the use of G. mellonella in aPDT. It provides a collection of references published in the last 10 years from this area of research, complemented by some practical experiences of the authors of this review. Additionally, the review summarizes in brief information on the G. mellonella model, its advantages and methods used in the processing of material from these larvae, as well as basic knowledge of the principles of aPDT.
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Affiliation(s)
| | | | - Helena Bujdáková
- Faculty of Natural Sciences, Department of Microbiology and Virology, Comenius University in Bratislava, Ilkovicova 6, 84215 Bratislava, Slovakia; (L.B.); (S.K.)
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10
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Asai M, Li Y, Newton SM, Robertson BD, Langford PR. Galleria mellonella-intracellular bacteria pathogen infection models: the ins and outs. FEMS Microbiol Rev 2023; 47:fuad011. [PMID: 36906279 PMCID: PMC10045907 DOI: 10.1093/femsre/fuad011] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 03/07/2023] [Accepted: 03/10/2023] [Indexed: 03/13/2023] Open
Abstract
Galleria mellonella (greater wax moth) larvae are used widely as surrogate infectious disease models, due to ease of use and the presence of an innate immune system functionally similar to that of vertebrates. Here, we review G. mellonella-human intracellular bacteria pathogen infection models from the genera Burkholderia, Coxiella, Francisella, Listeria, and Mycobacterium. For all genera, G. mellonella use has increased understanding of host-bacterial interactive biology, particularly through studies comparing the virulence of closely related species and/or wild-type versus mutant pairs. In many cases, virulence in G. mellonella mirrors that found in mammalian infection models, although it is unclear whether the pathogenic mechanisms are the same. The use of G. mellonella larvae has speeded up in vivo efficacy and toxicity testing of novel antimicrobials to treat infections caused by intracellular bacteria: an area that will expand since the FDA no longer requires animal testing for licensure. Further use of G. mellonella-intracellular bacteria infection models will be driven by advances in G. mellonella genetics, imaging, metabolomics, proteomics, and transcriptomic methodologies, alongside the development and accessibility of reagents to quantify immune markers, all of which will be underpinned by a fully annotated genome.
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Affiliation(s)
- Masanori Asai
- Section of Paediatric Infectious Disease, Department of Infectious Disease, St Mary’s campus, Imperial College London, London W2 1PG, United Kingdom
| | - Yanwen Li
- Section of Paediatric Infectious Disease, Department of Infectious Disease, St Mary’s campus, Imperial College London, London W2 1PG, United Kingdom
| | - Sandra M Newton
- Section of Paediatric Infectious Disease, Department of Infectious Disease, St Mary’s campus, Imperial College London, London W2 1PG, United Kingdom
| | - Brian D Robertson
- Centre for Bacterial Resistance Biology, Department of Infectious Disease, South Kensington campus, Imperial College London, London SW7 2AZ, United Kingdom
| | - Paul R Langford
- Section of Paediatric Infectious Disease, Department of Infectious Disease, St Mary’s campus, Imperial College London, London W2 1PG, United Kingdom
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11
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Updated Review on the Mechanisms of Pathogenicity in Mycobacterium abscessus, a Rapidly Growing Emerging Pathogen. Microorganisms 2022; 11:microorganisms11010090. [PMID: 36677382 PMCID: PMC9866562 DOI: 10.3390/microorganisms11010090] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/21/2022] [Accepted: 12/23/2022] [Indexed: 01/01/2023] Open
Abstract
In recent years, Mycobacterium abscessus has appeared as an emerging pathogen, with an increasing number of disease cases reported worldwide that mainly occur among patients with chronic lung diseases or impaired immune systems. The treatment of this pathogen represents a challenge due to the multi-drug-resistant nature of this species and its ability to evade most therapeutic approaches. However, although predisposing host factors for disease are well known, intrinsic pathogenicity mechanisms of this mycobacterium are still not elucidated. Like other mycobacteria, intracellular invasiveness and survival inside different cell lines are pathogenic factors related to the ability of M. abscessus to establish infection. Some of the molecular factors involved in this process are well-known and are present in the mycobacterial cell wall, such as trehalose-dimycolate and glycopeptidolipids. The ability to form biofilms is another pathogenic factor that is essential for the development of chronic disease and for promoting mycobacterial survival against the host immune system or different antibacterial treatments. This capability also seems to be related to glycopeptidolipids and other lipid molecules, and some studies have shown an intrinsic relationship between both pathogenic mechanisms. Antimicrobial resistance is also considered a mechanism of pathogenicity because it allows the mycobacterium to resist antimicrobial therapies and represents an advantage in polymicrobial biofilms. The recent description of hyperpathogenic strains with the potential interhuman transmission makes it necessary to increase our knowledge of pathogenic mechanisms of this species to design better therapeutic approaches to the management of these infections.
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12
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Santos AL, van Venrooy A, Reed AK, Wyderka AM, García‐López V, Alemany LB, Oliver A, Tegos GP, Tour JM. Hemithioindigo-Based Visible Light-Activated Molecular Machines Kill Bacteria by Oxidative Damage. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2203242. [PMID: 36002317 PMCID: PMC9596824 DOI: 10.1002/advs.202203242] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 07/26/2022] [Indexed: 06/15/2023]
Abstract
Antibiotic resistance is a growing health threat. There is an urgent and critical need to develop new antimicrobial modalities and therapies. Here, a set of hemithioindigo (HTI)-based molecular machines capable of specifically killing Gram-positive bacteria within minutes of activation with visible light (455 nm at 65 mW cm-2 ) that are safe for mammalian cells is described. Importantly, repeated exposure of bacteria to HTI does not result in detectable development of resistance. Visible light-activated HTI kill both exponentially growing bacterial cells and antibiotic-tolerant persister cells of various Gram-positive strains, including methicillin-resistant S. aureus (MRSA). Visible light-activated HTI also eliminate biofilms of S. aureus and B. subtilis in as little as 1 h after light activation. Quantification of reactive oxygen species (ROS) formation and protein carbonyls, as well as assays with various ROS scavengers, identifies oxidative damage as the underlying mechanism for the antibacterial activity of HTI. In addition to their direct antibacterial properties, HTI synergize with conventional antibiotics in vitro and in vivo, reducing the bacterial load and mortality associated with MRSA infection in an invertebrate burn wound model. To the best of the authors' knowledge, this is the first report on the antimicrobial activity of HTI-based molecular machines.
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Affiliation(s)
- Ana L. Santos
- Department of ChemistryRice UniversityHoustonTX77005USA
- IdISBA – Fundación de Investigación Sanitaria de las Islas BalearesPalma07120Spain
| | | | - Anna K. Reed
- Department of ChemistryRice UniversityHoustonTX77005USA
| | | | | | - Lawrence B. Alemany
- Department of ChemistryRice UniversityHoustonTX77005USA
- Shared Equipment AuthorityRice UniversityHoustonTX77005USA
| | - Antonio Oliver
- IdISBA – Fundación de Investigación Sanitaria de las Islas BalearesPalma07120Spain
- Servicio de MicrobiologiaHospital Universitari Son EspasesPalma07120Spain
| | - George P. Tegos
- Office of ResearchReading HospitalTower Health420 S. Fifth AvenueWest ReadingPA19611USA
| | - James M. Tour
- Department of ChemistryRice UniversityHoustonTX77005USA
- Smalley‐Curl InstituteRice UniversityHoustonTX77005USA
- Department of Materials Science and NanoengineeringRice UniversityHoustonTX77005USA
- NanoCarbon Center and the Welch Institute for Advanced MaterialsRice UniversityHoustonTX77005USA
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13
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Asai M, Li Y, Spiropoulos J, Cooley W, Everest DJ, Kendall SL, Martín C, Robertson BD, Langford PR, Newton SM. Galleria mellonella as an infection model for the virulent Mycobacterium tuberculosis H37Rv. Virulence 2022; 13:1543-1557. [PMID: 36052440 PMCID: PMC9481108 DOI: 10.1080/21505594.2022.2119657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB), is a leading cause of infectious disease mortality. Animal infection models have contributed substantially to our understanding of TB, yet their biological and non-biological limitations are a research bottleneck. There is a need for more ethically acceptable, economical, and reproducible TB infection models capable of mimicking key aspects of disease. Here, we demonstrate and present a basic description of how Galleria mellonella (the greater wax moth, Gm) larvae can be used as a low cost, rapid, and ethically more acceptable model for TB research. This is the first study to infect Gm with the fully virulent MTB H37Rv, the most widely used strain in research. Infection of Gm with MTB resulted in a symptomatic lethal infection, the virulence of which differed from both attenuated Mycobacterium bovis BCG and auxotrophic MTB strains. The Gm-MTB model can also be used for anti-TB drug screening, although CFU enumeration from Gm is necessary for confirmation of mycobacterial load reducing activity of the tested compound. Furthermore, comparative virulence of MTB isogenic mutants can be determined in Gm. However, comparison of mutant phenotypes in Gm against conventional models must consider the limitations of innate immunity. Our findings indicate that Gm will be a practical, valuable, and advantageous additional model to be used alongside existing models to advance tuberculosis research.
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Affiliation(s)
- Masanori Asai
- Section of Paediatric Infectious Diseases, Department of Infectious Disease, Imperial College London, London, UK
| | - Yanwen Li
- Section of Paediatric Infectious Diseases, Department of Infectious Disease, Imperial College London, London, UK
| | - John Spiropoulos
- Department of Pathology, Animal and Plant Health Agency, Addlestone, UK
| | - William Cooley
- Department of Pathology, Animal and Plant Health Agency, Addlestone, UK
| | - David J Everest
- Department of Pathology, Animal and Plant Health Agency, Addlestone, UK
| | - Sharon L Kendall
- Centre for Emerging, Endemic and Exotic Diseases, Pathobiology and Population Sciences, Royal Veterinary College, Hartfield, UK
| | - Carlos Martín
- Department of Microbiology, Facultad de Medicina Universidad de Zaragoza, CIBERES, (ISCIII), Spain
| | - Brian D Robertson
- MRC Centre for Molecular Bacteriology and Infection, Department of Infectious Disease, Imperial College London, UK
| | - Paul R Langford
- Section of Paediatric Infectious Diseases, Department of Infectious Disease, Imperial College London, London, UK
| | - Sandra M Newton
- Section of Paediatric Infectious Diseases, Department of Infectious Disease, Imperial College London, London, UK
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14
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Abdelaal HFM, Chan ED, Young L, Baldwin SL, Coler RN. Mycobacterium abscessus: It's Complex. Microorganisms 2022; 10:1454. [PMID: 35889173 PMCID: PMC9316637 DOI: 10.3390/microorganisms10071454] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 07/12/2022] [Accepted: 07/16/2022] [Indexed: 12/21/2022] Open
Abstract
Mycobacterium abscessus (M. abscessus) is an opportunistic pathogen usually colonizing abnormal lung airways and is often seen in patients with cystic fibrosis. Currently, there is no vaccine available for M. abscessus in clinical development. The treatment of M. abscessus-related pulmonary diseases is peculiar due to intrinsic resistance to several commonly used antibiotics. The development of either prophylactic or therapeutic interventions for M. abscessus pulmonary infections is hindered by the absence of an adequate experimental animal model. In this review, we outline the critical elements related to M. abscessus virulence mechanisms, host-pathogen interactions, and treatment challenges associated with M. abscessus pulmonary infections. The challenges of effectively combating this pathogen include developing appropriate preclinical animal models of infection, developing proper diagnostics, and designing novel strategies for treating drug-resistant M. abscessus.
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Affiliation(s)
- Hazem F. M. Abdelaal
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA 98145, USA; (H.F.M.A.); (S.L.B.)
| | - Edward D. Chan
- Department of Academic Affairs and Medicine, National Jewish Health, Denver, CO 80206, USA;
- Pulmonary Section, Rocky Mountain Regional Veterans Affairs Medical Center, Aurora, CO 80045, USA
| | - Lisa Young
- Department of Medicine, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA;
| | - Susan L. Baldwin
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA 98145, USA; (H.F.M.A.); (S.L.B.)
| | - Rhea N. Coler
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA 98145, USA; (H.F.M.A.); (S.L.B.)
- Department of Pediatrics, University of Washington School of Medicine, Seattle, WA 98195, USA
- Department of Global Health, University of Washington, Seattle, WA 98195, USA
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15
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Ferrell KC, Johansen MD, Triccas JA, Counoupas C. Virulence Mechanisms of Mycobacterium abscessus: Current Knowledge and Implications for Vaccine Design. Front Microbiol 2022; 13:842017. [PMID: 35308378 PMCID: PMC8928063 DOI: 10.3389/fmicb.2022.842017] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 02/08/2022] [Indexed: 12/22/2022] Open
Abstract
Mycobacterium abscessus is a member of the non-tuberculous mycobacteria (NTM) group, responsible for chronic infections in individuals with cystic fibrosis (CF) or those otherwise immunocompromised. While viewed traditionally as an opportunistic pathogen, increasing research into M. abscessus in recent years has highlighted its continued evolution into a true pathogen. This is demonstrated through an extensive collection of virulence factors (VFs) possessed by this organism which facilitate survival within the host, particularly in the harsh environment of the CF lung. These include VFs resembling those of other Mycobacteria, and non-mycobacterial VFs, both of which make a notable contribution in shaping M. abscessus interaction with the host. Mycobacterium abscessus continued acquisition of VFs is cause for concern and highlights the need for novel vaccination strategies to combat this pathogen. An effective M. abscessus vaccine must be suitably designed for target populations (i.e., individuals with CF) and incorporate current knowledge on immune correlates of protection against M. abscessus infection. Vaccination strategies must also build upon lessons learned from ongoing efforts to develop novel vaccines for other pathogens, particularly Mycobacterium tuberculosis (M. tb); decades of research into M. tb has provided insight into unconventional and innovative vaccine approaches that may be applied to M. abscessus. Continued research into M. abscessus pathogenesis will be critical for the future development of safe and effective vaccines and therapeutics to reduce global incidence of this emerging pathogen.
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Affiliation(s)
- Kia C. Ferrell
- School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW, Australia
- Tuberculosis Research Program, Centenary Institute, Sydney, NSW, Australia
- *Correspondence: Kia C. Ferrell,
| | - Matt D. Johansen
- Centre for Inflammation, Centenary Institute, University of Technology, Sydney, NSW, Australia
- Faculty of Science, School of Life Sciences, University of Technology, Sydney, NSW, Australia
| | - James A. Triccas
- School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW, Australia
- Sydney Institute for Infectious Diseases and the Charles Perkins Centre, The University of Sydney, Camperdown, NSW, Australia
| | - Claudio Counoupas
- School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW, Australia
- Tuberculosis Research Program, Centenary Institute, Sydney, NSW, Australia
- Sydney Institute for Infectious Diseases and the Charles Perkins Centre, The University of Sydney, Camperdown, NSW, Australia
- Claudio Counoupas,
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16
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Kam JY, Hortle E, Krogman E, Warner SE, Wright K, Luo K, Cheng T, Manuneedhi Cholan P, Kikuchi K, Triccas JA, Britton WJ, Johansen MD, Kremer L, Oehlers SH. Rough and smooth variants of Mycobacterium abscessus are differentially controlled by host immunity during chronic infection of adult zebrafish. Nat Commun 2022; 13:952. [PMID: 35177649 PMCID: PMC8854618 DOI: 10.1038/s41467-022-28638-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 02/03/2022] [Indexed: 11/09/2022] Open
Abstract
Prevalence of Mycobacterium abscessus infections is increasing in patients with respiratory comorbidities. After initial colonisation, M. abscessus smooth colony (S) variants can undergo an irreversible genetic switch into highly inflammatory, rough colony (R) variants, often associated with a decline in pulmonary function. Here, we use an adult zebrafish model of chronic infection with R and S variants to study M. abscessus pathogenesis in the context of fully functioning host immunity. We show that infection with an R variant causes an inflammatory immune response that drives necrotic granuloma formation through host TNF signalling, mediated by the tnfa, tnfr1 and tnfr2 gene products. T cell-dependent immunity is stronger against the R variant early in infection, and regulatory T cells associate with R variant granulomas and limit bacterial growth. In comparison, an S variant proliferates to high burdens but appears to be controlled by TNF-dependent innate immunity early during infection, resulting in delayed granuloma formation. Thus, our work demonstrates the applicability of adult zebrafish to model persistent M. abscessus infection, and illustrates differences in the immunopathogenesis induced by R and S variants during granulomatous infection. The pathogen Mycobacterium abscessus can switch from a smooth colony form (S) into a highly inflammatory, rough colony form (R) during infection. Here, Kam et al. use an adult zebrafish model of M. abscessus chronic infection to illustrate differences in the immunopathogenesis induced by R and S variants.
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Affiliation(s)
- Julia Y Kam
- Tuberculosis Research Program at the Centenary Institute, The University of Sydney, Camperdown, NSW, Australia
| | - Elinor Hortle
- Tuberculosis Research Program at the Centenary Institute, The University of Sydney, Camperdown, NSW, Australia.,The University of Sydney, Faculty of Medicine and Health & Marie Bashir Institute, Camperdown, NSW, Australia
| | - Elizabeth Krogman
- Tuberculosis Research Program at the Centenary Institute, The University of Sydney, Camperdown, NSW, Australia
| | - Sherridan E Warner
- Tuberculosis Research Program at the Centenary Institute, The University of Sydney, Camperdown, NSW, Australia.,The University of Sydney, Faculty of Medicine and Health & Marie Bashir Institute, Camperdown, NSW, Australia
| | - Kathryn Wright
- Tuberculosis Research Program at the Centenary Institute, The University of Sydney, Camperdown, NSW, Australia
| | - Kaiming Luo
- Tuberculosis Research Program at the Centenary Institute, The University of Sydney, Camperdown, NSW, Australia
| | - Tina Cheng
- Tuberculosis Research Program at the Centenary Institute, The University of Sydney, Camperdown, NSW, Australia
| | - Pradeep Manuneedhi Cholan
- Tuberculosis Research Program at the Centenary Institute, The University of Sydney, Camperdown, NSW, Australia
| | - Kazu Kikuchi
- Developmental and Stem Cell Biology Division, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia.,St. Vincent's Clinical School, University of New South Wales, Kensington, NSW, Australia
| | - James A Triccas
- The University of Sydney, Faculty of Medicine and Health & Marie Bashir Institute, Camperdown, NSW, Australia
| | - Warwick J Britton
- Tuberculosis Research Program at the Centenary Institute, The University of Sydney, Camperdown, NSW, Australia.,Department of Clinical Immunology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
| | - Matt D Johansen
- Centre National de la Recherche Scientifique UMR 9004, Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, Montpellier, France
| | - Laurent Kremer
- Centre National de la Recherche Scientifique UMR 9004, Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, Montpellier, France.,INSERM, IRIM, Montpellier, France
| | - Stefan H Oehlers
- Tuberculosis Research Program at the Centenary Institute, The University of Sydney, Camperdown, NSW, Australia. .,The University of Sydney, Faculty of Medicine and Health & Marie Bashir Institute, Camperdown, NSW, Australia. .,A*STAR Infectious Diseases Labs, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore.
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17
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The QcrB Inhibitors TB47 and Telacebec Do Not Potentiate the Activity of Clofazimine in Mycobacterium abscessus. Antimicrob Agents Chemother 2021; 65:e0096421. [PMID: 34543090 DOI: 10.1128/aac.00964-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The antituberculosis drug telacebec is ineffective against Mycobacterium abscessus. A recent study suggested that TB47, a telacebec analogue, potentiated the efficacy of clofazimine against M. abscessus. Here, we report that TB47 not only is ineffective against M. abscessus in vitro but also does not potentiate the activity of clofazimine.
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18
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Johansen MD, Alcaraz M, Dedrick RM, Roquet-Banères F, Hamela C, Hatfull GF, Kremer L. Mycobacteriophage-antibiotic therapy promotes enhanced clearance of drug-resistant Mycobacterium abscessus. Dis Model Mech 2021; 14:272140. [PMID: 34530447 PMCID: PMC8461822 DOI: 10.1242/dmm.049159] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 07/26/2021] [Indexed: 12/16/2022] Open
Abstract
Infection by multidrug-resistant Mycobacterium abscessus is increasingly prevalent in cystic fibrosis (CF) patients, leaving clinicians with few therapeutic options. A compassionate study showed the clinical improvement of a CF patient with a disseminated M. abscessus (GD01) infection, following injection of a phage cocktail, including phage Muddy. Broadening the use of phage therapy in patients as a potential antibacterial alternative necessitates the development of biological models to improve the reliability and successful prediction of phage therapy in the clinic. Herein, we demonstrate that Muddy very efficiently lyses GD01 in vitro, an effect substantially increased with standard drugs. Remarkably, this cooperative activity was retained in an M. abscessus model of infection in CFTR-depleted zebrafish, associated with a striking increase in larval survival and reduction in pathological signs. The activity of Muddy was lost in macrophage-ablated larvae, suggesting that successful phage therapy relies on functional innate immunity. CFTR-depleted zebrafish represent a practical model to rapidly assess phage treatment efficacy against M. abscessus isolates, allowing the identification of drug combinations accompanying phage therapy and treatment prediction in patients. This article has an associated First Person interview with the first author of the paper. Summary: A zebrafish model of infection was developed to evaluate the in vivo cooperative activity of specific phages and antibiotics for the treatment of Mycobacterium abscessus infection.
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Affiliation(s)
- Matt D Johansen
- Institut de Recherche en Infectiologie de Montpellier, Centre National de la Recherche Scientifique UMR 9004, Université de Montpellier, Montpellier 34293, France
| | - Matthéo Alcaraz
- Institut de Recherche en Infectiologie de Montpellier, Centre National de la Recherche Scientifique UMR 9004, Université de Montpellier, Montpellier 34293, France
| | - Rebekah M Dedrick
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Françoise Roquet-Banères
- Institut de Recherche en Infectiologie de Montpellier, Centre National de la Recherche Scientifique UMR 9004, Université de Montpellier, Montpellier 34293, France
| | - Claire Hamela
- Institut de Recherche en Infectiologie de Montpellier, Centre National de la Recherche Scientifique UMR 9004, Université de Montpellier, Montpellier 34293, France
| | - Graham F Hatfull
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Laurent Kremer
- Institut de Recherche en Infectiologie de Montpellier, Centre National de la Recherche Scientifique UMR 9004, Université de Montpellier, Montpellier 34293, France.,INSERM, Institut de Recherche en Infectiologie de Montpellier, Montpellier 34293, France
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19
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Pereira MF, Rossi CC, da Silva GC, Rosa JN, Bazzolli DMS. Galleria mellonella as an infection model: an in-depth look at why it works and practical considerations for successful application. Pathog Dis 2021; 78:5909969. [PMID: 32960263 DOI: 10.1093/femspd/ftaa056] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 09/18/2020] [Indexed: 12/14/2022] Open
Abstract
The larva of the greater wax moth Galleria mellonella is an increasingly popular model for assessing the virulence of bacterial pathogens and the effectiveness of antimicrobial agents. In this review, we discuss details of the components of the G. mellonella larval immune system that underpin its use as an alternative infection model, and provide an updated overview of the state of the art of research with G. mellonella infection models to study bacterial virulence, and in the evaluation of antimicrobial efficacy. Emphasis is given to virulence studies with relevant human and veterinary pathogens, especially Escherichia coli and bacteria of the ESKAPE group. In addition, we make practical recommendations for larval rearing and testing, and overcoming potential limitations of the use of the model, which facilitate intra- and interlaboratory reproducibility.
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Affiliation(s)
- Monalessa Fábia Pereira
- Laboratório de Bioquímica e Microbiologia, Departamento de Ciências Biológicas, Universidade do Estado de Minas Gerais, 36800-000, Carangola, MG, Brazil
| | - Ciro César Rossi
- Laboratório de Microbiologia Molecular, Departamento de Microbiologia Médica, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, 21941-901, Rio de Janeiro, RJ, Brazil
| | - Giarlã Cunha da Silva
- Laboratório de Genética Molecular de Bactérias, Instituto de Biotecnologia Aplicada à Agropecuária-BIOAGRO, Departamento de Microbiologia, Universidade Federal de Viçosa, 36570-900, Viçosa, MG, Brazil
| | - Jéssica Nogueira Rosa
- Laboratório de Genética Molecular de Bactérias, Instituto de Biotecnologia Aplicada à Agropecuária-BIOAGRO, Departamento de Microbiologia, Universidade Federal de Viçosa, 36570-900, Viçosa, MG, Brazil
| | - Denise Mara Soares Bazzolli
- Laboratório de Genética Molecular de Bactérias, Instituto de Biotecnologia Aplicada à Agropecuária-BIOAGRO, Departamento de Microbiologia, Universidade Federal de Viçosa, 36570-900, Viçosa, MG, Brazil
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20
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Asai M, Sheehan G, Li Y, Robertson BD, Kavanagh K, Langford PR, Newton SM. Innate Immune Responses of Galleria mellonella to Mycobacterium bovis BCG Challenge Identified Using Proteomic and Molecular Approaches. Front Cell Infect Microbiol 2021; 11:619981. [PMID: 33634038 PMCID: PMC7900627 DOI: 10.3389/fcimb.2021.619981] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 01/04/2021] [Indexed: 01/10/2023] Open
Abstract
The larvae of the insect Galleria mellonella, have recently been established as a non-mammalian infection model for the Mycobacterium tuberculosis complex (MTBC). To gain further insight into the potential of this model, we applied proteomic (label-free quantification) and transcriptomic (gene expression) approaches to characterise the innate immune response of G. mellonella to infection with Mycobacterium bovis BCG lux over a 168 h time course. Proteomic analysis of the haemolymph from infected larvae revealed distinct changes in the proteome at all time points (4, 48, 168 h). Reverse transcriptase quantitative PCR confirmed induction of five genes (gloverin, cecropin, IMPI, hemolin, and Hdd11), which encoded proteins found to be differentially abundant from the proteomic analysis. However, the trend between gene expression and protein abundance were largely inconsistent (20%). Overall, the data are in agreement with previous phenotypic observations such as haemocyte internalization of mycobacterial bacilli (hemolin/β-actin), formation of granuloma-like structures (Hdd11), and melanization (phenoloxidase activating enzyme 3 and serpins). Furthermore, similarities in immune expression in G. mellonella, mouse, zebrafish and in vitro cell-line models of tuberculosis infection were also identified for the mechanism of phagocytosis (β-actin). Cecropins (antimicrobial peptides), which share the same α-helical motif as a highly potent peptide expressed in humans (h-CAP-18), were induced in G. mellonella in response to infection, giving insight into a potential starting point for novel antimycobacterial agents. We believe that these novel insights into the innate immune response further contribute to the validation of this cost-effective and ethically acceptable insect model to study members of the MTBC.
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Affiliation(s)
- Masanori Asai
- Section of Paediatric Infectious Disease, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Gerard Sheehan
- SSPC Pharma Research Centre, Department of Biology, Maynooth University, Maynooth, Ireland.,Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Yanwen Li
- Section of Paediatric Infectious Disease, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Brian D Robertson
- MRC Centre for Molecular Bacteriology and Infection, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Kevin Kavanagh
- SSPC Pharma Research Centre, Department of Biology, Maynooth University, Maynooth, Ireland
| | - Paul R Langford
- Section of Paediatric Infectious Disease, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Sandra M Newton
- Section of Paediatric Infectious Disease, Department of Infectious Disease, Imperial College London, London, United Kingdom
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21
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Kirubakar G, Schäfer H, Rickerts V, Schwarz C, Lewin A. Mutation on lysX from Mycobacterium avium hominissuis impacts the host-pathogen interaction and virulence phenotype. Virulence 2020; 11:132-144. [PMID: 31996090 PMCID: PMC6999840 DOI: 10.1080/21505594.2020.1713690] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 10/18/2019] [Accepted: 11/26/2019] [Indexed: 01/02/2023] Open
Abstract
The lysX gene from Mycobacterium avium hominissuis (MAH) is not only involved in cationic antimicrobial resistance but also regulates metabolic activity. An MAH lysX deficient mutant was shown to exhibit a metabolic shift at the extracellular state preadapting the bacteria to the conditions inside host-cells. It further showed stronger growth in human monocytes. In the present study, the LysX activity on host-pathogen interactions were analyzed. The lysX mutant from MAH proved to be more sensitive toward host-mediated stresses such as reactive oxygen species. Further, the lysX mutant exhibited increased inflammatory response in PBMC and multinucleated giant cell (MGC) formation in human macrophages during infection studies. Coincidentally, the lysX mutant strain revealed to be more reproductive in the Galleria mellonella infection model. Together, these data demonstrate that LysX plays a role in regulating the bacillary load in host organisms and the lack of lysX gene facilitates MAH adaptation to intracellular host-habitat, thereby suggesting an essential role of LysX in the modulation of host-pathogen interaction.
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Affiliation(s)
- Greana Kirubakar
- Division 16, Mycotic and Parasitic Agents and Mycobacteria, Robert Koch Institute, Berlin, Germany
| | - Hubert Schäfer
- Division 16, Mycotic and Parasitic Agents and Mycobacteria, Robert Koch Institute, Berlin, Germany
| | - Volker Rickerts
- Division 16, Mycotic and Parasitic Agents and Mycobacteria, Robert Koch Institute, Berlin, Germany
| | - Carsten Schwarz
- Pediatric Pneumology, Immunology and Intensive Care Medicine, Division of Cystic Fibrosis, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Astrid Lewin
- Division 16, Mycotic and Parasitic Agents and Mycobacteria, Robert Koch Institute, Berlin, Germany
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22
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Piatek M, Sheehan G, Kavanagh K. UtilisingGalleria mellonella larvae for studying in vivo activity of conventional and novel antimicrobial agents. Pathog Dis 2020; 78:5917982. [DOI: 10.1093/femspd/ftaa059] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 10/02/2020] [Indexed: 12/15/2022] Open
Abstract
ABSTRACTThe immune response of insects displays many structural and functional similarities to the innate immune response of mammals. As a result of these conserved features, insects may be used for evaluating microbial virulence or for testing the in vivo efficacy and toxicity of antimicrobial compounds and results show strong similarities to those from mammals. Galleria mellonella larvae are widely used in this capacity and have the advantage of being easy to use, inexpensive to purchase and house, and being free from the ethical and legal restrictions that relate to the use of mammals in these tests. Galleria mellonella larvae may be used to assess the in vivo toxicity and efficacy of novel antimicrobial compounds. A wide range of antibacterial and antifungal therapies have been evaluated in G. mellonella larvae and results have informed subsequent experiments in mammals. While insect larvae are a convenient and reproducible model to use, care must be taken in their use to ensure accuracy of results. The objective of this review is to provide a comprehensive account of the use of G. mellonella larvae for assessing the in vivo toxicity and efficacy of a wide range of antibacterial and antifungal agents.
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Affiliation(s)
- Magdalena Piatek
- SSPC Pharma Research Centre, Department of Biology, Maynooth University, Co. Kildare W23 F2H6, Ireland
| | - Gerard Sheehan
- Institute of Microbiology and Infection, University of Birmingham, Birmingham B15 2TT, UK
| | - Kevin Kavanagh
- SSPC Pharma Research Centre, Department of Biology, Maynooth University, Co. Kildare W23 F2H6, Ireland
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23
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Giorgio S, Gallo-Francisco PH, Roque GAS, Flóro E Silva M. Granulomas in parasitic diseases: the good and the bad. Parasitol Res 2020; 119:3165-3180. [PMID: 32789534 DOI: 10.1007/s00436-020-06841-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 08/02/2020] [Indexed: 12/12/2022]
Abstract
Parasitic diseases affect more than one billion people worldwide, and most of them are chronic conditions in which the treatment and prevention are difficult. The appearance of granulomas, defined as organized and compact structures of macrophages and other immune cells, during various parasitic diseases is frequent, since these structures will only form when individual immune cells do not control the invading agent. Th2-typering various parasitic diseases are frequent, since these structures will only form when individual immune cells do not control the invading agent. The characterization of granulomas in different parasitic diseases, as well as recent findings in this field, is discussed in this review, in order to understand the significance of the granuloma and its modulation in the host-parasite interaction and in the immune, pathological, and parasitological aspects of this interaction. The parasitic granulomatous diseases granulomatous amebic encephalitis, toxoplasmosis, leishmaniasis, neurocysticercosis, and schistosomiasis mansoni are discussed as well as the mechanistic and dynamical aspects of the infectious granulomas.
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Affiliation(s)
- Selma Giorgio
- Department of Animal Biology, Biology Institute, State University of Campinas, Campinas, 13083-865, Brazil.
| | | | | | - Marina Flóro E Silva
- Department of Animal Biology, Biology Institute, State University of Campinas, Campinas, 13083-865, Brazil
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24
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Rampacci E, Stefanetti V, Passamonti F, Henao-Tamayo M. Preclinical Models of Nontuberculous Mycobacteria Infection for Early Drug Discovery and Vaccine Research. Pathogens 2020; 9:E641. [PMID: 32781698 PMCID: PMC7459799 DOI: 10.3390/pathogens9080641] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/03/2020] [Accepted: 08/04/2020] [Indexed: 12/11/2022] Open
Abstract
Nontuberculous mycobacteria (NTM) represent an increasingly prevalent etiology of soft tissue infections in animals and humans. NTM are widely distributed in the environment and while, for the most part, they behave as saprophytic organisms, in certain situations, they can be pathogenic, so much so that the incidence of NTM infections has surpassed that of Mycobacterium tuberculosis in developed countries. As a result, a growing body of the literature has focused attention on the critical role that drug susceptibility tests and infection models play in the design of appropriate therapeutic strategies against NTM diseases. This paper is an overview of the in vitro and in vivo models of NTM infection employed in the preclinical phase for early drug discovery and vaccine development. It summarizes alternative methods, not fully explored, for the characterization of anti-mycobacterial compounds.
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Affiliation(s)
- Elisa Rampacci
- Department of Veterinary Medicine, University of Perugia, Via San Costanzo 4, 06126 Perugia, Italy; (E.R.); (V.S.)
| | - Valentina Stefanetti
- Department of Veterinary Medicine, University of Perugia, Via San Costanzo 4, 06126 Perugia, Italy; (E.R.); (V.S.)
| | - Fabrizio Passamonti
- Department of Veterinary Medicine, University of Perugia, Via San Costanzo 4, 06126 Perugia, Italy; (E.R.); (V.S.)
| | - Marcela Henao-Tamayo
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO 80523, USA;
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25
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García-Coca M, Aguilera-Correa JJ, Ibáñez-Apesteguía A, Rodríguez-Sevilla G, Romera-García D, Mahíllo-Fernández I, Reina G, Fernández-Alonso M, Leiva J, Muñoz-Egea MC, Del Pozo JL, Esteban J. Non-pigmented rapidly growing mycobacteria smooth and rough colony phenotypes pathogenicity evaluated using in vitro and experimental models. Pathog Dis 2020; 77:5568367. [PMID: 31583400 DOI: 10.1093/femspd/ftz051] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 09/11/2019] [Indexed: 12/28/2022] Open
Abstract
Non-pigmented rapidly growing mycobacteria (NPRGM) are widely distributed in water, soil and animals. It has been observed an increasing importance of NPRGM related-infections, particularly due to the high antimicrobial resistance. NPRGM have rough and smooth colony phenotypes, and several studies have showed that rough colony variants are more virulent than smooth ones. However, other studies have failed to validate this observation. In this study, we have performed two models, invitro and in vivo, in order to assess the different pathogenicity of these two phenotypes. We used collection and clinical strains of Mycobacteriumabscessus, Mycobacterium fortuitum and Mycobacteriumchelonae. On the invitro model (macrophages), phagocytosis was higher for M. abscessus and M. fortuitum rough colony variant strains when compared to smooth colony variants. However, we did not find differences with colonial variants of M. chelonae. Survival of Galleriamellonella larvae in the experimental model was lower for M. abscessus and M. fortuitum rough colony variants when compared with larvae infected with smooth colony variants. We did not find differences in larvae infected with M. chelonae.Results of our in vivo study correlated well with the experimental model. This fact could have implications on the interpretation of the clinical significance of the NPRGM isolate colonial variants.
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Affiliation(s)
- Marta García-Coca
- Department of Clinical Microbiology, IIS-Fundación Jiménez Díaz, UAM, 28040, Madrid, Spain
| | | | | | | | - David Romera-García
- Department of Clinical Microbiology, IIS-Fundación Jiménez Díaz, UAM, 28040, Madrid, Spain
| | | | - Gabriel Reina
- Microbiology Service, Clínica Universidad de Navarra, 31008, Pamplona, Spain
| | | | - José Leiva
- Microbiology Service, Clínica Universidad de Navarra, 31008, Pamplona, Spain
| | | | - José Luis Del Pozo
- Microbiology Service and Infectious Diseases Area, Clínica Universidad de Navarra, 31008 Pamplona, Spain
| | - Jaime Esteban
- Department of Clinical Microbiology, IIS-Fundación Jiménez Díaz, UAM, 28040, Madrid, Spain
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26
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Budell WC, Germain GA, Janisch N, McKie-Krisberg Z, Jayaprakash AD, Resnick AE, Quadri LEN. Transposon mutagenesis in Mycobacterium kansasii links a small RNA gene to colony morphology and biofilm formation and identifies 9,885 intragenic insertions that do not compromise colony outgrowth. Microbiologyopen 2020; 9:e988. [PMID: 32083796 PMCID: PMC7142372 DOI: 10.1002/mbo3.988] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 12/09/2019] [Accepted: 12/10/2019] [Indexed: 01/05/2023] Open
Abstract
Mycobacterium kansasii (Mk) is a resilient opportunistic human pathogen that causes tuberculosis‐like chronic pulmonary disease and mortality stemming from comorbidities and treatment failure. The standard treatment of Mk infections requires costly, long‐term, multidrug courses with adverse side effects. The emergence of drug‐resistant isolates further complicates the already challenging drug therapy regimens and threatens to compromise the future control of Mk infections. Despite the increasingly recognized global burden of Mk infections, the biology of this opportunistic pathogen remains essentially unexplored. In particular, studies reporting gene function or generation of defined mutants are scarce. Moreover, no transposon (Tn) mutagenesis tool has been validated for use in Mk, a situation limiting the repertoire of genetic approaches available to accelerate the dissection of gene function and the generation of gene knockout mutants in this poorly characterized pathogen. In this study, we validated the functionality of a powerful Tn mutagenesis tool in Mk and used this tool in conjunction with a forward genetic screen to establish a previously unrecognized role of a conserved mycobacterial small RNA gene of unknown function in colony morphology features and biofilm formation. We also combined Tn mutagenesis with next‐generation sequencing to identify 12,071 Tn insertions that do not compromise viability in vitro. Finally, we demonstrated the susceptibility of the Galleria mellonella larva to Mk, setting the stage for further exploration of this simple and economical infection model system to the study of this pathogen.
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Affiliation(s)
- William C Budell
- Department of Biology, Brooklyn College, City University of New York, Brooklyn, NY, USA.,Biology Ph.D. Program, Graduate Center, City University of New York, New York, NY, USA
| | - Gabrielle A Germain
- Department of Biology, Brooklyn College, City University of New York, Brooklyn, NY, USA.,Biology Ph.D. Program, Graduate Center, City University of New York, New York, NY, USA
| | - Niklas Janisch
- Department of Biology, Brooklyn College, City University of New York, Brooklyn, NY, USA.,Biology Ph.D. Program, Graduate Center, City University of New York, New York, NY, USA
| | - Zaid McKie-Krisberg
- Department of Biology, Brooklyn College, City University of New York, Brooklyn, NY, USA
| | | | - Andrew E Resnick
- Department of Biology, Brooklyn College, City University of New York, Brooklyn, NY, USA
| | - Luis E N Quadri
- Department of Biology, Brooklyn College, City University of New York, Brooklyn, NY, USA.,Biology Ph.D. Program, Graduate Center, City University of New York, New York, NY, USA.,Biochemistry Ph.D. Program, Graduate Center, City University of New York, New York, NY, USA
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27
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Assessment of Clofazimine and TB47 Combination Activity against Mycobacterium abscessus Using a Bioluminescent Approach. Antimicrob Agents Chemother 2020; 64:AAC.01881-19. [PMID: 31843996 DOI: 10.1128/aac.01881-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 12/10/2019] [Indexed: 01/02/2023] Open
Abstract
Mycobacterium abscessus is intrinsically resistant to most antimicrobial agents. The emerging infections caused by M. abscessus and the lack of effective treatment call for rapid attention. Here, we intended to construct a selectable marker-free autoluminescent M. abscessus strain (designated UAlMab) as a real-time reporter strain to facilitate the discovery of effective drugs and regimens for treating M. abscessus The UAlMab strain was constructed using the dif/Xer recombinase system. In vitro and in vivo activities of several drugs, including clofazimine and TB47, a recently reported cytochrome bc 1 inhibitor, were assessed using UAlMab. Furthermore, the efficacy of multiple drug combinations, including the clofazimine and TB47 combination, were tested against 20 clinical M. abscessus isolates. The UAlMab strain enabled us to evaluate drug efficacy both in vitro and in live BALB/c mice in a real-time, noninvasive fashion. Importantly, although TB47 showed marginal activity either alone or in combination with clarithromycin, amikacin, or roxithromycin, the drug markedly potentiated the activity of clofazimine, both in vitro and in vivo This study demonstrates that the use of the UAlMab strain can significantly facilitate rapid evaluation of new drugs and regimens. The clofazimine and TB47 combination is effective against M. abscessus, and dual/triple electron transport chain (ETC) targeting can be an effective therapeutic approach for treating mycobacterial infections.
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28
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Johansen MD, Herrmann JL, Kremer L. Non-tuberculous mycobacteria and the rise of Mycobacterium abscessus. Nat Rev Microbiol 2020; 18:392-407. [PMID: 32086501 DOI: 10.1038/s41579-020-0331-1] [Citation(s) in RCA: 399] [Impact Index Per Article: 99.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/15/2020] [Indexed: 12/17/2022]
Abstract
Infections caused by non-tuberculous mycobacteria (NTM) are increasing globally and are notoriously difficult to treat due to intrinsic resistance of these bacteria to many common antibiotics. NTM are diverse and ubiquitous in the environment, with only a few species causing serious and often opportunistic infections in humans, including Mycobacterium abscessus. This rapidly growing mycobacterium is one of the most commonly identified NTM species responsible for severe respiratory, skin and mucosal infections in humans. It is often regarded as one of the most antibiotic-resistant mycobacteria, leaving us with few therapeutic options. In this Review, we cover the proposed infection process of M. abscessus, its virulence factors and host interactions and highlight the commonalities and differences of M. abscessus with other NTM species. Finally, we discuss drug resistance mechanisms and future therapeutic options. Taken together, this knowledge is essential to further our understanding of this overlooked and neglected global threat.
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Affiliation(s)
- Matt D Johansen
- Institut de Recherche en Infectiologie de Montpellier, Centre National de la Recherche Scientifique UMR 9004, Université de Montpellier, Montpellier, France
| | - Jean-Louis Herrmann
- Université Paris-Saclay, UVSQ, Inserm, Infection et Inflammation, Montigny-Le-Bretonneux, France.,AP-HP. GHU Paris Saclay, Hôpital Raymond Poincaré, Garches, France
| | - Laurent Kremer
- Institut de Recherche en Infectiologie de Montpellier, Centre National de la Recherche Scientifique UMR 9004, Université de Montpellier, Montpellier, France. .,Inserm, Institut de Recherche en Infectiologie de Montpellier, Montpellier, France.
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29
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Asai M, Li Y, Khara JS, Robertson BD, Langford PR, Newton SM. Galleria mellonella: An Infection Model for Screening Compounds Against the Mycobacterium tuberculosis Complex. Front Microbiol 2019; 10:2630. [PMID: 31824448 PMCID: PMC6882372 DOI: 10.3389/fmicb.2019.02630] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 10/29/2019] [Indexed: 01/08/2023] Open
Abstract
Drug screening models have a vital role in the development of novel antimycobacterial agents which are urgently needed to tackle drug-resistant tuberculosis (TB). We recently established the larvae of the insect Galleria mellonella (greater wax moth) as a novel infection model for the Mycobacterium tuberculosis complex. Here we demonstrate its use as a rapid and reproducible screen to evaluate antimycobacterial drug efficacy using larvae infected with bioluminescent Mycobacterium bovis BCG lux. Treatment improved larval survival outcome and, with the exception of pyrazinamide, was associated with a significant reduction in in vivo mycobacterial bioluminescence over a 96 h period compared to the untreated controls. Isoniazid and rifampicin displayed the greatest in vivo efficacy and survival outcome. Thus G. mellonella, infected with bioluminescent mycobacteria, can rapidly determine in vivo drug efficacy, and has the potential to significantly reduce and/or replace the number of animals used in TB research.
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Affiliation(s)
- Masanori Asai
- Section of Paediatric Infectious Diseases, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Yanwen Li
- Department of Pharmacy, National University of Singapore, Singapore, Singapore
| | - Jasmeet Singh Khara
- Section of Paediatric Infectious Diseases, Department of Infectious Disease, Imperial College London, London, United Kingdom.,Department of Pharmacy, National University of Singapore, Singapore, Singapore
| | - Brian D Robertson
- MRC Centre for Molecular Bacteriology and Infection, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Paul R Langford
- Section of Paediatric Infectious Diseases, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Sandra M Newton
- Section of Paediatric Infectious Diseases, Department of Infectious Disease, Imperial College London, London, United Kingdom
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30
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Synergistic Efficacy of β-Lactam Combinations against Mycobacterium abscessus Pulmonary Infection in Mice. Antimicrob Agents Chemother 2019; 63:AAC.00614-19. [PMID: 31109979 DOI: 10.1128/aac.00614-19] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 05/11/2019] [Indexed: 01/31/2023] Open
Abstract
Mycobacterium abscessus is an emerging pathogen capable of causing invasive pulmonary infections in patients with chronic lung diseases. These infections are difficult to treat, necessitating prolonged multidrug therapy, which is further complicated by extensive intrinsic and acquired resistance exhibited by clinical M. abscessus isolates. Therefore, development of novel treatment regimens effective against drug-resistant strains is crucial. Prior studies have demonstrated synergistic efficacy of several β-lactams against M. abscessus in vitro; however, these combinations have never been tested in an animal model of M. abscessus pulmonary disease. We utilized a recently developed murine system of sustained M. abscessus lung infection delivered via an aerosol route to test the bactericidal efficacy of four novel dual β-lactam combinations and one β-lactam/β-lactamase inhibitor combination. All five of the novel combinations exhibited synergy and resulted in at least 6-log10 reductions in bacterial burden in the lungs of mice at 4 weeks compared to untreated controls (P = 0.038).
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31
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New Perspectives on Galleria mellonella Larvae as a Host Model Using Riemerella anatipestifer as a Proof of Concept. Infect Immun 2019; 87:IAI.00072-19. [PMID: 31160365 DOI: 10.1128/iai.00072-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 05/16/2019] [Indexed: 02/07/2023] Open
Abstract
Galleria mellonella larvae have been used as a host model to study interactions between pathogens and hosts for several years. However, whether the model is useful to interrogate Riemerella anatipestifer infection biology remained unknown. This study aimed to exploit the potential of G. mellonella larvae and reveal their limitations as a host model for R. anatipestifer infection. G. mellonella larvae were shown to be effective for virulence evaluations of different R. anatipestifer strains. Furthermore, the virulent strain R. anatipestifer CH-1 had a stronger ability to proliferate than the attenuated strain R. anatipestifer ATCC 11845 in both G. mellonella larvae and ducklings. Unconventionally it was shown that G. mellonella larvae cannot be used to evaluate the efficacy of antimicrobials and their combinations. Additionally, it was shown that certain virulence factors, such as OmpA (B739_0861), B739_1208, B739_1343, and Wza (B739_1124), were specific only for ducklings, suggesting that G. mellonella larvae must be cautiously used to identify virulence factors of R. anatipestifer Evaluation of heme uptake-related virulence genes, such as tonB1 and tonB2, required preincubating the strains with hemoglobin before infection of G. mellonella larvae since R. anatipestifer cannot obtain a heme source from G. mellonella larvae. In conclusion, this study revealed the applicability and limitations of G. mellonella as a model with which to study the pathogen-host interaction, particularly in the context of R. anatipestifer infection.
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32
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Nguyen TV, Minrovic BM, Melander RJ, Melander C. Identification of Anti-Mycobacterial Biofilm Agents Based on the 2-Aminoimidazole Scaffold. ChemMedChem 2019; 14:927-937. [PMID: 30834698 DOI: 10.1002/cmdc.201900033] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 03/04/2019] [Indexed: 12/12/2022]
Abstract
Tuberculosis (TB) remains a significant global health problem for which new therapeutic options are sorely needed. The ability of the causative agent, Mycobacterium tuberculosis, to reside within host macrophages and form biofilm-like communities contributes to the persistent and drug-tolerant nature of the disease. Compounds that can prevent or reverse the biofilm-like phenotype have the potential to serve alongside TB antibiotics to overcome this tolerance, and decrease treatment duration. Using Mycobacterium smegmatis as a surrogate organism, we report the identification of two new 2-aminoimidazole compounds that inhibit and disperse mycobacterial biofilms, work synergistically with isoniazid and rifampicin to eradicate preformed M. smegmatis biofilms in vitro, are nontoxic toward Galleria mellonella, and exhibit stability in mouse plasma.
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Affiliation(s)
- T Vu Nguyen
- Department of Chemistry, North Carolina State University, Raleigh, NC, 27695, USA
| | - Bradley M Minrovic
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Roberta J Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Christian Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
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33
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Cools F, Torfs E, Aizawa J, Vanhoutte B, Maes L, Caljon G, Delputte P, Cappoen D, Cos P. Optimization and Characterization of a Galleria mellonella Larval Infection Model for Virulence Studies and the Evaluation of Therapeutics Against Streptococcus pneumoniae. Front Microbiol 2019; 10:311. [PMID: 30846978 PMCID: PMC6394149 DOI: 10.3389/fmicb.2019.00311] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 02/05/2019] [Indexed: 12/13/2022] Open
Abstract
Streptococcus pneumoniae is the leading cause of bacterial pneumonia. Infection is linked to high morbidity and mortality rates and antibiotic resistance within this pathogen is on the rise. Therefore, there is a need for novel antimicrobial therapies. To lower the time and costs of the drug discovery process, alternative in vivo models should be considered. As such, Galleria mellonella larvae can be of great value. The larval immunity consisting of several types of haemocytes is remarkably similar to the human innate immune system. Furthermore, these larvae don’t require specific housing, are cheap and are easy to handle. In this study, the use of a G. mellonella infection model to study early pneumococcal infections and treatment is proposed. Firstly, the fitness of this model to study pneumococcal virulence factors is confirmed using streptococcal strains TIGR4, ATCC®49619, D39 and its capsule-deficient counterpart R6 at different inoculum sizes. The streptococcal polysaccharide capsule is considered the most important virulence factor without which streptococci are unable to sustain an in vivo infection. Kaplan–Meier survival curves showed indeed a higher larval survival after infection with streptococcal strain R6 compared to strain D39. Then, the infection was characterized by determining the number of haemocytes, production of oxygen free radicals and bacterial burden at several time points during the course of infection. Lastly, treatment of infected larvae with the standard antibiotics amoxicillin and moxifloxacin was evaluated. Treatment has proven to have a positive outcome on the course of infection, depending on the administered dosage. These data imply that G. mellonella larvae can be used to evaluate antimicrobial therapies against S. pneumoniae, apart from using the larval model to study streptococcal properties. The in-depth knowledge acquired regarding this model, makes it more suitable for use in future research.
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Affiliation(s)
- Freya Cools
- Laboratory of Microbiology, Parasitology and Hygiene, Department of Pharmaceutical Sciences, University of Antwerp, Wilrijk, Belgium
| | - Eveline Torfs
- Laboratory of Microbiology, Parasitology and Hygiene, Department of Pharmaceutical Sciences, University of Antwerp, Wilrijk, Belgium
| | - Juliana Aizawa
- Laboratory of Microbiology, Parasitology and Hygiene, Department of Pharmaceutical Sciences, University of Antwerp, Wilrijk, Belgium
| | - Bieke Vanhoutte
- Laboratory of Microbiology, Parasitology and Hygiene, Department of Pharmaceutical Sciences, University of Antwerp, Wilrijk, Belgium
| | - Louis Maes
- Laboratory of Microbiology, Parasitology and Hygiene, Department of Pharmaceutical Sciences, University of Antwerp, Wilrijk, Belgium
| | - Guy Caljon
- Laboratory of Microbiology, Parasitology and Hygiene, Department of Pharmaceutical Sciences, University of Antwerp, Wilrijk, Belgium
| | - Peter Delputte
- Laboratory of Microbiology, Parasitology and Hygiene, Department of Pharmaceutical Sciences, University of Antwerp, Wilrijk, Belgium
| | - Davie Cappoen
- Laboratory of Microbiology, Parasitology and Hygiene, Department of Pharmaceutical Sciences, University of Antwerp, Wilrijk, Belgium
| | - Paul Cos
- Laboratory of Microbiology, Parasitology and Hygiene, Department of Pharmaceutical Sciences, University of Antwerp, Wilrijk, Belgium
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34
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Kamal F, Peters DL, McCutcheon JG, Dunphy GB, Dennis JJ. Use of Greater Wax Moth Larvae (Galleria mellonella) as an Alternative Animal Infection Model for Analysis of Bacterial Pathogenesis. Methods Mol Biol 2019; 1898:163-171. [PMID: 30570731 DOI: 10.1007/978-1-4939-8940-9_13] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Alternative infection models of bacterial pathogenesis are useful because they reproduce some of the disease characteristics observed in higher animals. Insect models are especially useful for modeling bacterial infections, as they are inexpensive, generally less labor-intensive, and more ethically acceptable than experimentation on higher organisms. Similar to animals, insects have been shown to possess innate immune systems that respond to pathogenic bacteria.
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Affiliation(s)
- Fatima Kamal
- Faculty of Science, Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Danielle L Peters
- Faculty of Science, Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Jaclyn G McCutcheon
- Faculty of Science, Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Gary B Dunphy
- Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, QC, Canada
| | - Jonathan J Dennis
- Faculty of Science, Biological Sciences, University of Alberta, Edmonton, AB, Canada.
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35
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Meir M, Bifani P, Barkan D. The addition of avibactam renders piperacillin an effective treatment for Mycobacterium abscessus infection in an in vivo model. Antimicrob Resist Infect Control 2018; 7:151. [PMID: 30564307 PMCID: PMC6293638 DOI: 10.1186/s13756-018-0448-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 12/06/2018] [Indexed: 11/10/2022] Open
Abstract
Treating M. abscessus infection is challenging due to the potent β-lactamase BlaMab (Beta-lactamase of M. abscessus ). Avibactam is a non-β-lactam, β-lactamase inhibitor shown to inhibit BlaMab. We tested whether avibactem can render piperacillin effective against M. Abscessus. In-vitro, avibactam enhanced the activity of piperacillin by 16-32 fold, with no significant effect on meropenem. In an in-vivo Galleria mellonella model, meropenem and piperacillin/avibactam significantly decreased infection burden compared to untreated controls. Neither piperacillin nor avibactam alone had a significant effect.
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Affiliation(s)
- Michal Meir
- 1The Ruth Rappaport Children's Hospital, Rambam Health Care Campus, Haifa, Israel
| | - Pablo Bifani
- 3Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,4Singapore Immunology Network (SIgN), ASTAR, Singapore, Singapore
| | - Daniel Barkan
- 2Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.,Faculty of Agriculture, School of Veterinary Medicine, POB12,, 76100 Rehovot, Israel
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Li Y, Spiropoulos J, Cooley W, Khara JS, Gladstone CA, Asai M, Bossé JT, Robertson BD, Newton SM, Langford PR. Galleria mellonella - a novel infection model for the Mycobacterium tuberculosis complex. Virulence 2018; 9:1126-1137. [PMID: 30067135 PMCID: PMC6086298 DOI: 10.1080/21505594.2018.1491255] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Animal models have long been used in tuberculosis research to understand disease pathogenesis and to evaluate novel vaccine candidates and anti-mycobacterial drugs. However, all have limitations and there is no single animal model which mimics all the aspects of mycobacterial pathogenesis seen in humans. Importantly mice, the most commonly used model, do not normally form granulomas, the hallmark of tuberculosis infection. Thus there is an urgent need for the development of new alternative in vivo models. The insect larvae, Galleria mellonella has been increasingly used as a successful, simple, widely available and cost-effective model to study microbial infections. Here we report for the first time that G. mellonella can be used as an infection model for members of the Mycobacterium tuberculosis complex. We demonstrate a dose-response for G. mellonella survival infected with different inocula of bioluminescent Mycobacterium bovis BCG lux, and demonstrate suppression of mycobacterial luminesence over 14 days. Histopathology staining and transmission electron microscopy of infected G. mellonella phagocytic haemocytes show internalization and aggregation of M. bovis BCG lux in granuloma-like structures, and increasing accumulation of lipid bodies within M. bovis BCG lux over time, characteristic of latent tuberculosis infection. Our results demonstrate that G. mellonella can act as a surrogate host to study the pathogenesis of mycobacterial infection and shed light on host-mycobacteria interactions, including latent tuberculosis infection.
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Affiliation(s)
- Yanwen Li
- a Section of Paediatric Infectious Diseases and Allergy, Department of Medicine , Imperial College London , London , UK
| | - John Spiropoulos
- b Department of Pathology , Animal and Plant Health Agency , Addlestone , UK
| | - William Cooley
- b Department of Pathology , Animal and Plant Health Agency , Addlestone , UK
| | - Jasmeet Singh Khara
- a Section of Paediatric Infectious Diseases and Allergy, Department of Medicine , Imperial College London , London , UK.,c Department of Pharmacy , National University of Singapore , Singapore
| | - Camilla A Gladstone
- a Section of Paediatric Infectious Diseases and Allergy, Department of Medicine , Imperial College London , London , UK
| | - Masanori Asai
- a Section of Paediatric Infectious Diseases and Allergy, Department of Medicine , Imperial College London , London , UK
| | - Janine T Bossé
- a Section of Paediatric Infectious Diseases and Allergy, Department of Medicine , Imperial College London , London , UK
| | - Brian D Robertson
- d MRC Centre for Molecular Bacteriology and Infection, Department of Medicine , Imperial College London , London , UK
| | - Sandra M Newton
- a Section of Paediatric Infectious Diseases and Allergy, Department of Medicine , Imperial College London , London , UK
| | - Paul R Langford
- a Section of Paediatric Infectious Diseases and Allergy, Department of Medicine , Imperial College London , London , UK
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Thelaus J, Lundmark E, Lindgren P, Sjödin A, Forsman M. Galleria mellonella Reveals Niche Differences Between Highly Pathogenic and Closely Related Strains of Francisella spp. Front Cell Infect Microbiol 2018; 8:188. [PMID: 29922601 PMCID: PMC5996057 DOI: 10.3389/fcimb.2018.00188] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 05/15/2018] [Indexed: 11/13/2022] Open
Abstract
Francisella tularensis, a highly virulent bacteria that causes the zoonotic disease tularemia, is considered a potential agent of biological warfare and bioterrorism. Although the host range for several species within the Francisella is known, little is known about the natural reservoirs of various Francisella species. The lack of knowledge regarding the environmental fates of these pathogens greatly reduces the possibilities for microbial risk assessments. The greater wax moth (Galleria mellonella) is an insect of the order Lepidoptera that has been used as an alternative model to study microbial infection during recent years. The aim of this study was to evaluate G. mellonella as a model system for studies of human pathogenic and closely related opportunistic and non-pathogenic strains within the Francisella genus. The employed G. mellonella larvae model demonstrated differences in lethality between human pathogenic and human non-pathogenic or opportunistic Francisella species. The F. novicida, F. hispaniensis and F. philomiragia strains were significantly more virulent in the G. mellonella model than the strains of human pathogens F. t. holarctica and F. t. tularensis. Our data show that G. mellonella is a possible in vivo model of insect immunity for studies of both opportunistic and virulent lineages of Francisella spp., that produces inverse results regarding lethality in G. mellonella and incapacitating disease in humans. The results provide insight into the potential host specificity of F. tularensis and closely related members of the same genus, thus increasing our present understanding of Francisella spp. ecology.
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