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Kovacs-Simon A, Metters G, Norville I, Hemsley C, Titball RW. Coxiella burnetii replicates in Galleria mellonella hemocytes and transcriptome mapping reveals in vivo regulated genes. Virulence 2021; 11:1268-1278. [PMID: 32970966 PMCID: PMC7549970 DOI: 10.1080/21505594.2020.1819111] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Larvae of the greater wax moth (Galleria mellonella) are susceptible to infection with C. burnetii, an obligate intracellular bacterial pathogen. We show that bacteria are found in hemocytes after infection, and occupy vacuoles which are morphologically similar to Coxiella-containing vacuoles seen in infected mammalian phagocytes. We characterized the infection by transcriptome profiling of bacteria isolated from the hemocytes of infected larvae and identified 46 highly upregulated genes. The encoded proteins are predicted to be involved in translation, LPS biosynthesis, biotin synthesis, scavenging of reactive oxygen species, and included a T4SS effector and 30 hypothetical proteins. Some of these genes had previously been shown to be upregulated in buffalo green monkey (BGM) cells or in mice, whilst others appear to be regulated in a host-specific manner. Altogether, our results demonstrate the value of the G. mellonella model to study intracellular growth and identify potential virulence factors of C. burnetii.
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Affiliation(s)
- Andrea Kovacs-Simon
- College of Life and Environmental Sciences - Biosciences, University of Exeter , Exeter, UK
| | - Georgie Metters
- College of Life and Environmental Sciences - Biosciences, University of Exeter , Exeter, UK
| | - Isobel Norville
- CBR Division, Defence Science and Technology Laboratory , Porton Down,Salisbury, UK
| | - Claudia Hemsley
- College of Life and Environmental Sciences - Biosciences, University of Exeter , Exeter, UK
| | - Richard W Titball
- College of Life and Environmental Sciences - Biosciences, University of Exeter , Exeter, UK
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Fisher JR, Chroust ZD, Onyoni F, Soong L. Pattern Recognition Receptors in Innate Immunity to Obligate Intracellular Bacteria. ZOONOSES (BURLINGTON, MASS.) 2021; 1:10. [PMID: 35282331 PMCID: PMC8909792 DOI: 10.15212/zoonoses-2021-0011] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Host pattern recognition receptors (PRRs) are crucial for sensing pathogenic microorganisms, launching innate responses, and shaping pathogen-specific adaptive immunity during infection. Rickettsia spp., Orientia tsutsugamushi, Anaplasma spp., Ehrlichia spp., and Coxiella burnetii are obligate intracellular bacteria, which can only replicate within host cells and must evade immune detection to successfully propagate. These five bacterial species are zoonotic pathogens of clinical or agricultural importance, yet, uncovering how immune recognition occurs has remained challenging. Recent evidence from in-vitro studies and animal models has offered new insights into the types and kinetics of PRR activation during infection with Rickettsia spp., A. phagocytophilum, E. chaffeensis, and C. burnetii, respectively. However, much less is known in these regards for O. tsutsugamushi infection, until the recent discovery for the role of the C-type lectin receptor Mincle during lethal infection in mice and in primary macrophage cultures. This review gives a brief summary for clinical and epidemiologic features of these five bacterial infections, focuses on fundamental biologic facets of infection, and recent advances in host recognition. In addition, we discuss knowledge gaps for innate recognition of these bacteria in the context of disease pathogenesis.
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Affiliation(s)
- James R. Fisher
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
- School of Medicine, University of Texas Medical Branch, Galveston, Texas, USA
| | - Zachary D. Chroust
- School of Medicine, University of Texas Medical Branch, Galveston, Texas, USA
| | - Florence Onyoni
- Graduate School of Biomedical Sciences, University of Texas Medical Branch, Galveston, Texas, USA
| | - Lynn Soong
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, USA
- Corresponding author: Lynn Soong, Department of Microbiology and Immunology, University of Texas Medical Branch, 301 University Blvd. MRB 3.142, Galveston, Texas 77555-1070,
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D’Amato F, Eldin C, Raoult D. The contribution of genomics to the study of Q fever. Future Microbiol 2016; 11:253-72. [DOI: 10.2217/fmb.15.137] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Coxiella burnetii is the etiological agent of Q fever, a worldwide zoonosis that can result in large outbreaks. The birth of genomics and sequencing of C. burnetii strains has revolutionized many fields of study of this infection. Accurate genotyping methods and comparative genomic analysis have enabled description of the diversity of strains around the world and their link with pathogenicity. Genomics has also permitted the development of qPCR tools and axenic culture medium, facilitating the diagnosis of Q fever. Moreover, several pathophysiological mechanisms can now be predicted and therapeutic strategies can be determined thanks to in silico genome analysis. An extensive pan-genomic analysis will allow for a comprehensive view of the clonal diversity of C. burnetii and its link with virulence.
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Affiliation(s)
- Felicetta D’Amato
- Aix-Marseille Université, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes, UM63, CNRS 7278, IRD 198, INSERM 1095, Marseille, France
| | - Carole Eldin
- Aix-Marseille Université, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes, UM63, CNRS 7278, IRD 198, INSERM 1095, Marseille, France
| | - Didier Raoult
- Aix-Marseille Université, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes, UM63, CNRS 7278, IRD 198, INSERM 1095, Marseille, France
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Schroeder CLC, Narra HP, Rojas M, Sahni A, Patel J, Khanipov K, Wood TG, Fofanov Y, Sahni SK. Bacterial small RNAs in the Genus Rickettsia. BMC Genomics 2015; 16:1075. [PMID: 26679185 PMCID: PMC4683814 DOI: 10.1186/s12864-015-2293-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 12/14/2015] [Indexed: 01/02/2023] Open
Abstract
Background Rickettsia species are obligate intracellular Gram-negative pathogenic bacteria and the etiologic agents of diseases such as Rocky Mountain spotted fever (RMSF), Mediterranean spotted fever, epidemic typhus, and murine typhus. Genome sequencing revealed that R. prowazekii has ~25 % non-coding DNA, the majority of which is thought to be either “junk DNA” or pseudogenes resulting from genomic reduction. These characteristics also define other Rickettsia genomes. Bacterial small RNAs, whose biogenesis is predominantly attributed to either the intergenic regions (trans-acting) or to the antisense strand of an open reading frame (cis-acting), are now appreciated to be among the most important post-transcriptional regulators of bacterial virulence and growth. We hypothesize that intergenic regions in rickettsial species encode for small, non-coding RNAs (sRNAs) involved in the regulation of its transcriptome, leading to altered virulence and adaptation depending on the host niche. Results We employed a combination of bioinformatics and in vitro approaches to explore the presence of sRNAs in a number of species within Genus Rickettsia. Using the sRNA Identification Protocol using High-throughput Technology (SIPHT) web interface, we predicted over 1,700 small RNAs present in the intergenic regions of 16 different strains representing 13 rickettsial species. We further characterized novel sRNAs from typhus (R. prowazekii and R. typhi) and spotted fever (R. rickettsii and R. conorii) groups for their promoters and Rho-independent terminators using Bacterial Promoter Prediction Program (BPROM) and TransTermHP prediction algorithms, respectively. Strong σ70 promoters were predicted upstream of all novel small RNAs, indicating the potential for transcriptional activity. Next, we infected human microvascular endothelial cells (HMECs) with R. prowazekii for 3 h and 24 h and performed Next Generation Sequencing to experimentally validate the expression of 26 sRNA candidates predicted in R. prowazekii. Reverse transcriptase PCR was also used to further verify the expression of six putative novel sRNA candidates in R. prowazekii. Conclusions Our results yield clear evidence for the expression of novel R. prowazekii sRNA candidates during infection of HMECs. This is the first description of novel small RNAs for a highly pathogenic species of Rickettsia, which should lead to new insights into rickettsial virulence and adaptation mechanisms. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-2293-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Casey L C Schroeder
- Department of Pathology, the University of Texas Medical Branch, 301 University Blvd, Galveston, TX, 77555, USA.
| | - Hema P Narra
- Department of Pathology, the University of Texas Medical Branch, 301 University Blvd, Galveston, TX, 77555, USA.
| | - Mark Rojas
- Department of Pharmacology, the University of Texas Medical Branch, 301 University Blvd, Galveston, TX, 77555, USA.
| | - Abha Sahni
- Department of Pathology, the University of Texas Medical Branch, 301 University Blvd, Galveston, TX, 77555, USA.
| | - Jignesh Patel
- Department of Pathology, the University of Texas Medical Branch, 301 University Blvd, Galveston, TX, 77555, USA.
| | - Kamil Khanipov
- Department of Pharmacology, the University of Texas Medical Branch, 301 University Blvd, Galveston, TX, 77555, USA.
| | - Thomas G Wood
- Department of Biochemistry and Molecular Biology, the University of Texas Medical Branch, 301 University Blvd, Galveston, TX, 77555, USA.
| | - Yuriy Fofanov
- Department of Pharmacology, the University of Texas Medical Branch, 301 University Blvd, Galveston, TX, 77555, USA.
| | - Sanjeev K Sahni
- Department of Pathology, the University of Texas Medical Branch, 301 University Blvd, Galveston, TX, 77555, USA.
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Kuley R, Smith HE, Frangoulidis D, Smits MA, Jan Roest HI, Bossers A. Cell-free propagation of Coxiella burnetii does not affect its relative virulence. PLoS One 2015; 10:e0121661. [PMID: 25793981 PMCID: PMC4368683 DOI: 10.1371/journal.pone.0121661] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 02/02/2015] [Indexed: 12/02/2022] Open
Abstract
Q fever is caused by the obligate intracellular bacterium Coxiella burnetii. In vitro growth of the bacterium is usually limited to viable eukaryotic host cells imposing experimental constraints for molecular studies, such as the identification and characterisation of major virulence factors. Studies of pathogenicity may benefit from the recent development of an extracellular growth medium for C. burnetii. However, it is crucial to investigate the consistency of the virulence phenotype of strains propagated by the two fundamentally different culturing systems. In the present study, we assessed the viability of C. burnetii and the lipopolysaccaride (LPS) encoding region of the bacteria in both culture systems as indirect but key parameters to the infection potential of C. burnetii. Propidium monoazide (PMA) treatment-based real-time PCR was used for enumeration of viable C. burnetii which were validated by fluorescent infectious focus forming unit counting assays. Furthermore, RNA isolated from C. burnetiipropagated in both the culture systems was examined for LPS-related gene expression. All thus far known LPS-related genes were found to be expressed in early passages in both culturing systems indicating the presence of predominantly the phase I form of C. burnetii. Finally, we used immune-competent mice to provide direct evidence, that the relative virulence of different C. burnetii strains is essentially the same for both axenic and cell-based methods of propagation.
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Affiliation(s)
- Runa Kuley
- Department of Infection Biology, Central Veterinary Institute part of Wageningen UR, Lelystad, The Netherlands
- Host Microbe Interactomics, Wageningen University, Wageningen, The Netherlands
| | - Hilde E. Smith
- Department of Infection Biology, Central Veterinary Institute part of Wageningen UR, Lelystad, The Netherlands
| | | | - Mari A. Smits
- Department of Infection Biology, Central Veterinary Institute part of Wageningen UR, Lelystad, The Netherlands
- Host Microbe Interactomics, Wageningen University, Wageningen, The Netherlands
| | - Hendrik I. Jan Roest
- Department of Bacteriology and TSEs, Central Veterinary Institute part of Wageningen UR, Lelystad, The Netherlands
| | - Alex Bossers
- Department of Infection Biology, Central Veterinary Institute part of Wageningen UR, Lelystad, The Netherlands
- * E-mail:
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Abstract
Coxiella burnetii is an extremely infectious, zoonotic agent that causes Q fever in humans. With the exception of New Zealand, the bacterium is distributed worldwide. Coxiella is classified as a select agent based on its past and potential use as a bioweapon and its threat to public health. Despite decades of research, we know relatively little regarding Coxiella?s molecular pathogenesis, and a vaccine is not widely available. This article briefly reviews the unusual genetics of C. burnetii; a pathogen that retains telltale genetic mementos collected over the course of its evolutionary path from a free-living bacterium to an obligate intracellular parasite of eukaryotic host cell phagosomes. Understanding why these genetic elements are maintained may help us better understand the biology of this fascinating pathogen.
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Affiliation(s)
- Michael F Minnick
- Division of Biological Sciences, The University of Montana, Missoula, MT 59812, USA.
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