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Robin B, Dewitte A, Alaimo V, Lecoeur C, Pierre F, Billon G, Sebbane F, Bontemps-Gallo S. The CpxAR signaling system confers a fitness advantage for flea gut colonization by the plague bacillus. J Bacteriol 2024; 206:e0017324. [PMID: 39158280 PMCID: PMC11411919 DOI: 10.1128/jb.00173-24] [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: 04/29/2024] [Accepted: 07/20/2024] [Indexed: 08/20/2024] Open
Abstract
The adaptation of Yersinia pestis, the flea-borne plague agent, to fluctuating environmental conditions is essential for the successful colonization of the flea vector. A previous comparative transcriptomic analysis showed that the Cpx pathway of Y. pestis is up-regulated in infected fleas. The CpxAR two-component system is a component of the envelope stress response and is critical for maintaining the integrity of the cell. Here, a phenotypic screening revealed a survival defect of the cpxAR mutant to oxidative stress and copper. The measured copper concentration in the digestive tract contents of fed fleas increased fourfold during the digestive process. By direct analysis of phosphorylation of CpxR by a Phos-Tag gel approach, we demonstrated that biologically relevant concentrations of copper triggered the system. Then, a competitive challenge highlighted the role of the CpxAR system in bacterial fitness during flea infection. Lastly, an in vitro sequential exposure to copper and then H2O2 to mimic the flea suggests a model in which, within the insect digestive tract, the CpxAR system would be triggered by copper, establishing an oxidative stress response. IMPORTANCE The bacterium Yersinia pestis is the agent of flea-borne plague. Our knowledge of the mechanisms used by the plague bacillus to infect the flea vector is limited. The up-regulation of the envelope stress response under the control of the Cpx signaling pathway was previously shown in a transcriptomic study. Here, our in vivo and in vitro approaches suggest a model in which Y. pestis uses the CpxAR phosphorelay system to sense and respond to the copper present in the flea gut, thereby optimizing the flea gut colonization. In other words, the system is essential for bacterial fitness in the flea.
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Affiliation(s)
- Brandon Robin
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Amélie Dewitte
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Véronique Alaimo
- Univ. Lille, CNRS, UMR 8516 - LASIRE, Laboratoire de Spectroscopie pour les Interactions, la Réactivité et l'Environnement, Lille, France
| | - Cecile Lecoeur
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - François Pierre
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Gabriel Billon
- Univ. Lille, CNRS, UMR 8516 - LASIRE, Laboratoire de Spectroscopie pour les Interactions, la Réactivité et l'Environnement, Lille, France
| | - Florent Sebbane
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Sébastien Bontemps-Gallo
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 - CIIL - Center for Infection and Immunity of Lille, Lille, France
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2
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Moore CO, André MR, Šlapeta J, Breitschwerdt EB. Vector biology of the cat flea Ctenocephalides felis. Trends Parasitol 2024; 40:324-337. [PMID: 38458883 PMCID: PMC11168582 DOI: 10.1016/j.pt.2024.02.006] [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: 11/28/2023] [Revised: 02/12/2024] [Accepted: 02/12/2024] [Indexed: 03/10/2024]
Abstract
Ctenocephalides felis, the cat flea, is among the most prevalent and widely dispersed vectors worldwide. Unfortunately, research on C. felis and associated pathogens (Bartonella and Rickettsia spp.) lags behind that of other vectors and vector-borne pathogens. Therefore, we aimed to review fundamental aspects of C. felis as a vector (behavior, epidemiology, phylogenetics, immunology, and microbiome composition) with an emphasis on key techniques and research avenues employed in other vector species. Future laboratory C. felis experimental infections with Bartonella, Rickettsia, and Wolbachia species/strains should examine the vector-pathogen interface utilizing contemporary visualization, transcriptomic, and gene-editing techniques. Further environmental sampling will inform the range and prevalence of C. felis and associated pathogens, improving the accuracy of vector and pathogen modeling to improve infection/infestation risk assessment and diagnostic recommendations.
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Affiliation(s)
- Charlotte O Moore
- Intracellular Pathogens Research Laboratory, Department of Clinical Science, North Carolina State University, NC, USA
| | - Marcos Rogério André
- Vector-Borne Bioagents Laboratory (VBBL), Department of Pathology, Reproduction, and One Health, Faculty of Agrarian and Veterinary Sciences, São Paulo State University (FCAV/UNESP), Jaboticabal, SP 14884-900, Brazil
| | - Jan Šlapeta
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, New South Wales, Australia
| | - Edward B Breitschwerdt
- Intracellular Pathogens Research Laboratory, Department of Clinical Science, North Carolina State University, NC, USA.
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3
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Immune defense mechanisms against a systemic bacterial infection in the cat flea (Ctenocephalides felis). J Invertebr Pathol 2022; 195:107850. [DOI: 10.1016/j.jip.2022.107850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 10/14/2022] [Accepted: 11/01/2022] [Indexed: 11/06/2022]
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4
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Brown LD, Maness R, Hall C, Gibson JD. Reactive oxygen species-mediated immunity against bacterial infection in the gut of cat fleas (Ctenocephalides felis). INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2021; 136:103620. [PMID: 34216781 DOI: 10.1016/j.ibmb.2021.103620] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 06/21/2021] [Accepted: 06/29/2021] [Indexed: 06/13/2023]
Abstract
Fleas (Order Siphonaptera) transmit numerous bacterial pathogens that cause severe human diseases (e.g., cat scratch disease, flea-borne spotted fever, murine typhus, plague). Because initial entry of these infectious agents occurs while blood feeding, the immune response in the flea gut is considered to be the first line of defense against invading microbes. However, relatively few studies have identified the flea immune molecules that effectively resist or limit infection in the gut. In other hematophagous insects, an immediate immune response to imbibed pathogens is the generation of reactive oxygen species (ROS). In this study, we utilized cat fleas (Ctenocephalides felis) to investigate whether oral infection with a well-known insect bacterial pathogen (Serratia marcescens) induces ROS synthesis in the flea gut, and whether production of ROS provides a defense mechanism against microbial colonization. Specifically, we treated fleas with an antioxidant to limit the number of free radicals in the digestive tract prior to infection, and then measured the following: S. marcescens infection loads, hydrogen peroxide (ROS) levels, and mRNA abundance of ROS signaling pathway genes. Overall, our data shows that ROS levels increase in response to infection in the flea gut, and that this increase helps to strengthen the flea immune response through the microbicidal activity of ROS.
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Affiliation(s)
- Lisa D Brown
- Department of Biology, Georgia Southern University, 4324 Old Register Rd., Statesboro, GA, 30460, USA.
| | - Ryne Maness
- Department of Biology, Georgia Southern University, 4324 Old Register Rd., Statesboro, GA, 30460, USA
| | - Clark Hall
- Department of Biology, Georgia Southern University, 4324 Old Register Rd., Statesboro, GA, 30460, USA
| | - Joshua D Gibson
- Department of Biology, Georgia Southern University, 4324 Old Register Rd., Statesboro, GA, 30460, USA
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Unpacking the intricacies of Rickettsia-vector interactions. Trends Parasitol 2021; 37:734-746. [PMID: 34162522 DOI: 10.1016/j.pt.2021.05.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/27/2021] [Accepted: 05/20/2021] [Indexed: 12/19/2022]
Abstract
Although Rickettsia species are molecularly detected among a wide range of arthropods, vector competence becomes an imperative aspect of understanding the ecoepidemiology of these vector-borne diseases. The synergy between vector homeostasis and rickettsial invasion, replication, and release initiated within hours (insects) and days (ticks) permits successful transmission of rickettsiae. Uncovering the molecular interplay between rickettsiae and their vectors necessitates examining the multifaceted nature of rickettsial virulence and vector infection tolerance. Here, we highlight the biological differences between tick- and insect-borne rickettsiae and the factors facilitating the incidence of rickettsioses. Untangling the complex relationship between rickettsial genetics, vector biology, and microbial interactions is crucial in understanding the intricate association between rickettsiae and their vectors.
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6
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Bouvenot T, Dewitte A, Bennaceur N, Pradel E, Pierre F, Bontemps-Gallo S, Sebbane F. Interplay between Yersinia pestis and its flea vector in lipoate metabolism. THE ISME JOURNAL 2021; 15:1136-1149. [PMID: 33479491 PMCID: PMC8182812 DOI: 10.1038/s41396-020-00839-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 10/22/2020] [Accepted: 11/11/2020] [Indexed: 01/29/2023]
Abstract
To thrive, vector-borne pathogens must survive in the vector's gut. How these pathogens successfully exploit this environment in time and space has not been extensively characterized. Using Yersinia pestis (the plague bacillus) and its flea vector, we developed a bioluminescence-based approach and employed it to investigate the mechanisms of pathogenesis at an unprecedented level of detail. Remarkably, lipoylation of metabolic enzymes, via the biosynthesis and salvage of lipoate, increases the Y. pestis transmission rate by fleas. Interestingly, the salvage pathway's lipoate/octanoate ligase LplA enhances the first step in lipoate biosynthesis during foregut colonization but not during midgut colonization. Lastly, Y. pestis primarily uses lipoate provided by digestive proteolysis (presumably as lipoyl peptides) rather than free lipoate in blood, which is quickly depleted by the vector. Thus, spatial and temporal factors dictate the bacterium's lipoylation strategies during an infection, and replenishment of lipoate by digestive proteolysis in the vector might constitute an Achilles' heel that is exploited by pathogens.
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Affiliation(s)
- Typhanie Bouvenot
- grid.503422.20000 0001 2242 6780Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 – CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Amélie Dewitte
- grid.503422.20000 0001 2242 6780Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 – CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Nadia Bennaceur
- grid.503422.20000 0001 2242 6780Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 – CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Elizabeth Pradel
- grid.503422.20000 0001 2242 6780Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 – CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - François Pierre
- grid.503422.20000 0001 2242 6780Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 – CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Sébastien Bontemps-Gallo
- grid.503422.20000 0001 2242 6780Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 – CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Florent Sebbane
- grid.503422.20000 0001 2242 6780Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 9017 – CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
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Hinnebusch BJ, Jarrett CO, Bland DM. Molecular and Genetic Mechanisms That Mediate Transmission of Yersinia pestis by Fleas. Biomolecules 2021; 11:210. [PMID: 33546271 PMCID: PMC7913351 DOI: 10.3390/biom11020210] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/26/2021] [Accepted: 01/27/2021] [Indexed: 12/19/2022] Open
Abstract
The ability to cause plague in mammals represents only half of the life history of Yersinia pestis. It is also able to colonize and produce a transmissible infection in the digestive tract of the flea, its insect host. Parallel to studies of the molecular mechanisms by which Y. pestis is able to overcome the immune response of its mammalian hosts, disseminate, and produce septicemia, studies of Y. pestis-flea interactions have led to the identification and characterization of important factors that lead to transmission by flea bite. Y. pestis adapts to the unique conditions in the flea gut by altering its metabolic physiology in ways that promote biofilm development, a common strategy by which bacteria cope with a nutrient-limited environment. Biofilm localization to the flea foregut disrupts normal fluid dynamics of blood feeding, resulting in regurgitative transmission. Many of the important genes, regulatory pathways, and molecules required for this process have been identified and are reviewed here.
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Affiliation(s)
- B. Joseph Hinnebusch
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA; (C.O.J.); (D.M.B.)
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Transcriptomic profiling of the digestive tract of the rat flea, Xenopsylla cheopis, following blood feeding and infection with Yersinia pestis. PLoS Negl Trop Dis 2020; 14:e0008688. [PMID: 32946437 PMCID: PMC7526888 DOI: 10.1371/journal.pntd.0008688] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 09/30/2020] [Accepted: 08/10/2020] [Indexed: 01/29/2023] Open
Abstract
Yersinia pestis, the causative agent of plague, is a highly lethal pathogen transmitted by the bite of infected fleas. Once ingested by a flea, Y. pestis establish a replicative niche in the gut and produce a biofilm that promotes foregut colonization and transmission. The rat flea Xenopsylla cheopis is an important vector to several zoonotic bacterial pathogens including Y. pestis. Some fleas naturally clear themselves of infection; however, the physiological and immunological mechanisms by which this occurs are largely uncharacterized. To address this, RNA was extracted, sequenced, and distinct transcript profiles were assembled de novo from X. cheopis digestive tracts isolated from fleas that were either: 1) not fed for 5 days; 2) fed sterile blood; or 3) fed blood containing ~5x108 CFU/ml Y. pestis KIM6+. Analysis and comparison of the transcript profiles resulted in identification of 23 annotated (and 11 unknown or uncharacterized) digestive tract transcripts that comprise the early transcriptional response of the rat flea gut to infection with Y. pestis. The data indicate that production of antimicrobial peptides regulated by the immune-deficiency pathway (IMD) is the primary flea immune response to infection with Y. pestis. The remaining infection-responsive transcripts, not obviously associated with the immune response, were involved in at least one of 3 physiological themes: 1) alterations to chemosensation and gut peristalsis; 2) modification of digestion and metabolism; and 3) production of chitin-binding proteins (peritrophins). Despite producing several peritrophin transcripts shortly after feeding, including a subset that were infection-responsive, no thick peritrophic membrane was detectable by histochemistry or electron microscopy of rat flea guts for the first 24 hours following blood-feeding. Here we discuss the physiological implications of rat flea infection-responsive transcripts, the function of X. cheopis peritrophins, and the mechanisms by which Y. pestis may be cleared from the flea gut. The goal of this study was to characterize the transcriptional response of the digestive tract of the rat flea, Xenopsylla cheopis, to infection with Yersinia pestis, the causative agent of plague. This flea is generally considered the most prevalent and efficient vector of Y. pestis. Because most pathogens transmitted by fleas, including Y. pestis, reside in the insect digestive tract prior to transmission, the transcriptional program induced in the gut epithelium likely influences bacterial colonization of the flea. To determine the specific response to infection, RNA profiles were generated from fleas that were either unfed, fed sterile blood, or fed blood containing Y. pestis. Comparative analyses of the transcriptomes resulted in identification of 34 infection-responsive transcripts. The functions of these differentially regulated genes indicate that infection of fleas with Y. pestis induces a limited immune response and potentially alters the insect’s behavior, metabolism, and other aspects of its physiology. Based on these data, we describe potential mechanisms fleas use to eliminate bacteria and the corresponding strategies Y. pestis uses to resist elimination. These findings may be helpful for developing targeted strategies to make fleas resistant to microbial infection and thereby reduce the incidence of diseases they spread.
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Putative Horizontally Acquired Genes, Highly Transcribed during Yersinia pestis Flea Infection, Are Induced by Hyperosmotic Stress and Function in Aromatic Amino Acid Metabolism. J Bacteriol 2020; 202:JB.00733-19. [PMID: 32205462 PMCID: PMC7221256 DOI: 10.1128/jb.00733-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 03/17/2020] [Indexed: 11/20/2022] Open
Abstract
Distinct gene repertoires are expressed during Y. pestis infection of its flea and mammalian hosts. The functions of many of these genes remain predicted or unknown, necessitating their characterization, as this may provide a better understanding of Y. pestis specialized biological adaptations to the discrete environments of its two hosts. This study provides functional context to adjacently clustered horizontally acquired genes predominantly expressed in the flea host by deciphering their fundamental processes with regard to (i) transcriptional organization, (ii) transcription activation signals, and (iii) biochemical function. Our data support a role for these genes in osmoadaptation and aromatic amino acid metabolism, highlighting these as preferential processes by which Y. pestis gene expression is modulated during flea infection. While alternating between insects and mammals during its life cycle, Yersinia pestis, the flea-transmitted bacterium that causes plague, regulates its gene expression appropriately to adapt to these two physiologically disparate host environments. In fleas competent to transmit Y. pestis, low-GC-content genes y3555, y3551, and y3550 are highly transcribed, suggesting that these genes have a highly prioritized role in flea infection. Here, we demonstrate that y3555, y3551, and y3550 are transcribed as part of a single polycistronic mRNA comprising the y3555, y3554, y3553, y355x, y3551, and y3550 genes. Additionally, y355x-y3551-y3550 compose another operon, while y3550 can be also transcribed as a monocistronic mRNA. The expression of these genes is induced by hyperosmotic salinity stress, which serves as an explicit environmental stimulus that initiates transcriptional activity from the predicted y3550 promoter. Y3555 has homology to pyridoxal 5′-phosphate (PLP)-dependent aromatic aminotransferases, while Y3550 and Y3551 are homologous to the Rid protein superfamily (YjgF/YER057c/UK114) members that forestall damage caused by reactive intermediates formed during PLP-dependent enzymatic activity. We demonstrate that y3551 specifically encodes an archetypal RidA protein with 2-aminoacrylate deaminase activity but Y3550 lacks Rid deaminase function. Heterologous expression of y3555 generates a critical aspartate requirement in a Salmonella entericaaspC mutant, while its in vitro expression, and specifically its heterologous coexpression with y3550, enhances the growth rate of an Escherichia coli ΔaspC ΔtyrB mutant in a defined minimal amino acid-supplemented medium. Our data suggest that the y3555, y3551, and y3550 genes operate cooperatively to optimize aromatic amino acid metabolism and are induced under conditions of hyperosmotic salinity stress. IMPORTANCE Distinct gene repertoires are expressed during Y. pestis infection of its flea and mammalian hosts. The functions of many of these genes remain predicted or unknown, necessitating their characterization, as this may provide a better understanding of Y. pestis specialized biological adaptations to the discrete environments of its two hosts. This study provides functional context to adjacently clustered horizontally acquired genes predominantly expressed in the flea host by deciphering their fundamental processes with regard to (i) transcriptional organization, (ii) transcription activation signals, and (iii) biochemical function. Our data support a role for these genes in osmoadaptation and aromatic amino acid metabolism, highlighting these as preferential processes by which Y. pestis gene expression is modulated during flea infection.
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10
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Dewitte A, Bouvenot T, Pierre F, Ricard I, Pradel E, Barois N, Hujeux A, Bontemps-Gallo S, Sebbane F. A refined model of how Yersinia pestis produces a transmissible infection in its flea vector. PLoS Pathog 2020; 16:e1008440. [PMID: 32294143 PMCID: PMC7185726 DOI: 10.1371/journal.ppat.1008440] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 04/27/2020] [Accepted: 02/27/2020] [Indexed: 12/25/2022] Open
Abstract
In flea-borne plague, blockage of the flea's foregut by Yersinia pestis hastens transmission to the mammalian host. Based on microscopy observations, we first suggest that flea blockage results from primary infection of the foregut and not from midgut colonization. In this model, flea infection is characterized by the recurrent production of a mass that fills the lumen of the proventriculus and encompasses a large number of Y. pestis. This recurrence phase ends when the proventricular cast is hard enough to block blood ingestion. We further showed that ymt (known to be essential for flea infection) is crucial for cast production, whereas the hmsHFRS operon (known to be essential for the formation of the biofilm that blocks the gut) is needed for cast consolidation. By screening a library of mutants (each lacking a locus previously known to be upregulated in the flea gut) for biofilm formation, we found that rpiA is important for flea blockage but not for colonization of the midgut. This locus may initially be required to resist toxic compounds within the proventricular cast. However, once the bacterium has adapted to the flea, rpiA helps to form the biofilm that consolidates the proventricular cast. Lastly, we used genetic techniques to demonstrate that ribose-5-phosphate isomerase activity (due to the recent gain of a second copy of rpiA (y2892)) accentuated blockage but not midgut colonization. It is noteworthy that rpiA is an ancestral gene, hmsHFRS and rpiA2 were acquired by the recent ancestor of Y. pestis, and ymt was acquired by Y. pestis itself. Our present results (i) highlight the physiopathological and molecular mechanisms leading to flea blockage, (ii) show that the role of a gene like rpiA changes in space and in time during an infection, and (iii) emphasize that evolution is a gradual process punctuated by sudden jumps.
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Affiliation(s)
- Amélie Dewitte
- Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR9017- CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Typhanie Bouvenot
- Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR9017- CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - François Pierre
- Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR9017- CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Isabelle Ricard
- Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR9017- CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Elizabeth Pradel
- Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR9017- CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Nicolas Barois
- Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR9017- CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Anaïs Hujeux
- Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR9017- CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Sébastien Bontemps-Gallo
- Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR9017- CIIL - Center for Infection and Immunity of Lille, Lille, France
| | - Florent Sebbane
- Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR9017- CIIL - Center for Infection and Immunity of Lille, Lille, France
- * E-mail:
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11
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Bontemps-Gallo S, Fernandez M, Dewitte A, Raphaël E, Gherardini FC, Elizabeth P, Koch L, Biot F, Reboul A, Sebbane F. Nutrient depletion may trigger the Yersinia pestis OmpR-EnvZ regulatory system to promote flea-borne plague transmission. Mol Microbiol 2019; 112:1471-1482. [PMID: 31424585 DOI: 10.1111/mmi.14372] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2019] [Indexed: 01/22/2023]
Abstract
The flea's lumen gut is a poorly documented environment where the agent of flea-borne plague, Yersinia pestis, must replicate to produce a transmissible infection. Here, we report that both the acidic pH and osmolarity of the lumen's contents display simple harmonic oscillations with different periods. Since an acidic pH and osmolarity are two of three known stimuli of the OmpR-EnvZ two-component system in bacteria, we investigated the role and function of this Y. pestis system in fleas. By monitoring the in vivo expression pattern of three OmpR-EnvZ-regulated genes, we concluded that the flea gut environment triggers OmpR-EnvZ. This activation was not, however, correlated with changes in pH and osmolarity but matched the pattern of nutrient depletion (the third known stimulus for OmpR-EnvZ). Lastly, we found that the OmpR-EnvZ and the OmpF porin are needed to produce the biofilm that ultimately obstructs the flea's gut and thus hastens the flea-borne transmission of plague. Taken as a whole, our data suggest that the flea gut is a complex, fluctuating environment in which Y. pestis senses nutrient depletion via OmpR-EnvZ. Once activated, the latter triggers a molecular program (including at least OmpF) that produces the biofilm required for efficient plague transmission.
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Affiliation(s)
- Sébastien Bontemps-Gallo
- University of Lille, INSERM, CNRS, CHU Lille, Institut Pasteur de Lille, U1019-UMR8204, CIIL-Center for Infection and Immunity of Lille, F-59000, Lille, France
| | - Marion Fernandez
- University of Lille, INSERM, CNRS, CHU Lille, Institut Pasteur de Lille, U1019-UMR8204, CIIL-Center for Infection and Immunity of Lille, F-59000, Lille, France
| | - Amélie Dewitte
- University of Lille, INSERM, CNRS, CHU Lille, Institut Pasteur de Lille, U1019-UMR8204, CIIL-Center for Infection and Immunity of Lille, F-59000, Lille, France
| | - Etienne Raphaël
- University of Lille, INSERM, CNRS, CHU Lille, Institut Pasteur de Lille, U1019-UMR8204, CIIL-Center for Infection and Immunity of Lille, F-59000, Lille, France
| | - Frank C Gherardini
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Pradel Elizabeth
- University of Lille, INSERM, CNRS, CHU Lille, Institut Pasteur de Lille, U1019-UMR8204, CIIL-Center for Infection and Immunity of Lille, F-59000, Lille, France
| | - Lionel Koch
- Institut de Recherche Biomédicale des Armées (IRBA), Brétigny-sur-Orge, France.,Aix Marseille University, INSERM, SSA, IRBA, MCT, Marseille, France.,Ecole du Val de Grace (EVDG), Paris, France
| | - Fabrice Biot
- Institut de Recherche Biomédicale des Armées (IRBA), Brétigny-sur-Orge, France.,Aix Marseille University, INSERM, SSA, IRBA, MCT, Marseille, France
| | - Angéline Reboul
- University of Lille, INSERM, CNRS, CHU Lille, Institut Pasteur de Lille, U1019-UMR8204, CIIL-Center for Infection and Immunity of Lille, F-59000, Lille, France
| | - Florent Sebbane
- University of Lille, INSERM, CNRS, CHU Lille, Institut Pasteur de Lille, U1019-UMR8204, CIIL-Center for Infection and Immunity of Lille, F-59000, Lille, France
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12
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Brown LD. Immunity of fleas (Order Siphonaptera). DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2019; 98:76-79. [PMID: 31002845 DOI: 10.1016/j.dci.2019.03.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 03/25/2019] [Accepted: 03/28/2019] [Indexed: 06/09/2023]
Abstract
The immune response of arthropod vectors plays a key role in the spread and transmission of vector-borne diseases. Although fleas transmit several human pathogens (e.g., Bartonella henselae, Rickettsia felis, R. typhi, and Yersinia pestis), few studies have examined how these vectors respond to infection. In hematophagous arthropods, imbibed pathogens must survive the hostile environment of blood meal digestion, which includes proteolytic digestive enzymes, protease inhibitors and expression of genes associated with protection of epithelial linings. Additionally, insect epithelial cells exhibit local immune defense against ingested pathogens by producing antimicrobial peptides and reactive oxygen species. This review details these and other aspects of insect immunity as it relates to fleas, with an emphasis on the gut immune response to two blood-borne pathogens, R. typhi and Y. pestis.
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Affiliation(s)
- Lisa D Brown
- Department of Biology, Georgia Southern University, P.O. Box 8042-1, Statesboro, GA, 30460, USA.
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13
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Liu L, Zheng S. Transcriptional regulation of Yersinia pestis biofilm formation. Microb Pathog 2019; 131:212-217. [PMID: 30980880 DOI: 10.1016/j.micpath.2019.04.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 04/08/2019] [Indexed: 01/27/2023]
Abstract
Yersinia pestis, the causative agent of plague, is transmitted primarily by infected fleas in nature. Y. pestis can produce biofilms that block flea's proventriculus and promote flea-borne transmission. Transcriptional regulation of Y. pestis biofilm formation plays an important role in the response to complex changes in environments, including temperature, pH, oxidative stress, and restrictive nutrition conditions, and contributes to Y. pestis growth, reproduction, transmission, and pathogenesis. A set of transcriptional regulators involved in Y. pestis biofilm production simultaneously controls a variety of biological functions and physiological pathways. Interactions between these regulators contribute to the development of Y. pestis gene regulatory networks, which are helpful for a quick response to complex environmental changes and better survival. The roles of crucial factors and regulators involved in response to complex environmental signals and Y. pestis biofilm formation as well as the precise gene regulatory networks are discussed in this review, which will give a better understanding of the complicated mechanisms of transcriptional regulation in Y. pestis biofilm formation.
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Affiliation(s)
- Lei Liu
- Department of Transfusion, General Hospital of Central Theater Command, Wuhan, 430070, Hubei, China; State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China
| | - Shangen Zheng
- Department of Transfusion, General Hospital of Central Theater Command, Wuhan, 430070, Hubei, China.
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14
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Schachterle JK, Stewart RM, Schachterle MB, Calder JT, Kang H, Prince JT, Erickson DL. Yersinia pseudotuberculosis BarA-UvrY Two-Component Regulatory System Represses Biofilms via CsrB. Front Cell Infect Microbiol 2018; 8:323. [PMID: 30280093 PMCID: PMC6153318 DOI: 10.3389/fcimb.2018.00323] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 08/24/2018] [Indexed: 01/07/2023] Open
Abstract
The formation of biofilms by Yersinia pseudotuberculosis (Yptb) and Y. pestis requires the hmsHFRS genes, which direct production of a polysaccharide extracellular matrix (Hms-ECM). Despite possessing identical hmsHFRS sequences, Yptb produces much less Hms-ECM than Y. pestis. The regulatory influences that control Yptb Hms-ECM production and biofilm formation are not fully understood. In this study, negative regulators of biofilm production in Yptb were identified. Inactivation of the BarA/UvrY two-component system or the CsrB regulatory RNA increased binding of Congo Red dye, which correlates with extracellular polysaccharide production. These mutants also produced biofilms that were substantially more cohesive than the wild type strain. Disruption of uvrY was not sufficient for Yptb to cause proventricular blockage during infection of Xenopsylla cheopis fleas. However, this strain was less acutely toxic toward fleas than wild type Yptb. Flow cytometry measurements of lectin binding indicated that Yptb BarA/UvrY/CsrB mutants may produce higher levels of other carbohydrates in addition to poly-GlcNAc Hms-ECM. In an effort to characterize the relevant downstream targets of the BarA/UvrY system, we conducted a proteomic analysis to identify proteins with lower abundance in the csrB::Tn5 mutant strain. Urease subunit proteins were less abundant and urease enzymatic activity was lower, which likely reduced toxicity toward fleas. Loss of CsrB impacted expression of several potential regulatory proteins that may influence biofilms, including the RcsB regulator. Overexpression of CsrB did not alter the Congo-red binding phenotype of an rcsB::Tn5 mutant, suggesting that the effect of CsrB on biofilms may require RcsB. These results underscore the regulatory and compositional differences between Yptb and Y. pestis biofilms. By activating CsrB expression, the Yptb BarA/UvrY two-component system has pleiotropic effects that impact biofilm production and stability.
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Affiliation(s)
- Jeffrey K Schachterle
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States
| | - Ryan M Stewart
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States
| | - M Brett Schachterle
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States
| | - Joshua T Calder
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States
| | - Huan Kang
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, United States
| | - John T Prince
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, United States
| | - David L Erickson
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States
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15
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Niu D, Wang R, Zhao Y, Yang R, Hu L. De novo RNA-seq and functional annotation of Ornithonyssus bacoti. EXPERIMENTAL & APPLIED ACAROLOGY 2018; 75:191-208. [PMID: 29855753 DOI: 10.1007/s10493-018-0264-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 05/16/2018] [Indexed: 06/08/2023]
Abstract
Ornithonyssus bacoti (Hirst) (Acari: Macronyssidae) is a vector and reservoir of pathogens causing serious infectious diseases, such as epidemic hemorrhagic fever, endemic typhus, tularemia, and leptospirosis. Its genome and transcriptome data are lacking in public databases. In this study, total RNA was extracted from live O. bacoti to conduct RNA-seq, functional annotation, coding domain sequence (CDS) prediction and simple sequence repeats (SSRs) detection. The results showed that 65.8 million clean reads were generated and assembled into 72,185 unigenes, of which 49.4% were annotated by seven functional databases. 23,121 unigenes were annotated and assigned to 457 species by non-redundant protein sequence database. The BLAST top-two hit species were Metaseiulus occidentalis and Ixodes scapularis. The procedure detected 12,426 SSRs, of which tri- and di-nucleotides were the most abundant types and the representative motifs were AAT/ATT and AC/GT. 26,936 CDS were predicted with a mean length of 711 bp. 87 unigenes of 30 functional genes, which are usually involved in stress responses, drug resistance, movement, metabolism and allergy, were further identified by bioinformatics methods. The unigenes putatively encoding cytochrome P450 proteins were further analyzed phylogenetically. In conclusion, this study completed the RNA-seq and functional annotation of O. bacoti successfully, which provides reliable molecular data for its future studies of gene function and molecular markers.
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Affiliation(s)
- DongLing Niu
- Department of Pathogen Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University, 76 Yanta West Road, Xi'an, 710061, China
| | - RuiLing Wang
- Department of Pathogen Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University, 76 Yanta West Road, Xi'an, 710061, China
- Assisted Reproduction Center, Northwest Womens and Childrens Hospital, Xi'an, 710003, China
| | - YaE Zhao
- Department of Pathogen Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University, 76 Yanta West Road, Xi'an, 710061, China.
| | - Rui Yang
- Department of Pathogen Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University, 76 Yanta West Road, Xi'an, 710061, China
| | - Li Hu
- Department of Pathogen Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University, 76 Yanta West Road, Xi'an, 710061, China
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16
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Hinnebusch BJ, Jarrett CO, Bland DM. "Fleaing" the Plague: Adaptations of Yersinia pestis to Its Insect Vector That Lead to Transmission. Annu Rev Microbiol 2018; 71:215-232. [PMID: 28886687 DOI: 10.1146/annurev-micro-090816-093521] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Interest in arthropod-borne pathogens focuses primarily on how they cause disease in humans. How they produce a transmissible infection in their arthropod host is just as critical to their life cycle, however. Yersinia pestis adopts a unique life stage in the digestive tract of its flea vector, characterized by rapid formation of a bacterial biofilm that is enveloped in a complex extracellular polymeric substance. Localization and adherence of the biofilm to the flea foregut is essential for transmission. Here, we review the molecular and genetic mechanisms of these processes and present a comparative evaluation and updated model of two related transmission mechanisms.
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Affiliation(s)
- B Joseph Hinnebusch
- Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840;
| | - Clayton O Jarrett
- Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840;
| | - David M Bland
- Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840;
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17
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Martínez-Chavarría LC, Vadyvaloo V. Yersinia pestis and Yersinia pseudotuberculosis infection: a regulatory RNA perspective. Front Microbiol 2015; 6:956. [PMID: 26441890 PMCID: PMC4585118 DOI: 10.3389/fmicb.2015.00956] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 08/28/2015] [Indexed: 12/27/2022] Open
Abstract
Yersinia pestis, responsible for causing fulminant plague, has evolved clonally from the enteric pathogen, Y. pseudotuberculosis, which in contrast, causes a relatively benign enteric illness. An ~97% nucleotide identity over 75% of their shared protein coding genes is maintained between these two pathogens, leaving much conjecture regarding the molecular determinants responsible for producing these vastly different disease etiologies, host preferences and transmission routes. One idea is that coordinated production of distinct factors required for host adaptation and virulence in response to specific environmental cues could contribute to the distinct pathogenicity distinguishing these two species. Small non-coding RNAs that direct posttranscriptional regulation have recently been identified as key molecules that may provide such timeous expression of appropriate disease enabling factors. Here the burgeoning field of small non-coding regulatory RNAs in Yersinia pathogenesis is reviewed from the viewpoint of adaptive colonization, virulence and divergent evolution of these pathogens.
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Affiliation(s)
- Luary C Martínez-Chavarría
- Departamento de Patología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, México Mexico
| | - Viveka Vadyvaloo
- Paul G. Allen School for Global Animal Health, Washington State University, Pullman, WA USA
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18
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Earl SC, Rogers MT, Keen J, Bland DM, Houppert AS, Miller C, Temple I, Anderson DM, Marketon MM. Resistance to Innate Immunity Contributes to Colonization of the Insect Gut by Yersinia pestis. PLoS One 2015; 10:e0133318. [PMID: 26177454 PMCID: PMC4503695 DOI: 10.1371/journal.pone.0133318] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 06/25/2015] [Indexed: 01/29/2023] Open
Abstract
Yersinia pestis, the causative agent of bubonic and pneumonic plague, is typically a zoonotic vector-borne disease of wild rodents. Bacterial biofilm formation in the proventriculus of the flea contributes to chronic infection of fleas and facilitates efficient disease transmission. However prior to biofilm formation, ingested bacteria must survive within the flea midgut, and yet little is known about vector-pathogen interactions that are required for flea gut colonization. Here we establish a Drosophila melanogaster model system to gain insight into Y. pestis colonization of the insect vector. We show that Y. pestis establishes a stable infection in the anterior midgut of fly larvae, and we used this model system to study the roles of genes involved in biofilm production and/or resistance to gut immunity stressors. We find that PhoP and GmhA both contribute to colonization and resistance to antimicrobial peptides in flies, and furthermore, the data suggest biofilm formation may afford protection against antimicrobial peptides. Production of reactive oxygen species in the fly gut, as in fleas, also serves to limit bacterial infection, and OxyR mediates Y. pestis survival in both insect models. Overall, our data establish the fruit fly as an informative model to elucidate the relationship between Y. pestis and its flea vector.
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Affiliation(s)
- Shaun C. Earl
- Department of Biology, Indiana University, Bloomington, IN, United States of America
| | - Miles T. Rogers
- Department of Biology, Indiana University, Bloomington, IN, United States of America
| | - Jennifer Keen
- Department of Biology, Indiana University, Bloomington, IN, United States of America
| | - David M. Bland
- Department of Veterinary Pathobiology, University of Missouri, Columbia, Missouri, United States of America
| | - Andrew S. Houppert
- Department of Biology, Indiana University, Bloomington, IN, United States of America
| | - Caitlynn Miller
- Department of Biology, Indiana University, Bloomington, IN, United States of America
| | - Ian Temple
- Department of Biology, Indiana University, Bloomington, IN, United States of America
| | - Deborah M. Anderson
- Department of Veterinary Pathobiology, University of Missouri, Columbia, Missouri, United States of America
| | - Melanie M. Marketon
- Department of Biology, Indiana University, Bloomington, IN, United States of America
- * E-mail:
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19
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Vadyvaloo V, Viall AK, Jarrett CO, Hinz AK, Sturdevant DE, Joseph Hinnebusch B. Role of the PhoP-PhoQ gene regulatory system in adaptation of Yersinia pestis to environmental stress in the flea digestive tract. MICROBIOLOGY-SGM 2015; 161:1198-1210. [PMID: 25804213 PMCID: PMC4635514 DOI: 10.1099/mic.0.000082] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The Yersinia pestis PhoPQ gene regulatory system is induced during infection of the flea digestive tract and is required to produce adherent biofilm in the foregut, which greatly enhances bacterial transmission during a flea bite. To understand the in vivo context of PhoPQ induction and to determine PhoP-regulated targets in the flea, we undertook whole-genome comparative transcriptional profiling of Y. pestis WT and ΔphoP strains isolated from infected fleas and from temperature-matched in vitro planktonic and flow-cell biofilm cultures. In the absence of PhoP regulation, the gene expression program indicated that the bacteria experienced diverse physiological stresses and were in a metabolically less active state. Multiple stress response genes, including several toxin–antitoxin loci and YhcN family genes responsible for increased acid tolerance, were upregulated in the phoP mutant during flea infection. The data implied that PhoPQ was induced by low pH in the flea gut, and that PhoP modulated physiological adaptation to acid and other stresses encountered during infection of the flea. This adaptive response, together with PhoP-dependent modification of the bacterial outer surface that includes repression of pH 6 antigen fimbriae, supports stable biofilm development in the flea foregut.
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Affiliation(s)
- Viveka Vadyvaloo
- 1Paul G. Allen School for Global Animal Health, Washington State University, Pullman, WA, 99164, USA
| | - Austin K Viall
- 2Plague Section, Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, 59840, USA
| | - Clayton O Jarrett
- 2Plague Section, Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, 59840, USA
| | - Angela K Hinz
- 1Paul G. Allen School for Global Animal Health, Washington State University, Pullman, WA, 99164, USA
| | - Daniel E Sturdevant
- 3Genomics Unit, Research Technologies Section, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, 59840, USA
| | - B Joseph Hinnebusch
- 2Plague Section, Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, 59840, USA
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20
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Williams SK, Schotthoefer AM, Montenieri JA, Holmes JL, Vetter SM, Gage KL, Bearden SW. Effects of low-temperature flea maintenance on the transmission of Yersinia pestis by Oropsylla montana. Vector Borne Zoonotic Dis 2013; 13:468-78. [PMID: 23590319 DOI: 10.1089/vbz.2012.1017] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Yersinia pestis, the causative agent of plague, is primarily a rodent-associated, flea-borne zoonosis maintained in sylvatic foci throughout western North America. Transmission to humans is mediated most commonly by the flea vector Oropsylla montana and occurs predominantly in the southwestern United States. With few exceptions, previous studies showed O. montana to be an inefficient vector at transmitting Y. pestis at ambient temperatures, particularly when such fleas were fed on susceptible hosts more than a few days after ingesting an infectious blood meal. We examined whether holding fleas at subambient temperatures affected the transmissibility of Y. pestis by this vector. An infectious blood meal containing a virulent Y. pestis strain (CO96-3188) was given to colony-reared O. montana fleas. Potentially infected fleas were maintained at different temperatures (6°C, 10°C, 15°C, or 23°C). Transmission efficiencies were tested by allowing up to 15 infectious fleas to feed on each of 7 naïve CD-1 mice on days 1-4, 7, 10, 14, 17, and 21 postinfection (p.i.). Mice were monitored for signs of infection for 21 days after exposure to infectious fleas. Fleas held at 6°C, 10°C, and 15°C were able to effectively transmit at every time point p.i. The percentage of transmission to naïve mice by fleas maintained at low temperatures (46.0% at 6°C, 71.4% at 10°C, 66.7% at 15°C) was higher than for fleas maintained at 23°C (25.4%) and indicates that O. montana fleas efficiently transmit Y. pestis at low temperatures. Moreover, pooled percent per flea transmission efficiencies for flea cohorts maintained at temperatures of 10°C and 15°C (8.67% and 7.87%, respectively) showed a statistically significant difference in the pooled percent per flea transmission efficiency from fleas maintained at 23°C (1.94%). This is the first comprehensive study to demonstrate efficient transmission of Y. pestis by O. montana fleas maintained at temperatures as low as 6°C. Our findings further contribute to the understanding of plague ecology in temperate climates by providing support for the hypothesis that Y. pestis is able to overwinter within the flea gut and potentially cause infection during the following transmission season. The findings also might hold implications for explaining the focality of plague in tropical regions.
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Affiliation(s)
- Shanna K Williams
- Bacterial Diseases Branch, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, USA
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21
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Severo MS, Sakhon OS, Choy A, Stephens KD, Pedra JHF. The 'ubiquitous' reality of vector immunology. Cell Microbiol 2013; 15:1070-8. [PMID: 23433059 DOI: 10.1111/cmi.12128] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 01/09/2013] [Accepted: 01/14/2013] [Indexed: 12/17/2022]
Abstract
Ubiquitination (ubiquitylation) is a common protein modification that regulates a multitude of processes within the cell. This modification is typically accomplished through the covalent binding of ubiquitin to a lysine residue onto a target protein and is catalysed by the presence of three enzymes: an activating enzyme (E1), ubiquitin-conjugating enzyme (E2) and ubiquitin-protein ligase (E3). In recent years, ubiquitination has risen as a major signalling regulator of immunity and microbial pathogenesis in the mammalian system. Still, little is known about how ubiquitin relates specifically to vector immunology. Here, we provide a brief overview of ubiquitin biochemistry and describe how ubiquitination regulates immune responses in arthropods of medical relevance. We also discuss scientific gaps in the literature and suggest that, similar to mammals, ubiquitin is a major regulator of immunity in medically important arthropods.
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Affiliation(s)
- Maiara S Severo
- Center for Disease Vector Research and Department of Entomology, University of California, Riverside, Riverside, CA 92521, USA
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22
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Liu M, Ferrandez Y, Bouhsira E, Monteil M, Franc M, Boulouis HJ, Biville F. Heme binding proteins of Bartonella henselae are required when undergoing oxidative stress during cell and flea invasion. PLoS One 2012; 7:e48408. [PMID: 23144761 PMCID: PMC3483173 DOI: 10.1371/journal.pone.0048408] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 10/01/2012] [Indexed: 11/24/2022] Open
Abstract
Bartonella are hemotropic bacteria responsible for emerging zoonoses. These heme auxotroph alphaproteobacteria must import heme for their growth, since they cannot synthesize it. To import exogenous heme, Bartonella genomes encode for a complete heme uptake system enabling transportation of this compound into the cytoplasm and degrading it to release iron. In addition, these bacteria encode for four or five outer membrane heme binding proteins (Hbps). The structural genes of these highly homologous proteins are expressed differently depending on oxygen, temperature and heme concentrations. These proteins were hypothesized as being involved in various cellular processes according to their ability to bind heme and their regulation profile. In this report, we investigated the roles of the four Hbps of Bartonella henselae, responsible for cat scratch disease. We show that Hbps can bind heme in vitro. They are able to enhance the efficiency of heme uptake when co-expressed with a heme transporter in Escherichia coli. Using B. henselae Hbp knockdown mutants, we show that these proteins are involved in defense against the oxidative stress, colonization of human endothelial cell and survival in the flea.
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Affiliation(s)
- MaFeng Liu
- UMR BIPAR Université Paris-Est, Ecole Nationale Vétérinaire d'Alfort, INRA-Anses-UPEC-ENVA, Maisons-Alfort, France.
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