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Didier Raoult - One of the best experts on this subject based on the ideXlab platform.
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Detection of Bartonella spp. in fleas by MALDI-TOF MS.
Public Library of Science (PLoS), 2018Co-Authors: Basma El Hamzaoui, Lionel Almeras, Jean Michel Berenger, Didier Raoult, Maureen Laroche, Philippe ParolaAbstract:Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) has recently emerged in the field of entomology as a promising method for the identification of arthropods and the detection of associated pathogens.An experimental model of Ctenocephalides felis (cat fleas) infected with Bartonella quintana and Bartonella henselae was developed to evaluate the efficacy of MALDI-TOF MS in distinguishing infected from uninfected fleas, and its ability to distinguish fleas infected with Bartonella quintana from fleas infected with Bartonella henselae. For B. quintana, two groups of fleas received three successive blood meals, infected or not. A total of 140 fleas (100 exposed fleas and 40 control fleas) were engorged on human blood, infected or uninfected with B. quintana. Regarding the second pathogen, two groups of fleas (200 exposed fleas and 40 control fleas) were fed in the same manner with human blood, infected or not with Bartonella henselae. Fleas were dissected longitudinally; one-half was used for assessment of B. quintana and B. henselae infectious status by real-time PCR, and the second half was subjected to MALDI-TOF MS analysis. Comparison of MS spectra from infected fleas and uninfected fleas revealed distinct MS profiles. Blind queries against our MALDI-TOF MS arthropod database, upgraded with reference spectra from B. quintana and B. henselae infected fleas but also non-infected fleas, provided the correct classification for 100% of the different categories of specimens tested on the first model of flea infection with Bartonella quintana. As for Bartonella henselae, 81% of exposed qPCR-positive fleas, 96% of exposed qPCR-negative fleas and 100% of control fleas were correctly identified on the second model of flea infection. MALDI-TOF MS successfully differentiated Bartonella spp.-infected and uninfected fleas and was also able to correctly differentiate fleas infected with Bartonella quintana and fleas infected with Bartonella henselae. MALDI-TOF MS correctly identified flea species as well as their infectious status, consistent with the results of real-time PCR.MALDI-TOF is a promising tool for identification of the infection status of fleas infected with Bartonella spp., which allows new possibilities for fast and accurate diagnosis in medical entomology and vector surveillance
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Peak masses distinguishing uninfected and infected fleas by Bartonella quintana analyzed with ClinProTools.
2018Co-Authors: Basma El Hamzaoui, Lionel Almeras, Jean Michel Berenger, Didier Raoult, Maureen Laroche, Philippe ParolaAbstract:Peak masses distinguishing uninfected and infected fleas by Bartonella quintana analyzed with ClinProTools.
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Detection of Bartonella spp. in fleas by MALDI-TOF MS - Fig 3
2018Co-Authors: Basma El Hamzaoui, Lionel Almeras, Jean Michel Berenger, Didier Raoult, Maureen Laroche, Philippe ParolaAbstract:(A, B, C and D) Comparison of MALDI-TOF MS profiles of body half of Ctenocephalides felis infected or not by Bartonella quintana using ClinProTools 2.2 software. Red and green peaks indicated by arrows correspond to discriminating peaks of control and infected fleas respectively.
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doi:10.4269/ajtmh.13-0707 Copyright © 2014 by The American Society of Tropical Medicine and Hygiene Detection of Bartonella quintana in African Body and Head Lice
2016Co-Authors: Abdoul Karim Sangaré, Rezak Drali, Amina Boutellis, Georges Diatta, Christophe Rogier, Mariemarie Olive, Ogobara K Doumbo, Stephen C. Barker, Didier RaoultAbstract:Abstract. Currently, the body louse is the only recognized vector of Bartonella quintana, an organism that causes trench fever. In this work, we investigated the prevalence of this bacterium in human lice in different African countries. We tested 616 head lice and 424 body lice from nine African countries using real-time polymerase chain reaction targeting intergenic spacer region 2 and specific B. quintana genes. Overall, B. quintana DNA was found in 54 % and 2 % of body and head lice, respectively. Our results also show that there are more body lice positive for B. quintana in poor countries, which was determined by the gross domestic product, than in wealthy areas (228/403 versus 0/21, P < 0.001). A similar finding was obtained for head lice (8/226 versus 2/390, P = 0.007). Our findings suggest that head lice in Africa may be infected by B. quintana when patients live in poor economic conditions and are also exposed to body lice
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a new clade of african body and head lice infected by Bartonella quintana and yersinia pestis democratic republic of the congo
American Journal of Tropical Medicine and Hygiene, 2015Co-Authors: Rezak Drali, Georges Diatta, Jeanchristophe Shako, B Davoust, Didier RaoultAbstract:Abstract The human body louse is known as a vector for the transmission of three serious diseases—specifically, epidemic typhus, trench fever, and relapsing fever caused by Rickettsia prowazekii, Bartonella quintana, and Borrelia recurrentis, respectively—that have killed millions of people. It is also suspected in the transmission of a fourth pathogen, Yersinia pestis, which is the etiologic agent of plague. To date, human lice belonging to the genus Pediculus have been classified into three mitochondrial clades: A, B, and C. Here, we describe a fourth mitochondrial clade, Clade D, comprising head and body lice. Clade D may be a vector of B. quintana and Y. pestis, which is prevalent in a highly plague-endemic area near the Rethy Health District, Orientale Province, Democratic Republic of the Congo.
Jane E Koehler - One of the best experts on this subject based on the ideXlab platform.
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Bartonella quintana aortitis in a man with aids diagnosed by needle biopsy and 16s rrna gene amplification
Journal of Clinical Microbiology, 2015Co-Authors: Sulggi A Lee, Sara K Plett, Anne F Luetkemeyer, Gina M Borgo, Michael A Ohliger, Miles Conrad, Brad T Cookson, Dhruba J Sengupta, Jane E KoehlerAbstract:A man with newly diagnosed AIDS presented with months of back pain and fever. Computed tomography (CT) results demonstrated aortitis with periaortic tissue thickening. DNA amplification of biopsy tissue revealed Bartonella quintana, and Bartonella serologies were subsequently noted to be positive. The patient improved with prolonged doxycycline and rifabutin treatment. This case illustrates how molecular techniques are increasingly important in diagnosing Bartonella infections.
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the Bartonella quintana extracytoplasmic function sigma factor rpoe has a role in bacterial adaptation to the arthropod vector environment
Journal of Bacteriology, 2013Co-Authors: Stephanie Abromaitis, Jane E KoehlerAbstract:Bartonella quintana is a vector-borne bacterial pathogen that causes fatal disease in humans. During the infectious cycle, B. quintana transitions from the hemin-restricted human bloodstream to the hemin-rich body louse vector. Because extracytoplasmic function (ECF) sigma factors often regulate adaptation to environmental changes, we hypothesized that a previously unstudied B. quintana ECF sigma factor, RpoE, is involved in the transition from the human host to the body louse vector. The genomic context of B. quintana rpoE identified it as a member of the ECF15 family of sigma factors found only in alphaproteobacteria. ECF15 sigma factors are believed to be the master regulators of the general stress response in alphaproteobacteria. In this study, we examined the B. quintana RpoE response to two stressors that are encountered in the body louse vector environment, a decreased temperature and an increased hemin concentration. We determined that the expression of rpoE is significantly upregulated at the body louse (28°C) versus the human host (37°C) temperature. rpoE expression also was upregulated when B. quintana was exposed to high hemin concentrations. In vitro and in vivo analyses demonstrated that RpoE function is regulated by a mechanism involving the anti-sigma factor NepR and the response regulator PhyR. The ΔrpoE ΔnepR mutant strain of B. quintana established that RpoE-mediated transcription is important in mediating the tolerance of B. quintana to high hemin concentrations. We present the first analysis of an ECF15 sigma factor in a vector-borne human pathogen and conclude that RpoE has a role in the adaptation of B. quintana to the hemin-rich arthropod vector environment.
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the Bartonella quintana extracytoplasmic function sigma factor rpoe has a role in bacterial adaptation to the arthropod vector environment
Journal of Bacteriology, 2013Co-Authors: Stephanie Abromaitis, Jane E KoehlerAbstract:Bartonella quintana is a vector-borne bacterial pathogen that causes fatal disease in humans. During the infectious cycle, B. quintana transitions from the hemin-restricted human bloodstream to the hemin-rich body louse vector. Because extracytoplasmic function (ECF) sigma factors often regulate adaptation to environmental changes, we hypothesized that a previously unstudied B. quintana ECF sigma factor, RpoE, is involved in the transition from the human host to the body louse vector. The genomic context of B. quintana rpoE identified it as a member of the ECF15 family of sigma factors found only in alphaproteobacteria. ECF15 sigma factors are believed to be the master regulators of the general stress response in alphaproteobacteria. In this study, we examined the B. quintana RpoE response to two stressors that are encountered in the body louse vector environment, a decreased temperature and an increased hemin concentration. We determined that the expression of rpoE is significantly upregulated at the body louse (28°C) versus the human host (37°C) temperature. rpoE expression also was upregulated when B. quintana was exposed to high hemin concentrations. In vitro and in vivo analyses demonstrated that RpoE function is regulated by a mechanism involving the anti-sigma factor NepR and the response regulator PhyR. The ΔrpoE ΔnepR mutant strain of B. quintana established that RpoE-mediated transcription is important in mediating the tolerance of B. quintana to high hemin concentrations. We present the first analysis of an ECF15 sigma factor in a vector-borne human pathogen and conclude that RpoE has a role in the adaptation of B. quintana to the hemin-rich arthropod vector environment.
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Proteomic and immunoblot analyses of Bartonella quintana total membrane proteins identify antigens recognized by sera from infected patients. Infect Immun 75
2007Co-Authors: Jenni K. Boonjakuakul, Michael F Minnick, Helen L. Gerns, Yu-ting Chen, Linda D. Hicks, Scott E. Dixon, Steven C. Hall, Jane E KoehlerAbstract:Bartonella quintana is a fastidious, gram-negative, rod-shaped bacterium that causes prolonged bacteremia in immunocompetent humans and severe infections in immunocompromised individuals. We sought to define the outer membrane subproteome of B. quintana in order to obtain insight into the biology and pathogenesis of this emerging pathogen and to identify the predominant B. quintana antigens targeted by the human immune system during infection. We isolated the total membrane proteins of B. quintana and identified 60 proteins by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis and peptide mass fingerprinting. Using the newly constructed proteome map, we then utilized two-dimensional immunoblotting with sera from 21 B. quintana-infected patients to identify 24 consistently recognized, immunoreactive B. quintana antigens that have potential relevance for pathogenesis and diagnosis. Among the outer membrane proteins, the variably expressed outer membrane protein adhesins (VompA and VompB), peptidyl-prolyl cis-trans-isomerase (PpI), and hemin-binding protein E (HbpE) were recognized most frequently by sera from patients, which is consistent with surface expression of these virulence factors during human infection. Bartonella quintana, the agent of trench fever, is a fastidious, gram-negative, rod-shaped organism that can cause prolonged bacteremia in immunocompetent humans and severe infection
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a family of variably expressed outer membrane proteins vomp mediates adhesion and autoaggregation in Bartonella quintana
Proceedings of the National Academy of Sciences of the United States of America, 2004Co-Authors: Peng Zhang, Bruno B Chomel, Maureen K Schau, Sara Droz, Karen L Kelminson, Smitha S George, Nicholas W Lerche, Jane E KoehlerAbstract:Bartonella species are fastidious, Gram-negative human pathogens that can persist in the host bloodstream for years and bind to and invade several types of host cells. For many pathogens, adhesion to host cells and extracellular matrix (ECM) components is a critical virulence determinant. Bacteria often vary expression of surface adhesins by phase or antigenic variation to subvert the host immune response and permit adaptive interaction with different host structures. We developed a macaque animal model for Bartonella quintana infection to detect changes in bacterial outer-membrane proteins (OMP) during prolonged bloodstream infection. We identified a gene family encoding four highly conserved, 100-kDa, variably expressed OMP (Vomp), two of which function as adhesins. The variable expression of Vomp family members appears to be mediated by deletion of one or more vomp genes during chronic bloodstream infection. vomp deletion was observed also in isolates from humans with chronic B. quintana infection. The Vomp are closely related to the afimbrial adhesin, YadA, a virulence factor of Yersinia enterocolitica. The surface-expressed Vomp contain conserved structural features of YadA, including collagen-binding motifs. We demonstrate that the B. quintana Vomp are multifunctional OMP involved in binding to collagen and autoaggregation: VompC confers the ability to bind collagen IV, and VompA is necessary and sufficient for autoaggregation. The B. quintana Vomp are members of the newly recognized family of YadA-like trimeric autotransporters; the Vomp constitute a multigene family, they are variably expressed, and different virulence properties are attributable to individual Vomp family members.
Philippe Brouqui - One of the best experts on this subject based on the ideXlab platform.
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no evidence of Bartonella quintana but detection of acinetobacter baumannii in head lice from elementary schoolchildren in paris
Comparative Immunology Microbiology and Infectious Diseases, 2011Co-Authors: Sophie Bouvresse, Didier Raoult, Cristina Socolovshi, Z Berdjane, Remy Durand, Arezki Izri, Olivier Chosidow, Philippe BrouquiAbstract:Abstract The human body louse is the only known vector of Bartonella quintana. However, the presence of this bacterium has recently been detected in the head lice of homeless individuals and Nepalese slum children. Previous studies have reported the isolation of Acinetobacter baumannii from the body lice of homeless individuals. An epidemiological survey including 74 schools was conducted between 2008 and 2009 in Paris. After a first visual examination, the hair of children with suspected pediculosis was combed with a fine-tooth comb to collect live adult head lice. Molecular studies were performed on randomly selected DNA samples to detect B. quintana and A. baumannii by specific quantitative real-time PCR. Among a collection of 288 DNA samples, B. quintana was not detected, but A. baumannii was detected in 95 DNA samples (33%). Further study is needed to determine the significance of the finding of A. baumannii in head lice.
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Bartonella quintana in head louse nits
Fems Immunology and Medical Microbiology, 2011Co-Authors: Emmanouil Angelakis, Jean-marc Rolain, Philippe BrouquiAbstract:The body louse is the principal vector of Bartonella quintana , the causative organism of trench fever, but B. quintana DNA has also been detected in adult head lice. Because there are no characteristics that distinguish the body louse from the head louse, we decided to test head louse nits collected from a homeless man for the presence of B. quintana DNA. All of the sampled nits tested positive by real-time PCR, and intergenic spacer region (ITS) gene sequences shared 100% similarity to the corresponding ITS fragment of the genome of B. quintana . The role of the head louse in the maintenance and transmission of B. quintana remains to be determined.
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Bartonella quintana characteristics and clinical management
Emerging Infectious Diseases, 2006Co-Authors: Cédric Foucault, Philippe BrouquiAbstract:Bartonella quintana, a pathogen that is restricted to human hosts and louse vectors, was first characterized as the agent of trench fever. The disease was described in 1915 on the basis of natural and experimental infections in soldiers. It is now recognized as a reemerging pathogen among homeless populations in cities in the United States and Europe and is responsible for a wide spectrum of conditions, including chronic bacteremia, endocarditis, and bacillary angiomatosis. Diagnosis is based on serologic analysis, culture, and molecular biology. Recent characterization of its genome allowed the development of modern diagnosis and typing methods. Guidelines for the treatment of B. quintana infections are presented.
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Autochthonous epidemic typhus associated with Bartonella quintana bacteremia in a homeless person.
The American journal of tropical medicine and hygiene, 2005Co-Authors: Sékéné Badiaga, Philippe BrouquiAbstract:Trench fever, a louse-borne disease caused by Bartonella quintana, is reemerging in homeless persons. Epidemic typhus is another life-threatening louse-borne disease caused by Rickettsia prowazekii and known to occur in conditions of war, famine, refugee camps, cold weather, poverty, or lapses in public health. We report the first case of seroconversion to R. prowazekii in a homeless person of Marseilles, France. This was associated with B. quintana bacteremia. Although no outbreaks of typhus have been notified yet in the homeless population, this disease is likely to reemerge in such situation.
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detection of Bartonella quintana by direct immunofluorescence examination of blood smears of a patient with acute trench fever
Journal of Clinical Microbiology, 2004Co-Authors: Cédric Foucault, Jean-marc Rolain, Didier Raoult, Philippe BrouquiAbstract:We report a case of Bartonella quintana acute symptomatic infection in a homeless man, presenting as a typical trench fever. B. quintana has been retrieved in erythrocytes in large clusters and in erythroblasts. Direct immunofluorescence of blood smears allows a rapid diagnosis.
Philippe Parola - One of the best experts on this subject based on the ideXlab platform.
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Detection of Bartonella spp. in fleas by MALDI-TOF MS - Fig 3
2018Co-Authors: Basma El Hamzaoui, Lionel Almeras, Jean Michel Berenger, Didier Raoult, Maureen Laroche, Philippe ParolaAbstract:(A, B, C and D) Comparison of MALDI-TOF MS profiles of body half of Ctenocephalides felis infected or not by Bartonella quintana using ClinProTools 2.2 software. Red and green peaks indicated by arrows correspond to discriminating peaks of control and infected fleas respectively.
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Peak masses distinguishing uninfected and infected fleas by Bartonella quintana analyzed with ClinProTools.
2018Co-Authors: Basma El Hamzaoui, Lionel Almeras, Jean Michel Berenger, Didier Raoult, Maureen Laroche, Philippe ParolaAbstract:Peak masses distinguishing uninfected and infected fleas by Bartonella quintana analyzed with ClinProTools.
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Detection of Bartonella spp. in fleas by MALDI-TOF MS.
Public Library of Science (PLoS), 2018Co-Authors: Basma El Hamzaoui, Lionel Almeras, Jean Michel Berenger, Didier Raoult, Maureen Laroche, Philippe ParolaAbstract:Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) has recently emerged in the field of entomology as a promising method for the identification of arthropods and the detection of associated pathogens.An experimental model of Ctenocephalides felis (cat fleas) infected with Bartonella quintana and Bartonella henselae was developed to evaluate the efficacy of MALDI-TOF MS in distinguishing infected from uninfected fleas, and its ability to distinguish fleas infected with Bartonella quintana from fleas infected with Bartonella henselae. For B. quintana, two groups of fleas received three successive blood meals, infected or not. A total of 140 fleas (100 exposed fleas and 40 control fleas) were engorged on human blood, infected or uninfected with B. quintana. Regarding the second pathogen, two groups of fleas (200 exposed fleas and 40 control fleas) were fed in the same manner with human blood, infected or not with Bartonella henselae. Fleas were dissected longitudinally; one-half was used for assessment of B. quintana and B. henselae infectious status by real-time PCR, and the second half was subjected to MALDI-TOF MS analysis. Comparison of MS spectra from infected fleas and uninfected fleas revealed distinct MS profiles. Blind queries against our MALDI-TOF MS arthropod database, upgraded with reference spectra from B. quintana and B. henselae infected fleas but also non-infected fleas, provided the correct classification for 100% of the different categories of specimens tested on the first model of flea infection with Bartonella quintana. As for Bartonella henselae, 81% of exposed qPCR-positive fleas, 96% of exposed qPCR-negative fleas and 100% of control fleas were correctly identified on the second model of flea infection. MALDI-TOF MS successfully differentiated Bartonella spp.-infected and uninfected fleas and was also able to correctly differentiate fleas infected with Bartonella quintana and fleas infected with Bartonella henselae. MALDI-TOF MS correctly identified flea species as well as their infectious status, consistent with the results of real-time PCR.MALDI-TOF is a promising tool for identification of the infection status of fleas infected with Bartonella spp., which allows new possibilities for fast and accurate diagnosis in medical entomology and vector surveillance
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Competence of Cimex lectularius Bed Bugs for the Transmission of Bartonella quintana, the Agent of Trench Fever
PLoS Neglected Tropical Diseases, 2015Co-Authors: Hamza Leulmi, Lionel Almeras, Jean Michel Berenger, Hubert Lepidi, Idir Bitam, Jean-marc Rolain, Philippe ParolaAbstract:BACKGROUND: Bartonella quintana, the etiologic agent of trench fever and other human diseases, is transmitted by the feces of body lice. Recently, this bacterium has been detected in other arthropod families such as bed bugs, which begs the question of their involvement in B. quintana transmission. Although several infectious pathogens have been reported and are suggested to be transmitted by bed bugs, the evidence regarding their competence as vectors is unclear. METHODOLOGY/PRINCIPAL FINDINGS: Bed bugs at the adult and instar developmental stages were fed three successive human blood meals inoculated with B. quintana bacterium from day one (D1) to D5; subsequently they were fed with pathogen-free human blood until the end of the experiment. Bed bugs and feces were collected in time series, to evaluate their capacities to acquire, multiply and expel viable B. quintana using molecular biology, immunohistochemistry and cultures assays. B. quintana was detected molecularly in 100% of randomly selected experimentally infected bed bug specimens (D3). The monitoring of B. quintana in bed bug feces showed that the bacterium was detectable starting on the 3rd day post-infection (pi) and persisted until day 18±1 pi. Although immunohistochemistry assays localized the bacteria to the gastrointestinal bed bug gut, the detection of B. quintana in the first and second instar larva stages suggested a vertical non-transovarial transmission of the bacterium. CONCLUSION: The present work demonstrated for the first time that bed bugs can acquire, maintain for more than 2 weeks and release viable B. quintana organisms following a stercorarial shedding. We also observed the vertical transmission of the bacterium to their progeny. Although the biological role of bed bugs in the transmission of B. quintana under natural conditions has yet to be confirmed, the present work highlights the need to reconsider monitoring of these arthropods for the transmission of human pathogens.
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Persistence of Bartonella quintana in the bodies of bed bugs.
2015Co-Authors: Hamza Leulmi, Lionel Almeras, Jean Michel Berenger, Hubert Lepidi, Idir Bitam, Jean-marc Rolain, Didier Raoult, Philippe ParolaAbstract:Persistence of Bartonella quintana in the bodies of bed bugs.
Stephanie Abromaitis - One of the best experts on this subject based on the ideXlab platform.
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the Bartonella quintana extracytoplasmic function sigma factor rpoe has a role in bacterial adaptation to the arthropod vector environment
Journal of Bacteriology, 2013Co-Authors: Stephanie Abromaitis, Jane E KoehlerAbstract:Bartonella quintana is a vector-borne bacterial pathogen that causes fatal disease in humans. During the infectious cycle, B. quintana transitions from the hemin-restricted human bloodstream to the hemin-rich body louse vector. Because extracytoplasmic function (ECF) sigma factors often regulate adaptation to environmental changes, we hypothesized that a previously unstudied B. quintana ECF sigma factor, RpoE, is involved in the transition from the human host to the body louse vector. The genomic context of B. quintana rpoE identified it as a member of the ECF15 family of sigma factors found only in alphaproteobacteria. ECF15 sigma factors are believed to be the master regulators of the general stress response in alphaproteobacteria. In this study, we examined the B. quintana RpoE response to two stressors that are encountered in the body louse vector environment, a decreased temperature and an increased hemin concentration. We determined that the expression of rpoE is significantly upregulated at the body louse (28°C) versus the human host (37°C) temperature. rpoE expression also was upregulated when B. quintana was exposed to high hemin concentrations. In vitro and in vivo analyses demonstrated that RpoE function is regulated by a mechanism involving the anti-sigma factor NepR and the response regulator PhyR. The ΔrpoE ΔnepR mutant strain of B. quintana established that RpoE-mediated transcription is important in mediating the tolerance of B. quintana to high hemin concentrations. We present the first analysis of an ECF15 sigma factor in a vector-borne human pathogen and conclude that RpoE has a role in the adaptation of B. quintana to the hemin-rich arthropod vector environment.
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the Bartonella quintana extracytoplasmic function sigma factor rpoe has a role in bacterial adaptation to the arthropod vector environment
Journal of Bacteriology, 2013Co-Authors: Stephanie Abromaitis, Jane E KoehlerAbstract:Bartonella quintana is a vector-borne bacterial pathogen that causes fatal disease in humans. During the infectious cycle, B. quintana transitions from the hemin-restricted human bloodstream to the hemin-rich body louse vector. Because extracytoplasmic function (ECF) sigma factors often regulate adaptation to environmental changes, we hypothesized that a previously unstudied B. quintana ECF sigma factor, RpoE, is involved in the transition from the human host to the body louse vector. The genomic context of B. quintana rpoE identified it as a member of the ECF15 family of sigma factors found only in alphaproteobacteria. ECF15 sigma factors are believed to be the master regulators of the general stress response in alphaproteobacteria. In this study, we examined the B. quintana RpoE response to two stressors that are encountered in the body louse vector environment, a decreased temperature and an increased hemin concentration. We determined that the expression of rpoE is significantly upregulated at the body louse (28°C) versus the human host (37°C) temperature. rpoE expression also was upregulated when B. quintana was exposed to high hemin concentrations. In vitro and in vivo analyses demonstrated that RpoE function is regulated by a mechanism involving the anti-sigma factor NepR and the response regulator PhyR. The ΔrpoE ΔnepR mutant strain of B. quintana established that RpoE-mediated transcription is important in mediating the tolerance of B. quintana to high hemin concentrations. We present the first analysis of an ECF15 sigma factor in a vector-borne human pathogen and conclude that RpoE has a role in the adaptation of B. quintana to the hemin-rich arthropod vector environment.
