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Rauch J, Barton J, Kwiatkowski M, Wunderlich M, Steffen P, Moderzynski K, Papp S, Höhn K, Schwanke H, Witt S, Richardt U, Mehlhoop U, Schlüter H, Pianka V, Fleischer B, Tappe D, Osterloh A. GroEL is an immunodominant surface-exposed antigen of Rickettsia typhi. PLoS One 2021; 16:e0253084. [PMID: 34111210 PMCID: PMC8191997 DOI: 10.1371/journal.pone.0253084] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 05/28/2021] [Indexed: 11/26/2022] Open
Abstract
Rickettsioses are neglected and emerging potentially fatal febrile diseases that are caused by obligate intracellular bacteria, rickettsiae. Rickettsia (R.) typhi and R. prowazekii constitute the typhus group (TG) of rickettsiae and are the causative agents of endemic and epidemic typhus, respectively. We recently generated a monoclonal antibody (BNI52) against R. typhi. Characterization of BNI52 revealed that it specifically recognizes TG rickettsiae but not the members of the spotted fever group (SFG) rickettsiae. We further show that BNI52 binds to protein fragments of ±30 kDa that are exposed on the bacterial surface and also present in the periplasmic space. These protein fragments apparently derive from the cytosolic GroEL protein of R. typhi and are also recognized by antibodies in the sera from patients and infected mice. Furthermore, BNI52 opsonizes the bacteria for the uptake by antigen presenting cells (APC), indicating a contribution of GroEL-specific antibodies to protective immunity. Finally, it is interesting that the GroEL protein belongs to 32 proteins that are differentially downregulated by R. typhi after passage through immunodeficient BALB/c CB17 SCID mice. This could be a hint that the rickettsia GroEL protein may have immunomodulatory properties as shown for the homologous protein from several other bacteria, too. Overall, the results of this study provide evidence that GroEL represents an immunodominant antigen of TG rickettsiae that is recognized by the humoral immune response against these pathogens and that may be interesting as a vaccine candidate. Apart from that, the BNI52 antibody represents a new tool for specific detection of TG rickettsiae in various diagnostic and experimental setups.
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Affiliation(s)
- Jessica Rauch
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Jessica Barton
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | | | - Malte Wunderlich
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Pascal Steffen
- University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | | | - Stefanie Papp
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Katharina Höhn
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Hella Schwanke
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Susanne Witt
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Ulricke Richardt
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Ute Mehlhoop
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | | | - Verena Pianka
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | | | - Dennis Tappe
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Anke Osterloh
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
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Abstract
Over the last decades, rickettsioses are emerging worldwide. These diseases are caused by intracellular bacteria. Although rickettsioses can be treated with antibiotics, a vaccine against rickettsiae is highly desired for several reasons. Rickettsioses are highly prevalent, especially in poor countries, and there are indications of the development of antibiotic resistance. In addition, some rickettsiae can persist and cause recurrent disease. The development of a vaccine requires the understanding of the immune mechanisms that are involved in protection as well as in immunopathology. Knowledge about these immune responses is accumulating, and efforts have been undertaken to identify antigenic components of rickettsiae that may be useful as a vaccine. This review provides an overview on current knowledge of adaptive immunity against rickettsiae, which is essential for defense, rickettsial antigens that have been identified so far, and on vaccination strategies that have been used in animal models of rickettsial infections.
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Newton PN, Keolouangkhot V, Lee SJ, Choumlivong K, Sisouphone S, Choumlivong K, Vongsouvath M, Mayxay M, Chansamouth V, Davong V, Phommasone K, Sirisouk J, Blacksell SD, Nawtaisong P, Moore CE, Castonguay-Vanier J, Dittrich S, Rattanavong S, Chang K, Darasavath C, Rattanavong O, Paris DH, Phetsouvanh R. A Prospective, Open-label, Randomized Trial of Doxycycline Versus Azithromycin for the Treatment of Uncomplicated Murine Typhus. Clin Infect Dis 2019; 68:738-747. [PMID: 30020447 PMCID: PMC6376095 DOI: 10.1093/cid/ciy563] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 07/07/2018] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Murine typhus, or infection with Rickettsia typhi, is a global but neglected disease without randomized clinical trials to guide antibiotic therapy. METHODS A prospective, open, randomized trial was conducted in nonpregnant, consenting inpatient adults with rapid diagnostic test evidence of uncomplicated murine typhus at 2 hospitals in Vientiane, Laos. Patients were randomized to 7 days (D7) or 3 days (D3) of oral doxycycline or 3 days of oral azithromycin (A3). Primary outcome measures were fever clearance time and frequencies of treatment failure and relapse. RESULTS Between 2004 and 2009, the study enrolled 216 patients (72 per arm); 158 (73.2%) had serology/polymerase chain reaction (PCR)-confirmed murine typhus, and 52 (24.1%) were R. typhi PCR positive. The risk of treatment failure was greater for regimen A3 (22.5%; 16 of 71 patients) than for D3 (4.2%; 3 of 71) or D7 (1.4%; 1 of 71) (P < .001). Among R. typhi PCR-positive patients, the area under the time-temperature curve and the fever clearance time were significantly higher for A3 than for D3 (1.8- and 1.9-fold higher, respectively; P = .005) and D7 (1.5- and 1.6-fold higher; P = .02). No patients returned with PCR-confirmed R. typhi relapse. CONCLUSION In Lao adults, azithromycin is inferior to doxycycline as oral therapy for uncomplicated murine typhus. For doxycycline, 3- and 7-day regimens have similar efficacy. Azithromycin use in murine typhus should be reconsidered. Investigation of genomic and phenotypic markers of R. typhi azithromycin resistance is needed. CLINICAL TRIAL REGISTRATION ISRCTN47812566.
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Affiliation(s)
- Paul N Newton
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
- Centre for Tropical Medicine & Global Health, University of Oxford, United Kingdom
| | - Valy Keolouangkhot
- Adult Infectious Disease Ward, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
| | - Sue J Lee
- Centre for Tropical Medicine & Global Health, University of Oxford, United Kingdom
- Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | | | - Siho Sisouphone
- Adult Infectious Disease Ward, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
| | | | - Manivanh Vongsouvath
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
| | - Mayfong Mayxay
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
- Centre for Tropical Medicine & Global Health, University of Oxford, United Kingdom
- Faculty of Postgraduate Studies, University of Health Sciences, Vientiane, Lao People's Democratic Republic
| | - Vilada Chansamouth
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
| | - Viengmon Davong
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
| | - Koukeo Phommasone
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
| | - Joy Sirisouk
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
| | - Stuart D Blacksell
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
- Centre for Tropical Medicine & Global Health, University of Oxford, United Kingdom
- Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Pruksa Nawtaisong
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
| | - Catrin E Moore
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
- Centre for Tropical Medicine & Global Health, University of Oxford, United Kingdom
| | - Josée Castonguay-Vanier
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
| | - Sabine Dittrich
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
- Centre for Tropical Medicine & Global Health, University of Oxford, United Kingdom
| | - Sayaphet Rattanavong
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
| | - Ko Chang
- Adult Infectious Disease Ward, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
| | - Chirapha Darasavath
- Adult Infectious Disease Ward, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
| | - Oudayvone Rattanavong
- Adult Infectious Disease Ward, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
| | - Daniel H Paris
- Centre for Tropical Medicine & Global Health, University of Oxford, United Kingdom
- Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Department of Medicine, Swiss Tropical and Public Health Institute, Switzerland
- Faculty of Medicine, University of Basel, Switzerland
| | - Rattanaphone Phetsouvanh
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
- Centre for Tropical Medicine & Global Health, University of Oxford, United Kingdom
- Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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Osterloh A. Immune response against rickettsiae: lessons from murine infection models. Med Microbiol Immunol 2017; 206:403-417. [PMID: 28770333 PMCID: PMC5664416 DOI: 10.1007/s00430-017-0514-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Accepted: 07/20/2017] [Indexed: 12/19/2022]
Abstract
Rickettsiae are small intracellular bacteria that can cause life-threatening febrile diseases. Rickettsioses occur worldwide with increasing incidence. Therefore, a vaccine is highly desired. A prerequisite for the development of a vaccine is the knowledge of the immune response against these bacteria, in particular protective immunity. In recent years murine models of rickettsial infections have been established, and the study of immune response against rickettsiae in mice provided many new insights into protective and pathological immune reactions. This review summarizes the current knowledge about immune mechanisms in protection and pathology in rickettsial infections.
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Affiliation(s)
- Anke Osterloh
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
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Moderzynski K, Papp S, Rauch J, Heine L, Kuehl S, Richardt U, Fleischer B, Osterloh A. CD4+ T Cells Are as Protective as CD8+ T Cells against Rickettsia typhi Infection by Activating Macrophage Bactericidal Activity. PLoS Negl Trop Dis 2016; 10:e0005089. [PMID: 27875529 PMCID: PMC5119731 DOI: 10.1371/journal.pntd.0005089] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 10/02/2016] [Indexed: 01/07/2023] Open
Abstract
Rickettsia typhi is an intracellular bacterium that causes endemic typhus, a febrile disease that can be fatal due to complications including pneumonia, hepatitis and meningoencephalitis, the latter being a regular outcome in T and B cell-deficient C57BL/6 RAG1-/- mice upon Rickettsia typhi infection. Here, we show that CD4+ TH1 cells that are generated in C57BL/6 mice upon R. typhi infection are as protective as cytotoxic CD8+ T cells. CD4+- as well as CD8+-deficient C57BL/6 survived the infection without showing symptoms of disease at any point in time. Moreover, adoptively transferred CD8+ and CD4+ immune T cells entered the CNS of C57BL/6 RAG1-/- mice with advanced infection and both eradicated the bacteria. However, immune CD4+ T cells protected only approximately 60% of the animals from death. They induced the expression of iNOS in infiltrating macrophages as well as in resident microglia in the CNS which can contribute to bacterial killing but also accelerate pathology. In vitro immune CD4+ T cells inhibited bacterial growth in infected macrophages which was in part mediated by the release of IFNγ. Collectively, our data demonstrate that CD4+ T cells are as protective as CD8+ T cells against R. typhi, provided that CD4+ TH1 effector cells are present in time to support bactericidal activity of phagocytes via the release of IFNγ and other factors. With regard to vaccination against TG Rickettsiae, our findings suggest that the induction of CD4+ TH1 effector cells is sufficient for protection. Endemic typhus caused by Rickettsia typhi usually is a relatively mild disease. However, CNS inflammation and neurological symptoms are complications that can occur in severe cases. This outcome of disease is regularly observed in T and B cell-deficient C57BL/6 RAG1-/- mice upon infection with R. typhi. We show here that CD4+ T cells are as protective as cytotoxic CD8+ T cells against R. typhi as long as they are present in time. This is evidenced by the fact that neither CD8+ nor CD4+ T cell-deficient C57BL/6 mice develop disease which is also true for R. typhi-infected C57BL/6 RAG1-/- mice that receive immune CD8+ or CD4+ at an early point in time. Moreover, adoptive transfer of immune CD4+ T cells still protects approximately 60% of C57BL/6 RAG1-/- mice when applied later in advanced infection when the bacteria start to rise. Although CD8+ T cells are faster and more efficient in bacterial elimination, R. typhi is not detectable in CD4+ T cell recipients anymore. We further show that immune CD4+ T cells activate bactericidal functions of microglia and macrophages in the CNS in vivo and inhibit bacterial growth in infected macrophages in vitro which is in part mediated by the release of IFNγ. Collectively, we demonstrate for the first time that CD4+ T cells alone are sufficient to protect against R. typhi infection. With regard to vaccination our findings suggest that the induction of R. typhi-specific CD4+ TH1 effector T cells may be as effective as the much more difficult targeting of cytotoxic CD8+ T cells.
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Affiliation(s)
- Kristin Moderzynski
- Department of Immunology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Stefanie Papp
- Department of Immunology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Jessica Rauch
- Department of Immunology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Liza Heine
- Department of Immunology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Svenja Kuehl
- Department of Immunology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Ulricke Richardt
- Department of Immunology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Bernhard Fleischer
- Department of Immunology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- Institute for Immunology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Anke Osterloh
- Department of Immunology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- * E-mail:
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6
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Persisting Rickettsia typhi Causes Fatal Central Nervous System Inflammation. Infect Immun 2016; 84:1615-1632. [PMID: 26975992 DOI: 10.1128/iai.00034-16] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 03/06/2016] [Indexed: 01/03/2023] Open
Abstract
Rickettsioses are emerging febrile diseases caused by obligate intracellular bacteria belonging to the family Rickettsiaceae. Rickettsia typhi belongs to the typhus group (TG) of this family and is the causative agent of endemic typhus, a disease that can be fatal. In the present study, we analyzed the course of R. typhi infection in C57BL/6 RAG1(-/-) mice. Although these mice lack adaptive immunity, they developed only mild and temporary symptoms of disease and survived R. typhi infection for a long period of time. To our surprise, 3 to 4 months after infection, C57BL/6 RAG1(-/-) mice suddenly developed lethal neurological disorders. Analysis of these mice at the time of death revealed high bacterial loads, predominantly in the brain. This was accompanied by a massive expansion of microglia and by neuronal cell death. Furthermore, high numbers of infiltrating CD11b(+) macrophages were detectable in the brain. In contrast to the microglia, these cells harbored R. typhi and showed an inflammatory phenotype, as indicated by inducible nitric oxide synthase (iNOS) expression, which was not observed in the periphery. Having shown that R. typhi persists in immunocompromised mice, we finally asked whether the bacteria are also able to persist in resistant C57BL/6 and BALB/c wild-type mice. Indeed, R. typhi could be recultivated from lung, spleen, and brain tissues from both strains even up to 1 year after infection. This is the first report demonstrating persistence and reappearance of R. typhi, mainly restricted to the central nervous system in immunocompromised mice.
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Botelho-Nevers E, Socolovschi C, Raoult D, Parola P. Treatment of Rickettsia spp. infections: a review. Expert Rev Anti Infect Ther 2013; 10:1425-37. [PMID: 23253320 DOI: 10.1586/eri.12.139] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Human rickettsioses caused by intracellular bacteria of the genus Rickettsia are distributed worldwide and are transmitted by arthropod vectors such as ticks, fleas, mites and lice. They have a wide range of manifestations from benign to life-threatening diseases. Mortality rates of up to 30% have been reported for some rickettsioses. Here, the authors will review in vitro and human studies of the various compounds that have been used for the treatment of Rickettsia spp. infections. The authors will also provide recommendations for the treatment of spotted fever and typhus group rickettsioses.
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Affiliation(s)
- Elisabeth Botelho-Nevers
- Unité de Recherche en Maladies Infectieuses et Tropicales Emergentes, Aix-Marseille Université, UMR CNRS 7278, IRD 198, INSERM U1095, Faculté de Médecine, Marseille, France
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Galanakis E, Bitsori M. Rickettsioses in children: a clinical approach. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 719:145-62. [PMID: 22125042 DOI: 10.1007/978-1-4614-0204-6_13] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
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Bechah Y, Capo C, Mege JL, Raoult D. Epidemic typhus. THE LANCET. INFECTIOUS DISEASES 2008; 8:417-26. [DOI: 10.1016/s1473-3099(08)70150-6] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Radulovic S, Price PW, Beier MS, Gaywee J, Macaluso JA, Azad A. Rickettsia-macrophage interactions: host cell responses to Rickettsia akari and Rickettsia typhi. Infect Immun 2002; 70:2576-82. [PMID: 11953398 PMCID: PMC127898 DOI: 10.1128/iai.70.5.2576-2582.2002] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The existence of intracellular rickettsiae requires entry, survival, and replication in the eukaryotic host cells and exit to initiate new infection. While endothelial cells are the preferred target cells for most pathogenic rickettsiae, infection of monocytes/macrophages may also contribute to the establishment of rickettsial infection and resulting pathogenesis. We initiated studies to characterize macrophage-Rickettsia akari and -Rickettsia typhi interactions and to determine how rickettsiae survive within phagocytic cells. Flow cytometry, microscopic analysis, and LDH release demonstrated that R. akari and R. typhi caused negligible cytotoxicity in mouse peritoneal macrophages as well as in macrophage-like cell line, P388D1. Host cells responded to rickettsial infection with increased secretion of proinflammatory cytokines such as interleukin-1beta (IL-1beta) and IL-6. Furthermore, macrophage infection with R. akari and R. typhi resulted in differential synthesis and expression of IL-beta and IL-6, which may correlate with the existence of biological differences among these two closely related bacteria. In contrast, levels of gamma interferon (IFN-gamma), IL-10, and IL-12 in supernatants of infected P388D1 cells and mouse peritoneal macrophages did not change significantly during the course of infection and remained below the enzyme-linked immunosorbent assay cytokine detection limits. In addition, differential expression of cytokines was observed between R. akari- and R. typhi-infected macrophages, which may correlate with the biological differences among these closely related bacteria.
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Affiliation(s)
- S Radulovic
- University of Maryland, School of Medicine, Department of Microbiology and Immunology, Baltimore, Maryland 21201, USA.
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Lawson ET, Mousseau TA, Klaper R, Hunter MD, Werren JH. Rickettsia associated with male-killing in a buprestid beetle. Heredity (Edinb) 2001; 86:497-505. [PMID: 11520350 DOI: 10.1046/j.1365-2540.2001.00848.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Many populations of the buprestid leaf-mining beetle, Brachys tessellatus, from central South Carolina, USA, show highly skewed sex ratios, ranging from 1.3 to 6.0 females per male. We have identified a Rickettsia bacterium that is associated with sex ratio distortion (SRD) and selective killing of male embryos in B. tessellatus. Molecular assays of infection by this bacterium are highly associated with SRD within families, and treatment with an antibiotic (tetracycline) increases the number of male eggs that hatch and develop. The 16S rDNA sequence indicates that this is a novel Rickettsia, most closely related to Rickettsia bellii (a tick-associated bacterium) and a pea-aphid Rickettsia. It is also related to a Rickettsial bacterium that causes male-killing in an unrelated ladybird beetle species. Low levels of parthenogenesis are also observed in this system (about 10% of females) and may be the result of selection due to male rarity, or a direct result of infection by the Rickettsia.
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Affiliation(s)
- E T Lawson
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
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