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Herrador Z, Fernandez-Martinez A, Gomez-Barroso D, León I, Vieira C, Muro A, Benito A. Mediterranean spotted fever in Spain, 1997-2014: Epidemiological situation based on hospitalization records. PLoS One 2017; 12:e0174745. [PMID: 28355307 PMCID: PMC5371374 DOI: 10.1371/journal.pone.0174745] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 03/14/2017] [Indexed: 11/18/2022] Open
Abstract
Introduction Mediterranean spotted fever (MSF) is a zoonotic disease caused by Rickettsia conorii. In Spain, deficiencies in the official reporting result in misreporting of this disease. This study aims to describe the clinical and temporal-spatial characteristics of MSF hospitalizations between 1997 and 2014. Materials and methods We performed a retrospective descriptive study using the Hospitalization Minimum Data Set (CMBD). All CMBD’s hospital discharges with ICD-9 CM code 082.1 were analyzed. Hospitalization rates were calculated and clinical characteristics were described. Spatial distribution of cases and their temporal behavior were also assessed. Results A total of 4,735 hospitalizations with MSF diagnosis were recorded during the study period, out of which 62.2% were male, mean age of 48. Diabetes mellitus, alcohol dependence syndrome, and chronic liver disease occurred in 10.8%, 2.4% and 2.8% hospitalizations, respectively. The median annual hospitalization rate showed a decreasing trend from a maximum of 12.9 in 1997 to a minimum rate of 3.1 in 2014. Most admissions occurred during the summer, showing a significant annual seasonal behavior. Important regional differences were found. Discussion Although MSF hospitalization rates have decreased considerably, it remains a public health problem due to its severity and economic impact. Therefore, it would be desirable to improve its oversight and surveillance.
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Affiliation(s)
- Zaida Herrador
- National Centre for Tropical Medicine, Health Institute Carlos III (ISCIII in Spanish), Madrid, Spain
- Network Biomedical Research on Tropical Diseases (RICET in Spanish), Madrid, Spain
- * E-mail:
| | - Amalia Fernandez-Martinez
- National Centre for Tropical Medicine, Health Institute Carlos III (ISCIII in Spanish), Madrid, Spain
- Network Biomedical Research on Tropical Diseases (RICET in Spanish), Madrid, Spain
| | - Diana Gomez-Barroso
- Network Biomedical Research Centre in Epidemiology and Public Health (CIBERESP in Spanish), Madrid, Spain
- National Centre of Epidemiology, Health Institute Carlos III (ISCIII in Spanish), Madrid, Spain
| | - Inmaculada León
- Network Biomedical Research Centre in Epidemiology and Public Health (CIBERESP in Spanish), Madrid, Spain
- National Centre of Epidemiology, Health Institute Carlos III (ISCIII in Spanish), Madrid, Spain
| | - Carmen Vieira
- Network Biomedical Research on Tropical Diseases (RICET in Spanish), Madrid, Spain
- Unidad de Investigación Enfermedades Infecciosas y Tropicales (e-INTRO), Instituto de Investigación Biomédica de Salamanca-Centro de Investigación de Enfermedades Tropicales de la Universidad de Salamanca (IBSAL-CIETUS), Facultad de Farmacia, Universidad de Salamanca, Salamanca, Spain
| | - Antonio Muro
- Network Biomedical Research on Tropical Diseases (RICET in Spanish), Madrid, Spain
- Unidad de Investigación Enfermedades Infecciosas y Tropicales (e-INTRO), Instituto de Investigación Biomédica de Salamanca-Centro de Investigación de Enfermedades Tropicales de la Universidad de Salamanca (IBSAL-CIETUS), Facultad de Farmacia, Universidad de Salamanca, Salamanca, Spain
| | - Agustín Benito
- National Centre for Tropical Medicine, Health Institute Carlos III (ISCIII in Spanish), Madrid, Spain
- Network Biomedical Research on Tropical Diseases (RICET in Spanish), Madrid, Spain
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Bechelli J, Smalley C, Milhano N, Walker DH, Fang R. Rickettsia massiliae and Rickettsia conorii Israeli Spotted Fever Strain Differentially Regulate Endothelial Cell Responses. PLoS One 2015; 10:e0138830. [PMID: 26394396 PMCID: PMC4578955 DOI: 10.1371/journal.pone.0138830] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 09/03/2015] [Indexed: 01/05/2023] Open
Abstract
Rickettsiae primarily target microvascular endothelial cells. However, it remains elusive how endothelial cell responses to rickettsiae play a role in the pathogenesis of rickettsial diseases. In the present study, we employed two rickettsial species with high sequence homology but differing virulence to investigate the pathological endothelial cell responses. Rickettsia massiliae is a newly documented human pathogen that causes a mild spotted fever rickettsiosis. The “Israeli spotted fever” strain of R. conorii (ISF) causes severe disease with a mortality rate up to 30% in hospitalized patients. At 48 hours post infection (HPI), R. conorii (ISF) induced a significant elevation of IL-8 and IL-6 while R. massiliae induced a statistically significant elevated amount of MCP-1 at both transcriptional and protein synthesis levels. Strikingly, R. conorii (ISF), but not R. massiliae, caused a significant level of cell death or injury in HMEC-1 cells at 72 HPI, demonstrated by live-dead cell staining, annexin V staining and lactate dehydrogenase release. Monolayers of endothelial cells infected with R. conorii (ISF) showed a statistically significant decrease in electrical resistance across the monolayer compared to both R. massiliae-infected and uninfected cells at 72 HPI, suggesting increased endothelial permeability. Interestingly, pharmacological inhibitors of caspase-1 significantly reduced the release of lactate dehydrogenase by R. conorii (ISF)-infected HMEC-1 cells, which suggests the role of caspase-1 in mediating the death of endothelial cells. Taken together, our data illustrated that a distinct proinflammatory cytokine profile and endothelial dysfunction, as evidenced by endothelial cell death/injury and increased permeability, are associated with the severity of rickettsial diseases.
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Affiliation(s)
- Jeremy Bechelli
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Claire Smalley
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Natacha Milhano
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - David H. Walker
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Rong Fang
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
- * E-mail:
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3
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Milhano N, Saito TB, Bechelli J, Fang R, Vilhena M, DE Sousa R, Walker DH. The role of Rhipicephalus sanguineus sensu lato saliva in the dissemination of Rickettsia conorii in C3H/HeJ mice. Med Vet Entomol 2015; 29:225-229. [PMID: 26011701 DOI: 10.1111/mve.12118] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 12/24/2014] [Accepted: 01/05/2015] [Indexed: 06/04/2023]
Abstract
Animal models have been developed for the study of rickettsial pathogenesis. However, to understand what occurs during the natural route of rickettsial transmission via the tick bite, the role of tick saliva should be considered in these models. To address this, we analysed the role of tick saliva in the transmission of Rickettsia conorii (Rickettsiales: Rickettsiaceae) in a murine host by intradermally (i.d.) inoculating two groups of susceptible C3H/HeJ mice with this Rickettsia, and infesting one group with nymphal Rhipicephalus sanguineus sensu lato (Ixodida: Ixodidae) ticks. Quantification of bacterial loads and mRNA levels of interleukin-1β (IL-1β), IL-10 and NF-κB was performed in C3H/HeJ lung samples by real-time quantitative polymerase chain reaction (PCR) and real-time reverse transcriptase PCR, respectively. Lung histology was examined to evaluate the pathological manifestations of infection. No statistically significant difference in bacterial load in the lungs of mice was observed between these two groups; however, a statistically significant difference was observed in levels of IL-1β and NF-κB, both of which were higher in the group inoculated with rickettsiae but not infected with ticks. Lung histology in both groups of animals revealed infiltration of inflammatory cells. Overall, this study showed that i.d. inoculation of R. conorii caused infection in the lungs of C3H/HeJ mice and tick saliva inhibited proinflammatory effects.
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Affiliation(s)
- N Milhano
- Centre for the Study of Vectors and Infectious Diseases Dr Francisco Cambournac, National Institute of Health Dr Ricardo Jorge, Águas de Moura, Portugal
| | - T B Saito
- Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX, U.S.A
| | - J Bechelli
- Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX, U.S.A
| | - R Fang
- Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX, U.S.A
| | - M Vilhena
- Department of Veterinary Medicine, University of Évora, Évora, Portugal
| | - R DE Sousa
- Centre for the Study of Vectors and Infectious Diseases Dr Francisco Cambournac, National Institute of Health Dr Ricardo Jorge, Águas de Moura, Portugal
| | - D H Walker
- Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX, U.S.A
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Levin ML, Zemtsova GE, Montgomery M, Killmaster LF. Effects of homologous and heterologous immunization on the reservoir competence of domestic dogs for Rickettsia conorii (israelensis). Ticks Tick Borne Dis 2014; 5:33-40. [PMID: 24201056 PMCID: PMC5659121 DOI: 10.1016/j.ttbdis.2013.07.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 06/24/2013] [Accepted: 07/03/2013] [Indexed: 11/28/2022]
Abstract
A number of spotted fever group (SFG) rickettsiae cause serious infections in humans. Several antigenically related rickettsial agents may coexist within the same geographical area, and humans or vertebrate hosts may be sequentially exposed to multiple SFG agents. We assessed whether exposure of a vertebrate reservoir to one SFG Rickettsia will affect the host's immune response to a related pathogen and the efficiency of transmission to uninfected ticks. Two pairs of dogs were each infected with either Rickettsia massiliae or Rickettsia conorii israelensis, and their immune response was monitored twice weekly by IFA. The four immunized dogs and a pair of naïve dogs were each challenged with R. conorii israelensis-infected Rhipicephalus sanguineus nymphs. Uninfected Rh. sanguineus larvae were acquisition-fed on the dogs on days 1, 7, and 14 post-challenge. These ticks were tested for the presence of rickettsial DNA after molting to the nymphal stage. The naive dogs became infected with R. conorii israelensis and were infectious to ticks for at least 3 weeks, whereas reservoir competence of dogs previously infected with either R. massiliae or R. conorii was significantly diminished. This opens an opportunity for decreasing the efficiency of transmission and propagation of pathogenic Rickettsia in natural foci by immunizing the primary hosts with closely related nonpathogenic SFG bacteria. However, neither homologous immunization nor cross-immunization significantly affected the efficiency of R. conorii transmission between cofeeding infected nymphs and uninfected larvae. At high densities of ticks, the efficiency of cofeeding transmission may be sufficient for yearly amplification and persistent circulation of a rickettsial pathogen in the vector population.
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Affiliation(s)
- M L Levin
- Rickettsial Zoonoses Branch, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
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Zemtsova G, Killmaster LF, Mumcuoglu KY, Levin ML. Co-feeding as a route for transmission of Rickettsia conorii israelensis between Rhipicephalus sanguineus ticks. Exp Appl Acarol 2010; 52:383-392. [PMID: 20589416 DOI: 10.1007/s10493-010-9375-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Accepted: 06/10/2010] [Indexed: 05/29/2023]
Abstract
Rickettsia conorii is widely distributed in Europe, Asia, and Africa. The brown dog tick, Rhipicephalus sanguineus, is the recognized vector of R. conorii. In this study, we assessed the efficiency of R. conorii israelensis transmission between co-feeding Rh. sanguineus ticks. Infected Rh. sanguineus adults and uninfected nymphs were fed simultaneously upon either naïve dogs or a dog previously exposed to this agent. When ticks were placed upon naïve dogs, 92-100% of nymphs acquired the infection and 80-88% of infected engorged nymphs transmitted it transstadially. When ticks were placed upon a seropositive dog, only 8-28.5% of recipient nymphs became infected. Our results establish the first evidence for efficient natural transmission of R. conorii israelensis between co-feeding ticks upon both naïve and seropositive dogs. This route of transmission can ensure continuous circulation of R. conorii israelensis in tick vectors even in the absence of naïve reservoir hosts.
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Affiliation(s)
- G Zemtsova
- Rickettsial Zoonoses Branch, Mail Stop G-13, National Center for Zoonotic, Vector-Borne and Enteric Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Atlanta, GA 30333, USA
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Levin ML, Killmaster L, Zemtsova G, Grant D, Mumcuoglu KY, Eremeeva ME, Dasch GA. Incongruent effects of two isolates of Rickettsia conorii on the survival of Rhipicephalus sanguineus ticks. Exp Appl Acarol 2009; 49:347-359. [PMID: 19421877 DOI: 10.1007/s10493-009-9268-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Accepted: 04/21/2009] [Indexed: 05/27/2023]
Abstract
Rickettsia conorii, the etiologic agent of Mediterranean spotted fever is widely distributed in Southern Europe, the Middle East, Africa, India and the Caspian region. In the Mediterranean region, the brown dog tick, Rhipicephalus sanguineus, is the recognized vector of R. conorii. To study tick-pathogen relationships and pathogenesis of infection caused in model animals by the bite of an infected tick, we attempted to establish a laboratory colony of Rh. sanguineus persistently infected with R. conorii. Rhipicephalus sanguineus ticks of North American and Mediterranean origin were exposed to R. conorii isolates of African (R. conorii conorii strain Malish) and Mediterranean (R. conorii israelensis strain ISTT) origin. Feeding of ticks upon infected mice and dogs, intra-hemocoel inoculation, and submersion in suspensions of purified rickettsiae were used to introduce the pathogen into uninfected ticks. Feeding success, molting success and the longevity of molted ticks were measured to assess the effects of R. conorii on the survival of Rh. sanguineus. In concordance with previously published results, Rh. sanguineus larvae and nymphs from both North American and Mediterranean colonies exposed to R. conorii conorii Malish experienced high mortality during feeding and molting or immediately after. The prevalence of infection in surviving ticks did not exceed 5%. On the other hand, exposure to ISTT strain had lesser effect on tick survival and resulted in 35-66% prevalence of infection. Rh. sanguineus of Mediterranean origin were more susceptible to infection with either strain of R. conorii than those from North America. Previous experimental studies had demonstrated transovarial and transstadial transmission of R. conorii in Rh. sanguineus; however, our data suggest that different strains of R. conorii may employ different means of maintenance in nature. The vertebrate host may be a more important reservoir than previously thought, or co-feeding transmission between different generations of ticks may obviate or lessen the requirement for transovarial maintenance of R. conorii.
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Affiliation(s)
- M L Levin
- Rickettsial Zoonoses Branch, Mail Stop G-13, National Center for Zoonotic, Vector-borne and Enteric Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
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Oztoprak N, Celebi G, Aydemir H, Pişkin N, Bektaş S, Koca R, Kuloğlu F. [Mediterranean spotted fever due to contact with dog-tick]. MIKROBIYOL BUL 2008; 42:701-706. [PMID: 19149095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Mediterranean spotted fever (MSF) is one of the tick-borne rickettsial infections caused by Rickettsia conorii. It is transmitted to humans by brown dog ticks (Rhipicephalus sanguineus). In this case report, a 16-years-old male patient who was diagnosed as MSF after an exposure to dog-tick in Bartin province (located at middle Black Sea region of Turkey) has been presented. His history revealed that, five days before admission to the hospital (on June, 2007) he had cleaned dog-ticks from his dog, and after 12 hours he found a stucked tick on his leg and he took it out right away with a tweezer. High fever, headache and generalized maculopapular rash including soles and palms and a black-colored lesion at the tick bite site developed three days later. In clinical examination, there was a black escar circled with a red-purple colored halo in front of the right tibia at the site of the tick bite showing high similarity to "tache noire" which was specific to MSF. Indirect immunofluorescence assay (IFA) for Rickettsia yielded negative result in the serum sample collected on admission day, however, it was found positive at 1/512 titer in the serum sample collected 10 days after admission. The patient has recovered completely without any complication after 10 days of doxycycline therapy. The aim of this presentation is to point out that MSF should be considered for the differential diagnosis of a patient with a history of tick bite, fever, maculopapular rash, headache, myalgia, arthralgia and especially with black escar during summer months in our country where the incidence of tick-borne infections has been increasing since recent years.
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Affiliation(s)
- Nefise Oztoprak
- Zonguldak Karaelmas Universitesi Tip Fakültesi, Enfeksiyon Hastaliklari ve Klinik Mikrobiyoloji Anabilim Dali, Zonguldak.
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Fang R, Ismail N, Soong L, Popov VL, Whitworth T, Bouyer DH, Walker DH. Differential interaction of dendritic cells with Rickettsia conorii: impact on host susceptibility to murine spotted fever rickettsiosis. Infect Immun 2007; 75:3112-23. [PMID: 17403875 PMCID: PMC1932850 DOI: 10.1128/iai.00007-07] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Spotted fever group rickettsioses are emerging and reemerging infectious diseases, some of which are life-threatening. In order to understand how dendritic cells (DCs) contribute to the host resistance or susceptibility to rickettsial diseases, we first characterized the in vitro interaction of rickettsiae with bone marrow-derived DCs (BMDCs) from resistant C57BL/6 (B6) and susceptible C3H/HeN (C3H) mice. In contrast to the exclusively cytosolic localization within endothelial cells, rickettsiae efficiently entered and localized in both phagosomes and cytosol of BMDCs from both mouse strains. Rickettsia conorii-infected BMDCs from resistant mice harbored higher bacterial loads compared to C3H mice. R. conorii infection induced maturation of BMDCs from both mouse strains as judged by upregulated expression of classical major histocompatibility complex (MHC) and costimulatory molecules. Compared to C3H counterparts, B6 BMDCs exhibited higher expression levels of MHC class II and higher interleukin-12 (IL-12) p40 production upon rickettsial infection and were more potent in priming naïve CD4(+) T cells to produce gamma interferon. In vitro DC infection and T-cell priming studies suggested a delayed CD4(+) T-cell activation and suppressed Th1/Th2 cell development in C3H mice. The suppressive CD4(+) T-cell responses seen in C3H mice were associated with a high frequency of Foxp3(+) T regulatory cells promoted by syngeneic R. conorii-infected BMDCs in the presence of IL-2. These data suggest that rickettsiae can target DCs to stimulate a protective type 1 response in resistant hosts but suppressive adaptive immunity in susceptible hosts.
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Affiliation(s)
- Rong Fang
- Center for Biodefense and Emerging Infectious Diseases, 301 University Blvd., Galveston, TX 77555-0609, USA
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Renesto P, Azza S, Dolla A, Fourquet P, Vestris G, Gorvel JP, Raoult D. Rickettsia conorii and R. prowazekii proteome analysis by 2DE-MS: a step toward functional analysis of rickettsial genomes. Ann N Y Acad Sci 2006; 1063:90-3. [PMID: 16481497 DOI: 10.1196/annals.1355.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In this work, we present a comparative two-dimensional (2D) PAGE analysis of Rickettsia conorii and Rickettsia prowazekii. This analysis reveals protein spots that were either unique to or common to both strains, some of them being identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry.
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Abstract
Rickettsiae primarily infect the microvascular endothelium, leading to changes in microvascular permeability that result in potentially severe pulmonary and cerebral edema. The mechanisms responsible for these changes are not well understood. One potential mechanism of increased vascular permeability is the anti-rickettsial nitric oxide response described by Walker and colleagues. We hypothesized that anti-rickettsial levels of nitric oxide adversely affects microvascular permeability in vitro. To this end we sought to describe the effects of exogenous nitric oxide on the proliferation of intracellular rickettsiae while monitoring the transendothelial electrical resistance as a measure of endothelial barrier integrity. It was determined that the addition of the NO-donor DETA NONOate at certain levels results in a dose-dependent change in electrical resistance across the monolayer while effectively limiting the number of intracellular rickettsiae in human microvascular endothelial cells. The data presented support the idea that nitric oxide produced by infected endothelial cells may be contributing to the changes in vascular permeability that occur during acute rickettsioses. Future experiments aim to elaborate on these results in a model that more clearly depicts the in vivo response as well as to describe the changes that occur with respect to interendothelial junctions.
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Affiliation(s)
- Michael E Woods
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas 77555-0609, USA
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Abstract
Listeria, Rickettsia, Burkholderia, Shigella and Mycobacterium species subvert cellular actin dynamics to facilitate their movement within the host cytosol and to infect neighbouring cells while evading host immune surveillance and promoting their intracellular survival. 'Attaching and effacing' Escherichia coli do not enter host cells but attach intimately to the cell surface, inducing motile actin-rich pedestals, the function of which is currently unclear. The molecular basis of actin-based motility of these bacterial pathogens reveals novel insights about bacterial pathogenesis and fundamental host-cell pathways.
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Affiliation(s)
- Joanne M Stevens
- Division of Microbiology, Institute for Animal Health, Compton Laboratory, Berkshire, RG20 7NN, UK
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Rovery C, Renesto P, Crapoulet N, Matsumoto K, Parola P, Ogata H, Raoult D. Transcriptional response of Rickettsia conorii exposed to temperature variation and stress starvation. Res Microbiol 2004; 156:211-8. [PMID: 15748986 DOI: 10.1016/j.resmic.2004.09.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2004] [Revised: 08/13/2004] [Accepted: 09/01/2004] [Indexed: 11/25/2022]
Abstract
Rickettsia conorii is an obligate intracellular bacterium transmitted to humans by Rhipicephalus sanguineus ticks. The success of this microorganism at surviving in nature implicates the ability to efficiently adapt to different environments, including the arthropod vector and the mammalian host. Numerous bacterial species possess a highly evolved system for stress adaptation. This so-called stringent response is mediated by guanosine 3',5'-bispyrophosphate and guanosine 3'-diphosphate 5'-triphosphate which are under spoT control in some Gram-negative bacteria. Interestingly, annotation of the R. conorii genome evidenced 5 spoT paralogs. We hypothesized that these spoT genes play a role in adaptation to environmental changes specifically encountered by rickettsiae during their different life cycles. Transcription of the spoT paralogs was examined by RT-PCR from infected Vero cells maintained in rich or deficient culture media, from infected C6/36 insect cells cultured at various temperatures and from infected ticks. Our results demonstrated that the 5 spoT genes can be transcribed. SpoT1 (RC0374) is only transcribed upon stringent response. Transcription of spoT3 (RC0888) was never observed in arthropod cells or ticks, but was specific to R. conorii RNA extracted from infected Vero cells. These results indicate that rickettsial spoT paralogs are independently transcribed, depending on the different infected hosts and the adaptive capacity of the pathogen. Bioinformatics analysis of these possibly encoded proteins is also reported.
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Affiliation(s)
- Clarisse Rovery
- Unité des Rickettsies, CNRS-UMR 6020, IFR48, Faculté de Médecine, 27, Bd Jean Moulin, Marseille, France
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Abstract
A recent study demonstrated that polyclonal antibodies to Rickettsia conorii and monoclonal antibodies to outer membrane proteins A (OmpA) and B (OmpB) provided effective, Fc-dependent, passive immunity, even in severe combined immunodeficient mice with an established infection. In order to determine the mechanism of protection, mouse endothelial and macrophage-like cell lines were infected with R. conorii that had been exposed to polyclonal antibodies, monoclonal antibodies to OmpA or OmpB, Fab fragments of the polyclonal antibodies, or normal serum or that were left untreated. At 0 h, Fc-dependent antibody enhancement of R. conorii adherence to endothelial and macrophage-like cell lines was inhibited by the presence of normal serum, suggesting Fc receptor-mediated adherence of opsonized rickettsiae. At 3 h, the opsonized rickettsiae had been internalized. After 72 h, inhibited survival of rickettsiae exposed to polyclonal antibodies or monoclonal antibodies to OmpA or OmpB was evident compared with growth of untreated and normal serum-treated and polyclonal Fab antibody-treated R. conorii. Polyclonal antibodies and an anti-OmpB monoclonal antibody inhibited the escape of R. conorii from the phagosome, resulting in intraphagolysosomal rickettsial death. At 48 h of infection, rickettsicidal activity of macrophages by opsonized rickettsiae was inhibited by NG-monomethyl-L-arginine, superoxide dismutase, mannitol, or supplemental L-tryptophan, and endothelial rickettsicidal activity against opsonized rickettsiae was inhibited by NG-monomethyl-L-arginine, superoxide dismutase, catalase, or supplemental L-tryptophan. Thus, Fc-dependent antibodies protected against R. conorii infection of endothelium and macrophages by opsonization that inhibited phagosomal escape and resulted in phagolysosomal killing mediated by nitric oxide, reactive oxygen intermediates, and L-tryptophan starvation.
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Affiliation(s)
- Hui-Min Feng
- Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas 77555-0609, USA
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Santos AS, Bacellar F, Santos-Silva M, Formosinho P, Grácio AJ, Franca S. Ultrastructural study of the infection process of Rickettsia conorii in the salivary glands of the vector tick Rhipicephalus sanguineus. Vector Borne Zoonotic Dis 2003; 2:165-77. [PMID: 12737546 DOI: 10.1089/15303660260613738] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This work was designed to study the infection process of Rickettsia conorii in the salivary glands of experimentally infected Rhipicephalus sanguineus ticks. One hundred six uninfected engorged nymphs were intracelomically inoculated with approximately 2 x 10(3) plaque-forming units of a rickettsial suspension. After the molt, unfed and fed adults were dissected, and the salivary glands were extracted and processed for transmission electron microscopy observation. Three different uninfected control groups were used for (1) evaluating the impact of the inoculation procedure, (2) establishing the feeding period of infected ticks, and (3) ultrastructural characterization of the salivary glands. Overall, 75.5% (80 of 106) of the nymphs inoculated with rickettsiae died during the molt or soon after hatching into adult instars; 50% (12 of 24) of the remaining infected adults showed severe malformations compromising their viability. In apparently healthy specimens, time of engorgement was longer. The contrast with the negative control groups was statistically significant, suggesting that R. conorii exerts a strong negative effect on the vector ticks. The ultrastructural study showed that in the salivary glands of infected ticks, rickettsial growth occurs preferentially in central, peripheral, and interstitial acini cells.
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Affiliation(s)
- A S Santos
- Centro de Estudos de Vectores e Doenças Infecciosas, Instituto Nacional de Saúde Dr. Ricardo Jorge, Aguas de Moura, Portugal.
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Ogata H, Audic S, Renesto-Audiffren P, Fournier PE, Barbe V, Samson D, Roux V, Cossart P, Weissenbach J, Claverie JM, Raoult D. Mechanisms of evolution in Rickettsia conorii and R. prowazekii. Science 2001; 293:2093-8. [PMID: 11557893 DOI: 10.1126/science.1061471] [Citation(s) in RCA: 342] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Rickettsia conorii is an obligate intracellular bacterium that causes Mediterranean spotted fever in humans. We determined the 1,268,755-nucleotide complete genome sequence of R. conorii, containing 1374 open reading frames. This genome exhibits 804 of the 834 genes of the previously determined R. prowazekii genome plus 552 supplementary open reading frames and a 10-fold increase in the number of repetitive elements. Despite these differences, the two genomes exhibit a nearly perfect colinearity that allowed the clear identification of different stages of gene alterations with gene remnants and 37 genes split in 105 fragments, of which 59 are transcribed. A 38-kilobase sequence inversion was dated shortly after the divergence of the genus.
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MESH Headings
- Adaptation, Physiological
- Chlamydia/genetics
- Computational Biology
- DNA, Bacterial/genetics
- DNA, Intergenic
- Evolution, Molecular
- Gene Dosage
- Gene Silencing
- Gene Transfer, Horizontal
- Genes, Bacterial
- Genome, Bacterial
- Open Reading Frames
- Phylogeny
- Polymerase Chain Reaction
- Repetitive Sequences, Nucleic Acid
- Rickettsia/genetics
- Rickettsia conorii/genetics
- Rickettsia conorii/physiology
- Rickettsia prowazekii/genetics
- Rickettsia prowazekii/physiology
- Sequence Analysis, DNA
- Transcription, Genetic
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Affiliation(s)
- H Ogata
- Information Génétique & Structurale, CNRS-AVENTIS UMR 1889, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
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Couzin J. Genomics. Painting a picture of genome evolution. Science 2001; 293:1969-70. [PMID: 11557851 DOI: 10.1126/science.293.5537.1969a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
A new analysis of the genome sequences of two bacteria shows that genes can be lost as well as gained during evolution. Even more intriguingly, the work provides snapshots capturing gene decay in the act and thus illuminates the actual genomic changes that occurred over tens of millions of years of evolution. The research, which is described on page 2093, focuses on two pathogenic bacteria: Rickettsia conorii, the culprit in Mediterranean spotted fever, and R. prowazekii, which causes typhus.
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Schmaier AH, Srikanth S, Elghetany MT, Normolle D, Gokhale S, Feng HM, Walker DH. Hemostatic/fibrinolytic protein changes in C3H/HeN mice infected with Rickettsia conorii--a model for Rocky Mountain spotted fever. Thromb Haemost 2001; 86:871-9. [PMID: 11583321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Changes in plasma hemostatic and fibrinolytic proteins were determined during courses of a murine model of fatal and non-fatal Rocky Mountain spotted fever. C3H/HeN mice were infected with Rickettsia conorii and coagulation and histopathologic studies were performed at prescribed periods of time. A significant decrease in plasma factor VIII activity and rise in plasma factor V procoagulant activity correlated with a fatal infection. Factor VII levels were unchanged; factor XI levels dropped early in the course in the lethally infected animals, but returned to normal. Factor XII, high molecular weight kininogen, and prekallikrein levels were unchanged by the sublethal infection. Prekallikrein levels fell during the lethal infection. Antithrombin concentrations were decreased significantly in all animals, but plasma plasminogen levels did not change in either group of animals. Nonocclusive thrombi were microscopically observed rarely and only in animals surviving a sublethal infection. A fall in tissue plasminogen activator activity and a rise in plasminogen activator inhibitor activity highly correlated with a lethal outcome. Lethal infection with R. conorii is associated with primary endothelial cell injury resulting in decreased tissue plasminogen activator and increased plasminogen activator inhibitor.
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Affiliation(s)
- A H Schmaier
- Department of Internal Medicine, University of Michigan, Ann Arbor 48109-0640, USA.
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Gouin E, Gantelet H, Egile C, Lasa I, Ohayon H, Villiers V, Gounon P, Sansonetti PJ, Cossart P. A comparative study of the actin-based motilities of the pathogenic bacteria Listeria monocytogenes, Shigella flexneri and Rickettsia conorii. J Cell Sci 1999; 112 ( Pt 11):1697-708. [PMID: 10318762 DOI: 10.1242/jcs.112.11.1697] [Citation(s) in RCA: 194] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Listeria monocytogenes, Shigella flexneri, and Rickettsia conorii are three bacterial pathogens that are able to polymerize actin into ‘comet tail’ structures and move within the cytosol of infected cells. The actin-based motilities of L. monocytogenes and S. flexneri are known to require the bacterial proteins ActA and IcsA, respectively, and several mammalian cytoskeleton proteins including the Arp2/3 complex and VASP (vasodilator-stimulated phosphoprotein) for L. monocytogenes and vinculin and N-WASP (the neural Wiskott-Aldrich syndrome protein) for S. flexneri. In contrast, little is known about the motility of R. conorii. In the present study, we have analysed the actin-based motility of this bacterium in comparison to that of L. monocytogenes and S. flexneri. Rickettsia moved at least three times more slowly than Listeria and Shigella in both infected cells and Xenopus laevis egg extracts. Decoration of actin with the S1 subfragment of myosin in infected cells showed that the comet tails of Rickettsia have a structure strikingly different from those of L. monocytogenes or S. flexneri. In Listeria and Shigella tails, actin filaments form a branching network while Rickettsia tails display longer and not cross-linked actin filaments. Immunofluorescence studies revealed that the two host proteins, VASP and (α)-actinin colocalized with actin in the tails of Rickettsia but neither the Arp2/3 complex which we detected in the Shigella actin tails, nor N-WASP, were detected in Rickettsia actin tails. Taken together, these results suggest that R. conorii may use a different mechanism of actin polymerization.
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Affiliation(s)
- E Gouin
- Unité des Interactions Bactéries-Cellules, Station Centrale de Microscopie Electronique, Institut Pasteur, 75724 Paris Cedex 15, France
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