Infection of Tick Cells By Two Nonpathogenic Strains of Rickettsia

1999 ◽  
Vol 5 (S2) ◽  
pp. 1140-1141
Author(s):  
Ann T. Palmer ◽  
Ulrike G. Munderloh ◽  
Timothy J. Kurtti
Keyword(s):  
Ixodes Scapularis ◽  
Spotted Fever ◽  
Spotted Fever Group ◽  
Tick Cell ◽  
Rickettsia Rickettsii ◽  
Endosymbiotic Bacteria ◽  
Transmission Electron ◽  
Obligate Intracellular Bacteria ◽  
Host Parasite ◽  
Sfg Rickettsia

Ticks harbor several different genera of endosymbiotic bacteria. These obligate intracellular bacteria, most of which appear to be nonpathogenic for the tick, persist in nature by being transmitted transovarially from generation to generation. Those in the genus Rickettsiabelong to the spotted fever group (SFG) of rickettsia which includes both mammalian pathogenic and nonpathogenic species. The species that cause spotted fevers in humans, e.g. Rickettsia rickettsii, are well characterized but those not known to cause disease remain poorly understood. Transmission electron microscopy on SFG rickettsia cultured in tick cell cultures offers a powerful way to examine dynamic host parasite interactions in these apparently nonpathogenic SFG species.We have successfully isolated two unknown, nonpathogenic rickettsia strains in tick cell lines. T2 was isolated from an Ixodes ricinus tick collected in the English Garden in Munich, Germany and is propagated in an Ixodes scapularis cell line, ISE6.

scholarly journals Ultrastructure of Rickettsia rickettsiiActin Tails and Localization of Cytoskeletal Proteins

2000 ◽  
Vol 68 (8) ◽  
pp. 4706-4713 ◽  
Author(s):  
Levi S. Van Kirk ◽  
Stanley F. Hayes ◽  
Robert A. Heinzen
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Spotted Fever ◽  
Cytoskeletal Proteins ◽  
Spotted Fever Group ◽  
Rocky Mountain Spotted Fever ◽  
Rhodamine Phalloidin ◽  
Rickettsia Rickettsii ◽  
Transmission Electron ◽  
Scanning Electron

ABSTRACT Actin-based motility (ABM) is a mechanism for intercellular spread that is utilized by vaccinia virus and the invasive bacteria within the genera Rickettsia, Listeria, andShigella. Within the Rickettsia, ABM is confined to members of the spotted fever group (SFG), such asRickettsia rickettsii, the agent of Rocky Mountain spotted fever. Infection by each agent induces the polymerization of host cell actin to form the typical F (filamentous)-actin comet tail. Assembly of the actin tail propels the pathogen through the host cytosol and into cell membrane protrusions that can be engulfed by neighboring cells, initiating a new infectious cycle. Little is known about the structure and morphogenesis of the Rickettsia rickettsii actin tail relative to Shigellaand Listeria actin tails. In this study we examined the ultrastructure of the rickettsial actin tail by confocal, scanning electron, and transmission electron microscopy. Confocal microscopy of rhodamine phalloidin-stained infected Vero cells revealed the typhus group rickettsiae, Rickettsia prowazekii andRickettsia typhi, to have no actin tails and short (∼1- to 3-μm) straight or hooked actin tails, respectively. The SFG rickettsia, R. rickettsii, displayed long actin tails (>10 μm) that were frequently comprised of multiple, distinct actin bundles, wrapping around each other in a helical fashion. Transmission electron microscopy, in conjunction with myosin S1 subfragment decoration, revealed that the individual actin filaments of R. rickettsii tails are >1 μm long, arranged roughly parallel to one another, and oriented with the fast-growing barbed end towards the rickettsial pole. Scanning electron microscopy of intracellular rickettsiae demonstrated R. rickettsii to have polar associations of cytoskeletal material and R. prowazekii to be devoid of cytoskeletal interactions. By indirect immunofluorescence, both R. rickettsii and Listeria monocytogenesactin tails were shown to contain the cytoskeletal proteins vasodilator-stimulated phosphoprotein profilin, vinculin, and filamin. However, rickettsial tails lacked ezrin, paxillin, and tropomyosin, proteins that were associated with actin tails of cytosolic or protrusion-bound Listeria. The unique ultrastructural and compositional characteristics of the R. rickettsii actin tail suggest that rickettsial ABM is mechanistically different from previously described microbial ABM systems.

scholarly journals Phylogenetic Placement of Rickettsiae from the Ticks Amblyomma americanum and Ixodes scapularis †

1998 ◽  
Vol 36 (5) ◽  
pp. 1305-1317 ◽  
Author(s):  
Susan J. Weller ◽  
Gerald D. Baldridge ◽  
Ulrike G. Munderloh ◽  
Hiroaki Noda ◽  
Jason Simser ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Ixodes Scapularis ◽  
Spotted Fever ◽  
Outer Membrane Proteins ◽  
Amblyomma Americanum ◽  
Spotted Fever Group ◽  
Rickettsia Rickettsii ◽  
Pcr Products ◽  
Relationship Of ◽  
The Relationship

A rickettsial isolate (isolate MOAa) belonging to the spotted fever group (SFG) was obtained from the lone star tick Amblyomma americanum. We used PCR to characterize the genes for the rickettsial outer membrane proteins rOmpA and rOmpB. We sequenced the PCR products (domains I of both the rompA gene and therompB gene) of MOAa and WB-8-2, another rickettsial isolate from A. americanum. To place MOAa and WB-8-2 and two other nonpathogenic isolates (Rickettsia rickettsii Hlp2 and Rickettsia montana M5/6) with respect to their putative sister species, we included them in a phylogenetic analysis of 9 Rickettsia species and 10 Rickettsia strains. Our phylogenetic results implied three evolutionary lineages of SFG rickettsiae and that WB-8-2 and MOAa were most closely related toR. montana. New World isolates were not the most closely related to each other (they did not form a clade). Rather, our results supported four independent origins (introductions) of rickettsiae into North America from different Old World regions. The results of our phylogenetic analysis did not support the hypothesis of a stable coevolution of rickettsiae and their tick hosts. Finally, we examined the rompA gene of a nonpathogenic rickettsial symbiont isolated from the tick Ixodes scapularis. In a phylogenetic analysis, the symbiont was placed as the sister toR. montana and its isolates. The relationship of this symbiont to R. montana raised questions as to the potential origin of pathogenic SFG rickettsiae from nonpathogenic tick symbionts, or vice versa.

scholarly journals Quantitative Analyses of Variations in the Injury of Endothelial Cells Elicited by 11 Isolates of Rickettsia rickettsii

2001 ◽  
Vol 8 (4) ◽  
pp. 788-796 ◽  
Author(s):  
Marina E. Eremeeva ◽  
Gregory A. Dasch ◽  
David J. Silverman
Keyword(s):  
North Carolina ◽  
Endothelial Cells ◽  
Reduced Glutathione ◽  
Spotted Fever ◽  
Ixodid Ticks ◽  
Spotted Fever Group ◽  
Cellular Injury ◽  
Rickettsia Rickettsii ◽  
Cytopathic Effects ◽  
Group I

ABSTRACT Eleven isolates of spotted fever group rickettsiae from the blood of patients or ixodid ticks from North and South America were characterized. All isolates were identified as Rickettsia rickettsii using restriction fragment length polymorphism analysis of a 532-bp rOmpA gene fragment obtained by PCR. The ability of the R. rickettsii isolates to elicit cytopathic effects and parameters of oxidative injury were examined in cultured human EA.hy 926 endothelial cells. Cytopathic effects were determined by direct observation of infected cultures, by measuring the release of cytoplasmic lactate dehydrogenase (LDH), and by determination of intracellular pools of peroxide and reduced glutathione. Four biotypes of R. rickettsii were defined. Group I included two highly cytopathic isolates from Montana, Bitterroot and Sheila Smith, and three isolates from Maryland, North Carolina, and Brazil. These isolates rapidly damaged cells, released large amounts of cytoplasmic LDH, caused accumulation of intracellular peroxide, and depleted intracellular pools of reduced glutathione. Group II contained three isolates, two from Montana, Hlp#2 and Lost Horse Canyon, and an isolate from Colombia, which were similar to group I but caused either lower responses in LDH release or smaller changes in intracellular peroxide levels. The group III isolates, Sawtooth from Montana and 84JG from North Carolina, caused lower cellular injury by all measures. Group IV isolate Price T from Montana was the least cytopathic and caused minimal alterations of all parameters measured. Understanding the molecular basis for the varied cellular injury caused by different isolates of R. rickettsii may contribute to improved treatment of Rocky Mountain spotted fever and to the rapid identification of those isolates which are more likely to cause fulminant disease.

Confirming Rickettsia rickettsii as the etiological agent of lethal spotted fever group rickettsiosis in human patients from Espírito Santo state, Brazil

2018 ◽  
Vol 9 (3) ◽  
pp. 496-499 ◽  
Author(s):  
Álvaro A. Faccini-Martínez ◽  
Sebastián Muñoz-Leal ◽  
Igor C.L. Acosta ◽  
Stefan Vilges de Oliveira ◽  
Ana Íris de Lima Duré ◽  
...  
Keyword(s):  
Spotted Fever ◽  
Etiological Agent ◽  
Spotted Fever Group ◽  
Espírito Santo ◽  
Rickettsia Rickettsii ◽  
Espirito Santo

scholarly journals Minimal Duration of Tick Attachment Sufficient for Transmission of Infectious Rickettsia rickettsii (Rickettsiales: Rickettsiaceae) by Its Primary Vector Dermacentor variabilis (Acari: Ixodidae): Duration of Rickettsial Reactivation in the Vector Revisited

2019 ◽  
Author(s):  
Michael L Levin ◽  
Shelby L Ford ◽  
Kris Hartzer ◽  
Lnna Krapiunaya ◽  
Hannah Stanley ◽  
...  
Keyword(s):  
Salivary Glands ◽  
Guinea Pigs ◽  
Pathogenic Bacteria ◽  
Spotted Fever ◽  
Dermacentor Variabilis ◽  
Control Group ◽  
Spotted Fever Group ◽  
Susceptible Host ◽  
Rickettsia Rickettsii ◽  
Tick Attachment

Abstract It has been reported that starving ticks do not transmit spotted fever group Rickettsia immediately upon attachment because pathogenic bacteria exist in a dormant, uninfectious state and require time for ‘reactivation’ before transmission to a susceptible host. To clarify the length of reactivation period, we exposed guinea pigs to bites of Rickettsia rickettsii-infected Dermacentor variabilis (Say) and allowed ticks to remain attached for predetermined time periods from 0 to 48 h. Following removal of attached ticks, salivary glands were immediately tested by PCR, while guinea pigs were observed for 10–12 d post-exposure. Guinea pigs in a control group were subcutaneously inoculated with salivary glands from unfed D. variabilis from the same cohort. In a parallel experiment, skin at the location of tick bite was also excised at the time of tick removal to ascertain dissemination of pathogen from the inoculation site. Animals in every exposure group developed clinical and pathological signs of infection. The severity of rickettsial infection in animals increased with the length of tick attachment, but even attachments for less than 8 h resulted in clinically identifiable infection in some guinea pigs. Guinea pigs inoculated with salivary glands from unfed ticks also became severely ill. Results of our study indicate that R. rickettsii residing in salivary glands of unfed questing ticks does not necessarily require a period of reactivation to precede the salivary transmission and ticks can transmit infectious Rickettsia virtually as soon as they attach to the host.

scholarly journals GroEL is an immunodominant surface-exposed antigen of Rickettsia typhi

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0253084
Author(s):  
Jessica Rauch ◽  
Jessica Barton ◽  
Marcel Kwiatkowski ◽  
Malte Wunderlich ◽  
Pascal Steffen ◽  
...  
Keyword(s):  
Spotted Fever ◽  
Spotted Fever Group ◽  
Protein Fragments ◽  
Bacterial Surface ◽  
Humoral Immune ◽  
Immunodominant Antigen ◽  
Groel Protein ◽  
Causative Agents ◽  
Epidemic Typhus ◽  
Obligate Intracellular Bacteria

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.

scholarly journals Indirect hemagglutination test for human antibody to typhus and spotted fever group rickettsiae

1975 ◽  
Vol 2 (5) ◽  
pp. 430-437
Author(s):  
A Shirai ◽  
J W Dietel ◽  
J V Osterman
Keyword(s):  
Complement Fixation ◽  
Spotted Fever ◽  
Fluorescent Antibody ◽  
Antibody Test ◽  
Cross Reactivity ◽  
Human Antibody ◽  
Spotted Fever Group ◽  
Rickettsia Rickettsii ◽  
Indirect Hemagglutination ◽  
Indirect Hemagglutination Test

An indirect hemagglutination (IHA) test is described that uses glutaraldehyde-stabilized erythrocytes treated with a rickettsial erythrocyte-sensitizing substance obtained from Rickettsia typhi or Rickettsia rickettsii. The serological reagent was stable for at least 3 months at room temperature and 6 months at 4 C. It exhibited group specificity and no group cross-reactivity. At a minimum dilution of 1:40, acute and early convalescent epidemic and murine typhus antisera showed 86% positive reactors, whereas similar spotted fever antisera had 74% positive reactors. In comparison with the indirect fluorescent antibody test, the IHA procedure gave lower titers but showed comparable detection of seroconversion with most paired sera. The IHA test demonstrated significantly higher titers than the complement fixation test and was more sensitive than either the complement fixation or Weil-Felix test in identifying seroconversion. No agglutination was observed when sensitized erythrocytes were tested with rodent sera known to contain rickettsial antibodies.

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