The Experts below are selected from a list of 20658 Experts worldwide ranked by ideXlab platform
Marcelo B. Labruna - One of the best experts on this subject based on the ideXlab platform.
-
Rickettsial infection in equids opossums and ticks in the municipality of monte mor state of sao paulo brazil
Revista Brasileira De Parasitologia Veterinaria, 2020Co-Authors: Tatiana Evelyn Hayama Ueno, Jonas Moraesfilho, Andre Antonio Cutolo, Thiago F Martins, Sergio Santos De Azevedo, Marcelo B. LabrunaAbstract:The aim of this study was to investigate Rickettsial infection in equids, opossums and ticks in the municipality of Monte Mor, a place where a Brazilian spotted fever case occurred in 2005. In addition, characteristics possibly associated with seropositivity in horses were analyzed. Serum samples from horses, mules and opossums (Didelphis albiventris) were subjected to indirect immunofluorescence assay (IFA) against Rickettsia rickettsii. The ticks collected from the animals were identified and Amblyomma sculptum ticks from the equids were tested using PCR for Rickettsia spp. Anti-R. rickettsii antibodies were detected in 22.6% (14/62) of the horses, none of the mules and 21.7% (5/23) of the opossums. Among the variables analyzed, only age > 12 years showed a statistically significant association with seropositivity among horses. All of the 166 A. sculptum ticks tested using PCR were negative. The results showed that Rickettsiae of the spotted fever group was circulating in the municipality of Monte Mor when the samples were collected and indicate a need for surveillance of Brazilian spotted fever in this region.
-
isolation of Rickettsia rickettsii from the tick amblyomma sculptum from a brazilian spotted fever endemic area in the pampulha lake region southeastern brazil
Veterinary Parasitology: Regional Studies and Reports, 2017Co-Authors: Marcelo B. Labruna, Amalia R M Barbieri, Felipe Da Silva Krawczak, Monize Gerardi, Lina C Binder, Gustavo Fontes Paz, Daniel Sobreira Rodrigues, Ricardo Araujo, Marcela Lanza Bernardes, R C LeiteAbstract:Abstract Brazilian spotted fever (BSF) is a tick-borne disease caused by the bacterium Rickettsia rickettsii , the deadliest spotted fever of the world, transmitted in southeastern Brazil mainly by the tick Amblyomma sculptum , a member of the Amblyomma cajennense species complex. In the present study, over 5000 adults of A . sculptum ticks were collected by dry ice traps in the Municipal Ecological Park, alongside the Pampulha Lake region, a BSF-endemic area of Belo Horizonte city, state of Minas Gerais, southeastern Brazil. Ticks were taken alive to the laboratory, where a sample of 2100 specimens was processed for isolation of R . rickettsii . For this purpose, ticks were macerated and intraperitoneally inoculated into guinea pigs. Only one out of 21 inoculated guinea pigs presented high fever within 21 days post inoculation with tick homogenates. This febrile animal was euthanized and its internal organs were macerated and inoculated into additional guinea pigs (guinea pig passage). A spleen sample from a febrile guinea pig was used to inoculate Vero cells, resulting in a successful isolation and in vitro establishment of Rickettsiae. Rickettsia -infected Vero cells were used for molecular characterization of the Rickettsial isolate through PCR and DNA sequencing of fragments of three Rickettsial genes ( gltA , ompA , and ompB ), which were all 100% identical to corresponding sequences of R . rickettsii from GenBank. The present R . rickettsii isolate was designated as strain Pampulha. A minimal infection rate of 0.05% R . rickettsii -infected ticks was estimated for A . sculptum population of the Pampulha Lake region. Our results, coupled with epidemiological evidences, suggest that R . rickettsii strain Pampulha, isolated from A . sculptum ticks in the present study, is the strain responsible for human clinical cases of BSF in the Pampulha Lake region of Belo Horizonte city.
-
detection of Rickettsiae in fleas and ticks from areas of costa rica with history of spotted fever group rickettsioses
Ticks and Tick-borne Diseases, 2016Co-Authors: Adriana Troyo, Marcelo B. Labruna, Rolando D Moreirasoto, Olger Calderonarguedas, Carlos Matasomarribas, Jusara Ortiztello, Amalia R M Barbieri, Adrian Avendano, Luis E Vargascastro, Laya HunAbstract:Abstract Outbreaks of spotted fevers have been reported in Costa Rica since the 1950s, although vectors responsible for transmission to humans have not been directly identified. In this study, species of Rickettsia were detected in ectoparasites from Costa Rica, mostly from five study sites where cases of spotted fevers have been reported. Ticks and fleas were collected using drag cloths or directly from domestic and wild animals and pooled according to species, host, and location. Pools were analyzed initially by PCR to detect a fragment of Rickettsia spp. specific gltA gene, and those positive were confirmed by detection of htrA and/or ompA gene fragments. Partial sequences of the gltA gene were obtained, as well as at least one ompA and/or ompB partial sequence of each species. Rickettsia spp. were confirmed in 119 of 497 (23.9%) pools of ticks and fleas analyzed. Rickettsia rickettsii was identified in one nymph of Amblyomma mixtum and one nymph of Amblyomma varium . Other Rickettsiae present were ‘ Candidatus Rickettsia amblyommii’ in A. mixtum , Amblyomma ovale , Dermacentor nitens , and Rhipicephalus sanguineus s. l.; Rickettsia bellii in Amblyomma sabanerae ; Rickettsia felis in Ctenocephalides felis ; and Rickettsia sp. similar to ‘ Candidatus R. asemboensis’ in C. felis, Pulex simulans, A. ovale , and Rhipicephalus microplus . Results show the presence of Rickettsiae in vectors that may be responsible for transmission to humans in Costa Rica, and evidence suggests exposure to Rickettsial organisms in the human environment may be common. This is the first study to report R. rickettsii in A. varium and in A. mixtum in Costa Rica.
-
Ticks and Rickettsiae from wildlife in Belize, Central America
Parasites & Vectors, 2016Co-Authors: Marcos G. Lopes, Arlei Marcili, Thiago F Martins, Joares May Junior, Rebecca J Foster, Bart J Harmsen, Emma Sanchez, Howard Quigley, Marcelo B. LabrunaAbstract:Background The agents of spotted fevers in Latin America are Rickettsia rickettsii , R. parkeri , Rickettsia sp. strain Atlantic rainforest, and R. massiliae . In Continental Central America, R. rickettsii remains the only known pathogenic tick-borne Rickettsia. In the present study, ticks were collected from wild mammals in natural areas of Belize. Besides providing new data of ticks from Belize, we investigated Rickettsial infection in some of these ticks. Our results provide ticks harboring Rickettsial agents for the first time in Central America. Methods Between 2010 and 2015, wild mammals were lived-trapped in the tropical broadleaf moist forests of central and southern Belize. Ticks were collected from the animals and identified to species by morphological and molecular analysis (DNA sequence of the tick mitochondrial 16S RNA gene). Some of the ticks were tested for Rickettsial infection by molecular methods (DNA sequences of the Rickettsial gltA and ompA genes). Results A total of 84 ticks were collected from 8 individual hosts, as follows: Amblyomma pacae from 3 Cuniculus paca ; Amblyomma ovale and Amblyomma coelebs from a Nasua narica ; A. ovale from an Eira Barbara ; A. ovale , Amblyomma cf. oblongoguttatum , and Ixodes affinis from a Puma concolor ; and A. ovale , A. coelebs, A . cf. oblongoguttatum , and I. affinis from two Panthera onca . Three Rickettsial agents were detected: Rickettsia amblyommii in A. pacae, Rickettsia sp. strain Atlantic rainforest in A. ovale, and Rickettsia sp. endosymbiont in Ixodes affinis . Conclusions The present study provides unprecedented records of ticks harboring Rickettsial agents in the New World. An emerging Rickettsial pathogen of South America, Rickettsia sp. strain Atlantic rainforest, is reported for the first time in Central America. Besides expanding the distribution of 3 Rickettsial agents in Central America, our results highlight the possible occurrence of Rickettsia sp. strain Atlantic rainforest-caused spotted fever human cases in Belize, since its possible vector, A. ovale , is recognized as one of the most important human-biting ticks in the Neotropical region.
-
Rickettsial infection in amblyomma cajennense ticks and capybaras hydrochoerus hydrochaeris in a brazilian spotted fever endemic area
Parasites & Vectors, 2014Co-Authors: Felipe Da Silva Krawczak, Fernanda A Nieribastos, Jonas Moraesfilho, Fernanda Battistella Passos Nunes, Joao F Soares, Marcelo B. LabrunaAbstract:Background: Brazilian spotted fever (BSF), caused by the bacterium Rickettsia rickettsii, is the deadliest spotted fever of the world. In most of the BSF-endemic areas, capybaras (Hydrochoerus hydrochaeris) are the principal host for the tick Amblyomma cajennense, which is the main vector of BSF. Methods: In 2012, a BSF case was confirmed in a child that was bitten by ticks in a residential park area inhabited by A. cajennense-infested capybaras in Itu municipality, southeastern Brazil. Host questing A. cajennense adult ticks were collected in the residential park and brought alive to the laboratory, where they were macerated and intraperitoneally inoculated into guinea pigs. A tick-inoculated guinea pig that presented high fever was euthanized and its internal organs were macerated and inoculated into additional guinea pigs (guinea pig passage). Tissue samples from guinea pig passages were also used to inoculate Vero cells through the shell vial technique. Infected cells were used for molecular characterization of the Rickettsial isolate through PCR and DNA sequencing of fragments of three Rickettsial genes (gltA, ompA, and ompB). Blood serum samples were collected from 172 capybaras that inhabited the residential park. Sera were tested through the immunofluorescence assay using R. rickettsii antigen. Results: A tick-inoculated guinea pig presented high fever accompanied by scrotal reactions (edema and marked redness). These signs were reproduced by consecutive guinea pig passages. Rickettsia was successfully isolated in Vero cells that were inoculated with brain homogenate derived from a 3 rd passage-febrile guinea pig. Molecular characterization of this Rickettsial isolate (designated as strain ITU) yielded DNA sequences that were all 100% identical to corresponding sequences of R. rickettsii in Genbank. A total of 83 (48.3%) out of 172 capybaras were seroreactive to R. rickettsii, with endpoint titers ranging from 64 to 8192. Conclusions: A viable isolate of R. rickettsii was obtained from the tick A. cajennense, comprising the first viable R. rickettsi isolate from this tick species during the last 60 years. Nearly half of the capybara population of the residential park was seroreactive to R. rickettsii, corroborating the findings that the local A. cajennense population was infected by R. rickettsii.
Marina E. Eremeeva - One of the best experts on this subject based on the ideXlab platform.
-
A focus of dogs and Rickettsia massiliae-infected Rhipicephalus sanguineus in California.
The American journal of tropical medicine and hygiene, 2011Co-Authors: Emily Beeler, Gregory A. Dasch, Kyle F. Abramowicz, Maria L. Zambrano, Michele M. Sturgeon, Nada Khalaf, Marina E. EremeevaAbstract:A recurrent focus of Rhipicephalus sanguineus infestation was investigated in a suburban area of southern California after reports of suspected Rocky Mountain spotted fever in two dogs on the same property. Abundant quantities of Rh. sanguineus were collected on the property and repeatedly from each dog, and Rickettsia massiliae DNA was detected by polymerase chain reaction (PCR). Whole blood and serum samples from four dogs were tested by using PCR and microimmunofluorescent assay for antibodies against spotted fever group Rickettsiae. Serum samples from all four dogs contained antibodies reactive with R. massiliae, R. rhipicephali, R. rickettsii, and 364D Rickettsia but no Rickettsial DNA was detected by PCR of blood samples. Serum cross-absorption and Western blot assays implicated R. massiliae as the most likely spotted fever group Rickettsiae responsible for seropositivity. To our knowledge, this is the first detection of R. massiliae in ticks in California.
-
detection and identification of spotted fever group Rickettsiae in dermacentor species from southern california
Journal of Medical Entomology, 2008Co-Authors: Gregory A. Dasch, Mary E Wikswo, Laura Krueger, Aaron Arugay, Keith Jones, Barry D Hess, Stephen G Bennett, Vicki Kramer, Marina E. EremeevaAbstract:Dermacentor occidentalis Marx and Dermacentor variabilis (Say) commonly bite humans in California. These Dermacentor species may play a role in transmitting spotted fever group (SFG) Rickettsiae to humans in many parts of the state where Dermacentor andersoni Stiles, a known vector for the etiologic agent of Rocky Mountain spotted fever, Rickettsia rickettsii, is absent. However, the specific Rickettsial agents present in these ticks and their current prevalence are poorly understood. In total, 365 D. occidentalis and 10 D. variabilis were collected by flagging vegetation at 16 sites in five counties of southern California. The presence of SFG Rickettsial DNA in these ticks was detected with rOmpA and GltA gene polymerase chain reaction (PCR) assays. The Rickettsial species were identified by sequencing PCR amplicons. Of 365 D. occidentalis, 90 (24.7%) contained R. rhipicephali DNA, 28 (7.7%) contained DNA of unclassified genotype 364D, two (0.55%) contained R. bellii DNA, and one (0.3%) contained R. rickettsii DNA. Of 10 D. variabilis, four (40%) contained only R. rhipicephali. Four new genotypes of R. rhipicephali were discovered. For the first time, we detected R. rickettsii in D. occidentalis. Our study provides the first molecular data on the prevalence and species identification of SFG Rickettsiae circulating in populations of these California ticks. Because neither D. variabilis nor R. rickettsii were abundant, 364D should be evaluated further as a potential cause of human SFG rickettsioses in southern California.
-
proposal to create subspecies of Rickettsia conorii based on multi locus sequence typing and an emended description of Rickettsia conorii
BMC Microbiology, 2005Co-Authors: Marina E. EremeevaAbstract:Background Rickettsiae closely related to the Malish strain, the reference Rickettsia conorii strain, include Indian tick typhus Rickettsia (ITTR), Israeli spotted fever Rickettsia (ISFR), and Astrakhan fever Rickettsia (AFR). Although closely related genotypically, they are distinct serotypically. Using multilocus sequence typing (MLST), we have recently found that distinct serotypes may not always represent distinct species within the Rickettsia genus. We investigated the possibility of classifying Rickettsiae closely related to R. conorii as R. conorii subspecies as proposed by the ad hoc committee on reconciliation of approaches to bacterial systematics. For this, we first estimated their genotypic variability by using MLST including the sequencing of 5 genes, of 31 Rickettsial isolates closely related to R. conorii strain Malish, 1 ITTR isolate, 2 isolates and 3 tick amplicons of AFR, and 2 ISFR isolates. Then, we selected a representative of each MLST genotype and used multi-spacer typing (MST) and mouse serotyping to estimate their degree of taxonomic relatedness.
-
evaluation of a pcr assay for quantitation of Rickettsia rickettsii and closely related spotted fever group Rickettsiae
Journal of Clinical Microbiology, 2003Co-Authors: Marina E. Eremeeva, Gregory A. Dasch, David J SilvermanAbstract:A spotted fever Rickettsia quantitative PCR assay (SQ-PCR) was developed for the detection and enumeration of Rickettsia rickettsii and other closely related spotted fever group Rickettsiae. The assay is based on fluorescence detection of SYBR Green dye intercalation in a 154-bp fragment of the rOmpA gene during amplification by PCR. As few as 5 copies of the rOmpA gene of R. rickettsii can be detected. SQ-PCR is suitable for quantitation of R. rickettsii and 10 other genotypes of spotted fever group Rickettsiae but not for R. akari, R. australis, R. bellii, or typhus group Rickettsiae. The sensitivity of SQ-PCR was comparable to that of a plaque assay using centrifugation for inoculation. The SQ-PCR assay was applied successfully to the characterization of Rickettsial stock cultures, the replication of Rickettsiae in cell culture, the recovery of Rickettsial DNA following different methods of extraction, and the quantitation of Rickettsial loads in infected animal tissues, clinical samples, and ticks.
-
Rickettsia rickettsii infection in the pine vole microtus pinetorum
Annals of the New York Academy of Sciences, 2003Co-Authors: John G Vandenbergh, Zhongxing Liang, Marina E. Eremeeva, Sherif R Zaki, Christopher D Paddock, Gregory A. Dasch, David J SilvermanAbstract:: The pine vole, Microtus pinetorum, was evaluated as a laboratory animal model for infection with Rickettsia rickettsii. Voles demonstrated signs of acute disease, and 45% of infected animals died following intraperitoneal infection with 3 x 10(6) plaque forming units of R. rickettsii. Spleen, liver, kidney, lung, brain, testes and blood were analyzed for Rickettsial burden by a quantitative PCR assay. The distribution of Rickettsiae in tissues during the course of infection was determined by immunohistochemical staining and pathological changes in tissues were correlated with the clinical severity of infection. Quantitative RT-PCR assays were designed to measure the mRNA levels of the antioxidant enzyme genes for catalase, glutathione peroxidase, glutathione reductase, heme oxygenase, Cu-Zn superoxide dismutase (SOD) and Mn-SOD, and 2 housekeeping genes, actin and glyceraldehyde phosphate dehydrogenase. Tissues from acutely ill animals on days 2 to 6 of infection, convalescent animals, and uninfected control animals were studied. The number of transcripts of each enzyme gene was determined and compared to the degree of Rickettsial infection present. These studies demonstrate that the pine vole is a valuable experimental model for studying infection with R. rickettsii. Our results provide the first experimental evidence that R. rickettsii causes alteration(s) of the anti-oxidant system in vivo.
David H. Walker - One of the best experts on this subject based on the ideXlab platform.
-
Rickettsia species infecting amblyomma cooperi ticks from an area in the state of sao paulo brazil where brazilian spotted fever is endemic
Journal of Clinical Microbiology, 2004Co-Authors: Ted Whitworth, Donald H Bouyer, Vsevolod L. Popov, Marcelo B. Labruna, Adriano Pinter, Mauricio Claudio Horta, Solange Maria Gennari, Jere W Mcbride, David H. WalkerAbstract:Owing to the potential role of the tick Amblyomma cooperi in the enzootic cycle of Rickettsia rickettsii, the etiologic agent of Brazilian spotted fever (BSF), this study evaluated infection by Rickettsia species in A. cooperi ticks collected from an area in Brazil where BSF is endemic. Among a total of 40 A. cooperi adult ticks collected in an area of BSF endemicity in the state of Sao Paulo, PCR analysis detected DNA of Rickettsia bellii in 16 ticks (40%), and 3 other ticks (7.5%) were positive for a previously unidentified spotted-fever-group (SFG) Rickettsia. Cultivation in Vero cell cultures by the shell vial technique with individual A. cooperi ticks resulted in two isolates of R. bellii and one isolate genotypically characterized as an SFG Rickettsia. The two R. bellii isolates were established in Vero cell cultures in the laboratory and were confirmed to be R. bellii by molecular analysis of the gltA and 17-kDa protein-encoding genes and by electron microscopic analysis. The SFG Rickettsial isolate could not be stably passaged in cell culture in the laboratory, but molecular analysis of early passages suggested that it was closely related to Rickettsia parkeri, Rickettsia africae, and Rickettsia sibirica. These results do not support the role of A. cooperi in the ecology of R. rickettsii in the area studied, but they add two more species of Rickettsiae to the poorly developed list of species occurring in ticks in South America.
-
ultrastructural and genetic evidence of a reptilian tick aponomma hydrosauri as a host of Rickettsia honei in australia possible transovarial transmission
Annals of the New York Academy of Sciences, 2003Co-Authors: Ted Whitworth, Stephen Graves, John Stenos, Donald H Bouyer, Lucy M Ndip, Vsevolod L. Popov, David H. WalkerAbstract:: In 1993, a novel Rickettsia was isolated from the blood of inhabitants of Flinders Island, Australia, with acute febrile illnesses. This Rickettsia was found to be a new species of spotted fever group (SFG) Rickettsia, eventually named Rickettsia honei. The suspected ectoparasite vector of this Rickettsia has yet to be identified. The purpose of this study was to evaluate the presence of this Rickettsial species in a suspected tick vector, Aponomma hydrosauri, by DNA sequencing and electron microscopy (EM). Ticks collected from an Australian blue-tongued lizard on Flinders Island and a copperhead snake in Tasmania were demonstrated to be infected with R. honei by PCR, DNA sequencing, and EM. Rickettsiae were found in ultrathin sections of salivary glands, malpighian tubules, and midgut epithelial cells. In a previous study with a R. honei-infected tick from Flinders Island, Rickettsiae were found in the nuclei of midgut epithelial cells, and EM also revealed the presence of Rickettsiae in the cytosol of oocytes and immature eggs, suggesting transovarial transmission. These results implicate A. hydrosauri as a possible host of R. honei on Flinders Island and Tasmania and also provide evidence favoring transovarial maintenance of R. honei.
-
phylogenetic analysis of the rompb genes of Rickettsia felis and Rickettsia prowazekii european human and north american flying squirrel strains
American Journal of Tropical Medicine and Hygiene, 2000Co-Authors: Cecilia Moron, Donald H Bouyer, Lane D. Foil, Patricia A Crocquetvaldes, David H. WalkerAbstract:The Rickettsial outer membrane protein B (rompB) gene encodes the major surface antigens of Rickettsia species. We undertook sequencing and molecular analysis of the rompB gene of Rickettsia felis and a comparison with its homologs in spotted fever group (SFG) and typhus group (TG) Rickettsiae, including the complete sequences of two North American flying squirrel strains and two European human strains of Rickettsia prowazekii. We sequenced 5,226 base pairs (bp) of the R. felis rompB, encoding a protein of 1,654 amino acids. We also sequenced 5,015 bp of rompB of the flying squirrel strains, encoding a protein of 1,643 amino acids. Analysis of the R. felis rompB gene sequence showed 10-13% divergence from SFG Rickettsiae and 18% divergence from the TG Rickettsiae. The rompB of all sequenced strains of R. prowazekii showed an overall similarity of 99.7-99.9%.
Donald H Bouyer - One of the best experts on this subject based on the ideXlab platform.
-
Rickettsia PROWAZEKII EUROPEAN-HUMAN AND NORTH AMERICAN FLYING-SQUIRREL STRAINS
2015Co-Authors: Cecilia G. Moron, Donald H Bouyer, Lane D. Foil, Patricia Crocquet-valdes, H. WalkerAbstract:Abstract. The Rickettsial outer membrane protein B (rompB) gene encodes the major surface antigens of Rickettsia species. We undertook sequencing and molecular analysis of the rompB gene of Rickettsia felis and a comparison with its homologs in spotted fever group (SFG) and typhus group (TG) Rickettsiae, including the complete sequences of two North American flying squirrel strains and two European human strains of Rickettsia prowazekii. We sequenced 5,226 base pairs (bp) of the R. felis rompB, encoding a protein of 1,654 amino acids. We also sequenced 5,015 bp of rompB of the flying squirrel strains, encoding a protein of 1,643 amino acids. Analysis of the R. felis rompB gene sequence showed 10–13 % divergence from SFG Rickettsiae and 18 % divergence from the TG Rickettsiae. The rompB of all sequenced strains of R. prowazekii showed an overall similarity of 99.7–99.9%
-
seroepidemiologic study of human infections with spotted fever group Rickettsiae in north carolina
Journal of Clinical Microbiology, 2014Co-Authors: Meagan F Vaughn, Donald H Bouyer, William L Nicholson, Josie Delisle, Joey Johnson, Gaylen Daves, Carl Williams, Jodi Reber, Nicole L Mendell, Abelardo C MoncayoAbstract:Increasing entomologic and epidemiologic evidence suggests that spotted fever group Rickettsiae (SFGR) other than Rickettsia rickettsii are responsible for spotted fever rickettsioses in the United States. A retrospective seroepidemiologic study was conducted on stored acute- and convalescent-phase sera that had been submitted for Rocky Mountain spotted fever testing to the North Carolina State Laboratory of Public Health. We evaluated the serologic reactivity of the paired sera to R. rickettsii, Rickettsia parkeri, and Rickettsia amblyommii antigens. Of the 106 eligible pairs tested, 21 patients seroconverted to one or more antigens. Cross-reactivity to multiple antigens was observed in 10 patients, and seroconversions to single antigens occurred in 11 patients, including 1 against R. rickettsii, 4 against R. parkeri, and 6 against R. amblyommii. Cross-absorption of cross-reactive sera and/or Western blots identified two presumptive cases of infection with R. parkeri, two presumptive cases of infection with R. rickettsii, and one presumptive case of infection with R. amblyommii. These findings suggest that species of SFGR other than R. rickettsii are associated with illness among North Carolina residents and that serologic testing using R. rickettsii antigen may miss cases of spotted fever rickettsioses caused by other species of SFGR.
-
Rickettsia monteiroi sp nov infecting the tick amblyomma incisum in brazil
Applied and Environmental Microbiology, 2011Co-Authors: Richard C. Pacheco, Donald H Bouyer, Leonardo Jose Richtzenhain, Arlei Marcili, Jonas Moraesfilho, Matias Pablo Juan Szabo, M H B Catroxo, Marcelo B. LabrunaAbstract:Free-living adult Amblyomma incisum ticks were collected in an Atlantic rainforest area at Intervales State Park, State of Sao Paulo, Brazil. From an A. incisum specimen, Rickettsiae were successfully isolated in Vero cell culture by the shell vial technique. Rickettsial isolation was confirmed by optical microscopy, transmission electron microscopy, and PCRs targeting portions of the Rickettsial genes gltA, htrA, rrs, and sca1 on infected cells. Fragments of 1,089, 457, 1,362, and 443 nucleotides of the gltA, htrA, rrs, and sca1 genes, respectively, were sequenced. By BLAST analysis, the partial sequence of rrs of the A. incisum Rickettsial isolate was closest to the corresponding sequence of Rickettsia bellii (99.1% similarity). The gltA partial sequence was closest to the corresponding sequences of "Candidatus Rickettsia tarasevichiae" (96.1% similarity) and Rickettsia canadensis (95.8% similarity). The htrA partial sequence was closest to the corresponding sequence of R. canadensis (89.8% similarity). The sca1 partial sequence was closest to the corresponding sequence of R. canadensis (95.2% similarity). Since our Rickettsial isolate was genetically distinct from other Rickettsia species, we propose a new species designated Rickettsia monteiroi sp. nov. Phylogenetic analyses indicated that R. monteiroi belongs to the canadensis group within the genus Rickettsia, together with the species R. canadensis and "Candidatus R. tarasevichiae". Little or no antibody cross-reaction was observed between sera of R. monteiroi-inoculated guinea pigs and R. bellii-, Rickettsia rickettsii-, or R. canadensis-inoculated guinea pigs.
-
Rickettsia species infecting amblyomma cooperi ticks from an area in the state of sao paulo brazil where brazilian spotted fever is endemic
Journal of Clinical Microbiology, 2004Co-Authors: Ted Whitworth, Donald H Bouyer, Vsevolod L. Popov, Marcelo B. Labruna, Adriano Pinter, Mauricio Claudio Horta, Solange Maria Gennari, Jere W Mcbride, David H. WalkerAbstract:Owing to the potential role of the tick Amblyomma cooperi in the enzootic cycle of Rickettsia rickettsii, the etiologic agent of Brazilian spotted fever (BSF), this study evaluated infection by Rickettsia species in A. cooperi ticks collected from an area in Brazil where BSF is endemic. Among a total of 40 A. cooperi adult ticks collected in an area of BSF endemicity in the state of Sao Paulo, PCR analysis detected DNA of Rickettsia bellii in 16 ticks (40%), and 3 other ticks (7.5%) were positive for a previously unidentified spotted-fever-group (SFG) Rickettsia. Cultivation in Vero cell cultures by the shell vial technique with individual A. cooperi ticks resulted in two isolates of R. bellii and one isolate genotypically characterized as an SFG Rickettsia. The two R. bellii isolates were established in Vero cell cultures in the laboratory and were confirmed to be R. bellii by molecular analysis of the gltA and 17-kDa protein-encoding genes and by electron microscopic analysis. The SFG Rickettsial isolate could not be stably passaged in cell culture in the laboratory, but molecular analysis of early passages suggested that it was closely related to Rickettsia parkeri, Rickettsia africae, and Rickettsia sibirica. These results do not support the role of A. cooperi in the ecology of R. rickettsii in the area studied, but they add two more species of Rickettsiae to the poorly developed list of species occurring in ticks in South America.
-
ultrastructural and genetic evidence of a reptilian tick aponomma hydrosauri as a host of Rickettsia honei in australia possible transovarial transmission
Annals of the New York Academy of Sciences, 2003Co-Authors: Ted Whitworth, Stephen Graves, John Stenos, Donald H Bouyer, Lucy M Ndip, Vsevolod L. Popov, David H. WalkerAbstract:: In 1993, a novel Rickettsia was isolated from the blood of inhabitants of Flinders Island, Australia, with acute febrile illnesses. This Rickettsia was found to be a new species of spotted fever group (SFG) Rickettsia, eventually named Rickettsia honei. The suspected ectoparasite vector of this Rickettsia has yet to be identified. The purpose of this study was to evaluate the presence of this Rickettsial species in a suspected tick vector, Aponomma hydrosauri, by DNA sequencing and electron microscopy (EM). Ticks collected from an Australian blue-tongued lizard on Flinders Island and a copperhead snake in Tasmania were demonstrated to be infected with R. honei by PCR, DNA sequencing, and EM. Rickettsiae were found in ultrathin sections of salivary glands, malpighian tubules, and midgut epithelial cells. In a previous study with a R. honei-infected tick from Flinders Island, Rickettsiae were found in the nuclei of midgut epithelial cells, and EM also revealed the presence of Rickettsiae in the cytosol of oocytes and immature eggs, suggesting transovarial transmission. These results implicate A. hydrosauri as a possible host of R. honei on Flinders Island and Tasmania and also provide evidence favoring transovarial maintenance of R. honei.
Ulrike G Munderloh - One of the best experts on this subject based on the ideXlab platform.
-
Rickettsia buchneri sp nov a Rickettsial endosymbiont of the blacklegged tick ixodes scapularis
International Journal of Systematic and Evolutionary Microbiology, 2015Co-Authors: Timothy J Kurtti, Jonathan D Oliver, Nicole Y Burkhardt, Roderick F Felsheim, Chan C Heu, Ulrike G MunderlohAbstract:We obtained a Rickettsial isolate from the ovaries of the blacklegged tick, Ixodes scapularis. The isolate (ISO7T) was grown in the Ixodes ricinus embryonic cell line IRE11. We characterized the isolate by transmission electron microscopy and gene sequencing. Phylogenetic analysis of 11 housekeeping genes demonstrated that the isolate fulfils the criteria to be classified as a representative of a novel Rickettsial species closely related to ‘Rickettsia monacensis’. These Rickettsiae form a clade separate from other species of Rickettsiae. Gene sequences indicated that several genes important in Rickettsial motility, invasiveness and temperature adaptation were mutated (e.g. sca2, rickA, hsp22, pldA and htrA). We propose the name Rickettsia buchneri sp. nov. for this bacterium that infects the ovaries of the tick I. scapularis to acknowledge the pioneering contributions of Professor Paul Buchner (1886–1978) to research on bacterial symbionts. The type strain of R. buchneri sp. nov. is strain ISO-7T ( = DSM 29016T = ATCC VR-1814T).
-
motility characteristics are altered for Rickettsia bellii transformed to overexpress a heterologous ricka gene
Applied and Environmental Microbiology, 2014Co-Authors: Jonathan D Oliver, Nicole Y Burkhardt, Roderick F Felsheim, Timothy J Kurtti, Ulrike G MunderlohAbstract:The Rickettsial protein RickA activates host cell factors associated with the eukaryotic actin cytoskeleton and is likely involved with Rickettsial host cell binding and infection and the actin-based motility of spotted fever group Rickettsiae. The rickA gene sequence and protein vary substantially between Rickettsia species, as do observed motility-associated phenotypes. To help elucidate the function of RickA and determine the effects of species-specific RickA variations, we compared extracellular binding, intracellular motility, and intercellular spread phenotypes of three Rickettsia bellii variants. These included two shuttle vector-transformed R. bellii strains and the wild-type isolate from which they were derived, R. bellii RML 369C. Both plasmid shuttle vectors carried spectinomycin resistance and a GFPuv reporter; one contained Rickettsia monacensis-derived rickA, and the other lacked the rickA gene. Rickettsia bellii transformed to express R. monacensis rickA highly overexpressed this transcript in comparison to its native rickA. These Rickettsiae also moved at higher velocities and followed a more curved path than the negative-control transformants. A lower proportion of R. monacensis rickA-expressing bacteria ever became motile, however, and they formed smaller plaques.
-
sequence and expression analysis of the ompa gene of Rickettsia peacockii an endosymbiont of the rocky mountain wood tick dermacentor andersoni
Applied and Environmental Microbiology, 2004Co-Authors: Gerald D Baldridge, Nicole Y Burkhardt, Timothy J Kurtti, Jason A Simser, Ulrike G MunderlohAbstract:The transmission dynamics of Rocky Mountain spotted fever in Montana appears to be regulated by Rickettsia peacockii, a tick symbiotic Rickettsia that interferes with transmission of virulent Rickettsia rickettsii. To elucidate the molecular relationships between the two Rickettsiae and glean information on how to possibly exploit this interference phenomenon, we studied a major Rickettsial outer membrane protein gene, ompA, presumed to be involved in infection and pathogenesis of spotted fever group Rickettsiae (SFGR) but which is not expressed in the symbiont. Based on PCR amplification and DNA sequence analysis of the SFGR ompA gene, we demonstrate that R. peacockii is the most closely related of all known SFGR to R. rickettsii. We show that R. peacockii, originally described as East Side agent in Dermacentor andersoni ticks from the east side of the Bitterroot Valley in Montana, is still present in that tick population as well as in D. andersoni ticks collected at two widely separated locations in Colorado. The ompA genes of R. peacockii from these locations share three identical premature stop codons and a weakened ribosome binding site consensus sequence relative to ompA of R. rickettsii. The R. peacockii ompA promoter closely resembles that of R. rickettsii and is functional based on reverse transcription-PCR results. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting showed that OmpA translation products were not detected in cultured tick cells infected with R. peacockii. Double immunolabeling studies revealed actin tail structures in tick cells infected with R. rickettsii strain Hlp#2 but not in cells infected with R. peacockii.
-
Rickettsia monacensis sp nov a spotted fever group Rickettsia from ticks ixodes ricinus collected in a european city park
Applied and Environmental Microbiology, 2002Co-Authors: Jason A Simser, Timothy J Kurtti, Ann T Palmer, Volker Fingerle, Bettina Wilske, Ulrike G MunderlohAbstract:We describe the isolation and characterization of Rickettsia monacensis sp. nov. (type strain, IrR/MunichT) from an Ixodes ricinus tick collected in a city park, the English Garden in Munich, Germany. Rickettsiae were propagated in vitro with Ixodes scapularis cell line ISE6. BLAST analysis of the 16S rRNA, the citrate synthase, and the partial 190-kDa Rickettsial outer membrane protein A (rOmpA) gene sequences demonstrated that the isolate was a spotted fever group (SFG) Rickettsia closely related to several yet-to-be-cultivated Rickettsiae associated with I. ricinus. Phylogenetic analysis of partial rompA sequences demonstrated that the isolate was genotypically different from other validated species of SFG Rickettsiae. R. monacensis also replicated in cell lines derived from the ticks I. ricinus (IRE11) and Dermacentor andersoni (DAE100) and in the mammalian cell lines L-929 and Vero, causing cell lysis. Transmission electron microscopy of infected ISE6 and Vero cells showed Rickettsiae within the cytoplasm, pseudopodia, nuclei, and vacuoles. Hamsters inoculated with R. monacensis had immunoglobulin G antibody titers as high as 1:16,384, as determined by indirect immunofluorescence assay. Western blot analyses demonstrated that the hamster sera cross-reacted with peptides from other phylogenetically distinct Rickettsiae, including rOmpA. R. monacensis induced actin tails in both tick and mammalian cells similar to those reported for R. rickettsii. R. monacensis joins a growing list of SFG Rickettsiae that colonize ticks but whose infectivity and pathogenicity for vertebrates are unknown.
-
phylogenetic placement of Rickettsiae from the ticks amblyomma americanum and ixodes scapularis
Journal of Clinical Microbiology, 1998Co-Authors: Susan J Weller, Ulrike G Munderloh, Gerald D Baldridge, Hiroaki Noda, Jason A Simser, Timothy J KurttiAbstract: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 the rompB 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 to R. 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 to R. 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.
