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Allen L. Richards - One of the best experts on this subject based on the ideXlab platform.
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Identification of trombiculid mites (Acari: Trombiculidae) on rodents from Chiloé Island and molecular evidence of infection with Orientia species.
PLoS neglected tropical diseases, 2020Co-Authors: Gerardo Acosta-jamett, Allen L. Richards, Ju Jiang, Constanza Martínez-valdebenito, Esperanza Beltrami, María Carolina Silva-de La Fuente, Thomas Weitzel, Katia AbarcaAbstract:Background Scrub typhus is an emerging vector-borne zoonosis, caused by Orientia spp. and transmitted by larvae of trombiculid mites, called chiggers. It mainly occurs within a region of the Asia-Pacific called the tsutsugamushi triangle, where rodents are known as the most relevant hosts for the trombiculid vector. However, the reservoir(s) and vector(s) of the scrub typhus outside Asia-Pacific are unknown. The disease has recently been discovered on and is considered endemic for Chiloe Island in southern Chile. The aim of the present work was to detect and determine the prevalence of chiggers on different rodent species captured in probable sites for the transmission of Orientiae responsible for scrub typhus on Chiloe Island in southern Chile and to molecularly examine collected chiggers for the presence of Orientia DNA. Methodology/Principal findings During the austral summer 2018, rodents were live-trapped in six sites and examined for chigger infestation. All study sites were rural areas on Chiloe Island, previously identified as probable localities where human cases acquired the scrub typhus. During a total of 4,713 trap-nights, 244 rodents of seven species were captured: the most abundant was Abrothrix olivacea. Chiggers were detected on all seven rodent species with a 55% prevalence rate. Chiggers showed low host specificity and varied according to site specific host abundance. Three genera of trombiculids were identified. Herpetacarus was the most abundant genus (93%), prevalent in five of the six sites. Infestation rates showed site specific differences, which were statistically significant using a GLM model with binomial errors. Molecular analyses proved that 21 of 133 (15.8%) mite pools were positive for Orientia species, all of them belonged to the genus Herpetacarus. Conclusions/Significance This study firstly reports the presence of different rodent-associated chigger mites positive for Orientia sp., in a region endemic for scrub typhus in southern Chile. Herpetacarus and two other genera of mites were found with high infestation rates of rodents in sites previously identified as probable exposure of scrub typhus cases. A substantial percentage of mite pools were positive for Orientia DNA, suggesting that chigger mites serve as vectors and reservoirs of this emerging zoonosis in South America.
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Molecular Description of a Novel Orientia Species Causing Scrub Typhus in Chile.
Emerging infectious diseases, 2020Co-Authors: Katia Abarca, Allen L. Richards, Ju Jiang, Gerardo Acosta-jamett, Constanza Martínez-valdebenito, Jenniffer Angulo, Christina M. Farris, Thomas WeitzelAbstract:Scrub typhus is a potentially fatal rickettsiosis caused by Orientia species intracellular bacteria of the genus Orientia. Although considered to be restricted to the Asia Pacific region, scrub typhus has recently been discovered in southern Chile. We analyzed Orientia gene sequences of 16S rRNA (rrs) and 47-kDa (htrA) from 18 scrub typhus patients from Chile. Sequences were ≥99.7% identical among the samples for both amplified genes. Their diversity was 3.1%-3.5% for rrs and 11.2%-11.8% for htrA compared with O. tsusugamushi and 3.0% for rrs and 14.8% for htrA compared with Candidatus Orientia chuto. Phylogenetic analyses of both genes grouped the specimens from Chile in a different clade from other Orientia species. Our results indicate that Orientia isolates from Chile constitute a novel species, which, until they are cultivated and fully characterized, we propose to designate as Candidatus Orientia chiloensis, after the Chiloe Archipelago where the pathogen was identified.
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Genotyping of Orientia tsutsugamushi from individual mites by next-generation sequencing.
2018Co-Authors: Ratree Takhampunya, Achareeya Korkusol, Sommai Promsathaporn, Bousaraporn Tippayachai, Surachai Leepitakrat, Allen L. Richards, Silas A. DavidsonAbstract:Genotyping of Orientia tsutsugamushi from individual mites by next-generation sequencing.
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Scrub Typhus: No Longer Restricted to the Tsutsugamushi Triangle
MDPI AG, 2018Co-Authors: Ju Jiang, Allen L. RichardsAbstract:Scrub typhus is the most important rickettsial disease in the world. Its previous endemic region was considered to be in Asia, Australia and islands in the Indian and Pacific Oceans; this area was referred to as the Tsutsugamushi Triangle. Accumulation of serological, molecular, genetic, and culture data have shown that not only is scrub typhus not limited to the Tsutsugamushi Triangle, but can be caused by Orientiae other than Orientia tsutsugamushi. This review describes evidence currently available that will be instrumental to researchers, healthcare providers and medical leaders in developing new research projects, performing diagnosis, and preventing scrub typhus in locations not previously thought to be endemic
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Long-read whole genome sequencing and comparative analysis of six strains of the human pathogen Orientia tsutsugamushi.
Public Library of Science (PLoS), 2018Co-Authors: Elizabeth M Batty, Allen L. Richards, Stuart D. Blacksell, Suwittra Chaemchuen, Rory Bowden, Caroline Chan, Ramkumar Lachumanan, Daniel Paris, Nicholas Day, Peter DonnellyAbstract:Orientia tsutsugamushi is a clinically important but neglected obligate intracellular bacterial pathogen of the Rickettsiaceae family that causes the potentially life-threatening human disease scrub typhus. In contrast to the genome reduction seen in many obligate intracellular bacteria, early genetic studies of Orientia have revealed one of the most repetitive bacterial genomes sequenced to date. The dramatic expansion of mobile elements has hampered efforts to generate complete genome sequences using short read sequencing methodologies, and consequently there have been few studies of the comparative genomics of this neglected species.We report new high-quality genomes of O. tsutsugamushi, generated using PacBio single molecule long read sequencing, for six strains: Karp, Kato, Gilliam, TA686, UT76 and UT176. In comparative genomics analyses of these strains together with existing reference genomes from Ikeda and Boryong strains, we identify a relatively small core genome of 657 genes, grouped into core gene islands and separated by repeat regions, and use the core genes to infer the first whole-genome phylogeny of Orientia.Complete assemblies of multiple Orientia genomes verify initial suggestions that these are remarkable organisms. They have larger genomes compared with most other Rickettsiaceae, with widespread amplification of repeat elements and massive chromosomal rearrangements between strains. At the gene level, Orientia has a relatively small set of universally conserved genes, similar to other obligate intracellular bacteria, and the relative expansion in genome size can be accounted for by gene duplication and repeat amplification. Our study demonstrates the utility of long read sequencing to investigate complex bacterial genomes and characterise genomic variation
Ju Jiang - One of the best experts on this subject based on the ideXlab platform.
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Identification of trombiculid mites (Acari: Trombiculidae) on rodents from Chiloé Island and molecular evidence of infection with Orientia species.
PLoS neglected tropical diseases, 2020Co-Authors: Gerardo Acosta-jamett, Allen L. Richards, Ju Jiang, Constanza Martínez-valdebenito, Esperanza Beltrami, María Carolina Silva-de La Fuente, Thomas Weitzel, Katia AbarcaAbstract:Background Scrub typhus is an emerging vector-borne zoonosis, caused by Orientia spp. and transmitted by larvae of trombiculid mites, called chiggers. It mainly occurs within a region of the Asia-Pacific called the tsutsugamushi triangle, where rodents are known as the most relevant hosts for the trombiculid vector. However, the reservoir(s) and vector(s) of the scrub typhus outside Asia-Pacific are unknown. The disease has recently been discovered on and is considered endemic for Chiloe Island in southern Chile. The aim of the present work was to detect and determine the prevalence of chiggers on different rodent species captured in probable sites for the transmission of Orientiae responsible for scrub typhus on Chiloe Island in southern Chile and to molecularly examine collected chiggers for the presence of Orientia DNA. Methodology/Principal findings During the austral summer 2018, rodents were live-trapped in six sites and examined for chigger infestation. All study sites were rural areas on Chiloe Island, previously identified as probable localities where human cases acquired the scrub typhus. During a total of 4,713 trap-nights, 244 rodents of seven species were captured: the most abundant was Abrothrix olivacea. Chiggers were detected on all seven rodent species with a 55% prevalence rate. Chiggers showed low host specificity and varied according to site specific host abundance. Three genera of trombiculids were identified. Herpetacarus was the most abundant genus (93%), prevalent in five of the six sites. Infestation rates showed site specific differences, which were statistically significant using a GLM model with binomial errors. Molecular analyses proved that 21 of 133 (15.8%) mite pools were positive for Orientia species, all of them belonged to the genus Herpetacarus. Conclusions/Significance This study firstly reports the presence of different rodent-associated chigger mites positive for Orientia sp., in a region endemic for scrub typhus in southern Chile. Herpetacarus and two other genera of mites were found with high infestation rates of rodents in sites previously identified as probable exposure of scrub typhus cases. A substantial percentage of mite pools were positive for Orientia DNA, suggesting that chigger mites serve as vectors and reservoirs of this emerging zoonosis in South America.
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Molecular Description of a Novel Orientia Species Causing Scrub Typhus in Chile.
Emerging infectious diseases, 2020Co-Authors: Katia Abarca, Allen L. Richards, Ju Jiang, Gerardo Acosta-jamett, Constanza Martínez-valdebenito, Jenniffer Angulo, Christina M. Farris, Thomas WeitzelAbstract:Scrub typhus is a potentially fatal rickettsiosis caused by Orientia species intracellular bacteria of the genus Orientia. Although considered to be restricted to the Asia Pacific region, scrub typhus has recently been discovered in southern Chile. We analyzed Orientia gene sequences of 16S rRNA (rrs) and 47-kDa (htrA) from 18 scrub typhus patients from Chile. Sequences were ≥99.7% identical among the samples for both amplified genes. Their diversity was 3.1%-3.5% for rrs and 11.2%-11.8% for htrA compared with O. tsusugamushi and 3.0% for rrs and 14.8% for htrA compared with Candidatus Orientia chuto. Phylogenetic analyses of both genes grouped the specimens from Chile in a different clade from other Orientia species. Our results indicate that Orientia isolates from Chile constitute a novel species, which, until they are cultivated and fully characterized, we propose to designate as Candidatus Orientia chiloensis, after the Chiloe Archipelago where the pathogen was identified.
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a review of scrub typhus Orientia tsutsugamushi and related organisms then now and tomorrow
Tropical Medicine and Infectious Disease, 2018Co-Authors: Daryl J. Kelly, Alison Lucefedrow, Marcie L Lehman, Kristin Mullins, Alice N Maina, Richard L Stewart, Heidi K St John, Ju JiangAbstract:Scrub typhus and the rickettsial diseases represent some of the oldest recognized vector-transmitted diseases, fraught with a rich historical aspect, particularly as applied to military/wartime situations. The vectors of Orientia tsutsugamushi were once thought to be confined to an area designated as the Tsutsugamushi Triangle. However, recent reports of scrub typhus caused by Orientia species other than O. tsutsugamushi well beyond the limits of the Tsutsugamushi Triangle have triggered concerns about the worldwide presence of scrub typhus. It is not known whether the vectors of O. tsutsugamushi will be the same for the new Orientia species, and this should be a consideration during outbreak/surveillance investigations. Additionally, concerns surrounding the antibiotic resistance of O. tsutsugamushi have led to considerations for the amendment of treatment protocols, and the need for enhanced public health awareness in both the civilian and medical professional communities. In this review, we discuss the history, outbreaks, antibiotic resistance, and burgeoning genomic advances associated with one of the world’s oldest recognized vector-borne pathogens, O. tsutsugamushi.
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Scrub Typhus: No Longer Restricted to the Tsutsugamushi Triangle
MDPI AG, 2018Co-Authors: Ju Jiang, Allen L. RichardsAbstract:Scrub typhus is the most important rickettsial disease in the world. Its previous endemic region was considered to be in Asia, Australia and islands in the Indian and Pacific Oceans; this area was referred to as the Tsutsugamushi Triangle. Accumulation of serological, molecular, genetic, and culture data have shown that not only is scrub typhus not limited to the Tsutsugamushi Triangle, but can be caused by Orientiae other than Orientia tsutsugamushi. This review describes evidence currently available that will be instrumental to researchers, healthcare providers and medical leaders in developing new research projects, performing diagnosis, and preventing scrub typhus in locations not previously thought to be endemic
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Diversity of the 47-kD HtrA nucleic acid and translated amino acid sequences from 17 recent human isolates of Orientia.
Vector borne and zoonotic diseases (Larchmont N.Y.), 2013Co-Authors: Ju Jiang, Rattanaphone Phetsouvanh, Daniel H. Paris, Stuart D. Blacksell, Leonard Izzard, Nuntipa Aukkanit, Paul N. Newton, John Stenos, Stephen Graves, Nicholas P. J. DayAbstract:Orientia tsutsugamushi, the etiologic agent of potentially fatal scrub typhus, is characterized by a high antigenic diversity, which complicates the development of a broadly protective vaccine. Efficacy studies in murine and nonhuman primate models demonstrated the DNA vaccine candidate pKarp47, based upon the O. tsutsugamushi Karp 47-kD HtrA protein gene, to be a successful immunoprophylactic against scrub typhus. To characterize 47-kD HtrA protein diversity among human isolates of Orientia, we sequenced the full open reading frame (ORF) of the 47-kD HtrA gene and analyzed the translated amino acid sequences of 17 patient isolates from Thailand (n=13), Laos (n=2), Australia (n=1), and the United Arab Emirates (UAE) (n=1) and 9 reference strains: Karp (New Guinea), Kato (Japan), Ikeda (Japan), Gilliam (Burma), Boryong (Korea), TA763, TH1811 and TH1817 (Thailand), and MAK243 (China). The percentage identity (similarity) of translated amino acid sequences between 16 new isolates and 9 reference strains of O. tsutsugamushi ranged from 96.4% to 100% (97.4% to 100%). However, inclusion of the recently identified Orientia chuto sp. nov. reduced identity (similarity) values to 82.2% to 83.3% (90.4% to 91.4%). These results demonstrate the diversity of Orientia 47-kD HtrA among isolates encountered by humans and therefore provide support for the necessity of developing a broadly protective scrub typhus vaccine that takes this diversity into account.
Nicholas P. J. Day - One of the best experts on this subject based on the ideXlab platform.
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Scrub typhus
Oxford Textbook of Medicine, 2020Co-Authors: Daniel H. Paris, Nicholas P. J. DayAbstract:Orientia spp. are obligate intracellular Gram-negative bacteria that cause scrub typhus, historically known as ‘tsutsugamushi disease’, a febrile illness characterized by early non-specific ‘flu-like’ symptoms, and sometimes a diffuse, macular, or maculopapular rash and/or a necrotic lesion eschar at the inoculation site. Leptotrombidium mites transmit Orientia spp. to humans via the bite of the larval stage, while all mite stages act as bacterial reservoirs through vertical transovarial and transstadial transmission. Scrub typhus is a leading cause of treatable undifferentiated febrile illness in many regions of Asia, and unfortunately remains an underappreciated neglected disease, mainly due to diagnostic difficulties and lack of awareness among medical staff. Complications include meningo-encephalitis, respiratory and renal failure, and severe multiorgan failure. Scrub typhus can be treated effectively with tetracyclines, macrolides, and chloramphenicol. Humans are dead-end hosts and do not participate in the Orientia life cycle, hence treatment does not affect overall disease incidence.
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long read whole genome sequencing and comparative analysis of six strains of the human pathogen Orientia tsutsugamushi
bioRxiv, 2018Co-Authors: Elizabeth M Batty, Daniel H. Paris, Stuart D. Blacksell, Nicholas P. J. Day, Suwittra Chaemchuen, Rory Bowden, Caroline Chan, Ramkumar Lachumanan, Peter Donnelly, Swaine L ChenAbstract:Background: Orientia tsutsugamushi is a clinically important but neglected obligate intracellular bacterial pathogen of the Rickettsiaceae family that causes the potentially life-threatening human disease scrub typhus. In contrast to the genome reduction seen in many obligate intracellular bacteria, early genetic studies of Orientia have revealed one of the most repetitive bacterial genomes sequenced to date. The dramatic expansion of mobile elements has hampered efforts to generate complete genome sequences using short read sequencing methodologies, and consequently there have been few studies of the comparative genomics of this neglected species. Results: We report new high-quality genomes of Orientia tsutsugamushi, generated using PacBio single molecule long read sequencing, for six strains: Karp, Kato, Gilliam, TA686, UT76 and UT176. In comparative genomics analyses of these strains together with existing reference genomes from Ikeda and Boryong strains, we identify a relatively small core genome of 657 genes, grouped into core gene islands and separated by repeat regions, and use the core genes to infer the first whole-genome phylogeny of Orientia. Conclusions: Complete assemblies of multiple Orientia genomes verify initial suggestions that these are remarkable organisms. They have large genomes with widespread amplification of repeat elements and massive chromosomal rearrangements between strains. At the gene level, Orientia has a relatively small set of universally conserved genes, similar to other obligate intracellular bacteria, and the relative expansion in genome size can be accounted for by gene duplication and repeat amplification. Our study demonstrates the utility of long read sequencing to investigate complex bacterial genomes and characterise genomic variation.
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Chapter 112 – Orientia
Molecular Medical Microbiology, 2015Co-Authors: Daniel H. Paris, Allen L. Richards, Nicholas P. J. DayAbstract:Orientia spp. are obligate intracellular Gram-negative bacteria, with Leptotrombidium mites acting as both reservoirs and transmission vectors. The disease, caused by Orientia spp. (commonly called scrub typhus) is characterised by early non-specific ‘flu-like’ symptoms, and sometimes a diffuse, macular and/or maculopapular rash and/or an eschar at the mite bite site. Complicated scrub typhus includes meningoencephalitis, respiratory and renal failure, which can develop into severe multiorgan failure. Scrub typhus is the leading cause of undifferentiated febrile illness in many regions of Asia. Despite its treatable nature, scrub typhus remains an underappreciated, neglected disease, mainly due to diagnostic difficulties and lack of awareness among medical staff. The development of diagnostics and vaccines difficulties challenging, due to the immunogenic diversity of Orientia strains, the weak and transient cross-protection among divergent isolates, and the loss of heterologous protection within a few years after natural infection.
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chapter 112 Orientia
Molecular Medical Microbiology (Second Edition), 2015Co-Authors: Daniel H. Paris, Allen L. Richards, Nicholas P. J. DayAbstract:Orientia spp. are obligate intracellular Gram-negative bacteria, with Leptotrombidium mites acting as both reservoirs and transmission vectors. The disease, caused by Orientia spp. (commonly called scrub typhus) is characterised by early non-specific ‘flu-like’ symptoms, and sometimes a diffuse, macular and/or maculopapular rash and/or an eschar at the mite bite site. Complicated scrub typhus includes meningoencephalitis, respiratory and renal failure, which can develop into severe multiorgan failure. Scrub typhus is the leading cause of undifferentiated febrile illness in many regions of Asia. Despite its treatable nature, scrub typhus remains an underappreciated, neglected disease, mainly due to diagnostic difficulties and lack of awareness among medical staff. The development of diagnostics and vaccines difficulties challenging, due to the immunogenic diversity of Orientia strains, the weak and transient cross-protection among divergent isolates, and the loss of heterologous protection within a few years after natural infection.
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Diversity of the 47-kD HtrA nucleic acid and translated amino acid sequences from 17 recent human isolates of Orientia.
Vector borne and zoonotic diseases (Larchmont N.Y.), 2013Co-Authors: Ju Jiang, Rattanaphone Phetsouvanh, Daniel H. Paris, Stuart D. Blacksell, Leonard Izzard, Nuntipa Aukkanit, Paul N. Newton, John Stenos, Stephen Graves, Nicholas P. J. DayAbstract:Orientia tsutsugamushi, the etiologic agent of potentially fatal scrub typhus, is characterized by a high antigenic diversity, which complicates the development of a broadly protective vaccine. Efficacy studies in murine and nonhuman primate models demonstrated the DNA vaccine candidate pKarp47, based upon the O. tsutsugamushi Karp 47-kD HtrA protein gene, to be a successful immunoprophylactic against scrub typhus. To characterize 47-kD HtrA protein diversity among human isolates of Orientia, we sequenced the full open reading frame (ORF) of the 47-kD HtrA gene and analyzed the translated amino acid sequences of 17 patient isolates from Thailand (n=13), Laos (n=2), Australia (n=1), and the United Arab Emirates (UAE) (n=1) and 9 reference strains: Karp (New Guinea), Kato (Japan), Ikeda (Japan), Gilliam (Burma), Boryong (Korea), TA763, TH1811 and TH1817 (Thailand), and MAK243 (China). The percentage identity (similarity) of translated amino acid sequences between 16 new isolates and 9 reference strains of O. tsutsugamushi ranged from 96.4% to 100% (97.4% to 100%). However, inclusion of the recently identified Orientia chuto sp. nov. reduced identity (similarity) values to 82.2% to 83.3% (90.4% to 91.4%). These results demonstrate the diversity of Orientia 47-kD HtrA among isolates encountered by humans and therefore provide support for the necessity of developing a broadly protective scrub typhus vaccine that takes this diversity into account.
Young-sang Koh - One of the best experts on this subject based on the ideXlab platform.
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intracellular invasion of Orientia tsutsugamushi activates inflammasome in asc dependent manner
PLOS ONE, 2012Co-Authors: Jung-eun Koo, Hyejin Hong, Andrea Dearth, Koichi Kobayashi, Young-sang KohAbstract:Orientia tsutsugamushi, a causative agent of scrub typhus, is an obligate intracellular bacterium, which escapes from the endo/phagosome and replicates in the host cytoplasm. O. tsutsugamushi infection induces production of pro-inflammatory mediators including interleukin-1β (IL-1β), which is secreted mainly from macrophages upon cytosolic stimuli by activating cysteine protease caspase-1 within a complex called the inflammasome, and is a key player in initiating and maintaining the inflammatory response. However, the mechanism for IL-1β maturation upon O. tsutsugamushi infection has not been identified. In this study, we show that IL-1 receptor signaling is required for efficient host protection from O. tsutsugamushi infection. Live Orientia, but not heat- or UV-inactivated Orientia, activates the inflammasome through active bacterial uptake and endo/phagosomal maturation. Furthermore, Orientia-stimulated secretion of IL-1β and activation of caspase-1 are ASC- and caspase-1- dependent since IL-1β production was impaired in Asc- and caspase-1-deficient macrophages but not in Nlrp3-, Nlrc4- and Aim2-deficient macrophages. Therefore, live O. tsutsugamushi triggers ASC inflammasome activation leading to IL-1β production, which is a critical innate immune response for effective host defense.
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Structural and transcriptional analysis of gene clusters for a type IV secretion system in Orientia tsutsugamushi
World Journal of Microbiology and Biotechnology, 2009Co-Authors: Jung-eun Koo, Young-sang KohAbstract:Orientia tsutsugamushi, an obligatory intracellular bacterium, is the causative agent of scrub typhus. Here, we identified and characterized Orientia clusters of genes for a type IV secretion system (T4SS). Two clusters of virB-virD4 loci were found in the Orientia genome. One cluster consisted of three vir genes (virB3, virB4, and virB6) and included three additional virB6-like coding sequences. The other cluster was composed of five genes (virB8, virB9, virB10, virB11, and virD4). These five genes were polycistronically transcribed as an operon. Several virB and virD4 genes of O. tsutsugamushi were transcriptionally active in cultured fibroblast and macrophage cell lines as well as in experimentally infected animals. This finding suggests that the T4SS may function in Orientia and may have a significant role in pathogenesis of scrub typhus.
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Mitogen-activated protein kinases and tumor necrosis factor alpha responses of macrophages infected with Orientia tsutsugamushi
World Journal of Microbiology and Biotechnology, 2009Co-Authors: Ji-hyun Yun, Jung-eun Koo, Young-sang KohAbstract:Orientia tsutsugamushi , an obligatory intracellular bacterium, is the causative agent of scrub typhus. The disease is histopathologically characterized by inflammatory manifestations, indicating that Orientiae induce mechanisms that amplify the inflammatory response. Here we investigated the transcriptional response of tumor necrosis factor alpha (TNF-α) gene and the host cell responses of nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs) to O. tsutsugamushi . Induction of the TNF-α gene was not blocked by a eukaryotic protein synthesis inhibitor cycloheximide, suggesting that de novo synthesis of host cell protein is not required for this transcriptional response. The induction of TNF-α mRNA by O. tsutsugamushi was not blocked by the inhibitors of NF-κB activation. Inactivation of Orientia by heat abolished both MAPK activation and TNF-α production, whereas treatment of host cells with cytochalasin D impaired neither NF-κB and MAPK activation nor TNF-α production. In conclusion, our data suggest that O. tsutsugamushi -stimulated TNF-α production and MAPK activation requires cellular attachment by viable Orientiae but not bacterial internalization into the host cells.
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Activation of mitogen‐activated protein kinases is involved in the induction of interferon β gene in macrophages infected with Orientia tsutsugamushi
Microbiology and immunology, 2009Co-Authors: Jung-eun Koo, Ji-hyun Yun, Keun-hwa Lee, Jin-won Hyun, Hee-kyoung Kang, Won-jong Jang, Kyung-hee Park, Young-sang KohAbstract:We investigated the role of MAPK in IFN-β gene expression in macrophages after infection with Orientia tsutsugamushi. ERK1/2 became phosphorylated in Orientia-stimulated macrophages. Selective inhibition of ERK1/2 and p38 MAPK could all significantly reduce Orientia-stimulated IFN-β mRNA expression. Orientia inactivation by heat abolished IFN-β mRNA induction only, whereas cytochalasin D treatment completely blocked both IFN-β and chemokine expression, suggesting requirement of cellular internalization by viable bacteria for IFN-β gene induction. In conclusion, our data indicate that MAPK pathways are required to induce maximal IFN-β gene expression in macrophages during Orientia infection.
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Mitogen-activated protein kinases are involved in tumor necrosis factor alpha production in macrophages infected with Orientia tsutsugamushi.
Microbiology and immunology, 2009Co-Authors: Ji-hyun Yun, Jung-eun Koo, Young-sang KohAbstract:Orientia tsutsugamushi, an obligatory intracellular bacterium, is the causative agent of scrub typhus. Here the role of MAPK in TNF-α production in macrophages after infection with O. tsutsugamushi has been investigated. ERK1/2, JNK, and p38 MAPK became phosphorylated in Orientia-stimulated macrophages. Selective inhibitors of MAPK cascades could all significantly reduce Orientia-stimulated TNF-α production. Orientia-stimulated TNF-α production via p38 and JNK pathways was regulated by a post-transcriptional mechanism, whereas the ERK pathway mainly controlled the transcriptional step of TNF-α gene expression during infection. In conclusion, our data indicate that MAPK signaling is required to induce maximal TNF-α production in macrophages during Orientia infection.
Katia Abarca - One of the best experts on this subject based on the ideXlab platform.
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Identification of trombiculid mites (Acari: Trombiculidae) on rodents from Chiloé Island and molecular evidence of infection with Orientia species.
PLoS neglected tropical diseases, 2020Co-Authors: Gerardo Acosta-jamett, Allen L. Richards, Ju Jiang, Constanza Martínez-valdebenito, Esperanza Beltrami, María Carolina Silva-de La Fuente, Thomas Weitzel, Katia AbarcaAbstract:Background Scrub typhus is an emerging vector-borne zoonosis, caused by Orientia spp. and transmitted by larvae of trombiculid mites, called chiggers. It mainly occurs within a region of the Asia-Pacific called the tsutsugamushi triangle, where rodents are known as the most relevant hosts for the trombiculid vector. However, the reservoir(s) and vector(s) of the scrub typhus outside Asia-Pacific are unknown. The disease has recently been discovered on and is considered endemic for Chiloe Island in southern Chile. The aim of the present work was to detect and determine the prevalence of chiggers on different rodent species captured in probable sites for the transmission of Orientiae responsible for scrub typhus on Chiloe Island in southern Chile and to molecularly examine collected chiggers for the presence of Orientia DNA. Methodology/Principal findings During the austral summer 2018, rodents were live-trapped in six sites and examined for chigger infestation. All study sites were rural areas on Chiloe Island, previously identified as probable localities where human cases acquired the scrub typhus. During a total of 4,713 trap-nights, 244 rodents of seven species were captured: the most abundant was Abrothrix olivacea. Chiggers were detected on all seven rodent species with a 55% prevalence rate. Chiggers showed low host specificity and varied according to site specific host abundance. Three genera of trombiculids were identified. Herpetacarus was the most abundant genus (93%), prevalent in five of the six sites. Infestation rates showed site specific differences, which were statistically significant using a GLM model with binomial errors. Molecular analyses proved that 21 of 133 (15.8%) mite pools were positive for Orientia species, all of them belonged to the genus Herpetacarus. Conclusions/Significance This study firstly reports the presence of different rodent-associated chigger mites positive for Orientia sp., in a region endemic for scrub typhus in southern Chile. Herpetacarus and two other genera of mites were found with high infestation rates of rodents in sites previously identified as probable exposure of scrub typhus cases. A substantial percentage of mite pools were positive for Orientia DNA, suggesting that chigger mites serve as vectors and reservoirs of this emerging zoonosis in South America.
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Molecular Description of a Novel Orientia Species Causing Scrub Typhus in Chile.
Emerging infectious diseases, 2020Co-Authors: Katia Abarca, Allen L. Richards, Ju Jiang, Gerardo Acosta-jamett, Constanza Martínez-valdebenito, Jenniffer Angulo, Christina M. Farris, Thomas WeitzelAbstract:Scrub typhus is a potentially fatal rickettsiosis caused by Orientia species intracellular bacteria of the genus Orientia. Although considered to be restricted to the Asia Pacific region, scrub typhus has recently been discovered in southern Chile. We analyzed Orientia gene sequences of 16S rRNA (rrs) and 47-kDa (htrA) from 18 scrub typhus patients from Chile. Sequences were ≥99.7% identical among the samples for both amplified genes. Their diversity was 3.1%-3.5% for rrs and 11.2%-11.8% for htrA compared with O. tsusugamushi and 3.0% for rrs and 14.8% for htrA compared with Candidatus Orientia chuto. Phylogenetic analyses of both genes grouped the specimens from Chile in a different clade from other Orientia species. Our results indicate that Orientia isolates from Chile constitute a novel species, which, until they are cultivated and fully characterized, we propose to designate as Candidatus Orientia chiloensis, after the Chiloe Archipelago where the pathogen was identified.
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endemic scrub typhus like illness chile
Emerging Infectious Diseases, 2011Co-Authors: Maria Elvira Balcells, Daryl J. Kelly, Ju Jiang, Katia Abarca, Ricardo Rabagliati, Patricia Garcia, Helena Poggi, D Oddo, Marcela Concha, Allen L. RichardsAbstract:We report a case of scrub typhus in a 54-year-old man who was bitten by several terrestrial leeches during a trip to Chiloe Island in southern Chile in 2006. A molecular sample, identified as related to Orientia tsutsugamushi based on the sequence of the16S rRNA gene, was obtained from a biopsy specimen of the eschar on the patient’s leg. Serologic analysis showed immunoglobulin G conversion against O. tsutsugamushi whole cell antigen. This case and its associated molecular analyses suggest that an Orientia-like agent is present in the Western Hemisphere that can produce scrub typhus–like illness. The molecular analysis suggests that the infectious agent is closely related, although not identical, to members of the Orientia sp. from Asia.