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Multiple Orientia clusters and Th1-skewed chemokine profile: a cross-sectional study in patients with scrub typhus from Nepal. Int J Infect Dis 2023; 128:78-87. [PMID: 36566774 DOI: 10.1016/j.ijid.2022.12.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 12/13/2022] [Accepted: 12/18/2022] [Indexed: 12/24/2022] Open
Abstract
OBJECTIVES Scrub typhus is an emerging infectious disease in Asia caused by Orientia tsutsugamushi (Ot). From Nepal, only scant data on the genetic epidemiology of this agent is available, and determinants of immunoregulation are poorly understood. METHODS Patients (n = 238) referred to the National Public Health Laboratory (Kathmandu, Nepal) from all over Nepal for suspected scrub typhus were enrolled upon positive immunoglobulin (Ig)M testing between July and October 2015. From Ot 16S and 47 kD polymerase chain reaction (PCR)-positive samples, the variable domain I of the 56 kD gene was sequenced and phylogenetically analyzed. T helper (Th) cell-associated cytokines (n = 13) and chemokines (n = 12) were quantified by multiplex bead arrays. RESULTS In 93/238 (39.1%) IgM-positive samples, Ot DNA was detected by quantitative PCR. Phylogenetic analysis of 56 kD sequences revealed seven distinct clusters, six of them with high homologies to strains detected in other countries. The Th1-related cytokines interferon-γ and C-X-C motif chemokine ligand 10 were strongly upregulated and correlated with bacteremia, while levels of Th2-associated chemokines were reduced. Bacteremia also correlated with concentrations of interleukin (IL)-6 and IL-10 but not tumor necrosis factor-α. CONCLUSION We identified a considerable genetic heterogeneity of human-pathogenic Ot strains circulating in Nepal. Acute Nepalese scrub typhus patients showed strong Th1 but impaired Th2 responses, especially on the chemokine level.
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An Alternative Splicing Variant of the Mixed-Lineage Leukemia 5 Protein Is a Cellular Adhesion Receptor for ScaA of Orientia tsutsugamushi. mBio 2023; 14:e0154322. [PMID: 36541760 PMCID: PMC9973269 DOI: 10.1128/mbio.01543-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Scrub typhus is a mite-borne disease caused by the obligately intracellular bacterium Orientia tsutsugamushi. We previously demonstrated that ScaA, an autotransporter membrane protein of O. tsutsugamushi, is commonly shared in various genotypes and involved in adherence to host cells. Here, we identified a mixed-lineage leukemia 5 (MLL5) mammalian trithorax group protein as a host receptor that interacts with ScaA. MLL5, identified by yeast two-hybrid screening, is an alternative splicing variant of MLL5 (vMLL5) which contains 13 exons with additional intron sequences encoding a tentative transmembrane domain. Indeed, vMLL5 is expressed on the plasma membrane as well as in intracellular compartments in eukaryotic cells and colocalized with adherent O. tsutsugamushi. In addition, ScaA-expressing Escherichia coli showed significantly increased adherence to vMLL5-overexpressing cells compared with vector control cells. We mapped the C-terminal region of the passenger domain of ScaA as a ligand for vMLL5 and determined that the Su(var)3-9, Enhancer of zeste, Trithorax (SET) domain of MLL5 is an essential and sufficient motif for ScaA binding. We observed significant and specific inhibition of bacterial adhesion to host cells in competitive inhibition assays using the C-terminal fragment of ScaA or the SET domain of vMLL5. Moreover, immunization with the C-terminal fragment of ScaA provided neutralizing activity and protective immunity against lethal challenge with O. tsutsugamushi as efficiently as vaccination with the whole passenger domain of ScaA. These results indicate that vMLL5 is a novel cellular receptor for ScaA-mediated adhesion of O. tsutsugamushi and facilitates bacterial adhesion to host cells, thereby enhancing bacterial infection. IMPORTANCE O. tsutsugamushi is a mite-borne pathogen that causes scrub typhus. As an obligately intracellular pathogen, its adhesion to and invasion of host cells are critical steps for bacterial growth. However, the molecular basis of the bacterial ligand and host receptor interaction is poorly defined. Here, we identified a splicing variant of MLL5 (vMLL5) as a cellular adhesion receptor of ScaA, an outer membrane autotransporter protein of O. tsutsugamushi. We mapped the interacting domains in the bacterial ligand and host receptor and confirmed their functional interaction. In addition, immunization with the C-terminal region of ScaA, which involves an interaction with the SET domain of vMLL5, not only induces enhanced neutralizing antibodies but also provides protective immunity against lethal challenge with O. tsutsugamushi.
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Genetic recombination of Orientia tsutsugamushi strains from scrub typhus patients in Guangxi, Southwest China, and the analysis of clinical features. Microbes Infect 2023; 25:105098. [PMID: 36621527 DOI: 10.1016/j.micinf.2023.105098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 12/27/2022] [Accepted: 12/31/2022] [Indexed: 01/07/2023]
Abstract
Three Orientia tsutsugamushi genotypic groups belonging to two prototypes (Gilliam and Karp) were identified in scrub typhus patients from Guangxi, Southwest China. Fever, headache, pneumonia, fatigue, chill, and anorexia were the most common clinical signs. Frequent recombination was observed for their 47-kDa gene compared to 56-kDa and 16S genes. Furthermore, patients infected with the Gilliam prototype represent a much higher proportion of pneumonia (6/6, 100%) than those infected with the Karp prototype (4/8, 50%) (p-value=0.040). This discrepancy is consistent with recent animal tests on rhesus and may indicate different virulence and tissue tropism between different O. tsutsugamushi prototypes.
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Tang C, Zhang L, Huang Y, Mai W, Xue L, Wang G, Wen S, Peng R, Wu K, Tian X, Pei H, Du J, Yuen KY, Chan JFW, Du Y, Yin F. Mixed genotypes of Orientia tsutsugamushi in conserved genes and a single immune-dominant tsa56 genotype discovered from a patient with scrub typhus in Hainan Island, China: a case report. BMC Infect Dis 2022; 22:698. [PMID: 35986264 PMCID: PMC9389790 DOI: 10.1186/s12879-022-07682-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 08/11/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Orientia tsutsugamushi (O. tsutsugamushi), an obligate intracellular bacterium, is transmitted to humans through infected larval trombiculid mite bites, causing scrub typhus. Mixed genotypes of O. tsutsugamushi in canonical conserved genes were reported in 8–25% of blood samples from patients. Yet, there are few clinical descriptions of these mixed O. tsutsugamushi-infected patients.
Case presentation
We report a patient with scrub typhus complicated with pulmonary involvement and hepatic dysfunction, who carried mixed genotypes of the conserved genes but had a single immune-dominant 56-kDa type-specific antigen (tsa56) genotype. The patient was successfully recovered by doxycycline treatment.
Conclusions
In this reported case, both patient’s eschar and blood samples have repeatedly shown the same results, i.e., no variants were discovered in tsa56 gene that bears multiple hypervariable regions. Whereas the selected highly conserved genes were identified with up to 32 variants in a 2700 base-pair concatenated sequence. The prevalence, disease severity and mechanism of these single-tsa56-genotype mixed infections remain to be investigated on a large scale with more cases.
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Hwang JH, Kim J, Sun IO, Lee TH, Chung KM, Lee CS. New Genotypes and Diversity of Orientia tsutsugamushi DNA samples from Patients with Scrub Typhus in South Korea as Determined by Multilocus Sequence Typing. Am J Trop Med Hyg 2022; 107:420-426. [PMID: 35895396 PMCID: PMC9393445 DOI: 10.4269/ajtmh.21-0850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 03/19/2022] [Indexed: 08/03/2023] Open
Abstract
Orientia tsutsugamushi, an obligate intracellular organism, is the causative agent of scrub typhus. Multilocus sequence typing (MLST) is a genetic typing method that provides a unified bacterial isolate characterization approach. However, there are no comparative studies in South Korea on the genotypic properties of O. tsutsugamushi based on MLST. To conduct a comparative analysis with previous data collected from Thailand, Laos, and Japan, we investigated the genetic diversity of O. tsutsugamushi from 51 patients with scrub typhus in South Korea by using MLST. The MLST analysis revealed 10 new alleles in the housekeeping genes: gpsA, n = 2; mdh, n = 1; nrdB, n = 1; nuoF, n = 1; ppdK, n = 1; sucB, n = 2; and sucD, n = 2. These novel alleles led to the assignment of six new sequence types (STs) (ST93-98). The 51 samples corresponded to seven different STs (ST48 and ST93-98), with ST48 accounting for the largest proportion (49.0%) of O. tsutsugamushi STs in South Korea. Interestingly, O. tsutsugamushi from patients with scrub typhus in South Korea were clustered in two different clades, and the five Korean STs (ST48, ST93, ST94, ST95, and ST98) were close genetically to ST80, which was isolated from Laos. The remaining two STs (ST96 and ST97) were close genetically to ST49 (Ikeda, Japan). Overall, our results suggest that the relative genetic stability and the clonal populations of O. tsutsugamushi strains in South Korea have remained mostly conserved.
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Affiliation(s)
- Joo-Hee Hwang
- Department of Internal Medicine, Jeonbuk National University Medical School, Jeonju, Republic of Korea
- Research Institute of Clinical Medicine of Jeonbuk National University–Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju, Republic of Korea
| | - Jeongsik Kim
- Faculty of Science Education, Jeju National University, Jeju, Republic of Korea
- Interdisciplinary Graduate Program in Advanced Convergence Technology & Science, Jeju National University, Jeju, Republic of Korea
| | - In O. Sun
- Department of Internal Medicine, Presbyterian Medical Center, Jeonju, Republic of Korea
| | - Tae Hee Lee
- Department of Microbiology and Immunology, Jeonbuk National University Medical School, Jeonju, Republic of Korea
- Institute for Medical Science, Jeonbuk National University Medical School, Jeonju, Republic of Korea
| | - Kyung Min Chung
- Research Institute of Clinical Medicine of Jeonbuk National University–Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju, Republic of Korea
- Department of Microbiology and Immunology, Jeonbuk National University Medical School, Jeonju, Republic of Korea
- Institute for Medical Science, Jeonbuk National University Medical School, Jeonju, Republic of Korea
| | - Chang-Seop Lee
- Department of Internal Medicine, Jeonbuk National University Medical School, Jeonju, Republic of Korea
- Research Institute of Clinical Medicine of Jeonbuk National University–Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju, Republic of Korea
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Baidya A, Gunasekaran D, Dhodapkar R, Parameswaran N, Kaliaperumal V. Prevalence, clinico-laboratory features, and the functional outcome of children with scrub typhus meningoencephalitis-a cohort study. J Trop Pediatr 2022; 68:6712681. [PMID: 36150144 DOI: 10.1093/tropej/fmac077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Scrub typhus is being reported as the most common cause of childhood meningoencephalitis (ME) in India. Hence, we planned to estimate the proportion of scrub typhus infection among children aged 1 month to 12 years with the clinical diagnosis of ME and to evaluate their demographic, clinical and laboratory characteristics. This cohort study was conducted in the Department of Pediatrics of a tertiary care teaching hospital in south India. One hundred and twenty-seven consecutive children aged 1 month to 12 years with the clinical diagnosis of ME were the participants. Their socio-demographic factors, clinical details, laboratory reports and outcomes were analyzed. The etiological agent was identified in 71 (56%) children. Orientia tsutsugamushi (Scrub typhus) was the most common infection (24.4%), of all children with ME. Children aged ≥5 years were frequently affected by scrub typhus ME. Eschar, capillary leak, hepatomegaly and splenomegaly were the predominant clinical features of scrub typhus ME. Thrombocytopenia and deranged liver function tests were common in scrub typhus ME. To conclude, Orientia tsutsugamushi was the most common organism identified in our study. Prompt recognition of some tell-tale clinical signs of scrub typhus (such as eschar, thrombocytopenia and hepatosplenomegaly), and timely initiation of antibiotics would lead to better outcomes as evident from the study.
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Affiliation(s)
- Amitava Baidya
- Department of Pediatrics, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry 605006, India
| | - Dhandapany Gunasekaran
- Department of Pediatrics, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry 605006, India
| | - Rahul Dhodapkar
- Department of Microbiology, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry 605006, India
| | - Narayanan Parameswaran
- Department of Pediatrics, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry 605006, India
| | - Venkatesh Kaliaperumal
- Department of Microbiology, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry 605006, India
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Orientia tsutsugamushi Nucleomodulin Ank13 Exploits the RaDAR Nuclear Import Pathway To Modulate Host Cell Transcription. mBio 2021; 12:e0181621. [PMID: 34340535 PMCID: PMC8406279 DOI: 10.1128/mbio.01816-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Orientia tsutsugamushi is the etiologic agent of scrub typhus, the deadliest of all diseases caused by obligate intracellular bacteria. Nucleomodulins, bacterial effectors that dysregulate eukaryotic transcription, are being increasingly recognized as key virulence factors. How they translocate into the nucleus and their functionally essential domains are poorly defined. We demonstrate that Ank13, an O. tsutsugamushi effector conserved among clinical isolates and expressed during infection, localizes to the nucleus in an importin β1-independent manner. Rather, Ank13 nucleotropism requires an isoleucine at the thirteenth position of its fourth ankyrin repeat, consistent with utilization of eukaryotic RaDAR (RanGDP-ankyrin repeats) nuclear import. RNA-seq analyses of cells expressing green fluorescent protein (GFP)-tagged Ank13, nucleotropism-deficient Ank13I127R, or Ank13ΔF-box, which lacks the F-box domain essential for interacting with SCF ubiquitin ligase, revealed Ank13 to be a nucleomodulin that predominantly downregulates transcription of more than 2,000 genes. Its ability to do so involves its nucleotropism and F-box in synergistic and mutually exclusive manners. Ank13 also acts in the cytoplasm to dysregulate smaller cohorts of genes. The effector’s toxicity in yeast heavily depends on its F-box and less so on its nucleotropism. Genes negatively regulated by Ank13 include those involved in the inflammatory response, transcriptional control, and epigenetics. Importantly, the majority of genes that GFP-Ank13 most strongly downregulates are quiescent or repressed in O. tsutsugamushi-infected cells when Ank13 expression is strongest. Ank13 is the first nucleomodulin identified to coopt RaDAR and a multifaceted effector that functions in the nucleus and cytoplasm via F-box-dependent and -independent mechanisms to globally reprogram host cell transcription.
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Imported scrub typhus in Europe: Report of three cases and a literature review. Travel Med Infect Dis 2021; 42:102062. [PMID: 33862243 DOI: 10.1016/j.tmaid.2021.102062] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 04/07/2021] [Accepted: 04/09/2021] [Indexed: 11/21/2022]
Abstract
BACKGROUND Scrub typhus is a vector-borne rickettsial infection, which can cause relevant morbidity and mortality. While the number of cases is around a million per year globally, the infection is seldom diagnosed in travellers from Europe. METHODS We herein report three cases diagnosed in Italian travellers and review the literature about imported cases in Europe in the last 60 years. RESULTS Three participants to the same hiking trip to the forest of northern Laos presented fever and other symptoms, including eschars (2 individuals) and skin rash (2 individuals). Overall, they didn't report complications, and recovered soon after doxycycline treatment. Diagnosis was retrospectively confirmed with PCR in one of them. The review collected data from 40 patients. Almost all of them (95%) presented fever, more than a half had headache, skin rash, eschars, arthromyalgias. 73% of them were hospitalized, and 16.2% needed intensive care. Diagnosis was confirmed by serology in almost all cases (94.6%). Most patients (88%) were treated with doxycycline. All patients survived, although one case resulted in incomplete tetraparesis. CONCLUSIONS Scrub typhus should be considered in all travellers coming back from endemic areas and presenting with acute febrile illness. Laboratory diagnosis can be challenging, as specific tests are not widely available. In case of clinical suspicion, a prompt treatment with oral doxycycline could avoid severe complications.
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Elliott I, Thangnimitchok N, de Cesare M, Linsuwanon P, Paris DH, Day NPJ, Newton PN, Bowden R, Batty EM. Targeted capture and sequencing of Orientia tsutsugamushi genomes from chiggers and humans. INFECTION GENETICS AND EVOLUTION 2021; 91:104818. [PMID: 33771726 PMCID: PMC8164161 DOI: 10.1016/j.meegid.2021.104818] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 03/18/2021] [Accepted: 03/22/2021] [Indexed: 12/12/2022]
Abstract
Scrub typhus is a febrile disease caused by Orientia tsutsugamushi, transmitted by larval stage Trombiculid mites (chiggers), whose primary hosts are small mammals. The phylogenomics of O. tsutsugamushi in chiggers, small mammals and humans remains poorly understood. To combat the limitations imposed by the low relative quantities of pathogen DNA in typical O. tsutsugamushi clinical and ecological samples, along with the technical, safety and cost limitations of cell culture, a novel probe-based target enrichment sequencing protocol was developed. The method was designed to capture variation among conserved genes and facilitate phylogenomic analysis at the scale of population samples. A whole-genome amplification step was incorporated to enhance the efficiency of sequencing by reducing duplication rates. This resulted in on-target capture rates of up to 93% for a diverse set of human, chigger, and rodent samples, with the greatest success rate in samples with real-time PCR Ct values below 35. Analysis of the best-performing samples revealed phylogeographic clustering at local, provincial and international scales. Applying the methodology to a comprehensive set of samples could yield a more complete understanding of the ecology, genomic evolution and population structure of O. tsutsugamushi and other similarly challenging organisms, with potential benefits in the development of diagnostic tests and vaccines.
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Affiliation(s)
- Ivo Elliott
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom.
| | - Neeranuch Thangnimitchok
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
| | | | - Piyada Linsuwanon
- Department of Entomology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Daniel H Paris
- Department of Medicine, Swiss Tropical and Public Health Institute, Basel, Switzerland; Department of Clinical Research, University of Basel, Basel, Switzerland
| | - Nicholas P J Day
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom; Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Paul N Newton
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom; Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Rory Bowden
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom; Division of Advanced Technology and Biology, Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Elizabeth M Batty
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom; Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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Jiang J, Farris CM, Yeh KB, Richards AL. International Rickettsia Disease Surveillance: An Example of Cooperative Research to Increase Laboratory Capability and Capacity for Risk Assessment of Rickettsial Outbreaks Worldwide. Front Med (Lausanne) 2021; 8:622015. [PMID: 33738293 PMCID: PMC7960665 DOI: 10.3389/fmed.2021.622015] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 01/20/2021] [Indexed: 01/30/2023] Open
Abstract
Cooperative research that addresses infectious disease surveillance and outbreak investigations relies heavily on availability and effective use of appropriate diagnostic tools, including serological and molecular assays, as exemplified by the current COVID-19 pandemic. In this paper, we stress the importance of using these assays to support collaborative epidemiological studies to assess risk of rickettsial disease outbreaks among international partner countries. Workforce development, mentorship, and training are important components in building laboratory capability and capacity to assess risk of and mitigate emerging disease outbreaks. International partnerships that fund cooperative research through mentoring and on-the-job training are successful examples for enhancing infectious disease surveillance. Cooperative research studies between the Naval Medical Research Center's Rickettsial Diseases Research Program (RDRP) and 17 institutes from nine countries among five continents were conducted to address the presence of and the risk for endemic rickettsial diseases. To establish serological and molecular assays in the collaborative institutes, initial training and continued material, and technical support were provided by RDRP. The laboratory methods used in the research studies to detect and identify the rickettsial infections included (1) group-specific IgM and IgG serological assays and (2) molecular assays. Twenty-six cooperative research projects performed between 2008 and 2020 enhanced the capability and capacity of 17 research institutes to estimate risk of rickettsial diseases. These international collaborative studies have led to the recognition and/or confirmation of rickettsial diseases within each of the partner countries. In addition, with the identification of specific pathogen and non-pathogen Rickettsia species, a more accurate risk assessment could be made in surveillance studies using environmental samples. The discoveries from these projects reinforced international cooperation benefiting not only the partner countries but also the scientific community at large through presentations (n = 40) at international scientific meetings and peer-reviewed publications (n = 18). The cooperative research studies conducted in multiple international institutes led to the incorporation of new SOPs and trainings for laboratory procedures; biosafety, biosurety, and biosecurity methods; performance of rickettsia-specific assays; and the identification of known and unknown rickettsial agents through the introduction of new serologic and molecular assays that complemented traditional microbiology methods.
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Affiliation(s)
- Ju Jiang
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD, United States
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD, United States
| | - Christina M. Farris
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD, United States
| | | | - Allen L. Richards
- Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
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Paris DH, Kelly DJ, Fuerst PA, Day NPJ, Richards AL. A Brief History of the Major Rickettsioses in the Asia-Australia-Pacific Region: A Capstone Review for the Special Issue of TMID. Trop Med Infect Dis 2020; 5:tropicalmed5040165. [PMID: 33121158 PMCID: PMC7709643 DOI: 10.3390/tropicalmed5040165] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 10/15/2020] [Accepted: 10/16/2020] [Indexed: 12/19/2022] Open
Abstract
The rickettsioses of the "Far East" or Asia-Australia-Pacific region include but are not limited to endemic typhus, scrub typhus, and more recently, tick typhus or spotted fever. These diseases embody the diversity of rickettsial disease worldwide and allow us to interconnect the various contributions to this special issue of Tropical Medicine and Infectious Disease. The impact of rickettsial diseases-particularly of scrub typhus-was substantial during the wars and "police actions" of the last 80 years. However, the post-World War II arrival of effective antibiotics reduced their impact, when recognized and adequately treated (chloramphenicol and tetracyclines). Presently, however, scrub typhus appears to be emerging and spreading into regions not previously reported. Better diagnostics, or higher population mobility, change in antimicrobial policies, even global warming, have been proposed as possible culprits of this phenomenon. Further, sporadic reports of possible antibiotic resistance have received the attention of clinicians and epidemiologists, raising interest in developing and testing novel diagnostics to facilitate medical diagnosis. We present a brief history of rickettsial diseases, their relative importance within the region, focusing on the so-called "tsutsugamushi triangle", the past and present impact of these diseases within the region, and indicate how historically, these often-confused diseases were ingeniously distinguished from each another. Moreover, we will discuss the importance of DNA-sequencing efforts for Orientia tsutsugamushi, obtained from patient blood, vector chiggers, and rodent reservoirs, particularly for the dominant 56-kD type-specific antigen gene (tsa56), and whole-genome sequences, which are increasing our knowledge of the diversity of this unique agent. We explore and discuss the potential of sequencing and other effective tools to geographically trace rickettsial disease agents, and develop control strategies to better mitigate the rickettsioses.
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Affiliation(s)
- Daniel H. Paris
- Department of Medicine, Swiss Tropical and Public Health Institute, 4051 Basel, Switzerland
- Department of Clinical Research, University of Basel, 4051 Basel, Switzerland
- Correspondence: ; Tel.: +41-61-284-8111
| | - Daryl J. Kelly
- Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, OH 43210, USA; (D.J.K.); (P.A.F.)
| | - Paul A. Fuerst
- Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, OH 43210, USA; (D.J.K.); (P.A.F.)
| | - Nicholas P. J. Day
- Mahidol-Oxford Tropical Medicine Research Programme, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithee Road, Bangkok 10400, Thailand;
- Center for Tropical Medicine, Nuffield Department of Clinical Medicine, Churchill Hospital, Old Road, Headington, Oxford OX3 7LJ, UK
| | - Allen L. Richards
- Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA;
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Low VL, Tan TK, Khoo JJ, Lim FS, AbuBakar S. An overview of rickettsiae in Southeast Asia: Vector-animal-human interface. Acta Trop 2020; 202:105282. [PMID: 31778642 DOI: 10.1016/j.actatropica.2019.105282] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 11/24/2019] [Accepted: 11/24/2019] [Indexed: 02/07/2023]
Abstract
Rickettsioses are emerging, and re-emerging diseases caused by obligate intracellular arthropod-borne bacteria that infect humans and animals worldwide. Various rickettsiae such as Orientia, Rickettsia, Anaplasma and Ehrlichia have been circulated in companion, domesticated and wild animals through bites of infected ticks, fleas, lice or mites. This review summarizes the infections of rickettsiae, including the newly discovered regional species Rickettsia thailandii, Candidatus Rickettsia sepangensis, Candidatus Rickettsia johorensis, Candidatus Rickettsia laoensis, Candidatus Rickettsia mahosotii, Candidatus Rickettsia khammouanensis, Candidatus Anaplasma pangolinii, and other novel genotypes in vectors, humans and animals in Southeast Asia. Issues on some unidentified rickettsiae that elicit immune responses and production of antibodies that are cross-reactive with the antigens used are discussed. Knowledge gaps which required attention are also identified in this review.
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Affiliation(s)
- Van Lun Low
- Higher Institution Centre of Excellence (HICoE), Tropical Infectious Diseases Research and Education Centre (TIDREC), University of Malaya, Kuala Lumpur, Malaysia.
| | - Tiong Kai Tan
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Jing Jing Khoo
- Higher Institution Centre of Excellence (HICoE), Tropical Infectious Diseases Research and Education Centre (TIDREC), University of Malaya, Kuala Lumpur, Malaysia
| | - Fang Shiang Lim
- Higher Institution Centre of Excellence (HICoE), Tropical Infectious Diseases Research and Education Centre (TIDREC), University of Malaya, Kuala Lumpur, Malaysia
| | - Sazaly AbuBakar
- Higher Institution Centre of Excellence (HICoE), Tropical Infectious Diseases Research and Education Centre (TIDREC), University of Malaya, Kuala Lumpur, Malaysia; Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
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13
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Elliott I, Pearson I, Dahal P, Thomas NV, Roberts T, Newton PN. Scrub typhus ecology: a systematic review of Orientia in vectors and hosts. Parasit Vectors 2019; 12:513. [PMID: 31685019 PMCID: PMC6829833 DOI: 10.1186/s13071-019-3751-x] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 10/12/2019] [Indexed: 01/06/2023] Open
Abstract
Scrub typhus, caused by Orientia tsutsugamushi, is an important and neglected vector-borne zoonotic disease with an expanding known distribution. The ecology of the disease is complex and poorly understood, impairing discussion of public health interventions. To highlight what we know and the themes of our ignorance, we conducted a systematic review of all studies investigating the pathogen in vectors and non-human hosts. A total of 276 articles in 7 languages were included, with 793 study sites across 30 countries. There was no time restriction for article inclusion, with the oldest published in 1924. Seventy-six potential vector species and 234 vertebrate host species were tested, accounting for over one million trombiculid mites ('chiggers') and 83,000 vertebrates. The proportion of O. tsutsugamushi positivity was recorded for different categories of laboratory test and host species. Vector and host collection sites were geocoded and mapped. Ecological data associated with these sites were summarised. A further 145 articles encompassing general themes of scrub typhus ecology were reviewed. These topics range from the life-cycle to transmission, habitats, seasonality and human risks. Important gaps in our understanding are highlighted together with possible tools to begin to unravel these. Many of the data reported are highly variable and inconsistent and minimum data reporting standards are proposed. With more recent reports of human Orientia sp. infection in the Middle East and South America and enormous advances in research technology over recent decades, this comprehensive review provides a detailed summary of work investigating this pathogen in vectors and non-human hosts and updates current understanding of the complex ecology of scrub typhus. A better understanding of scrub typhus ecology has important relevance to ongoing research into improving diagnostics, developing vaccines and identifying useful public health interventions to reduce the burden of the disease.
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Affiliation(s)
- Ivo Elliott
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Isabelle Pearson
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | - Prabin Dahal
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Worldwide Anti Malarial Resistance Network, University of Oxford, Oxford, UK
- Linacre College, University of Oxford, St Cross Road, Oxford, UK
| | - Nigel V. Thomas
- Worldwide Anti Malarial Resistance Network, University of Oxford, Oxford, UK
| | - Tamalee Roberts
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | - Paul N. Newton
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Worldwide Anti Malarial Resistance Network, University of Oxford, Oxford, UK
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14
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Pruvot M, Khammavong K, Milavong P, Philavong C, Reinharz D, Mayxay M, Rattanavong S, Horwood P, Dussart P, Douangngeun B, Theppangna W, Fine AE, Olson SH, Robinson M, Newton P. Toward a quantification of risks at the nexus of conservation and health: The case of bushmeat markets in Lao PDR. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 676:732-745. [PMID: 31054417 PMCID: PMC7112076 DOI: 10.1016/j.scitotenv.2019.04.266] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 04/16/2019] [Accepted: 04/17/2019] [Indexed: 04/14/2023]
Abstract
Trade of bushmeat and other wildlife for human consumption presents a unique set of challenges to policy-makers who are confronted with multiple trade-offs between conservation, food security, food safety, culture and tradition. In the face of these complex issues, risk assessments supported by quantitative information would facilitate evidence-based decision making. We propose a conceptual model for disease transmission risk analysis, inclusive of these multiple other facets. To quantify several processes included in this conceptual model we conducted questionnaire surveys with wildlife consumers and vendors in semi-urban centers in Lao People's Democratic Republic (Lao PDR, Laos) and direct observations of consumer behaviors. Direct observation of market stalls indicated an estimated average of 10 kg bushmeat biomass per stall per hour. The socio-demographic data suggested that consumption of bushmeat in urban areas was not for subsistence but rather driven by dietary preference and tradition. Consumer behavioral observations indicated that each animal receives an average of 7 contacts per hour. We provide other key parameters to estimate the risk of disease transmission from bushmeat consumption and illustrate their use in assessing the total public health and socio-economic impact of bushmeat consumption. Pursuing integrative approaches to the study of bushmeat consumption is essential to develop effective and balanced policies that support conservation, public health, and rural development goals.
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Affiliation(s)
- Mathieu Pruvot
- Wildlife Conservation Society, Wildlife Health Program, 2300 Southern Blvd, Bronx, NY 10460, USA.
| | - Kongsy Khammavong
- Wildlife Conservation Society, Lao PDR Program, Vientiane, Lao Democratic People's Republic
| | - Phonesavanh Milavong
- Wildlife Conservation Society, Lao PDR Program, Vientiane, Lao Democratic People's Republic
| | | | - Daniel Reinharz
- Institut de la Francophonie pour la Médecine Tropicale, Vientiane, Lao Democratic People's Republic; Département de Médecine sociale et préventive, Université Laval, Québec, Canada
| | - Mayfong Mayxay
- Lao-Oxford-Mahosot Hospital Wellcome Trust Research Unit, Vientiane, Lao Democratic People's Republic; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Sayapeth Rattanavong
- Lao-Oxford-Mahosot Hospital Wellcome Trust Research Unit, Vientiane, Lao Democratic People's Republic
| | - Paul Horwood
- Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Australia; Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | | | - Bounlom Douangngeun
- National Animal Health Laboratory, Department of Livestock and Fisheries, Ministry of Agriculture, Ban Khunta, Vientiane, Lao Democratic People's Republic
| | - Watthana Theppangna
- National Animal Health Laboratory, Department of Livestock and Fisheries, Ministry of Agriculture, Ban Khunta, Vientiane, Lao Democratic People's Republic
| | - Amanda E Fine
- Wildlife Conservation Society, Wildlife Health Program, 2300 Southern Blvd, Bronx, NY 10460, USA
| | - Sarah H Olson
- Wildlife Conservation Society, Wildlife Health Program, 2300 Southern Blvd, Bronx, NY 10460, USA
| | - Matthew Robinson
- Lao-Oxford-Mahosot Hospital Wellcome Trust Research Unit, Vientiane, Lao Democratic People's Republic; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Paul Newton
- Lao-Oxford-Mahosot Hospital Wellcome Trust Research Unit, Vientiane, Lao Democratic People's Republic; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
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15
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Kelly DJ, Fuerst PA, Richards AL. Origins, Importance and Genetic Stability of the Prototype Strains Gilliam, Karp and Kato of Orientia tsutsugamushi. Trop Med Infect Dis 2019; 4:E75. [PMID: 31052283 PMCID: PMC6631653 DOI: 10.3390/tropicalmed4020075] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 04/17/2019] [Accepted: 04/24/2019] [Indexed: 11/16/2022] Open
Abstract
Scrub typhus, a chigger-borne febrile illness, occurs primarily in countries of the Asia-Pacific rim and islands of the Western Pacific. The etiologic agent is the obligate intracellular rickettsial bacterium Orientia tsutsugamushi. Research on O. tsutsugamushi has relied on the availability of several prototype strains, which were isolated from human cases of scrub typhus in the 1940s and 1950s. We review the history of the three original, and most important, prototype strains, Gilliam, Karp and Kato, including information on their isolation, their culture history, their clinical characteristics, their importance within the research literature on scrub typhus, and recent advances in elucidating their molecular genomics. The importance of these strains to the research and development of clinical tools related to scrub typhus is also considered. Finally, we examine whether the strains have been genetically stable since their isolation, and whether prototype strains maintained in separate laboratories are identical, based on pairwise comparisons of several sequences from four genes. By using genetic information archived in international DNA databases, we show that the prototype strains used by different laboratories are essentially identical, and that the strains have retained their genetic integrity at least since the 1950s. The three original prototype strains should remain a standard by which new diagnostic procedures are measured. Given their fundamental position in any comparative studies, they are likely to endure as a critical part of present and future research on scrub typhus and Orientia.
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Affiliation(s)
- Daryl J Kelly
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA, and Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, OH 43210, USA.
| | - Paul A Fuerst
- Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, OH 43210, USA.
| | - Allen L Richards
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA, and Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA.
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16
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Fleshman A, Mullins K, Sahl J, Hepp C, Nieto N, Wiggins K, Hornstra H, Kelly D, Chan TC, Phetsouvanh R, Dittrich S, Panyanivong P, Paris D, Newton P, Richards A, Pearson T. Comparative pan-genomic analyses of Orientia tsutsugamushi reveal an exceptional model of bacterial evolution driving genomic diversity. Microb Genom 2018; 4. [PMID: 30035711 PMCID: PMC6202447 DOI: 10.1099/mgen.0.000199] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Orientia tsutsugamushi, formerly Rickettsia tsutsugamushi, is an obligate intracellular pathogen that causes scrub typhus, an underdiagnosed acute febrile disease with high morbidity. Scrub typhus is transmitted by the larval stage (chigger) of Leptotrombidium mites and is irregularly distributed across endemic regions of Asia, Australia and islands of the western Pacific Ocean. Previous work to understand population genetics in O. tsutsugamushi has been based on sub-genomic sampling methods and whole-genome characterization of two genomes. In this study, we compared 40 genomes from geographically dispersed areas and confirmed patterns of extensive homologous recombination likely driven by transposons, conjugative elements and repetitive sequences. High rates of lateral gene transfer (LGT) among O. tsutsugamushi genomes appear to have effectively eliminated a detectable clonal frame, but not our ability to infer evolutionary relationships and phylogeographical clustering. Pan-genomic comparisons using 31 082 high-quality bacterial genomes from 253 species suggests that genomic duplication in O. tsutsugamushi is almost unparalleled. Unlike other highly recombinant species where the uptake of exogenous DNA largely drives genomic diversity, the pan-genome of O. tsutsugamushi is driven by duplication and divergence. Extensive gene innovation by duplication is most commonly attributed to plants and animals and, in contrast with LGT, is thought to be only a minor evolutionary mechanism for bacteria. The near unprecedented evolutionary characteristics of O. tsutsugamushi, coupled with extensive intra-specific LGT, expand our present understanding of rapid bacterial evolutionary adaptive mechanisms.
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Affiliation(s)
- Amy Fleshman
- 1Northern Arizona University, Flagstaff, AZ, USA
| | | | - Jason Sahl
- 1Northern Arizona University, Flagstaff, AZ, USA
| | - Crystal Hepp
- 1Northern Arizona University, Flagstaff, AZ, USA
| | - Nathan Nieto
- 1Northern Arizona University, Flagstaff, AZ, USA
| | | | | | - Daryl Kelly
- 2Naval Medical Research Center, Silver Spring, MD, USA.,3The Ohio State University, Columbus, OH, USA
| | | | - Rattanaphone Phetsouvanh
- 4Lao-Oxford-Mahosot Hospital-Wellcome Trust, Research Unit, Mahosot Hospital, Vientiane, Vientiane, Lao People's Democratic Republic
| | - Sabine Dittrich
- 5University of Oxford, Centre for Tropical Medicine and Global Health, Oxford, UK.,6Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Mahosot Hospital, Vientiane, Lao People's Democratic Republic.,7Foundation of Innovative New Diagnostics, Geneva, Switzerland
| | - Phonepasith Panyanivong
- 6Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
| | - Daniel Paris
- 8Mahidol-Oxford Tropical Medicine Research Unit, Bangkok, Thailand.,9Swiss Tropical and Public Health Institute, Basel, Switzerland.,10University of Basel, Basel, Switzerland
| | - Paul Newton
- 5University of Oxford, Centre for Tropical Medicine and Global Health, Oxford, UK.,6Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Mahosot Hospital, Vientiane, Lao People's Democratic Republic
| | - Allen Richards
- 2Naval Medical Research Center, Silver Spring, MD, USA.,11Uniformed Services University of the Health Sciences, Bethesda, MD, USA
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17
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Batty EM, Chaemchuen S, Blacksell S, Richards AL, Paris D, Bowden R, Chan C, Lachumanan R, Day N, Donnelly P, Chen S, Salje J. Long-read whole genome sequencing and comparative analysis of six strains of the human pathogen Orientia tsutsugamushi. PLoS Negl Trop Dis 2018; 12:e0006566. [PMID: 29874223 PMCID: PMC6005640 DOI: 10.1371/journal.pntd.0006566] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 06/18/2018] [Accepted: 05/28/2018] [Indexed: 11/25/2022] Open
Abstract
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 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. CONCLUSIONS 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.
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Affiliation(s)
- Elizabeth M Batty
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Suwittra Chaemchuen
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Stuart Blacksell
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Allen L Richards
- US Naval Medicine Research Center, Silver Spring, Maryland, United States of America
| | - Daniel Paris
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- Faculty of Medicine, University Basel, Basel, Switzerland
| | - Rory Bowden
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Caroline Chan
- Pacific Biosciences, 1305 O'Brien Drive, Menlo Park, California, United States of America
| | - Ramkumar Lachumanan
- Pacific Biosciences, 1305 O'Brien Drive, Menlo Park, California, United States of America
| | - Nicholas Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Peter Donnelly
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Department of Statistics, University of Oxford, Oxford, United Kingdom
| | - Swaine Chen
- Department of Medicine, Division of Infectious Diseases, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- Genome Institute of Singapore, A*STAR, Singapore
| | - Jeanne Salje
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Public Health Research Institute, Rutgers Biomedical and Health Science, Newark, New Jersey, United States of America
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18
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Díaz FE, Abarca K, Kalergis AM. An Update on Host-Pathogen Interplay and Modulation of Immune Responses during Orientia tsutsugamushi Infection. Clin Microbiol Rev 2018; 31:e00076-17. [PMID: 29386235 PMCID: PMC5967693 DOI: 10.1128/cmr.00076-17] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The obligate intracellular bacterium Orientia tsutsugamushi is the causative agent of scrub typhus in humans, a serious mite-borne disease present in a widespread area of endemicity, which affects an estimated 1 million people every year. This disease may exhibit a broad range of presentations, ranging from asymptomatic to fatal conditions, with the latter being due to disseminated endothelial infection and organ injury. Unique characteristics of the biology and host-pathogen interactions of O. tsutsugamushi, including the high antigenic diversity among strains and the highly variable, short-lived memory responses developed by the host, underlie difficulties faced in the pursuit of an effective vaccine, which is an imperative need. Other factors that have hindered scientific progress relative to the infectious mechanisms of and the immune response triggered by this bacterium in vertebrate hosts include the limited number of mechanistic studies performed on animal models and the lack of genetic tools currently available for this pathogen. However, recent advances in animal model development are promising to improve our understanding of host-pathogen interactions. Here, we comprehensively discuss the recent advances in and future perspectives on host-pathogen interactions and the modulation of immune responses related to this reemerging disease, highlighting the role of animal models.
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Affiliation(s)
- Fabián E Díaz
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Katia Abarca
- Departamento en Enfermedades Infecciosas e Inmunología Pediátricas, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Alexis M Kalergis
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- Departamento de Endocrinología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
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19
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Luce-Fedrow A, Lehman ML, Kelly DJ, Mullins K, Maina AN, Stewart RL, Ge H, John HS, Jiang J, Richards AL. A Review of Scrub Typhus (Orientia tsutsugamushi and Related Organisms): Then, Now, and Tomorrow. Trop Med Infect Dis 2018; 3:E8. [PMID: 30274407 PMCID: PMC6136631 DOI: 10.3390/tropicalmed3010008] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 01/09/2018] [Accepted: 01/10/2018] [Indexed: 12/26/2022] Open
Abstract
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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Affiliation(s)
- Alison Luce-Fedrow
- Department of Biology, Shippensburg University, Shippensburg, PA 17202, USA.
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA.
| | - Marcie L Lehman
- Department of Biology, Shippensburg University, Shippensburg, PA 17202, USA.
| | - Daryl J Kelly
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA.
- Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, OH 43210, USA.
| | - Kristin Mullins
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA.
| | - Alice N Maina
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA.
| | - Richard L Stewart
- Department of Biology, Shippensburg University, Shippensburg, PA 17202, USA.
| | - Hong Ge
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA.
| | - Heidi St John
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA.
| | - Ju Jiang
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA.
| | - Allen L Richards
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA.
- Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA.
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20
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Kim G, Ha NY, Min CK, Kim HI, Yen NTH, Lee KH, Oh I, Kang JS, Choi MS, Kim IS, Cho NH. Diversification of Orientia tsutsugamushi genotypes by intragenic recombination and their potential expansion in endemic areas. PLoS Negl Trop Dis 2017; 11:e0005408. [PMID: 28248956 PMCID: PMC5348041 DOI: 10.1371/journal.pntd.0005408] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Revised: 03/13/2017] [Accepted: 02/13/2017] [Indexed: 12/31/2022] Open
Abstract
Background Scrub typhus is a mite-borne febrile disease caused by O. tsutsugamushi infection. Recently, emergence of scrub typhus has attracted considerable attention in several endemic countries in Asia and the western Pacific. In addition, the antigenic diversity of the intracellular pathogen has been a serious obstacle for developing effective diagnostics and vaccine. Methodology/Principal findings To understand the evolutionary pathway of genotypic diversification of O. tsutsugamushi and the environmental factors associated with the epidemiological features of scrub typhus, we analyzed sequence data, including spatiotemporal information, of the tsa56 gene encoding a major outer membrane protein responsible for antigenic variation. A total of 324 tsa56 sequences covering more than 85% of its open reading frame were analyzed and classified into 17 genotypes based on phylogenetic relationship. Extensive sequence analysis of tsa56 genes using diverse informatics tools revealed multiple intragenic recombination events, as well as a substantially higher mutation rate than other house-keeping genes. This suggests that genetic diversification occurred via frequent point mutations and subsequent genetic recombination. Interestingly, more diverse bacterial genotypes and dominant vector species prevail in Taiwan compared to other endemic regions. Furthermore, the co-presence of identical and sub-identical clones of tsa56 gene in geographically distant areas implies potential spread of O. tsutsugamushi genotypes. Conclusions/Significance Fluctuation and diversification of vector species harboring O. tsutsugamushi in local endemic areas may facilitate genetic recombination among diverse genotypes. Therefore, careful monitoring of dominant vector species, as well as the prevalence of O. tsutsugamushi genotypes may be advisable to enable proper anticipation of epidemiological changes of scrub typhus. Scrub typhus, caused by Orientia tsutsugamushi infection, is a mite-borne febrile illness endemic in the Asia-Pacific region. Recent emergence and continuous local outbreaks in many of the endemic countries make it a serious public health issue. In addition, the antigenic diversity of the tsa56 gene, encoding a major outer membrane protein, hampers the development of effective diagnostics and vaccine. Here, we extensively analyzed tsa56 sequences and their spatiotemporal information to elucidate the evolutionary pathway of genotypic diversification, as well as the environmental basis associated with the epidemiological changes of scrub typhus. Based on various informatics analyses, we found that genetic diversification of tsa56 might have been attained via frequent point mutations and subsequent genetic recombination among diverse genotypes. Prevalence of numerous bacterial genotypes and dominant vector species in Taiwan also suggest that the subtropical area located at the center of endemicity, may serve as a local mixing ground for genotype diversification. In addition, detection of identical and sub-identical clones of tsa56 genes in geographically distant countries indicates a potential spreading of bacterial genotypes. Continuous monitoring of dominant vector species and the associated O. tsutsugamushi genotypes might be required for developing better diagnostics and an effective vaccine for scrub typhus.
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Affiliation(s)
- Gwanghun Kim
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Republic of Korea
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Na-Young Ha
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Republic of Korea
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Chan-Ki Min
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Republic of Korea
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Hong-Il Kim
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Republic of Korea
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Nguyen Thi Hai Yen
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Republic of Korea
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Keun-Hwa Lee
- Department of Microbiology and Immunology, Jeju National University School of Medicine, Jeju, Republic of Korea
| | - Inbo Oh
- Environmental Health Center, University of Ulsan College of Medicine, Ulsan, Republic of Korea
| | - Jae-Seung Kang
- Department of Microbiology, Inha University School of Medicine, Incheon, Republic of Korea
| | - Myung-Sik Choi
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Ik-Sang Kim
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Nam-Hyuk Cho
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Republic of Korea
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea
- Institute of Endemic Disease, Seoul National University Medical Research Center and Bundang Hospital, Seoul, Republic of Korea
- * E-mail:
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Phetsouvanh R, Sonthayanon P, Pukrittayakamee S, Paris DH, Newton PN, Feil EJ, Day NPJ. Correction: The Diversity and Geographical Structure of Orientia tsutsugamushi Strains from Scrub Typhus Patients in Laos. PLoS Negl Trop Dis 2016; 10:e0004742. [PMID: 27187179 PMCID: PMC4871325 DOI: 10.1371/journal.pntd.0004742] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
[This corrects the article DOI: 10.1371/journal.pntd.0004024.].
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