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Sit B, Lamason RL. Pathogenic Rickettsia spp. as emerging models for bacterial biology. J Bacteriol 2024; 206:e0040423. [PMID: 38315013 PMCID: PMC10883807 DOI: 10.1128/jb.00404-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024] Open
Abstract
Our understanding of free-living bacterial models like Escherichia coli far outpaces that of obligate intracellular bacteria, which cannot be cultured axenically. All obligate intracellular bacteria are host-associated, and many cause serious human diseases. Their constant exposure to the distinct biochemical niche of the host has driven the evolution of numerous specialized bacteriological and genetic adaptations, as well as innovative molecular mechanisms of infection. Here, we review the history and use of pathogenic Rickettsia species, which cause an array of vector-borne vascular illnesses, as model systems to probe microbial biology. Although many challenges remain in our studies of these organisms, the rich pathogenic and biological diversity of Rickettsia spp. constitutes a unique backdrop to investigate how microbes survive and thrive in host and vector cells. We take a bacterial-focused perspective and highlight emerging insights that relate to new host-pathogen interactions, bacterial physiology, and evolution. The transformation of Rickettsia spp. from pathogens to models demonstrates how recalcitrant microbes may be leveraged in the lab to tap unmined bacterial diversity for new discoveries. Rickettsia spp. hold great promise as model systems not only to understand other obligate intracellular pathogens but also to discover new biology across and beyond bacteria.
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Affiliation(s)
- Brandon Sit
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Rebecca L. Lamason
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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2
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Curran EH, Devine MD, Hartley CD, Huang Y, Conrady CD, Debiec MR, Justin GA, Thomas J, Yeh S. Ophthalmic implications of biological threat agents according to the chemical, biological, radiological, nuclear, and explosives framework. Front Med (Lausanne) 2024; 10:1349571. [PMID: 38293299 PMCID: PMC10824978 DOI: 10.3389/fmed.2023.1349571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 12/27/2023] [Indexed: 02/01/2024] Open
Abstract
As technology continues to evolve, the possibility for a wide range of dangers to people, organizations, and countries escalate globally. The United States federal government classifies types of threats with the capability of inflicting mass casualties and societal disruption as Chemical, Biological, Radiological, Nuclear, and Energetics/Explosives (CBRNE). Such incidents encompass accidental and intentional events ranging from weapons of mass destruction and bioterrorism to fires or spills involving hazardous or radiologic material. All of these have the capacity to inflict death or severe physical, neurological, and/or sensorial disabilities if injuries are not diagnosed and treated in a timely manner. Ophthalmic injury can provide important insight into understanding and treating patients impacted by CBRNE agents; however, improper ophthalmic management can result in suboptimal patient outcomes. This review specifically addresses the biological agents the Center for Disease Control and Prevention (CDC) deems to have the greatest capacity for bioterrorism. CBRNE biological agents, encompassing pathogens and organic toxins, are further subdivided into categories A, B, and C according to their national security threat level. In our compendium of these biological agents, we address their respective CDC category, systemic and ophthalmic manifestations, route of transmission and personal protective equipment considerations as well as pertinent vaccination and treatment guidelines.
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Affiliation(s)
- Emma H. Curran
- Creighton University School of Medicine, Omaha, NE, United States
| | - Max D. Devine
- College of Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Caleb D. Hartley
- Department of Ophthalmology and Visual Sciences, Stanley M. Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE, United States
| | - Ye Huang
- Department of Ophthalmology, University of Illinois-Chicago, Chicago, IL, United States
| | - Christopher D. Conrady
- Department of Ophthalmology and Visual Sciences, Stanley M. Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE, United States
- Department of Microbiology and Pathology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Matthew R. Debiec
- Walter Reed National Military Medical Center, Bethesda, MD, United States
| | - Grant A. Justin
- Walter Reed National Military Medical Center, Bethesda, MD, United States
| | - Joanne Thomas
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA, United States
| | - Steven Yeh
- Department of Ophthalmology and Visual Sciences, Stanley M. Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE, United States
- Global Center for Health Security, University of Nebraska Medical Center, Omaha, NE, United States
- National Strategic Research Institute, University of Nebraska Medical Center, Omaha, NE, United States
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3
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Gautret P. La Valentine disease: An outbreak of exanthematic typhus in Marseille, France, in 1810. J R Coll Physicians Edinb 2023; 53:290-294. [PMID: 37936398 DOI: 10.1177/14782715231210333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2023] Open
Abstract
BACKGROUND Exanthematic typhus was highly frequent in the early 19th century among military troops and prisoners and at hospitals. METHODS Based on old reports, we describe an outbreak in a village, in Southern France, in 1810. RESULTS Twenty-eight cases were identified, over a period of 10 days following the death of the index case, in a soldier. Symptoms included notably persistent constant fever, myalgia and headaches, gastro-intestinal symptoms, prostration and stupor. Three patients suffered delirium and nine died (31.0%). Overall, symptoms persisted for 13-14 days. A total of 16 cases were secondary to contacts with the index case, and 10 cases were in house-hold contacts of secondary cases. Five familial clusters were described. CONCLUSION This data suggest that exanthematic typhus outbreaks among civilian populations also occurred outside the context of hospitals, in link with introduction of the disease by prisoners or soldiers.
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Affiliation(s)
- Philippe Gautret
- Aix Marseille University, IRD, AP-HM, SSA, VITROME, Marseille, France
- IHU-Méditerranée Infection, Marseille, France
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Laroche M, Weeks ENI. Vector-borne bacterial diseases: a neglected field of infectious diseases research. MEDICAL AND VETERINARY ENTOMOLOGY 2023; 37:177-178. [PMID: 36789732 DOI: 10.1111/mve.12646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Affiliation(s)
- Maureen Laroche
- Department of Microbiology and Immunology, The University of Texas Medical Branch at Galveston, Galveston, Texas, USA
| | - Emma N I Weeks
- University of Florida Entomology and Nematology Department, Gainesville, Florida, USA
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5
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Breedlove B. Specter of Epidemic Typhus. Emerg Infect Dis 2023. [DOI: 10.3201/eid2904.ac2904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/31/2023] Open
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6
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Biselli R, Nisini R, Lista F, Autore A, Lastilla M, De Lorenzo G, Peragallo MS, Stroffolini T, D’Amelio R. A Historical Review of Military Medical Strategies for Fighting Infectious Diseases: From Battlefields to Global Health. Biomedicines 2022; 10:2050. [PMID: 36009598 PMCID: PMC9405556 DOI: 10.3390/biomedicines10082050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 08/12/2022] [Accepted: 08/13/2022] [Indexed: 11/17/2022] Open
Abstract
The environmental conditions generated by war and characterized by poverty, undernutrition, stress, difficult access to safe water and food as well as lack of environmental and personal hygiene favor the spread of many infectious diseases. Epidemic typhus, plague, malaria, cholera, typhoid fever, hepatitis, tetanus, and smallpox have nearly constantly accompanied wars, frequently deeply conditioning the outcome of battles/wars more than weapons and military strategy. At the end of the nineteenth century, with the birth of bacteriology, military medical researchers in Germany, the United Kingdom, and France were active in discovering the etiological agents of some diseases and in developing preventive vaccines. Emil von Behring, Ronald Ross and Charles Laveran, who were or served as military physicians, won the first, the second, and the seventh Nobel Prize for Physiology or Medicine for discovering passive anti-diphtheria/tetanus immunotherapy and for identifying mosquito Anopheline as a malaria vector and plasmodium as its etiological agent, respectively. Meanwhile, Major Walter Reed in the United States of America discovered the mosquito vector of yellow fever, thus paving the way for its prevention by vector control. In this work, the military relevance of some vaccine-preventable and non-vaccine-preventable infectious diseases, as well as of biological weapons, and the military contributions to their control will be described. Currently, the civil-military medical collaboration is getting closer and becoming interdependent, from research and development for the prevention of infectious diseases to disasters and emergencies management, as recently demonstrated in Ebola and Zika outbreaks and the COVID-19 pandemic, even with the high biocontainment aeromedical evacuation, in a sort of global health diplomacy.
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Affiliation(s)
- Roberto Biselli
- Ispettorato Generale della Sanità Militare, Stato Maggiore della Difesa, Via S. Stefano Rotondo 4, 00184 Roma, Italy
| | - Roberto Nisini
- Dipartimento di Malattie Infettive, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Roma, Italy
| | - Florigio Lista
- Dipartimento Scientifico, Policlinico Militare, Comando Logistico dell’Esercito, Via S. Stefano Rotondo 4, 00184 Roma, Italy
| | - Alberto Autore
- Osservatorio Epidemiologico della Difesa, Ispettorato Generale della Sanità Militare, Stato Maggiore della Difesa, Via S. Stefano Rotondo 4, 00184 Roma, Italy
| | - Marco Lastilla
- Istituto di Medicina Aerospaziale, Comando Logistico dell’Aeronautica Militare, Viale Piero Gobetti 2, 00185 Roma, Italy
| | - Giuseppe De Lorenzo
- Comando Generale dell’Arma dei Carabinieri, Dipartimento per l’Organizzazione Sanitaria e Veterinaria, Viale Romania 45, 00197 Roma, Italy
| | - Mario Stefano Peragallo
- Centro Studi e Ricerche di Sanità e Veterinaria, Comando Logistico dell’Esercito, Via S. Stefano Rotondo 4, 00184 Roma, Italy
| | - Tommaso Stroffolini
- Dipartimento di Malattie Infettive e Tropicali, Policlinico Umberto I, 00161 Roma, Italy
| | - Raffaele D’Amelio
- Dipartimento di Medicina Clinica e Molecolare, Sapienza Università di Roma, Via di Grottarossa 1035-1039, 00189 Roma, Italy
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Involvement of Pore Formation and Osmotic Lysis in the Rapid Killing of Gamma Interferon-Pretreated C166 Endothelial Cells by Rickettsia prowazekii. Trop Med Infect Dis 2022; 7:tropicalmed7080163. [PMID: 36006255 PMCID: PMC9415803 DOI: 10.3390/tropicalmed7080163] [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: 07/02/2022] [Revised: 07/24/2022] [Accepted: 07/25/2022] [Indexed: 11/16/2022] Open
Abstract
Rickettsia prowazekii, the bacterial cause of epidemic typhus in humans, proliferates mainly within the microvascular endothelial cells. Previous studies have shown that murine macrophage-like RAW264.7 cells are rapidly damaged if they are pretreated with gamma interferon (IFN-γ) and then infected with R. prowazekii. In the present study, the effects of IFN-γ and R. prowazekii on murine C166 endothelial cells were evaluated. In the IFN-γ-pretreated R. prowazekii-infected endothelial cell cultures, evidence of cell damage was observed within several hours after addition of the rickettsiae. Considerable numbers of the cells became permeable to trypan blue dye and ethidium bromide, and substantial amounts of lactate dehydrogenase (LDH) were released from the cells. Such evidence of cellular injury was not observed in the untreated infected cultures or in any of the mock-infected cultures. Polyethylene glycols (PEGs) of different nominal average molecular weights were used to assess the possible involvement of pore formation and osmotic lysis in this cellular injury. PEG 8000 dramatically suppressed LDH release, PEG 4000 partially inhibited it, and PEGs 2000 and 1450 had no effect. Despite its inhibition of LDH release, PEG 8000 did not prevent the staining of the IFN-γ-pretreated infected endothelial cells by ethidium bromide. These findings suggest that the observed cellular injury involves the formation of pores in the endothelial cell membranes, followed by osmotic lysis of the cells.
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Epidemic typhus in the Lithuanian army from 1919 to 1923. VOJNOSANIT PREGL 2022. [DOI: 10.2298/vsp201114139s] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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McGinn J, Lamason RL. The enigmatic biology of rickettsiae: recent advances, open questions and outlook. Pathog Dis 2021; 79:ftab019. [PMID: 33784388 PMCID: PMC8035066 DOI: 10.1093/femspd/ftab019] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 03/26/2021] [Indexed: 02/05/2023] Open
Abstract
Rickettsiae are obligate intracellular bacteria that can cause life-threatening illnesses and are among the oldest known vector-borne pathogens. Members of this genus are extraordinarily diverse and exhibit a broad host range. To establish intracellular infection, Rickettsia species undergo complex, multistep life cycles that are encoded by heavily streamlined genomes. As a result of reductive genome evolution, rickettsiae are exquisitely tailored to their host cell environment but cannot survive extracellularly. This host-cell dependence makes for a compelling system to uncover novel host-pathogen biology, but it has also hindered experimental progress. Consequently, the molecular details of rickettsial biology and pathogenesis remain poorly understood. With recent advances in molecular biology and genetics, the field is poised to start unraveling the molecular mechanisms of these host-pathogen interactions. Here, we review recent discoveries that have shed light on key aspects of rickettsial biology. These studies have revealed that rickettsiae subvert host cells using mechanisms that are distinct from other better-studied pathogens, underscoring the great potential of the Rickettsia genus for revealing novel biology. We also highlight several open questions as promising areas for future study and discuss the path toward solving the fundamental mysteries of this neglected and emerging human pathogen.
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Affiliation(s)
- Jon McGinn
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, United States
| | - Rebecca L Lamason
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, United States
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10
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Abstract
In December 2019, the first cases of a new contagious disease were diagnosed in the city of Wuhan, the capital of Hubei province in China. Within a short period of time the outbreak developed exponentially into a pandemic that infected millions of people, with a global death toll of more than 500,000 during its first 6 months. Eventually, the novel disease was named coronavirus disease 2019 (COVID-19), and the new virus was identified as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Similar to all known pandemics throughout history, COVID-19 has been accompanied by a large degree of fear, anxiety, uncertainty, and economic disaster worldwide. Despite multiple publications and increasing knowledge regarding the biological secrets of SARS-CoV-2, as of the writing of this paper, there is neither an approved vaccine nor medication to prevent infection or cure for this highly infectious disease. Past pandemics were caused by a wide range of microbes, primarily viruses, but also bacteria. Characteristically, a significant proportion of them originated in different animal species (zoonoses). Since an understanding of the microbial cause of these diseases was unveiled relatively late in human history, past pandemics were often attributed to strange causes including punishment from God, demonic activity, or volatile unspecified substances. Although a high case fatality ratio was common to all pandemic diseases, some striking clinical characteristics of each disease allowed contemporaneous people to clinically diagnose the infection despite null microbiological information. In comparison to past pandemics, SARS-CoV-2 has tricky and complex mechanisms that have facilitated its rapid and catastrophic spread worldwide.
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11
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Gao Y, Yan D, Liu K, Sun J, Niu Y, Liu X, Wu H, Zhao C, Yue Y, Wang J, Zhao N, Lu L, Liu Q. Epidemiological characteristics and spatiotemporal patterns of typhus group rickettsiosis at the county level in China, 2005-2017. Int J Infect Dis 2019; 91:60-67. [PMID: 31760046 DOI: 10.1016/j.ijid.2019.11.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 11/13/2019] [Accepted: 11/15/2019] [Indexed: 12/31/2022] Open
Abstract
OBJECTIVE To explore the epidemiological characteristics and spatiotemporal patterns of typhus group rickettsiosis (TGR) in mainland China. METHODS A chi-squared test was used to compare the differences in the age and occupation distributions across the different years. Time-series analyses, spatial clustering analyses, and spatiotemporal scan statistics were used to detect the spatiotemporal patterns of the TGR incidence. RESULTS A total of 29,211 TGR cases were collected. Of these cases, 63.1% occurred from May to October, and 88.4% occurred in individuals between 0 and 59 years old. There was a significant spatial TGR heterogeneity from 2005 to 2017. The hotspots were located mainly in the southwestern, southern, and circum-Bohai Sea regions of northern China. Eighteen spatiotemporal clusters were observed using Kulldorff's space-time scan statistic, and the primary cluster included three counties, Jinghong city, Menghai county, and Mengla county. CONCLUSIONS TGR is widely distributed in China, and it is a serious threat to public health. The hotspots were located mainly in the southwestern, southern, and circum-Bohai Sea regions of northern China, and the primary spatiotemporal cluster showed a trend shifting from circum-Bohai Sea regions to the southwestern regions. Targeted interventions should be executed in high-risk regions for precise prevention and control.
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Affiliation(s)
- Yuan Gao
- State Key Laboratory of Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Dongming Yan
- State Key Laboratory of Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China; Shandong First Medical University, Tai'an, China
| | - Keke Liu
- Shandong Academy of Clinical Medicine, Shandong Provincial Hospital, Jinan, China
| | - Jimin Sun
- Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China
| | - Yanlin Niu
- State Key Laboratory of Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China; Beijing Center for Diseases Prevention and Control, Beijing, China
| | - Xiaobo Liu
- State Key Laboratory of Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Haixia Wu
- State Key Laboratory of Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Chunchun Zhao
- State Key Laboratory of Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Yujuan Yue
- State Key Laboratory of Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Jun Wang
- State Key Laboratory of Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Ning Zhao
- State Key Laboratory of Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Liang Lu
- State Key Laboratory of Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Qiyong Liu
- State Key Laboratory of Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.
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Abstract
Rickettsia are small, obligately intracellular, gram-negative bacilli. They are distributed among a variety of hematophagous arthropod vectors and cause illness throughout the world. Rickettsioses present as an acute undifferentiated febrile illness and are often accompanied by headache, myalgias, and malaise. Cutaneous manifestations include rash and eschar, which both occur at varying incidence depending on the infecting species. Serology is the mainstay of diagnosis, and the indirect immunofluorescence assay is the test of choice. Reactive antibodies are seldom present during early illness, so testing should be performed on both acute-phase and convalescent-phase sera. Doxycycline is the treatment of choice.
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Affiliation(s)
- Lucas S Blanton
- Department of Internal Medicine, Division of Infectious Diseases, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0435, USA.
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Munderloh UG. The beginning of an era of functional genomics in Rickettsiology is steeped in history. Proc Natl Acad Sci U S A 2019; 116:20252-20253. [PMID: 31530726 PMCID: PMC6789924 DOI: 10.1073/pnas.1913411116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2024] Open
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Rauch J, Eisermann P, Noack B, Mehlhoop U, Muntau B, Schäfer J, Tappe D. Typhus Group Rickettsiosis, Germany, 2010-2017 1. Emerg Infect Dis 2019; 24:1213-1220. [PMID: 29912688 PMCID: PMC6038764 DOI: 10.3201/eid2407.180093] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Typhus group rickettsiosis is caused by the vectorborne bacteria Rickettsia typhi and R. prowazekii. R. typhi, which causes murine typhus, the less severe endemic form of typhus, is transmitted by fleas; R. prowazekii, which causes the severe epidemic form of typhus, is transmitted by body lice. To examine the immunology of human infection with typhus group rickettsiae, we retrospectively reviewed clinical signs and symptoms, laboratory changes, and travel destinations of 28 patients who had typhus group rickettsiosis diagnosed by the German Reference Center for Tropical Pathogens, Hamburg, Germany, during 2010-2017. Immunofluorescence assays of follow-up serum samples indicated simultaneous seroconversion of IgM, IgA, and IgG or concurrence in the first serum sample. Cytokine levels peaked during the second week of infection, coinciding with organ dysfunction and seroconversion. For 3 patients, R. typhi was detected by species-specific nested quantitative PCR. For all 28 patients, R. typhi was the most likely causative pathogen.
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Suspected and Confirmed Vector-Borne Rickettsioses of North America Associated with Human Diseases. Trop Med Infect Dis 2018; 3:tropicalmed3010002. [PMID: 30274401 PMCID: PMC6136625 DOI: 10.3390/tropicalmed3010002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 12/18/2017] [Accepted: 12/19/2017] [Indexed: 11/27/2022] Open
Abstract
The identification of pathogenic rickettsial agents has expanded over the last two decades. In North America, the majority of human cases are caused by tick-borne rickettsioses but rickettsiae transmitted by lice, fleas, mites and other arthropods are also responsible for clinical disease. Symptoms are generally nonspecific or mimic other infectious diseases; therefore, diagnosis and treatment may be delayed. While infection with most rickettsioses is relatively mild, delayed diagnosis and treatment may lead to increased morbidity and mortality. This review will discuss the ecology, epidemiology and public health importance of suspected and confirmed vector-transmitted Rickettsia species of North America associated with human diseases.
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Outer Membrane Protein OmpB Methylation May Mediate Bacterial Virulence. Trends Biochem Sci 2017; 42:936-945. [PMID: 29037863 DOI: 10.1016/j.tibs.2017.09.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 09/16/2017] [Accepted: 09/20/2017] [Indexed: 12/29/2022]
Abstract
Methylation of outer membrane proteins (OMPs) has been implicated in bacterial virulence. Lysine methylation in rickettsial OmpB is correlated with rickettsial virulence, and N- and O-methylations are also observed in virulence-relevant OMPs from several pathogenic bacteria that cause typhus, leptospirosis, tuberculosis, and anaplasmosis. We summarize recent findings on the structure of methylated OmpB, biochemical characterization, and crystal structures of OmpB methyltransferases. Native rickettsial OmpB purified from highly virulent strains contains multiple clusters of trimethyllysine, in contrast with mostly monomethyllysine, and no trimethyllysine is found in an avirulent strain. Crystal structure of the methyltransferases reveals mechanistic insights for catalysis, and a working model is discussed for this unusual post-translational modification.
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