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Yasuko Rikihisa - One of the best experts on this subject based on the ideXlab platform.
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Isolation and Molecular Analysis of a Novel Neorickettsia Species That Causes Potomac Horse Fever.
Mbio, 2020Co-Authors: Omid Teymournejad, John D. Baird, Luis G. Arroyo, Hannah Bekebrede, Mingqun Lin, Ahmed Kamr, Ramiro E. Toribio, Yasuko RikihisaAbstract:ABSTRACT Potomac horse fever (PHF), a severe and frequently fatal febrile diarrheal disease, has been known to be caused only by Neorickettsia risticii, an endosymbiont of digenean trematodes. Here, we report the cell culture isolation of a new Neorickettsia species found in two locations in eastern Ontario, Canada, in 2016 and 2017 (in addition to 10 variable strains of N. risticii) from N. risticii PCR-negative horses with clinical signs of PHF. Gene sequences of 16S rRNA and the major surface antigen P51 of this new Neorickettsia species were distinct from those of all previously characterized N. risticii strains and Neorickettsia species, except for those from an uncharacterized Neorickettsia species culture isolate from a horse with PHF in northern Ohio in 1991. The new Neorickettsia species nonetheless had the characteristic intramolecular repeats within strain-specific antigen 3 (Ssa3), which were found in all sequenced Ssa3s of N. risticii strains. Experimental inoculation of two naive ponies with the new Neorickettsia species produced severe and subclinical PHF, respectively, and the bacteria were reisolated from both of them, fulfilling Koch’s postulates. Serological assay titers against the new Neorickettsia species were higher than those against N. risticii. Whole-genome sequence analysis of the new Neorickettsia species revealed unique features of this bacterium compared with N. risticii. We propose to classify this new bacterium as Neorickettsia finleia sp. nov. This finding will improve the laboratory diagnosis of and vaccine for PHF, environmental risk assessment of PHF, and understanding of PHF pathogenesis and Neorickettsia biology in general. IMPORTANCE Despite the detection of Neorickettsia species DNA sequences in various trematode species and their hosts, only three Neorickettsia species have been cell culture isolated and whole-genome sequenced and are known to infect mammals and/or cause disease. The molecular mechanisms that enable the obligatory intracellular bacterium Neorickettsia to colonize trematodes and to horizontally transmit from trematodes to mammals, as well as the virulence factors associated with specific mammalian hosts, are unknown. Potomac horse fever (PHF) is a severe and acute systemic infectious disease of horses, with clinical signs that include diarrhea. Neorickettsia risticii is the only known bacterial species that causes PHF. Ingestion of insects harboring N. risticii-infected trematodes by horses leads to PHF. Our discovery of a new Neorickettsia species that causes PHF and whole-genome sequence analysis of this bacterium will improve laboratory diagnosis and vaccine development for PHF and will contribute to our understanding of Neorickettsia ecology, pathogenesis, and biology.
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The Importance of Rickettsiales Infections
Rickettsiales, 2016Co-Authors: Sunil Thomas, Walker Alexander, John Gilligan, Yasuko RikihisaAbstract:The Gram-negative bacteria of the order Rickettsiales are obligate intracellular parasites that infect a variety of hosts including humans, animals, and insects. The order Rickettsiales comprises the families Rickettsiaceae, Anaplasmataceae, and Midichloriaceae. The bacteria of the genus Rickettsia, Orientia, Ehrlichia, Anaplasma, and Neorickettsia cause diseases such as epidemic louse-borne typhus fever, Rocky Mountain spotted fever, scrub typhus, ehrlichiosis, bovine anaplasmosis, and sennetsu fever. Most species of Rickettsiales are zoonotic pathogens that cause diseases transmitted by ectoparasites such as fleas, lice, mites, and ticks or endoparasites such as trematodes. The maternally inherited intracellular bacteria Wolbachia are Rickettsiales that infect >65 % of the insect species. Recently, Wolbachia has received attention as a potential bio-control agent that may be used in insect control strategies. This chapter describes the importance of Rickettsiales infections including the vectors that transmit the disease.
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An Ecotype of Neorickettsia risticii Causing Potomac Horse Fever in Canada.
Applied and Environmental Microbiology, 2016Co-Authors: Qingming Xiong, John D. Baird, Luis G. Arroyo, Hannah Bekebrede, Pratibha Sharma, Yasuko RikihisaAbstract:ABSTRACT Neorickettsia (formerly Ehrlichia) risticii is an obligatory intracellular bacterium of digenetic trematodes. When a horse accidentally ingests aquatic insects containing encysted trematodes infected with N. risticii, the bacterium is transmitted from trematodes to horse cells and causes an acute and often fatal disease called Potomac horse fever (PHF). Since the discovery of N. risticii in the United States in 1984, using immunofluorescence and PCR assays, PHF has been increasingly recognized throughout North America and South America. However, so far, there exist only a few stable N. risticii culture isolates, all of which are from horses within the United States, and the strain diversity and environmental spreading and distribution of pathogenic N. risticii strains remain poorly understood. This paper reports the isolation of N. risticii from the blood of a horse with acute PHF in Ontario, Canada. Intracellular N. risticii colonies were detected in P388D1 cells after 47 days of culturing and 8 days after the addition of rapamycin. Molecular phylogenetic analysis based on amino acid sequences of major surface proteins P51 and Ssa1 showed that this isolate is distinct from any previously sequenced strains but closely related to midwestern U.S. strains. This is the first Canadian strain cultured, and a new method was developed to reactivate dormant N. risticii to improve culture isolation. IMPORTANCENeorickettsia risticii is an environmental bacterium that lives inside flukes that are parasitic to aquatic snails, insects, and bats. When a horse accidentally ingests insects harboring flukes infected with N. risticii, the bacterium is transmitted to the horse and causes an acute and often fatal disease called Potomac horse fever. Although the disease has been increasingly recognized throughout North and South America, N. risticii has not been cultured outside the United States. This paper reports the first Canadian strain cultured and a new method to effectively culture isolate N. risticii from the horse blood sample. Molecular analysis showed that the genotype of this Canadian strain is distinct from previously sequenced strains but closely related to midwestern U.S. strains. Culture isolation of N. risticii strains would confirm the geographic presence of pathogenic N. risticii, help elucidate N. risticii strain diversity and environmental spreading and distribution, and improve diagnosis and development of vaccines for this dreadful disease.
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Germs within Worms: Localization of Neorickettsia sp. within Life Cycle Stages of the Digenean Plagiorchis elegans.
Applied and environmental microbiology, 2016Co-Authors: Stephen E Greiman, Yasuko Rikihisa, Jefferson A Vaughan, Jacob Cain, Vasyl V TkachAbstract:Neorickettsia spp. are bacterial endosymbionts of parasitic flukes (Digenea) that also have the potential to infect and cause disease (e.g., Sennetsu fever) in the vertebrate hosts of the fluke. One of the largest gaps in our knowledge of Neorickettsia biology is the very limited information available regarding the localization of the bacterial endosymbiont within its digenean host. In this study, we used indirect immunofluorescence microscopy to visualize Neorickettsia sp. within several life cycle stages of the digenean Plagiorchis elegans Individual sporocysts, cercariae, metacercariae, and adults of P. elegans naturally infected with Neorickettsia sp. were obtained from our laboratory-maintained life cycle, embedded, sectioned, and prepared for indirect immunofluorescence microscopy using anti-Neorickettsia risticiihorse serum as the primary antibody. Neorickettsiasp. was found within the tegument of sporocysts, throughout cercarial embryos (germ balls) and fully formed cercariae (within the sporocysts), throughout metacercariae, and within the tegument, parenchyma, vitellaria, uteri, testes, cirrus sacs, and eggs of adults. Interestingly, Neorickettsia sp. was not found within the ovarian tissue. This suggests that vertical transmission of Neorickettsia within adult digeneans occurs via the incorporation of infected vitelline cells into the egg rather than direct infection of the ooplasm of the oocyte, as has been described for other bacterial endosymbionts of invertebrates (e.g.,Rickettsia and Wolbachia).
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and Tropical Veterinary
2013Co-Authors: Stephen J. Dumler, Yasuko Rikihisa, A F Barbet, G A Dasch, Stuart C Ray, Cornelis P. J. Bekker, Guy H. Palmer, F R RurangirwaAbstract:order Rickettsiales: unification of some species of Ehrlichia with Anaplasma, Cowdria with Ehrlichia and Ehrlichia with Neorickettsia, descriptions of six new species combinations and designation of Ehrlichia equi and ‘HGE agent ’ as subjective synonyms of Ehrlichia phagocytophila 1 Division of Medical Microbiology
Didier Raoult - One of the best experts on this subject based on the ideXlab platform.
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sennetsu neorickettsiosis spotted fever group and typhus group rickettsioses in three provinces in thailand
American Journal of Tropical Medicine and Hygiene, 2016Co-Authors: Saithip Bhengsri, Didier Raoult, G A Dasch, Henry C Baggett, Sophie Edouard, Scott F Dowell, Tami L Fisk, Philippe ParolaAbstract:We estimated the seroprevalence and determined the frequency of acute infections with Neorickettsia sennetsu, spotted fever group rickettsiae, Rickettsia typhi, and Orientia tsutsugamushi among 2,225 febrile patients presenting to community hospitals in three rural Thailand provinces during 2002-2005. The seroprevalence was 0.2% for sennetsu neorickettsiosis (SN), 0.8% for spotted fever group (SFG) rickettsiae, 4.2% for murine typhus (MT), and 4.2% for scrub typhus (ST). The frequency of acute infections was 0.1% for SN, 0.6% for SFG, 2.2% for MT, and 1.5% for ST. Additional studies to confirm the distribution of these pathogens and to identify animal reservoirs and transmission cycles are needed to understand the risk of infection.
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Development of a new PCR-based assay to detect Anaplasmataceae and the first report of Anaplasma phagocytophilum and Anaplasma platys in cattle from Algeria.
Comparative immunology microbiology and infectious diseases, 2015Co-Authors: Mustapha Dahmani, Bernard Davoust, Mohamed Seghir Benterki, Florence Fenollar, Didier Raoult, Oleg MediannikovAbstract:Abstract Bovine anaplasmosis is a hemoparasitic disease considered as a major constraint to cattle production in many countries. This pathology is at least partially caused by Anaplasma phagocytophilum, Anaplasma marginale, Anaplasma centrale, and Anaplasma bovis. The global threat and emergence of these species in animals require the reliable identification of these bacteria in animal samples. In this study, we developed a new qPCR tool targeting the 23S rRNA gene for the detection of Anaplasmataceae bacteria. The primers and probe for the qPCR reaction had 100% specificity and could identify at least A. phagocytophilum, A. marginale, A. centrale, Anaplasma ovis, Anaplasma platys, Ehrlichia canis, Ehrlichia ruminantium, Neorickettisa sennetsu, and Neorickettsia risticii. We used this tool to test samples of bovines from Batna (Algeria), an area from which bovine anaplasmosis have never been reported. We identified three genetic variants of A. phagocytophilum, A. platys and Anaplasma sp. “variant 4”. This finding should attract the attention of public authorities to assess the involvement of these pathogens in human and animal health.
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Topley and Wilson's Microbiology and Microbial Infections - Ehrlichia and Anaplasma
Topley & Wilson's Microbiology and Microbial Infections, 2010Co-Authors: J. Stephen Dumler, Didier RaoultAbstract:1 Introduction 2 Historical Perspectives 3 Habitat 4 Microenvironment and Morphology 5 Staining Procedures 6 Laboratory Isolation, Cultural Characteristics, and Growth Requirements 7 Replication 8 Metabolism 9 Classification 10 Genome 11 Cell-Wall Composition and Antigenic Properties 12 Identification and Typing Methods 13 Transmission, Pathogenesis, and Clinical Manifestations 14 Epidemiology and Natural History 15 Specimen Collection and Diagnosis 16 Susceptibility to Antimicrobial Agents 17 Tick Testing as a Predictor of Disease Keywords: Ehrlichia and Anaplasma; Rickettsiaceae family; Anaplasmataceae-important pathogens of man and animals; replication of Ehrlichia, Anaplasma, Wolbachia, and Neorickettsia spp-occurring by binary fission; Rickettsiae classification-undergoing significant change; cell-wall composition and antigenic properties; Ehrlichia genus human infections; ‘EHRLICHIOSIS EWINGII’ (Ehrlichia ewingii)
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Detection of new Anaplasmataceae in the digestive tract of fish from southeast Asia
Clinical Microbiology and Infection, 2009Co-Authors: Piseth Seng, Didier Raoult, Jean-marc Rolain, Philippe BrouquiAbstract:The bacteria of the genus Neorickettsia are strict intracellular bacteria of the Anaplasmataceae family. They are transmitted to their definitive host (humans and animals) by ingestion of raw fish, snails or aquatic insects that are parasitised by infected trematodes. Among them, three species (N. sennetsu, N. helminthoeca and N. risticii) are known to cause diseases in mammals (humans and animals) [1] but two have not yet been associated with the disease (SF agent, and Ehrlichia species trout isolate). About 50 million people in the world are infested by food-borne trematodes, predominantly in southeast Asia. Uncooked fish and shellfish consumption is the principal mode of transmission. Fish-borne trematodes in humans are increasing in endemic areas, and are emerging in Europe and America [2]. Globalisation, international travels and new cooking fashions such as eating raw fish ‘Sushi’ and ‘Sashimi’ are likely to lead to new emerging infections caused by Neorickettsia. We studied here the presence of Neorickettsia in fish and fish-based ingredients that are usually consumed uncooked in southeast Asia. A total of 126 fish and 19 ingredients made from uncooked fish were studied. Between January and February 2007, 57 frozen fish and seven ingredients imported from Thailand and Vietnam were bought in the Asian market in Marseille. In March 2007, 69 other fish preserved in 70% ethanol and 12 supplementary ingredients were collected in Cambodia. After dissection of defrosted fish, stomach and intestine were collected for direct examination for parasite by binocular microscope, and then processed for PCR analysis, culture and histology. Found worms were kept in the 70% ethanol for morphological and molecular identification of the 18S gene by using primers P6.F and 18sr2R [3]. Following DNA extraction of the fish digestive tract, DNA of Anaplasmataceae was detected by rrS PCR using primers: Ehr16SD and Ehr16SR [1]. We completed rrS sequences found by using specific primers (Ncs-614F: 5¢-TTG-GTG-TAG-GGG-TGAAAT-CC, Ncs-606R: 5¢-CCC-CTA-CAC-CAA-AAATTC-CA) and non-specific primers (NcsMA-14F: 5¢-GGC-AGA-CGG-GTG-CGT-AAC, Ncs-1321R: 5¢-GAC-GGG-CAG-TGT-GTA-CAA-GA) newly designed respectively by alignment of rrS sequences of three new Anaplasmataceae with Neorickettsia sequences available in GenBank and by alignment of rrS sequence of all Anaplasmataceae available in GenBank. DNA fragment of the citrate synthase gene (gltA) of Anaplasmataceae was identified by using F1 and R1b as previously described [1]. Negative controls consisted of DNA extracted from human colon, uninfected fish and sterile water. DNA of A. phagocytophilum was used as positive control of rrS PCR and N. sennetsu for gltA PCR. We designed new primers CG-442F (5¢-GGC-CCATAC-CCC-ARN-AAT-G) and CG-877R (5¢-GCDAGT-TTT-TGT-CAR-GTN-GA) to confirm the species of positive fishes. The sequence diversity of the rrS gene was used to define a new species when it was at least 3% between bacterial species. The new genus was definite when rrs gene sequence similarities were lower than 97% [4]. We identified 35 worms in six Channa striata imported into Marseille from Thailand. Sequence analysis of the 18S gene showed that all worms were belonging to Neoechinorhynchus pseudemydis species. Three new Anaplasmataceae were detected in three fish by rrS PCR by using Ehr16SD and Ehr16SR primers (Table 1). After completion of the rrS sequences, the Anaplasmataceae from the stomach of Channa striata fish imported from Thailand was identified as a new genus with a Corresponding author and reprint requests: P. Brouqui, URMITE CNRS ⁄ IRD UMR 6236, IFR 48, Universite de la Mediterranee, Faculte de Medecine, 27 Boulevard Jean Moulin, 13385 Marseille cedex 5, France E-mail: philippe.brouqui@univmed.fr
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Detection of Anaplasmataceae in ticks collected in Morocco
Clinical Microbiology and Infection, 2009Co-Authors: Piseth Seng, Didier Raoult, Philippe Parola, M'hammed Sarih, Cristina Socolovschi, Najma Boudebouch, Mohammed Hassar, P. BrouquiAbstract:Bacteria within the Anaplasmataceae include Gram-negative intracellular bacteria that have been known for a long time as the agents of veterinary diseases. However, in the recent years, five members of Anaplasmataceae have been reported to infect humans, including Anaplasma phagocytophilum, the agent of human granulocytic anaplasmosis, Ehrlichia chaffeensis, the agent of human monocytic ehrlichiosis, and E. ewingii, E. canis and Neorickettsia sennetsu [1]. The abundance of ticks in North Africa represents potential risks for animal and human public health. However, agents within the Anaplasmataceae family have been poorly investigated in North Africa, including in Morocco. In this work, we analysed ticks collected in this country for evidence of infection by Anaplasmataceae.
Vasyl V Tkach - One of the best experts on this subject based on the ideXlab platform.
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Ultrastructure and localization of Neorickettsia in adult digenean trematodes provides novel insights into helminth-endobacteria interaction.
Parasites & vectors, 2017Co-Authors: Kerstin Fischer, Vasyl V Tkach, Kurt C. Curtis, Peter U. FischerAbstract:Neorickettsia are a group of intracellular α proteobacteria transmitted by digeneans (Platyhelminthes, Trematoda). These endobacteria can also infect vertebrate hosts of the helminths and cause serious diseases in animals and humans. Neorickettsia have been isolated from infected animals and maintained in cell cultures, and their morphology in mammalian cells has been described. However, limited information is available on the morphology and localization of Neorickettsia in the trematode host. We used a Neorickettsia-infected strain of the model trematode Plagiorchis elegans to infect Syrian Golden hamsters to produce adult worms. Ultrastructure of Neorickettsia was assessed by transmission electron microscopy of high pressure freezing/freeze substitution fixed specimens. A Neorickettsia surface protein from P. elegans (PeNsp-3) was cloned and antibodies against the recombinant protein were used to localize Neorickettsia by immunohistochemistry. Ultrastructural analysis revealed moderate numbers of pleomorphic endobacteria with a median size of 600 × 400 nm and characteristic double membranes in various tissue types. Endobacteria showed tubular membrane invaginations and secretion of polymorphic vesicles. Endobacteria were unevenly localized as single cells, or less frequently as small morula-like clusters in the ovary, Mehlis’ gland, vitelline follicles, uterus, intrauterine eggs, testis, cirrus-sac, tegument, intestine and the oral and ventral sucker. Examination of hamster small intestine infected with P. elegans showed many endobacteria at the host-parasite interface such as the oral and ventral sucker, the tegument and the excretory pore. We conclude that adult P. elegans trematodes carry Neorickettsia endobacteria in varying numbers in many tissue types that support vertical transmission, trematode to trematode transmission via seminal fluid, and possibly horizontal transmission from trematodes to vertebrate hosts. These means appear to be novel mechanisms of pathogen transmission by endoparasitic worms.
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Ultrastructure and localization of Neorickettsia in adult digenean trematodes provides novel insights into helminth-endobacteria interaction
Parasites & Vectors, 2017Co-Authors: Kerstin Fischer, Vasyl V Tkach, Kurt C. Curtis, Peter U. FischerAbstract:Background Neorickettsia are a group of intracellular α proteobacteria transmitted by digeneans (Platyhelminthes, Trematoda). These endobacteria can also infect vertebrate hosts of the helminths and cause serious diseases in animals and humans. Neorickettsia have been isolated from infected animals and maintained in cell cultures, and their morphology in mammalian cells has been described. However, limited information is available on the morphology and localization of Neorickettsia in the trematode host. Methods We used a Neorickettsia- infected strain of the model trematode Plagiorchis elegans to infect Syrian Golden hamsters to produce adult worms. Ultrastructure of Neorickettsia was assessed by transmission electron microscopy of high pressure freezing/freeze substitution fixed specimens. A Neorickettsia surface protein from P. elegans ( PeN sp-3) was cloned and antibodies against the recombinant protein were used to localize Neorickettsia by immunohistochemistry. Results Ultrastructural analysis revealed moderate numbers of pleomorphic endobacteria with a median size of 600 × 400 nm and characteristic double membranes in various tissue types. Endobacteria showed tubular membrane invaginations and secretion of polymorphic vesicles. Endobacteria were unevenly localized as single cells, or less frequently as small morula-like clusters in the ovary, Mehlis’ gland, vitelline follicles, uterus, intrauterine eggs, testis, cirrus-sac, tegument, intestine and the oral and ventral sucker. Examination of hamster small intestine infected with P. elegans showed many endobacteria at the host-parasite interface such as the oral and ventral sucker, the tegument and the excretory pore. Conclusions We conclude that adult P. elegans trematodes carry Neorickettsia endobacteria in varying numbers in many tissue types that support vertical transmission, trematode to trematode transmission via seminal fluid, and possibly horizontal transmission from trematodes to vertebrate hosts. These means appear to be novel mechanisms of pathogen transmission by endoparasitic worms.
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Transmission Biology, Host Associations, Distribution and Molecular Diagnostics of Neorickettsia
Rickettsiales, 2016Co-Authors: Vasyl V Tkach, Stephen E GreimanAbstract:The genus Neorickettsia includes a small number of obligate intracellular rickettsial bacteria normally endosymbiotic within all stages of digenean complex life cycles, where they are maintained through vertical transmission. Under some circumstances Neorickettsia may also be transmitted horizontally by digenean parasites to their vertebrate definitive hosts where they may infect macrophages and other cell types and cause diseases, in some cases severe. This chapter briefly discusses the history of research on Neorickettsia, their phylogenetic interrelationships, transmission biology of different species and species-level genetic lineages within the genus, associations among Neorickettsia and their digenean and vertebrate hosts, geographic distribution, and PCR-based molecular diagnostics and identification of Neorickettsia.
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Nanophyetus salmincola, vector of the salmon poisoning disease agent Neorickettsia helminthoeca, harbors a second pathogenic Neorickettsia species.
Veterinary parasitology, 2016Co-Authors: Stephen E Greiman, Michael L. Kent, John Betts, Deborah Cochell, Tiah Sigler, Vasyl V TkachAbstract:The trematode Nanophyetus salmincola is known as the carrier of Neorickettsia helminthoeca, an obligate intracellular endosymbiotic bacterium that causes salmon poisoning disease (SPD), a fatal disease of dogs. The bacteria are maintained through the complex life cycle of N. salmincola that involves snails Juga plicifera as the first intermediate host, salmonid fishes as the second intermediate host and fish-eating mammals as definitive hosts. N. salmincola was also found to harbor a second species of Neorickettsia that causes the Elokomin fluke fever disease (EFF) which has clinical signs similar to SPD in bears, but only low grade illness in dogs. The EFF agent has not been sequenced. In this study we identified N. salmincola as the vector of yet additional species of Neorickettsia known as Stellanchasmus falcatu (SF) agent using DNA sequencing.
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Large Scale Screening of Digeneans for Neorickettsia Endosymbionts Using Real-Time PCR Reveals New Neorickettsia Genotypes, Host Associations and Geographic Records
2016Co-Authors: Stephen E Greiman, Vasyl V Tkach, Thomas J. Fayton, Eric Pulis, Stephen S. CurranAbstract:Digeneans are endoparasitic flatworms with complex life cycles including one or two intermediate hosts (first of which is always a mollusk) and a vertebrate definitive host. Digeneans may harbor intracellular endosymbiotic bacteria belonging to the genus Neorickettsia (order Rickettsiales, family Anaplasmataceae). Some Neorickettsia are able to invade cells of the digenean’s vertebrate host and are known to cause diseases of wildlife and humans. In this study we report the results of screening 771 digenean samples for Neorickettsia collected from various vertebrates in terrestrial, freshwater, brackish, and marine habitats in the United States, China and Australia. Neorickettsia were detected using a newly designed real-time PCR protocol targeting a 152 bp fragment of the heat shock protein coding gene, GroEL, and verified with nested PCR and sequencing of a 1371 bp long region of 16S rRNA. Eight isolates of Neorickettsia have been obtained. Sequence comparison and phylogenetic analysis demonstrated that 7 of these isolates, provisionally named Neorickettsia sp. 1–7 (obtained from allocreadiid Crepidostomum affine, haploporids Saccocoelioides beauforti and Saccocoelioides lizae, faustulid Bacciger sprenti, deropegid Deropegus aspina, a lecithodendriid, and a pleurogenid) represent new genotypes and one (obtained from Metagonimoides oregonensis) was identical to a published sequence of Neorickettsia known as SF agent. All digenean species reported in this study represent new host records. Three of the 6 digenean families (Haploporidae, Pleurogenidae, and Faustulidae) are also reported for the first time as hosts of Neorickettsia. We have detected Neorickettsia in digeneans fro
Michel Drancourt - One of the best experts on this subject based on the ideXlab platform.
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RNA polymerase β-subunit-based phylogeny of Ehrlichia spp., Anaplasma spp., Neorickettsia spp. and Wolbachia pipientis
International Journal of Systematic and Evolutionary Microbiology, 2003Co-Authors: Anne-véronique Taillardat-bisch, Didier Raoult, Michel DrancourtAbstract:Sequence analysis of rpoB, the gene encoding the β-subunit of RNA polymerase, was used in a phylogenetic investigation of nine species from the genera Ehrlichia, Neorickettsia, Wolbachia and Anaplasma. The complete nucleotide sequences obtained for Anaplasma phagocytophilum (HGE agent), Ehrlichia chaffeensis, Neorickettsia sennetsu, Neorickettsia risticii, Anaplasma marginale and Wolbachia pipientis were amongst the longest rpoB sequences in GenBank and ranged from 4074 bp for N. sennetsu to 4311 bp for W. pipientis. Additional partial rpoB sequences were obtained for Ehrlichia canis, Ehrlichia ruminantium and Ehrlichia muris. Identical phylogenetic trees were inferred from multiple sequence alignments of the nucleotide sequences and the derived amino acid sequences using either distance, maximum-likelihood or parsimony methods. This study confirms the phylogeny previously inferred from sequence analyses of the 16S rRNA gene, groESL and gltA and allows the confirmation of four monophyletic clades. The rpoB nucleotide sequences were more variable than the 16S rRNA gene and groESL sequences at the species level.
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RNA polymerase beta-subunit-based phylogeny of Ehrlichia spp., Anaplasma spp., Neorickettsia spp. and Wolbachia pipientis.
International journal of systematic and evolutionary microbiology, 2003Co-Authors: Anne-véronique Taillardat-bisch, Didier Raoult, Michel DrancourtAbstract:Sequence analysis of rpoB, the gene encoding the beta-subunit of RNA polymerase, was used in a phylogenetic investigation of nine species from the genera Ehrlichia, Neorickettsia, Wolbachia and Anaplasma. The complete nucleotide sequences obtained for Anaplasma phagocytophilum (HGE agent), Ehrlichia chaffeensis, Neorickettsia sennetsu, Neorickettsia risticii, Anaplasma marginale and Wolbachia pipientis were amongst the longest rpoB sequences in GenBank and ranged from 4074 bp for N. sennetsu to 4311 bp for W. pipientis. Additional partial rpoB sequences were obtained for Ehrlichia canis, Ehrlichia ruminantium and Ehrlichia muris. Identical phylogenetic trees were inferred from multiple sequence alignments of the nucleotide sequences and the derived amino acid sequences using either distance, maximum-likelihood or parsimony methods. This study confirms the phylogeny previously inferred from sequence analyses of the 16S rRNA gene, groESL and gltA and allows the confirmation of four monophyletic clades. The rpoB nucleotide sequences were more variable than the 16S rRNA gene and groESL sequences at the species level.
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Citrate synthase gene sequence: a new tool for phylogenetic analysis and identification of Ehrlichia.
Journal of clinical microbiology, 2001Co-Authors: Hisashi Inokuma, Michel Drancourt, Philippe Brouqui, Didier RaoultAbstract:The sequence of the citrate synthase gene (gltA) of 13 ehrlichial species (Ehrlichia chaffeensis, Ehrlichia canis, Ehrlichia muris, an Ehrlichia species recently detected from Ixodes ovatus, Cowdria ruminantium, Ehrlichia phagocytophila, Ehrlichia equi, the human granulocytic ehrlichiosis [HGE] agent, Anaplasma marginale, Anaplasma centrale, Ehrlichia sennetsu, Ehrlichia risticii, and Neorickettsia helminthoeca) have been determined by degenerate PCR and the Genome Walker method. The ehrlichial gltA genes are 1,197 bp (E. sennetsu and E. risticii) to 1,254 bp (A. marginale and A. centrale) long, and GC contents of the gene vary from 30.5% (Ehrlichia sp. detected from I. ovatus) to 51.0% (A. centrale). The percent identities of the gltA nucleotide sequences among ehrlichial species were 49.7% (E. risticii versus A. centrale) to 99.8% (HGE agent versus E. equi). The percent identities of deduced amino acid sequences were 44.4% (E. sennetsu versus E. muris) to 99.5% (HGE agent versus E. equi), whereas the homology range of 16S rRNA genes was 83.5% (E. risticii versus the Ehrlichia sp. detected from I. ovatus) to 99.9% (HGE agent, E. equi, and E. phagocytophila). The architecture of the phylogenetic trees constructed by gltA nucleotide sequences or amino acid sequences was similar to that derived from the 16S rRNA gene sequences but showed more-significant bootstrap values. Based upon the alignment analysis of the ehrlichial gltA sequences, two sets of primers were designed to amplify tick-borne Ehrlichia and Neorickettsia genogroup Ehrlichia (N. helminthoeca, E. sennetsu, and E. risticii), respectively. Tick-borne Ehrlichia species were specifically identified by restriction fragment length polymorphism (RFLP) patterns of AcsI and XhoI with the exception of E. muris and the very closely related ehrlichia derived from I. ovatus for which sequence analysis of the PCR product is needed. Similarly, Neorickettsia genogroup Ehrlichia species were specifically identified by RFLP patterns of RcaI digestion. If confirmed this technique will be useful in rapidly identifying Ehrlichia spp.
Stephen E Greiman - One of the best experts on this subject based on the ideXlab platform.
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Transmission Biology, Host Associations, Distribution and Molecular Diagnostics of Neorickettsia
Rickettsiales, 2016Co-Authors: Vasyl V Tkach, Stephen E GreimanAbstract:The genus Neorickettsia includes a small number of obligate intracellular rickettsial bacteria normally endosymbiotic within all stages of digenean complex life cycles, where they are maintained through vertical transmission. Under some circumstances Neorickettsia may also be transmitted horizontally by digenean parasites to their vertebrate definitive hosts where they may infect macrophages and other cell types and cause diseases, in some cases severe. This chapter briefly discusses the history of research on Neorickettsia, their phylogenetic interrelationships, transmission biology of different species and species-level genetic lineages within the genus, associations among Neorickettsia and their digenean and vertebrate hosts, geographic distribution, and PCR-based molecular diagnostics and identification of Neorickettsia.
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Nanophyetus salmincola, vector of the salmon poisoning disease agent Neorickettsia helminthoeca, harbors a second pathogenic Neorickettsia species.
Veterinary parasitology, 2016Co-Authors: Stephen E Greiman, Michael L. Kent, John Betts, Deborah Cochell, Tiah Sigler, Vasyl V TkachAbstract:The trematode Nanophyetus salmincola is known as the carrier of Neorickettsia helminthoeca, an obligate intracellular endosymbiotic bacterium that causes salmon poisoning disease (SPD), a fatal disease of dogs. The bacteria are maintained through the complex life cycle of N. salmincola that involves snails Juga plicifera as the first intermediate host, salmonid fishes as the second intermediate host and fish-eating mammals as definitive hosts. N. salmincola was also found to harbor a second species of Neorickettsia that causes the Elokomin fluke fever disease (EFF) which has clinical signs similar to SPD in bears, but only low grade illness in dogs. The EFF agent has not been sequenced. In this study we identified N. salmincola as the vector of yet additional species of Neorickettsia known as Stellanchasmus falcatu (SF) agent using DNA sequencing.
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Large Scale Screening of Digeneans for Neorickettsia Endosymbionts Using Real-Time PCR Reveals New Neorickettsia Genotypes, Host Associations and Geographic Records
2016Co-Authors: Stephen E Greiman, Vasyl V Tkach, Thomas J. Fayton, Eric Pulis, Stephen S. CurranAbstract:Digeneans are endoparasitic flatworms with complex life cycles including one or two intermediate hosts (first of which is always a mollusk) and a vertebrate definitive host. Digeneans may harbor intracellular endosymbiotic bacteria belonging to the genus Neorickettsia (order Rickettsiales, family Anaplasmataceae). Some Neorickettsia are able to invade cells of the digenean’s vertebrate host and are known to cause diseases of wildlife and humans. In this study we report the results of screening 771 digenean samples for Neorickettsia collected from various vertebrates in terrestrial, freshwater, brackish, and marine habitats in the United States, China and Australia. Neorickettsia were detected using a newly designed real-time PCR protocol targeting a 152 bp fragment of the heat shock protein coding gene, GroEL, and verified with nested PCR and sequencing of a 1371 bp long region of 16S rRNA. Eight isolates of Neorickettsia have been obtained. Sequence comparison and phylogenetic analysis demonstrated that 7 of these isolates, provisionally named Neorickettsia sp. 1–7 (obtained from allocreadiid Crepidostomum affine, haploporids Saccocoelioides beauforti and Saccocoelioides lizae, faustulid Bacciger sprenti, deropegid Deropegus aspina, a lecithodendriid, and a pleurogenid) represent new genotypes and one (obtained from Metagonimoides oregonensis) was identical to a published sequence of Neorickettsia known as SF agent. All digenean species reported in this study represent new host records. Three of the 6 digenean families (Haploporidae, Pleurogenidae, and Faustulidae) are also reported for the first time as hosts of Neorickettsia. We have detected Neorickettsia in digeneans fro
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Real-time PCR detection and phylogenetic relationships of Neorickettsia spp. in digeneans from Egypt, Philippines, Thailand, Vietnam and the United States.
Parasitology international, 2016Co-Authors: Stephen E Greiman, Jefferson A Vaughan, Rasha Elmahy, Poom Adisakwattana, Nguyen Van Ha, Thomas J. Fayton, Amal I. Khalil, Vasyl V TkachAbstract:Neorickettsia (Rickettsiales, Anaplasmataceae) is a genus of obligate intracellular bacterial endosymbionts of digeneans (Platyhelminthes, Digenea). Some Neorickettsia are able to invade cells of the digenean's vertebrate host and are known to cause diseases of domestic animals, wildlife, and humans. In this study we report the results of screening digenean samples for Neorickettsia collected from bats in Egypt and Mindoro Island, Philippines, snails and fishes from Thailand, and fishes from Vietnam and the USA. Neorickettsia were detected using a real-time PCR protocol targeting a 152bp fragment of the heat shock protein coding gene, GroEL, and verified with nested PCR and sequencing of a 1853bp long region of the GroESL operon and a 1371bp long region of 16S rRNA. Eight unique genotypes of Neorickettsia were obtained from digenean samples. Neorickettsia sp. 8 obtained from Lecithodendrium sp. from Egypt; Neorickettsia sp. 9 and 10 obtained from two species of Paralecithodendrium from Mindoro, Philippines; Neorickettsia sp. 11 from Lecithodendrium sp. and Neorickettsia sp. 4 (previously identified from Saccocoelioides lizae, from China) from Thailand; Neorickettsia sp. 12 from Dicrogaster sp. Florida, USA; Neorickettsia sp. 13 and SF agent from Vietnam. Sequence comparison and phylogenetic analysis demonstrated that the forms, provisionally named Neorickettsia sp. 8-13, represent new genotypes. We have for the first time detected Neorickettsia in a digenean from Egypt (and the African continent as a whole), the Philippines, Thailand and Vietnam based on PCR and sequencing evidence. Our findings suggest that further surveys from the African continent, SE Asia, and island countries are likely to reveal new Neorickettsia lineages as well as new digenean host associations.
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The numbers game: quantitative analysis of Neorickettsia sp. propagation through complex life cycle of its digenean host using realtime qPCR
Parasitology Research, 2016Co-Authors: Stephen E Greiman, Volodymyr V TkachAbstract:Bacteria of the genus Neorickettsia are obligate intracellular endosymbionts of parasitic flukes (Digenea) and are passed through the entire complex life cycle of the parasite by vertical transmission. Several species of Neorickettsia are known to cause diseases in domestic animals, wildlife, and humans. Quantitative data on the transmission of the bacteria through the digenean life cycle is almost completely lacking. This study quantified for the first time the abundance of Neorickettsia within multiple stages of the life cycle of the digenean Plagiorchis elegans . Snails Lymnaea stagnalis collected from a pond in North Dakota were screened for the presence of digenean cercariae, which were subsequently tested for the presence of Neorickettsia . Three L. stagnalis were found shedding P. elegans cercariae infected with Neorickettsia . These snails were used to initiate three separate laboratory life cycles and obtain all life cycle stages for bacterial quantification. A quantitative real-time PCR assay targeting the GroEL gene was developed to enumerate Neorickettsia sp. within different stages of the digenean life cycle. The number of bacteria significantly increased throughout all stages, from eggs to adults. The two largest increases in number of bacteria occurred during the period from eggs to cercariae and from 6-day metacercariae to 48-h juvenile worms. These two periods seem to be the most important for Neorickettsia propagation through the complex digenean life cycle and maturation in the definitive host.
