Swiss Army Survey in Switzerland to Determine the Prevalence of Francisella tularensis , Members of the Ehrlichia phagocytophila Genogroup, Borrelia burgdorferi Sensu Lato, and Tick-Borne Encephalitis Virus in Ticks
Roland WickiPierre SauterC. MettlerAndreas NatschThomas EnzlerNicola PusterlaPeter KuhnertG. EgliMichele BernasconiReto LienhardH. LutzChristian M. Leutenegger
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Medical microbiology
Ehrlichia chaffeensis
Abstract The obligately intracellular bacterium Ehrlichia chaffeensis that resides in mononuclear phagocytes is the etiologic agent of human monocytotropic ehrlichiosis (HME). HME is an emerging, highly prevalent, and often life-threatening tick-transmitted infectious disease in the United States. As yet there are no vaccines against ehrlichiosis. We had recently demonstrated that Ehrlichia Hsp60 and p28 are the major antigens of Ehrlichia, and both the proteins are post-translationally modified as determined by eastern blotting. Based on these observations we designed peptides specific to Ehrlichia Hsp60 and p28-19. The designed peptide sequences were highly conserved in Ehrlichia. In initial studies we tested the peptides as probes to detect antibodies to Ehrlichia. Both the Ehrlichia Hsp60 and p28 could detect antibodies stimulated by E. chaffeensis, E. canis, E. muris, and E. ewingii. However, the p28-19 peptide was more sensitive than Ehrlichia Hsp60 in diagnosis of ehrlichiosis. Both Ehrlichia peptides-Hsp60 and p28-19-could function as a vaccine. The bacteria were cleared more rapidly within 14 days in vaccinated mice. The p28-19 peptide elicited higher levels of IgG1, IgG2b, and IgG3 antibodies compared to Ehrlichia Hsp60. The experiments demonstrate that Ehrlichia antigenic peptides Hsp60 and p28-19 are good candidates to be used in diagnostics and also could function as vaccines to protect against ehrlichiosis.
Ehrlichia chaffeensis
Ehrlichiosis
Ehrlichia canis
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Ehrlichiosis is the collective name for infections caused by obligate intracellular gram-negative bacteria in the genera Ehrlichia and Anaplasma that belong to the family Anaplasmataceae. Members of these two genera cycle in nature between invertebrate (arthropod) and vertebrate (mammalian) hosts, and some species occasionally cause zoonotic infections in humans. Three species are currently known to cause human tick-borne infection in the United States and Europe and include Ehrlichia chaffeensis, the agent of human monocytic ehrlichiosis (HME), Ehrlichia ewingii, the agent of human ewingii ehrlichiosis (HEE), and Anaplasma phagocytophilum, the agent of human granulocytic anaplasmosis (HGA).
Ehrlichia chaffeensis
Ehrlichiosis
Anaplasmataceae
Anaplasma phagocytophilum
Obligate
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Ehrlichia chaffeensis
Ehrlichiosis
Anaplasmataceae
Anaplasma phagocytophilum
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Ehrlichia chaffeensis
Ehrlichiosis
Pathogenesis
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Ehrlichiosis is the collective name for infections caused by obligate intracellular gram-negative bacteria in the genera Ehrlichia, Anaplasma, and Neoehrlichia, family Anaplasmataceae. Members of these genera cycle between invertebrate (arthropod) and vertebrate hosts, and some cause human zoonoses. At least seven species cause human tick-borne infection in the United States and Europe, including Ehrlichia chaffeensis, the agent of human monocytic ehrlichiosis (HME), Ehrlichia ewingii, the agent of human ewingii ehrlichiosis (HEE), Anaplasma phagocytophilum, the agent of human granulocytic anaplasmosis (HGA), an Ehrlichia muris-like agent (EMLA), the Panola Mountain ehrlichia, an agent phylogenetically similar to Ehrlichia ruminantium that has caused fever in humans in the United States, Ehrlichia canis, thought limited to canids but identified as an agent of human febrile illness in Venezuela, and Candidatus Neoehrlichia mikurensis, which has caused severe sepsis-like conditions in Europe, but mild febrile disease in Asia. While human infection by Neorickettsia sennetsu periodically surfaces in Asia, the transmission and disease processes are distinct and it will not be considered here.
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Anaplasmataceae
Ehrlichiosis
Ehrlichia canis
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Ehrlichiosis is a non contagious infectious disease, mainly transmitted by thick bites. In 1998, this infection was detected in dogs, for the first time, in Chile.To establish if there is human exposure to Ehrlichia sp in Chile.Blood samples from 17 dogs with ehrlichiosis and 19 humans who had contact with them were studied to determine human exposure to Ehrlichia equi and Ehrlichia chaffeensis in Chile. Samples were analyzed by indirect immunofluorecence and by polymerase chain reaction (PCR).Six dogs had positive titers against both species of ehrlichia; 2 with titers of 1/256; 3 with titers over 1/512 to Ehrlichia equi and titers of 1/256, 1/128 and 1/64 to Ehrlichia chaffeensis respectively, and 1 with titers of 1/256 to Ehrlichia equi and titers of 1/128 to Ehrlichia chaffeensis. Two of the 19 humans, had positive titers against both antigens (1/128). PCR reactions were negative in both human and canine sera.These results confirm that human exposure to Ehrlichia sp. Epidemiological surveillance for human ehrlichiosis should be implemented in the country.
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Ehrlichiosis
Ehrlichia canis
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Ehrlichia chaffeensis
Ehrlichiosis
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Anaplasmosis, caused by Anaplasma phagocytophilum and Anaplasma platys, and ehrlichiosis, caused by Ehrlichia chaffeensis, Ehrlichia ewingii, the "Panola Mountain Ehrlichia" and Ehrlichia muris- like pathogens have been identified as emerging tick borne infectious diseases in dogs and human patients. Persistent intravascular infection with these bacteria is well documented in dogs, but is less well documented in human beings. Serology and PCR targeting multiple microbial genes, followed by DNA sequencing, was used to test sequential blood samples. Tissue culture isolation was attempted in two laboratories. A. platys, E. chaffeensis, and E. ewingii DNA was amplified from two Anaplasma and Ehrlichia seronegative family members and their dog, all lacking typical symptoms of anaplasmosis or ehrlichiosis. Following treatment with doxycycline, the dog and mother were Anaplasma and Ehrlichia spp. PCR negative. Sequential PCR testing provided molecular evidence supporting intravascular persistence of A. platys and Ehrlichia spp. in two humans and their dog. Diagnosticians and clinicians should consider the potential for co-infections due to these tick borne organisms.
Ehrlichia chaffeensis
Ehrlichiosis
Anaplasmosis
Anaplasma phagocytophilum
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Background The obligately intracellular bacterium Ehrlichia chaffeensis that resides in mononuclear phagocytes is the causative agent of human monocytotropic ehrlichiosis. Ehrlichia muris and Ixodes ovatus Ehrlichia (IOE) are agents of mouse models of ehrlichiosis. The mechanism by which Ehrlichia are transported from an infected host cell to a non-infected cell has not been demonstrated. Methodology/Principal Findings Using fluorescence microscopy and transmission and scanning electron microscopy, we demonstrated that Ehrlichia was transported through the filopodia of macrophages during early stages of infection. If host cells were not present in the vicinity of an Ehrlichia-infected cell, the leading edge of the filopodium formed a fan-shaped structure filled with the pathogen. Formation of filopodia in the host macrophages was inhibited by cytochalasin D and ehrlichial transport were prevented due to the absence of filopodia formation. At late stages of infection the host cell membrane was ruptured, and the bacteria were released. Conclusions/Significance Ehrlichia are transported through the host cell filopodium during initial stages of infection, but are released by host cell membrane rupture during later stages of infection.
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Abstract Background The genus Ehrlichia consists of tick-borne obligatory intracellular bacteria that can cause deadly diseases of medical and agricultural importance. Ehrlichia sp. HF, isolated from Ixodes ovatus ticks in Japan [also referred to as I. ovatus Ehrlichia (IOE) agent], causes acute fatal infection in laboratory mice that resembles acute fatal human monocytic ehrlichiosis caused by Ehrlichia chaffeensis . As there is no small laboratory animal model to study fatal human ehrlichiosis, Ehrlichia sp. HF provides a needed disease model. However, the inability to culture Ehrlichia sp. HF and the lack of genomic information have been a barrier to advance this animal model. In addition, Ehrlichia sp. HF has several designations in the literature as it lacks a taxonomically recognized name. Results We stably cultured Ehrlichia sp. HF in canine histiocytic leukemia DH82 cells from the HF strain-infected mice, and determined its complete genome sequence. Ehrlichia sp. HF has a single double-stranded circular chromosome of 1,148,904 bp, which encodes 866 proteins with a similar metabolic potential as E. chaffeensis . Ehrlichia sp. HF encodes homologs of all virulence factors identified in E. chaffeensis , including 23 paralogs of P28/OMP-1 family outer membrane proteins, type IV secretion system apparatus and effector proteins, two-component systems, ankyrin-repeat proteins, and tandem repeat proteins. Ehrlichia sp. HF is a novel species in the genus Ehrlichia , as demonstrated through whole genome comparisons with six representative Ehrlichia species, subspecies, and strains, using average nucleotide identity, digital DNA-DNA hybridization, and core genome alignment sequence identity. Conclusions The genome of Ehrlichia sp. HF encodes all known virulence factors found in E. chaffeensis , substantiating it as a model Ehrlichia species to study fatal human ehrlichiosis. Comparisons between Ehrlichia sp. HF and E. chaffeensis will enable identification of in vivo virulence factors that are related to host specificity, disease severity, and host inflammatory responses. We propose to name Ehrlichia sp. HF as Ehrlichia japonica sp. nov. (type strain HF), to denote the geographic region where this bacterium was initially isolated.
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Ehrlichiosis
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