Disease relevance of Ehrlichia

• Genogroup II ehrlichia, including the agent of human granulocytic ehrlichiosis, Ehrlichia phagocytophila, and the bovine pathogen Anaplasma marginale, express a markedly immunodominant outer membrane protein designated major surface protein 2 (MSP2) [1].
• Doxycycline hyclate treatment of experimental canine ehrlichiosis followed by challenge inoculation with two Ehrlichia canis strains [2].
• Antibodies in the sera of healthy individuals or patients with Ehrlichia chaffeensis or Borrelia burgdorferi infection did not recognize HGE-44 [3].
• In vitro activities of telithromycin compared to those of erythromycin against Rickettsia spp., Bartonella spp., Coxiella burnetii, and Ehrlichia chaffeensis were determined [4].
• 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 [5].

High impact information on Ehrlichia

• The species present were identified by species-specific PCR assays and nucleotide sequencing of the gene encoding ehrlichia 16S ribosomal RNA [6].
• Polymerase chain reaction products obtained with primers for E phagocytophila, E equi, and the granulocytotropic Ehrlichia revealed that seven patients were infected with the same agent [7].
• In 1988, the Centers for Disease Control and the Oklahoma State Department of Health identified 40 patients who had a fourfold or greater change in antibody titer in response to Ehrlichia canis [8].
• The Miyayama strain of Ehrlichia sennetsu and the Maryland and Illinois strains of Ehrlichia risticii were cultivated in a mouse macrophage cell line, separated from host cell constituents by procedures that included Renografin or Percoll gradient centrifugation, and tested after cryopreservation [9].
• When the Ehrlichia cells were incubated for 1 hr at 34 degrees C with glutamine, significant amounts of ATP were detected [9].

Chemical compound and disease context of Ehrlichia

• Dogs were experimentally inoculated with Ehrlichia canis Florida to assess the efficacy of doxycycline hyclate for the treatment of acute ehrlichiosis [2].
• The glycoprotein genes of Ehrlichia chaffeensis (1,644 bp) and Ehrlichia canis (2,064 bp) encode proteins of 548 to 688 amino acids with predicted molecular masses of only 61 and 73 kDa but with electrophoretic mobilities of 120 kDa (P120) and 140 kDa (P140), respectively [10].
• An immunoreactive 38-kilodalton protein of Ehrlichia canis shares structural homology and iron-binding capacity with the ferric ion-binding protein family [11].
• Protective studies were conducted with mice by using recombinantly produced antigens, polyacrylamide gel electrophoresis-fractionated antigens, and a monoclonal antibody specific to the 28-kDa antigen of Ehrlichia risticii [12].
• A substantial elevation of nitrite levels indicative of NO production occurred in cultures of Cowdria ruminantium-infected bovine pulmonary endothelial cells (BPEC) incubated in medium alone [13].

Biological context of Ehrlichia

• Mice lacking either B cells or FcgammaRI were unable to resolve a low-dose (sublethal) I. ovatus ehrlichia infection, which suggested that humoral immunity is essential for resistance [14].
• Human neutrophils migrate towards Ehrlichia sp.-infected cells in a chemotaxis chamber assay, and this movement can be blocked with antibodies to IL-8 [15].
• The msp2 gene in the A. phagocytophilum strain HZ genome was a single-copy gene and was located downstream of two Ehrlichia chaffeensis omp-1 homologs and a decarboxylase gene (ubiD) [16].
• The trematodes obtained from each snail were pooled and tested for Ehrlichia risticii, the agent of PHF, by nested PCR using primers specific to the 16S rRNA gene [17].
• Characterization of the SF agent, an Ehrlichia sp. isolated from the fluke Stellantchasmus falcatus, by 16S rRNA base sequence, serological, and morphological analyses [18].

Anatomical context of Ehrlichia

• Intraperitoneal (i.p.) infection with a high dose of a highly virulent Ehrlichia strain (IOE) results in a toxic shock-like syndrome characterized by severe liver injury and systemic overproduction of tumor necrosis factor alpha (TNF-alpha) by CD8+ T cells [19].
• Two human ehrlichioses occur in the United States: monocytic ehrlichiosis (HME), which is caused by Ehrlichia chaffeensis that infects mononuclear phagocytes in blood and tissues, and granulocytic ehrlichiosis (HGE), an infection of granulocytes that is due to a phylogenetically distinct organism [20].
• The diagnosis is confirmed by elevated antibody titers to Ehrlichia chaffeensis or visualization of inclusions in white blood cells and the disease is easily cured with tetracyclines or chloramphenicol [21].
• Attempts were made at counteracting the effects of vaso-active substances released by mast cells by treating mice infected with Cowdria ruminantium with antagonists to histamin and serotonin on one hand, and with mast cell stabilizers on the other, but were not successful [22].

Gene context of Ehrlichia

• First, E. chaffeensis avoided stimulation of or repressed the transcription of cytokines involved in the early innate immune response and cell-mediated immune response to intracellular microbes, such as the interleukin-12 (IL-12), IL-15, and IL-18 genes, which might make Ehrlichia a stealth organism for the macrophage [23].
• The major antigenic protein 2 (MAP2) homolog of Ehrlichia chaffeensis was cloned and expressed [24].
• The response of PBMC collected from cattle immunized with killed Cowdria to MAP1, MAP1-B, MAP2 and to a lysate of Cowdria was characterized in vitro [25].
• To verify this hypothesis, we sequenced the entire gyrA gene of the quinolone-susceptible species Ehrlichia sennetsu and designed specific primers to amplify and sequence the QRDR of four other Ehrlichia species as well as the closely related species Cowdria ruminantium [26].
• Ehrlichia ruminantium major antigenic protein gene (map1) variants are not geographically constrained and show no evidence of having evolved under positive selection pressure [27].

Analytical, diagnostic and therapeutic context of Ehrlichia

• A confirmed case was defined as either (1) a 4-fold change in total antibody titer to Ehrlichia equi by indirect immunofluorescence or (2) a polymerase chain reaction assay positive for Ehrlichia phagocytophila/E equi group DNA [28].
• We present evidence that supports the carrier status of dogs experimentally infected with Ehrlichia canis after treatment with doxycycline [29].
• Molecular cloning and characterization of the Ehrlichia chaffeensis variable-length PCR target: an antigen-expressing gene that exhibits interstrain variation [30].
• DNA vaccination with map1 gene followed by protein boost augments protection against challenge with Cowdria ruminantium, the agent of heartwater [31].
• The immunodominant 120 kDa protein (p120) of Ehrlichia chaffeensis was demonstrated to be exposed on the surface of purified whole ehrlichial cells examined by immunoelectron microscopy with a rabbit antibody against a portion of the domain containing tandem repeat units [32].

References