1. Ultrastructural evidence of the ehrlichial developmental cycle in naturally infected Ixodes persulcatus ticks in the course of coinfection with Rickettsia, Borrelia, and a flavivirus.
- Author
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Popov VL, Korenberg EI, Nefedova VV, Han VC, Wen JW, Kovalevskii YV, Gorelova NB, and Walker DH
- Subjects
- Anaplasma phagocytophilum classification, Anaplasma phagocytophilum physiology, Animals, Arachnid Vectors virology, Bacterial Proteins genetics, Base Sequence, Borrelia burgdorferi Group classification, Borrelia burgdorferi Group physiology, Borrelia burgdorferi Group ultrastructure, Cells, Cultured, Digestive System microbiology, Digestive System pathology, Digestive System ultrastructure, Ehrlichia growth & development, Ehrlichia ultrastructure, Female, Flavivirus physiology, Flavivirus ultrastructure, Gram-Negative Bacteria classification, Gram-Negative Bacteria growth & development, Ixodes virology, Male, Molecular Sequence Data, RNA, Ribosomal, 16S genetics, Rickettsia classification, Rickettsia physiology, Rickettsia ultrastructure, Russia, Salivary Glands microbiology, Salivary Glands pathology, Salivary Glands ultrastructure, Arachnid Vectors microbiology, Arachnid Vectors ultrastructure, Ehrlichia physiology, Gram-Negative Bacteria physiology, Ixodes microbiology, Ixodes ultrastructure
- Abstract
Ehrlichiae are small gram-negative obligately intracellular bacteria that multiply within vacuoles of their host cells and are associated for a part of their life cycle with ticks, which serve as vectors for vertebrate hosts. Two morphologically and physiologically different ehrlichial cell types, reticulate cells (RC) and dense-cored cells (DC), are observed during experimental infection of cell cultures, mice, and ticks. Dense-cored cells and reticulate cells in vertebrate cell lines alternate in a developmental cycle. We observed ultrastructure of RC and DC of Ehrlichia muris in morulae in salivary gland cells and coinfection with Borrelia burgdorferi sensu lato (sl), "Candidatus Rickettsia tarasevichiae," and a flavivirus (presumably, tick-borne encephalitis virus [TBEV]) of Ixodes persulcatusticks collected in the Cis-Ural region of Russia. Polymerase chain reaction revealed 326 (81.5%) of 400 ticks carrying at least one infectious agent, and 41.5% (166 ticks) were coinfected with two to four agents. Ehrlichiae and rickettsiae were identified by sequencing of 359 bp of the 16S rRNA gene of E. muris and of 440 bp of the 16S rRNA gene and 385 bp of the gltA gene of "R. tarasevichiae." Different organs of the same tick harbored different microorganisms: TBEV in salivary gland and borreliae in midgut; E. muris in salivary gland; and "R. tarasevichiae" in midgut epithelium. Salivary gland cells contained both RC and DC, a finding that confirmed the developmental cycle in naturally infected ticks. Dense-cored cells in tick salivary glands were denser and of more irregular shape than DC in cell cultures. Ehrlichia-infected salivary gland cells had lysed cytoplasm, suggesting pathogenicity of E. muris for the tick host at the cellular level, as well as potential transmission during feeding. Rickettsiae in the midgut epithelial cells multiplied to significant numbers without altering the host cell ultrastructure. This is the first demonstration of E. muris, "R. tarasevichiae," and the ehrlichial developmental cycle in naturally infected I. persulcatus sticks.
- Published
- 2007
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