title: Ultrastructure of Ehrlichia mineirensis, a new member of the Ehrlichia genus.
abstract: Recently, we reported the in vitro isolation and the molecular characterization of a new species of Ehrlichia (Ehrlichia mineirensis) from haemolymph of Brazilian Rhipicephalus (Boophilus) microplus ticks. This organism shows an ortholog of Ehrlichia canis major immunogenic protein gp36 with a new structure of tandem repeats. In the present study, we used electron microscopy (high pressure freezing and freeze substitution preparative techniques) to characterize morphologically this new agent growing in IDE8 tick cells. The results showed that E. mineirensis shares ultrastructural features with other members of the genus Ehrlichia (Ehrlichia muris, E. canis and Ehrlichia chaffeensis); typical parasitophorous vacuoles (morulae) contain electron-dense and reticulated Ehrlichiae embedded inside a fibrillar matrix. We observed the characteristic Gram-negative-type cell wall composed of both cytoplasmic and rippled outer membrane. We found organisms undergoing binary fission and rarely altered cells with unusual invagination of the cytoplasmic membrane.
authors.affiliation: University of South Bohemia, Faculty of Science and Biology Centre of the ASCR, Institute of Parasitology, České Budějovice, Czech Republic. Electronic address: alejandrocabezascruz@yahoo.es.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Cabezas-Cruz
authors.forename: Marie
authors.initials: M
authors.lastname: Vancová
authors.forename: Erich
authors.initials: E
authors.lastname: Zweygarth
authors.forename: Mucio Flavio Barbosa
authors.initials: MF
authors.lastname: Ribeiro
authors.forename: Libor
authors.initials: L
authors.lastname: Grubhoffer
authors.forename: Lygia Maria Friche
authors.initials: LM
authors.lastname: Passos
mesh_terms: D000818:Animals; D001938:Brazil; D002478:Cells, Cultured; D004536:Ehrlichia / Q000145:classification* / Q000648:ultrastructure*; D016873:Ehrlichiosis / Q000382:microbiology; D046529:Microscopy, Electron, Transmission; D013045:Species Specificity; D013987:Ticks / Q000382:microbiology
keywords: Ehrlichia mineirensis; Electron microscopy; In vitro culture