A Novel Obligate Intracellular Gamma-Proteobacterium Associated with Ixodid Ticks,Diplorickettsia massiliensis,Gen. Nov., Sp. Nov |
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Authors: | Oleg Mediannikov Zuzana Sekeyová Marie-Laure Birg Didier Raoult |
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Affiliation: | 1. Unité des Recherches sur les Maladies Infectieuses et Emergentes, Centre National de la Recherche Scientifique 6236, Institut de Recherche pour le Développement 198, Université de la Méditerranée, Marseille, France.; 2. Institute of Virology, Slovak Academy of Sciences, Bratislava, Slovak Republic.;Duke University Medical Center, United States of America |
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Abstract: | BackgroundObligate intracellular bacteria of arthropods often exhibit a significant role in either human health or arthropod ecology.Methodology/Principal FindingsAn obligate intracellular gamma-proteobacterium was isolated from the actively questing hard tick Ixodes ricinus using mammalian and amphibian cell lines. Transmission electron microscopy revealed a unique morphology of the bacterium, including intravacuolar localization of bacteria grouped predominantly in pairs and internal structures composed of electron-dense crystal-like structures and regular multilayer sheath-like structures. The isolate 20B was characterized to determine its taxonomic position using a polyphasic approach. Comparative 16S rRNA gene sequence analysis showed that this strain belongs to the family Coxiellaceae, order Legionellales of Gamma-proteobacteria, and the closest relatives are different Rickettsiella spp. The level of 16S rRNA gene sequence similarity between strain 20B and other recognized species of the family was below 94.5%. Partial sequences of the rpoB, parC and ftsY genes confirmed the phylogenetic position of the new isolate. The G+C content estimated on the basis of whole genome analysis of strain 20B was 37.88%. On the basis of its phenotypic and genotypic properties, together with phylogenetic distinctiveness, we propose that strain 20B to be classified in the new genus Diplorickettsia as the type strain of a novel species named Diplorickettsia massiliensis sp. nov.Conclusions/SignificanceConsidering the source of its isolation (hard tick, often biting humans) the role of this bacterium in the pathology of humans, animals and ticks should be further investigated. |
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