A novel obligate intracellular gamma-proteobacterium associated with ixodid ticks, Diplorickettsia massiliensis, Gen. Nov., Sp. Nov.

• Main Authors: Oleg Mediannikov, Zuzana Sekeyová, Marie-Laure Birg, Didier Raoult
• Format: Article
• Language: English
• Published: Public Library of Science (PLoS) 2010-07-01
• Series: PLoS ONE
• Online Access: https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/20644718/pdf/?tool=EBI

<h4>Background</h4>Obligate intracellular bacteria of arthropods often exhibit a significant role in either human health or arthropod ecology.<h4>Methodology/principal findings</h4>An 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.<h4>Conclusions/significance</h4>Considering 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.