title: Neochlamydia hartmannellae gen. nov., sp. nov. (Parachlamydiaceae), an endoparasite of the amoeba Hartmannella vermiformis.
abstract: Free-living amoebae are increasingly being recognized to serve as vehicles of dispersal for various bacterial human pathogens and as hosts for a variety of obligate bacterial endocytobionts. Several Chlamydia-like Acanthamoeba endocytobionts constituting the recently proposed family Parachlamydiaceae are of special interest as potential human pathogens. In this study coccoid bacterial endocytobionts of a Hartmannella vermiformis isolate were analysed. Infection of H. vermiformis with these bacteria resulted in prevention of cyst formation and subsequent host-cell lysis. Transfection experiments demonstrated that the parasites were not capable of propagating within other closely related free-living amoebae but were able to infect the distantly related species Dictyostelium discoideum. Electron microscopy of the parasites revealed typical morphological characteristics of the Chlamydiales, including the existence of a Chlamydia-like life-cycle, but indicated that these endocytobionts, in contrast to Chlamydia species, do not reside within a vacuole. Comparative 16S rRNA sequence analysis showed that the endocytobiont of H. vermiformis, classified as Neochlamydia hartmannellae gen. nov., sp. nov., is affiliated to the family Parachlamydiaceae. Confocal laser scanning microscopy in combination with fluorescence in situ hybridization using rRNA-targeted oligonucleotide probes confirmed the intracellular localization of the parasites and demonstrated the absence of other bacterial species within the Hartmannella host. These findings extend our knowledge of the phylogenetic diversity of the Parachlamydiaceae and demonstrate for the first time that these endocytobionts can naturally develop within amoebae of the genus Hartmannella.
authors.affiliation: Lehrstuhl für Mikrobiologie, Technische Universität München, Am Hochanger 4, D-83530 Freising, Germany1.
authors.forename: Matthias
authors.initials: M
authors.lastname: Horn
authors.affiliation: Lehrstuhl für Mikrobiologie, Technische Universität München, Am Hochanger 4, D-83530 Freising, Germany1.
authors.forename: Michael
authors.initials: M
authors.lastname: Wagner
authors.affiliation: Central Institute of the Federal Armed Forces Medical Service, D-56065 Koblenz, Germany2.
authors.forename: Karl-Dieter
authors.initials: KD
authors.lastname: Müller
authors.affiliation: Central Institute of the Federal Armed Forces Medical Service, D-56065 Koblenz, Germany2.
authors.forename: Ernst N
authors.initials: EN
authors.lastname: Schmid
authors.affiliation: Department of Laboratory Medicine, University of Washington, Seattle, WA 98195, USA3.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Fritsche
authors.affiliation: Lehrstuhl für Mikrobiologie, Technische Universität München, Am Hochanger 4, D-83530 Freising, Germany1.
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Schleifer
authors.affiliation: Central Institute of the Federal Armed Forces Medical Service, D-56065 Koblenz, Germany2.
authors.forename: Rolf
authors.initials: R
authors.lastname: Michel
mesh_terms: D000818:Animals; D002689:Chlamydia / Q000145:classification / Q000302:isolation & purification / Q000502:physiology*; D004269:DNA, Bacterial / Q000032:analysis; D004275:DNA, Ribosomal / Q000032:analysis; D016972:Enterobacter cloacae / Q000235:genetics; D006249:Hartmannella / Q000469:parasitology*; D006790:Host-Parasite Interactions; D017403:In Situ Hybridization; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D014170:Transformation, Genetic
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S