title: 'Candidatus Rhabdochlamydia crassificans', an intracellular bacterial pathogen of the cockroach Blatta orientalis (Insecta: Blattodea).
abstract: The genus Rickettsiella comprises various intracellular bacterial pathogens of arthropods, exhibiting a chlamydia-like developmental cycle. Species may be divided into two main groups, the R. popilliae-R. grylli group and the R. chironomi group. Previous phylogenetic studies based on the 16S ribosomal RNA encoding gene showed that two Rickettsiella species, one from each group, belong in reality to two distantly related lineages, the gamma-Proteobacteria (R. grylli) and the Chlamydiales ('Candidatus Rhabdochlamydia porcellionis', a pathogen of terrestrial isopods). In the present work, the 16S rDNA sequence of another Rickettsiella-like species, causing abdominal swelling to its cockroach host Blatta orientalis, was determined and phylogenetic analysis performed. Identical 16S rDNA sequences of 1495 nucleotides were obtained from fat body and ovary tissues of both healthy and diseased cockroach individuals. The sequence shared only 73% of similarity with R. grylli, but 82-87% with most Chlamydiales, and even 96.3% with 'Candidatus Rhabdochlamydia porcellionis'. Phylogenetic analyses confirmed the affiliation of the cockroach pathogen within the order Chlamydiales, and based on ultrastructural characteristics and genetic analyses, we propose its inclusion in the 'Candidatus Rhabdochlamydia' as a distinct taxon, 'Candidatus Rhabdochlamydia crassificans'. These results extend our knowledge of the phylogenetic diversity of the Chlamydiales.
authors.affiliation: CHLAREAS Chlamydia Research Association, 12 rue du Maconnais, 54500 Vandoeuvre-les-Nancy, France.
authors.forename: Daniele
authors.initials: D
authors.lastname: Corsaro
authors.forename: Vincent
authors.initials: V
authors.lastname: Thomas
authors.forename: Genevieve
authors.initials: G
authors.lastname: Goy
authors.forename: Danielle
authors.initials: D
authors.lastname: Venditti
authors.forename: Renate
authors.initials: R
authors.lastname: Radek
authors.forename: Gilbert
authors.initials: G
authors.lastname: Greub
mesh_terms: D000818:Animals; D002695:Chlamydiales / Q000145:classification* / Q000235:genetics; D003058:Cockroaches / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S