"Candidatus Cryptoprodotis polytropus," a novel Rickettsia-like organism in the ciliated protist Pseudomicrothorax dubius (Ciliophora, Nassophorea).
Rickettsia-like organisms (RLO) are obligate, often highly fastidious, intracellular bacterial parasites associated with a variety of vertebrate and invertebrate hosts. Despite their importance as causative agents of severe mortality outbreaks in farmed aquatic species, little is known about their life cycle and their host range. The present work reports the characterization of "Candidatus Cryptoprodotis polytropus," a novel Rickettsia-like bacterium associated with the common ciliate species Pseudomicrothorax dubius by means of the "Full-Cycle rRNA Approach" and ultrastructural observations. The morphological description by in vivo and scanning electron microscopy and the 18S rRNA gene sequence of the host species is provided as well. Phylogenetic analysis based on the 16S rRNA gene supports the inclusion of "Candidatus Cryptoprodotis polytropus" within the family Rickettsiaceae (cl. Alphaproteobacteria) together with the genera Rickettsia and Orientia. Observations on natural ciliate populations account for the occasional nature of this likely parasitic association. The presence of a previously unknown RLO in ciliates sheds a new light on the possible role of protists as transient hosts, vectors or natural reservoir for some economically important pathogens.
Ferrantini
Filippo
F
Department of Biology, Protistology and Zoology Unit, University of Pisa, Via A. Volta 4/6, I-56126 Pisa, Italy.
Fokin
Sergei I
SI
Modeo
Letizia
L
Andreoli
Ilaria
I
Dini
Fernando
F
Görtz
Hans-Dieter
HD
Verni
Franco
F
Petroni
Giulio
G
D001483:Base Sequence; D016798:Ciliophora / Q000235:genetics* / Q000382:microbiology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D020459:Genes, rRNA; D058507:Host Specificity; D054884:Host-Pathogen Interactions; D007558:Italy; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics*; D012337:RNA, Ribosomal, 18S / Q000235:genetics*; D012287:Rickettsiaceae / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification* / Q000648:ultrastructure; D017422:Sequence Analysis, DNA
D004269:DNA, Bacterial; D016054:DNA, Protozoan; D012336:RNA, Ribosomal, 16S; D012337:RNA, Ribosomal, 18S