Rickettsiales

Rickettsiales
	Rickettsia rickettsii (red dots) in the cell of a deer tick
Scientific classification
Domain:	Bacteria
Phylum:	Pseudomonadota
Class:	Alphaproteobacteria
Order:	Rickettsiales; Gieszczykiewicz 1939 (Approved Lists 1980)
Families
	"Candidatus Deianiraeaceae" Castelli et al. 2019; Ehrlichiaceae Moshkovski 1945 (Approved Lists 1980); "Candidatus Midichloriaceae" Montagna et al. 2013; Rickettsiaceae Pinkerton 1936 (Approved Lists 1980); "Candidatus Tenuibacteraceae" Kroer et al. 2016; Genera incertae sedis "Candidatus Anadelfobacter veles" Vannini et al. 2010; "Candidatus Repentibacter" corrig. Prokopchuk et al. 2019; "Sinorickettsia" Li et al. 2021; ;

The Rickettsiales, informally called rickettsias, are an order of small Alphaproteobacteria. They are obligate intracellular parasites, and some are notable pathogens, including Rickettsia, which causes a variety of diseases in humans, and Ehrlichia, which causes diseases in livestock. Another genus of well-known Rickettsiales is the Wolbachia, which infect about two-thirds of all arthropods and nearly all filarial nematodes.^[2] Genetic studies support the endosymbiotic theory according to which mitochondria and related organelles developed from members of this group.^[3]

The Rickettsiales are difficult to culture, as they rely on living eukaryotic host cells for their survival.

^ Li D, Fang J, Wen B, Wua X (2021). "Molecular identification of a novel intracellular proteobacteria from scallop Chlamys farreri". Aquaculture. 539: 736565. Bibcode:2021Aquac.53936565L. doi:10.1016/j.aquaculture.2021.736565. S2CID 233921822.
^ Werren JH, Baldo L, Clark ME (2008). "Wolbachia: master manipulators of invertebrate biology". Nat. Rev. Microbiol. 6 (10): 741–51. doi:10.1038/nrmicro1969. PMID 18794912. S2CID 12816914.
^ Thomas S. (2016). Rickettsiales:Biology, Molecular Biology, Epidemiology, and Vaccine Development. pp.529. Springer•ISBN 978-3-319-46857-0

[1] Li D, Fang J, Wen B, Wua X (2021). "Molecular identification of a novel intracellular proteobacteria from scallop Chlamys farreri". Aquaculture. 539: 736565. Bibcode:2021Aquac.53936565L. doi:10.1016/j.aquaculture.2021.736565. S2CID 233921822.

[Werren2008-2] Werren JH, Baldo L, Clark ME (2008). "Wolbachia: master manipulators of invertebrate biology". Nat. Rev. Microbiol. 6 (10): 741–51. doi:10.1038/nrmicro1969. PMID 18794912. S2CID 12816914.

[3] Thomas S. (2016). Rickettsiales:Biology, Molecular Biology, Epidemiology, and Vaccine Development. pp.529. Springer•ISBN 978-3-319-46857-0

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Rickettsiales

Rickettsia rickettsii (red dots) in the cell of a deer tick
Scientific classification
Domain:	Bacteria
Phylum:	Pseudomonadota
Class:	Alphaproteobacteria
Order:	Rickettsiales Gieszczykiewicz 1939 (Approved Lists 1980)
Families
"Candidatus Deianiraeaceae" Castelli et al. 2019 Ehrlichiaceae Moshkovski 1945 (Approved Lists 1980) "Candidatus Midichloriaceae" Montagna et al. 2013 Rickettsiaceae Pinkerton 1936 (Approved Lists 1980) "Candidatus Tenuibacteraceae" Kroer et al. 2016 Genera incertae sedis "Candidatus Anadelfobacter veles" Vannini et al. 2010 "Candidatus Repentibacter" corrig. Prokopchuk et al. 2019 "Sinorickettsia" Li et al. 2021^[1]