Coxiella (bacterium)

Coxiella refers to a genus of Gram-negative bacteria in the family Coxiellaceae. It is named after Herald Rea Cox (1907–1986), an American bacteriologist. It is one of the Gammaproteobacteria.[2]

Coxiella
Coxiella burnetii
Scientific classification
Domain: Bacteria
Phylum: Pseudomonadota
Class: Gammaproteobacteria
Order: Legionellales
Family: Coxiellaceae
Genus: Coxiella
(Philip 1943) Philip 1948[1]
Type species
Coxiella burnetii[1]
Species

C. burnetii

Coxiella burnetii is the best known member of this genus. It is an intracellular parasite and it survives within the phagolysosomes of its host. It causes Q fever.

The majority of Coxiella’s described members are non pathogenic forms which are often found in ticks.[3] Approximately two-thirds of tick species harbour Coxiella-like endosymbionts required for tick survival and reproduction. Genomes of Coxiella-like endosymbionts encode pathways for the biosynthesis of major B vitamins and co-factors that fit closely with the expected nutritional complements required for strict haematophagy.[4] The experimental elimination of Coxiella-like endosymbionts typically results in decreased tick survival, molting, fecundity and egg viability, as well as in physical abnormalities.[4] Coxiella-like endosymbionts are often misidentified as Coxiella burnetii; however, Coxiella-like endosymbionts lack virulence genes and cannot infect humans.[5]

Molecular Signatures

[6] Seven conserved signature indels (CSIs) were identified through genomic analyses as exclusively shared by C. burnetii and other unnamed Coxiella-related species in the proteins glutamine-hydrolyzing GMP synthase, type I methionyl aminopeptidase, ribonucleoside-diphosphate reductase subunit alpha, translation initiation factor IF-3, phosphomannomutase-phosphoglucomutase, LPS export ABC transporter ATP-binding protein, and NADH-quinone oxidoreductase subunit G. These CSIs serves to reliably demarcate the genus from other Legionellales species in molecular terms.

Additionally, three CSIs were identified as uniquely shared between the genus Coxiella, and two other genera belonging to the family Coxiellaceae, Diplorickettsia and Rickettsiella. The absence of Aquicella species (the remaining genus within the family Coxiellaceae) from the shared CSIs suggests that the genera Coxiella, Diplorickettsia and Rickettsiella share a common ancestor exclusive of Aquicella.

References
  1. Parte, A.C. "Coxiella". LPSN.
  2. Coxiella at the US National Library of Medicine Medical Subject Headings (MeSH)
  3. Duron, Olivier; Doublet, Patricia; Vavre, Fabrice; Bouchon, Didier (2018-12-01). "The Importance of Revisiting Legionellales Diversity". Trends in Parasitology. 34 (12): 1027–1037. doi:10.1016/j.pt.2018.09.008. ISSN 1471-4922. PMID 30322750.
  4. Duron, Olivier; Gottlieb, Yuval (2020-10-01). "Convergence of Nutritional Symbioses in Obligate Blood Feeders". Trends in Parasitology. 36 (10): 816–825. doi:10.1016/j.pt.2020.07.007. ISSN 1471-4922. PMID 32811753.
  5. Buysse, Marie; Duron, Olivier (2021-04-29). "Evidence that microbes identified as tick-borne pathogens are nutritional endosymbionts". Cell. 184 (9): 2259–2260. doi:10.1016/j.cell.2021.03.053. ISSN 0092-8674. PMID 33930290.
  6. Saini, Navneet; Gupta, Radhey S. (July 2021). "A robust phylogenetic framework for members of the order Legionellales and its main genera (Legionella, Aquicella, Coxiella and Rickettsiella) based on phylogenomic analyses and identification of molecular markers demarcating different clades". Antonie van Leeuwenhoek. 114 (7): 957–982. doi:10.1007/s10482-021-01569-9. ISSN 1572-9699. PMID 33881638.
  • Coxiella genomes and related information at PATRIC, a Bioinformatics Resource Center funded by NIAID


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