Coxiella
RANK: Genus
TAXONOMY: cellular organisms -> Bacteria -> Proteobacteria -> Gammaproteobacteria -> Legionellales -> Coxiellaceae -> Coxiella
OVERVIEW:
Strictly intracellular bacteria, usually 0.2–0.4 µm × 0.4–1.0 µm. Best stained by Gimenez staining. They have no flagella or capsule. They live in close natural association with arthropod and vertebrate hosts. The genus includes Coxiella burnetii—the agent of Q fever—and endosymbionts of ticks and aquatic invertebrates. C. burnetii grows well in cultured cell lines and in the yolk sac of chicken embryos, where it undergoes a cycle of development with formation of an endospore-like body. Coxiella burnetii possesses two antigenic phases: natural virulent phase I and attenuated phase II, which is obtained after passage in cultured cell lines and yolk sac. The organism grows in vacuoles of the host cell rather than in the cytoplasm or the nucleus. C. burnetii phase I vacuoles share characteristics of late-stage, immature phagosomes whereas C. burnetii phase II vacuoles are bactericidal phagolysosomes. Highly resistant to chemical agents and elevated temperature. Coxiellae occur worldwide in ticks and various vertebrates, including humans. Infection is particularly prevalent in cattle, sheep and goats. Extremely infectious; a single aerosol-borne organism can cause the human disease Q fever. C. burnetii is one of the ten most feared potential bioterrorism agents.The mol% G + C of the DNA is: 42.7.Type species: Coxiella burnetii
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