A small gram-negative pleomorphic coccobacilli classified to the phylum Proteobacteria, class γ-Proteobacteria, order Legionellales
Obligate intracellular pathogen
Two morphologically distinct cell types that comprise a bi-phasic developmental cycle. A small cell variant, with its characteristic condensed chromatin, is thought to be an extracellular survival form with enhanced resistance to environmental stressors such as desiccation and heat. When the small cell variant invades the host, it develops into a large cell variant that is metabolically and divisionally active
C. burnetii has a tropism for professional phagocytes and invades such cells using classic phagocytic mechanisms that rely on specific receptor-ligand interactions. Inside the host cell, C. burnetii actively directs the maturation of a phagolysosome-like compartment known as the Coxiella-containing vacuole (CCV).
C. burnetii, the causative agent of Q fever, a zoonosis that is most often transmitted by aerosolized soil or animal products
Human infection, through the inhalation of contaminated aerosols, can cause a broad spectrum of presentations ranging from asymptomatic infection to life-threatening systemic infection
Genomes (comparative pathogenomics):
C. burnetii CbuG_Q212, 2008870 bp, NC_011527
C. burnetii CbuK_Q154, 2063100 bp, NC_011528
C. burnetii Dugway 5J108-111, 2158758 bp, NC_009727
C. burnetii RSA 331, 2016427 bp, NC_010117
C. burnetii RSA 493, 1995281 bp, NC_002971
C. burnetii CbuK_Q154 pQpRS_K_Q154, 39280 bp, NC_011526
C. burnetii Dugway 5J108-111 pQpDG, 54179 bp, NC_009726
C. burnetii RSA 331 QpH1, 37317 bp, NC_010115
C. burnetii RSA 493 pQpH1, 37393 bp, NC_004704
Beare PA, et al., 2009. Comparative genomics reveal extensive transposon-mediated genomic plasticity and diversity among potential effector proteins within the genus Coxiella. Infect Immun 77(2):642-56.
Seshadri R, et al., 2003. Complete genome sequence of the Q-fever pathogen Coxiella burnetii. Proc Natl Acad Sci U S A 100(9):5455-60.
The intracellular trafficking pathway of Coxiella burnetii (From: van Schaik EJ, et al., 2013. Molecular pathogenesis of the obligate intracellular bacterium Coxiella burnetii. Nat Rev Microbiol 11(8):561-73.)
Major virulence factors in Coxiella:
Location of virulence-associated genes in C. burnetii: