C. burnetii is an agent suitable for bioterrorism since it is highly infectious; it is believed that one organism can produce a symptomatic infection in a person . Also, C. burnetii can produce a sporelike form resistant to heat and drying and can persist in the environment for long periods. C. burnetii could be used in bioterrorism attacks in an aerosolized form or as a contaminant of food, water, or possibly even postal mail. Ingestion of moderate doses of C. burnetii would be unlikely to produce clinical symptoms, and it has been demonstrated that ingestion of milk contaminated with C. burnetii has resulted in seroconversion, without clinical disease, in human volunteers. Release of the aerosolized form of C. burnetii, as studied in the model we report here, in a densely populated area could cause the abrupt onset of an illness similar to that seen with the naturally occurring disease. Madariaga et al. evaluated the effects of 50 kg of C. burnetii being released along a 2-km front upwind of a population of 500,000. The organism would spread over an area of at least 20 km, would cause ca. 150 deaths, and would lead to 125,000 people becoming incapacitated. Of the latter, 9,000 would develop chronic Q fever and an uncertain number would develop acute and chronic psychiatric disorders .

Random shotgun method was used to sequence the genome of Coxiella burnetti. The genome of this organism contains a single 1,995,281 base-pair circular chromosome and a single 37,393 base-pair QpH1 circular plasmid. ( In the chromosome, there are 1,022 protein-coding genes found for known proteins, 179 genes for proteins of unknown function, 3 stable rRNAs, and 42 stable tRNAs. Percent of G+C content is approximately 42.6% and percent coding is approximately 89.1% in the chromosome. As for QpH1, there are 11 genes found for known proteins, 5 for proteins of unknown function, and no stable RNAs. 39.3% represents the percent of G+C content and 78.8% is the percent coding in the plasmid.  Examining 20 highly conserved proteins in 16S rRNA gene sequence analysis proved the fundamental phylogenetic difference with the α-proteobacterial Rickettsia organisms and confirmed that Coxiella are truly γ-proteobacterial. In genomic comparison with other similar obligate parasites such as those from Rickettsia, the genome of Coxiella was found to contain mobile elements, metabolic and transport capabilities not typically found for the kind of bacteria they are. In addition, 29 insertion sequences were located in the genome; this is noteworthy information because other obligate parasites have very little or none of these elements. However, the presence of pathogenecity islands along with the unique transposons found in the genome does not suggest recent exchange of mobile genetic elements with other organisms. A notion that Coxiella burnetti are enduring a genome reduction, in which certain genes that encode important genetic information ultimately lose their functionality and degrade, has been proposed due to the fact that 83 pseudogenes have been identified. Proteins synthesized by this bacterium has a particularly high pI, which may be due to the acidic environments Coxiella burnetti reside in.

detection of Coxiella burnetii in human serum samples. Two pairs of oligonucleotide primers were designed to amplify a 438-bp fragment of the com1 gene encoding a 27-kDa outer membrane protein of C. burnetii. The primers amplified the predicted fragments of 21 various strains of C. burnetii but did not react with DNA samples from other microorganisms

The obligate intracellular bacterium Coxiella burnetii is the etiological agent of acute Q-fever and chronic endocarditis in humans and of several zoonotic infections

http://www.microbiologyresearch.org/docserver/fulltext/micro/141/11/mic

http://mbio.asm.org/content/2/4/e00175-11.full

https://microbewiki.kenyon.edu/index.php/Coxiella_burnetti

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Article COXIELLA BURNETII PATHOGENICITY MOLECULAR BASIS

The genome of this organism contains a single 1,995,281 base-pair circular chromosome and a single 37,393 base-pair QpH1 circular plasmid. ( In the chromosome, there are 1,022 protein-coding genes found for known proteins, 179 genes for proteins of unknown function, 3 stable rRNAs, and 42 stable tRNAs. Percent of G+C content is approximately 42.6% and percent coding is approximately 89.1% in the chromosome. As for QpH1, there are 11 genes found for known proteins, 5 for proteins of unknown function, and no stable RNAs. 39.3% represents the percent of G+C content and 78.8% is the percent coding in the plasmid.

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Coxiella burnetii is an intracellular gram-negative bacterium responsible for the zoonosis Q fever, a disease that manifests as an acute flu-like illness. Coxiella mainly targets macrophages but its infection pattern differs from that of any other known pathogen.

Coxiella thrives in a parasitophorous vacuole, which is biochemically indistinguishable from lysosomes. Little is known about its virulence factors and their impact on host functions due to the impossibility of genetic manipulation and growth in broth. To overcome this, scientists on the EU-funded Q-SCREEN (Large-scale identification of Coxiella burnetii virulence factors) project set out to perform a large-scale identification of Coxiella virulence factors.

Q-SCREEN exploited recent advances in specific growth media of Coxiella. They generated a large number of mutants for subsequent phenotypic screen of those bacterial factors that are involved in host cell invasion and colonisation. The outcome of the functional assays was cross-referenced with previous bioinformatics database containing putative Coxiella virulence factors.

The consortium investigated over 1000 Coxiella mutations and identified several bacterial proteins involved in the key steps of host cells' colonisation. One membrane protein proved to be essential for bacterial internalisation within non-phagocytic cells, a finding that was validated in a non-mammalian animal model of Coxiella infection. Structural analysis of this protein unveiled the existence of OmpA domains, which comprise the most immunodominant antigens in the outer membrane of Gram-negative bacteria.

Collectively, the Q-SCREEN project demonstrated that the investigation of host/pathogen interactions is an efficient method for the study of infectious diseases. Understanding how intracellular bacteria adhere to and invade their host is also essential for developing targeted vaccines.

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https://microbewiki.kenyon.edu/index.php/Coxiella_burnetti

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Coxiella burnetii is a ubiquitous zoonotic bacterial pathogen and the cause of human acute Q fever, a disabling influenza-like illness. C. burnetii's former obligate intracellular nature significantly impeded the genetic characterization of putative virulence factors. However, recent host cell-free (axenic) growth of the organism has enabled development of shuttle vector, transposon, and inducible gene expression technologies, with targeted gene inactivation remaining an important challenge. In the present study, we describe two methods for generating targeted gene deletions in C. burnetii that exploit pUC/ColE1 ori-based suicide plasmids encoding sacB for positive selection of mutants. As proof of concept, C. burnetii dotA and dotB, encoding structural components of the type IVB secretion system (T4BSS), were selected for deletion. The first method exploited Cre-lox-mediated recombination. Two suicide plasmids carrying different antibiotic resistance markers and a loxP site were integrated into 5′ and 3′ flanking regions of dotA. Transformation of this strain with a third suicide plasmid encoding Cre recombinase resulted in the deletion of dotA under sucrose counterselection. The second method utilized a loop-in/loop-out strategy to delete dotA and dotB. A single suicide plasmid was first integrated into 5′ or 3′ target gene flanking regions. Resolution of the plasmid cointegrant by a second crossover event under sucrose counterselection resulted in gene deletion that was confirmed by PCR and Southern blot. ΔdotA and ΔdotB mutants failed to secrete T4BSS substrates and to productively infect host cells. The repertoire of C. burnetii genetic tools now allows ready fulfillment of molecular Koch's postulates for suspected virulence genes.

possible virulence factor inCoxiella burnetii is acid phosphatase activity

Coxiella thrives in a parasitophorous vacuole, which is biochemically indistinguishable from lysosomes. Little is known about its virulence factors and their impact on host functions due to the impossibility of genetic manipulation and growth in broth. To overcome this, scientists on the EU-funded Q-SCREEN (Large-scale identification of Coxiella burnetii virulence factors) project set out to perform a large-scale identification of Coxiella virulence factors.

Q-SCREEN exploited recent advances in specific growth media of Coxiella. They generated a large number of mutants for subsequent phenotypic screen of those bacterial factors that are involved in host cell invasion and colonisation. The outcome of the functional assays was cross-referenced with previous bioinformatics database containing putative Coxiella virulence factors.

What are the virulence factors in Coxiella burnetii?. Available from: https://www.researchgate.net/post/What_are_the_virulence_factors_in_Coxiella_burnetii [accessed May 14, 2017].

Q fever is a global disease caused by the pathogen Coxiella burnetii. Without any symptoms and a low dosage that leads to infection, the disease can go unnoticed until serious health consequences begin to present themselves. Because of its natural high resistance to harsh environmental conditions, including dessication, heat, and antibacterial compounds, the transmission of Q fever to other organisms is very effective through contaminated air, the main mode of transmission. In reference to virulence factors, genes encoding adhesive structures in the genome such as pili are absent, but there are 13 ankyrin domains that may assist in the bacterium’s attachment to its host. (3) The method in which humans get infected is by infected animals such as sheep, cattle, goat, dogs, and cats. These infected animals can produce excretions through urine, feces, and milk that contain infectious dosages of this pathogenic bacterium, which can be dangerously mistakenly inhaled, consumed, or be in contact with. The bacterium can be isolated in the placentas of infected animals and can cause abortions due to inflammation. Not just livestock and domestic animals can get infected. Even fish and rodents can acquire Q fever as well.