Cell-Free Propagation of Coxiella burnetii Does Not Affect Its Relative Virulence

Q fever is caused by the obligate intracellular bacterium Coxiella burnetii. In vitro growth of the bacterium is usually limited to viable eukaryotic host cells imposing experimental constraints for molecular studies, such as the identification and characterisation of major virulence factors. Studies of pathogenicity may benefit from the recent development of an extracellular growth medium for C. burnetii. However, it is crucial to investigate the consistency of the virulence phenotype of strains propagated by the two fundamentally different culturing systems. In the present study, we assessed the viability of C. burnetii and the lipopolysaccaride (LPS) encoding region of the bacteria in both culture systems as indirect but key parameters to the infection potential of C. burnetii. Propidium monoazide (PMA) treatment-based real-time PCR was used for enumeration of viable C. burnetii which were validated by fluorescent infectious focus forming unit counting assays. Furthermore, RNA isolated from C. burnetiipropagated in both the culture systems was examined for LPS-related gene expression. All thus far known LPS-related genes were found to be expressed in early passages in both culturing systems indicating the presence of predominantly the phase I form of C. burnetii. Finally, we used immune-competent mice to provide direct evidence, that the relative virulence of different C. burnetii strains is essentially the same for both axenic and cell-based methods of propagation

Particle simulation of lower hybrid wave propagation in fusion plasmas

Global particle simulations of the lower hybrid (LH) waves have been carried out using fully kinetic ions and drift kinetic electrons with a realistic electron-to-ion mass ratio. The LH wave frequency, mode structure, and electron Landau damping from the electrostatic simulations agree very well with the analytic theory. Linear simulation of the propagation of a LH wave-packet in the toroidal geometry shows that the wave propagates faster in the high field side than the low field side, in agreement with a ray tracing calculation. This poloidal asymmetry arises from the non-conservation of the poloidal mode number due to the non-uniform magnetic field. In contrast, the poloidal mode number is conserved in the cylindrical geometry with the uniform magnetic field.Physics, Fluids & PlasmasPhysics, NuclearSCI(E)[email protected]

Major differential gene regulation in Coxiella burnetii between in vivo and in vitro cultivation models

BackgroundCoxiella burnetii is the causative agent of the zoonotic disease Q fever. As it is an intracellular pathogen, infection by C. burnetii requires adaptation to its eukaryotic host and intracellular environment. The recently developed cell-free medium also allows the bacteria to propagate without host cells, maintaining its infection potential. The adaptation to different hosts or extracellular environments has been assumed to involve genome-wide modulation of C. burnetii gene expression. However, little is currently known about these adaptation events which are critical for understanding the intracellular survival of C. burnetii.ResultsWe studied C. burnetii genome–wide transcriptional patterns in vivo (mice spleen) and in cell and cell-free in vitro culture models to examine its metabolic pathways and virulence associated gene expression patterns that are required to colonize and persist in different environments. Within each model, the gene expression profiles of the Dutch C. burnetii outbreak strain (602) and NM reference strains were largely similar. In contrast, modulation of gene-expression was strongly influenced by the cultivation method, indicating adaptation of the bacterium to available components. Genome–wide expression profiles of C. burnetii from in vitro cell culture were more similar to those seen for in vivo conditions, while gene expression profiles of cell-free culture were more distant to in vivo. Under in vivo conditions, significant alterations of genes involved in metabolism and virulence were identified. We observed that C. burnetii under in vivo conditions predominantly uses glucose as a carbon source (mostly for biosynthetic processes) and fatty acids for energy generation. C. burnetii experienced nutrient limitation and anaerobiosis as major stressors, while phosphate limitation was identified as an important signal for intracellular growth inside eukaryotic host cells. Finally, the in vivo environment significantly induced expression of several virulence genes, including those implicated in LPS synthesis, colonization, host component modulation and DNA repair mechanisms.ConclusionOur study shows that C. burnetii, with its relative small genome, requires only a subset of core gene functions to survive under in vitro conditions, but requires the induction of full repertoire of genes for successful pathogenesis and thriving in harsh environments in vivo

The Use of Laryngeal Mask Airway in Vitreoretinal Surgery

Purpose: To study the efficiency and utility of laryngeal mask airway (LMA) compared to endotracheal intubation (ETI) in vitreoretinal surgery. Methods: A retrospective chart review was conducted on vitreoretinal surgery cases using LMA or ETI from 2014-2018. 278 vitreoretinal surgery patients (139 LMA patients, 139 ETI patients) were included from one health system and two surgeons. Operating room efficiency and airway complications were analyzed using Cohcran-Armitage Trend, Wilcoxon Rank Sum, Chi-Square, and Two-Sample t-Tests. Results: Compared to ETI, LMA patients had a statistically significant faster time to successful airway insertion (3 minutes faster), time to case start (8 minutes faster), and total time in operating room (25 minutes faster). These trends remained statistically significant after subanalysis by type of vitreoretinal surgery and American Society of Anesthesiologists (ASA) score. Demographics were balanced by age and gender. No complications occurred with LMA No patients were converted from LMA to ETI. Conclusions: LMA is an efficient and safe alternative to ETI for vitreoretinal surgery

Coxiella burnetii isolates originating from infected cattle induce a more pronounced proinflammatory cytokine response compared to isolates from infected goats and sheep

Coxiella burnetii is the causative agent of Q fever. Although the prevalence of C. burnetii in cattle is much higher than in goats and sheep, infected cattle are rarely associated with human outbreaks. We investigated whether the immune response of humans differs after contact with C. burnetii isolates from different host origins or with different multilocus variable number of tandem repeat analysis (MLVA) genotypes. Cytokine responses were measured in human peripheral blood mononuclear cells (PBMCs) stimulated with 16 C. burnetii isolates with known MLVA genotype from goats, sheep, cattle, acute and chronic Q fever patients. Coxiella burnetii isolates originating from cattle induce significantly more IL-1β, TNF-α and IL-22 than the isolates from goats, sheep or chronic Q fever patients. Comparing the cytokine induction of the isolates based on their MVLA genotype did not reveal differences in response between the MLVA genotypes. The proinflammatory cytokine response induced in human PBMCs by C. burnetii isolates from cattle may explain the low incidence of human Q fever outbreaks caused by cattle. The cytokine profile of PBMCs stimulated with C. burnetii isolates from chronic Q fever patients resembles isolates from goats. Furthermore, cytokine responses seem to be depending on host origin than on MLVA genotype

Bilateral pulmonary emboli following macular hole surgery with postoperative prone positioning

Purpose: To report a rare case of bilateral pulmonary emboli following pars plana vitrectomy with postoperative prone positioning. Observations: A 60 year-old female presented with a fourmonth history of unilateral distorted vision. Ocular coherence tomography revealed a full thickness macular hole. Two weeks later, the patient underwent a 23-gauge pars plana vitrectomy with internal limiting membrane peeling and 12% perfluoropropane gas tamponade. Postoperatively, she completed two weeks of prone positioning. Five days later, she presented with a two day history of abdominal pain and shortness of breath. Computed tomography angiography revealed bilateral pulmonary emboli. The patient received six months of anticoagulation to prevent further thromboembolic events. Conclusions: Life threatening blood clots can form due to prolonged immobilization from prone positioning. Patients should be educated to perform light exercise postoperatively to prevent complications of blood stasis

Coxiella burnetii strain:3345937 Genome sequencing and assembly

The aim of the sequencing project is to see the similarities in genomes of veterinary and Human strains to find the source of infection of Q-fever in the Netherland

Coxiella burnetii strain:3262 Genome sequencing

The goal of the present study is to sequence and annotate 3262 Coxiella burnetii strain which was majorly involved in the outbreak of Q-fever in The Netherlands. Comparison of annotated 3262 Coxiella burnetii genomes with other genomes present in the databases might aid additional information on characterization of this high virulent dutch goat strain

Coxiella burnetii strain:3345937 Genome sequencing and assembly

The aim of the sequencing project is to see the similarities in genomes of veterinary and Human strains to find the source of infection of Q-fever in the Netherland