scholarly journals Selective Inhibition of Coxiella burnetii Replication by the Steroid Hormone Progesterone

2020 ◽  
Vol 88 (12) ◽  
Author(s):  
Zachary P. Howard ◽  
Anders Omsland
Keyword(s):  
Coxiella Burnetii ◽  
Efflux Pump ◽  
Q Fever ◽  
Steroid Hormone ◽  
Natural Infection ◽  
Placental Tissue ◽  
Selective Inhibition ◽  
Inhibitory Effect ◽  
Content Type ◽  
Direct Inhibitory Effect

ABSTRACT Coxiella burnetii is a zoonotic bacterial obligate intracellular parasite and the cause of query (Q) fever. During natural infection of female animals, C. burnetii shows tropism for the placenta and is associated with late-term abortion, at which time the pathogen titer in placental tissue can exceed one billion bacteria per gram. During later stages of pregnancy, placental trophoblasts serve as the major source of progesterone, a steroid hormone known to affect the replication of some pathogens. During infection of placenta-derived JEG-3 cells, C. burnetii showed sensitivity to progesterone but not the immediate precursor pregnenolone or estrogen, another major mammalian steroid hormone. Using host cell-free culture, progesterone was determined to have a direct inhibitory effect on C. burnetii replication. Synergy between the inhibitory effect of progesterone and the efflux pump inhibitors verapamil and 1-(1-naphthylmethyl)-piperazine is consistent with a role for efflux pumps in preventing progesterone-mediated inhibition of C. burnetii activity. The sensitivity of C. burnetii to progesterone, but not structurally related molecules, is consistent with the ability of progesterone to influence pathogen replication in progesterone-producing tissues.

scholarly journals Coxiella burnetii Interaction with Neutrophils and MacrophagesIn Vitroand in SCID Mice following Aerosol Infection

2013 ◽  
Vol 81 (12) ◽  
pp. 4604-4614 ◽  
Author(s):  
Alexandra Elliott ◽  
Ying Peng ◽  
Guoquan Zhang
Keyword(s):  
Immune Response ◽  
Coxiella Burnetii ◽  
Q Fever ◽  
Natural Infection ◽  
Scid Mice ◽  
Innate Immune ◽  
Content Type ◽  
Aerosol Infection

ABSTRACTCoxiella burnetiiis an obligate intracellular bacterium that causes acute and chronic Q fever in humans. Human Q fever is mainly transmitted by aerosol infection. However, there is a fundamental gap in the knowledge regarding the mechanisms of pulmonary immunity againstC. burnetiiinfection. This study focused on understanding the interaction betweenC. burnetiiand innate immune cellsin vitroandin vivo. Both virulentC. burnetiiNine Mile phase I (NMI) and avirulent Nine Mile phase II (NMII) were able to infect neutrophils, while the infection rates were lower than 29%, suggesting thatC. burnetiican infect neutrophils, but infection is limited. Interestingly,C. burnetiiinside neutrophils can infect and replicate within macrophages, suggesting that neutrophils cannot killC. burnetiiandC. burnetiimay be using infection of neutrophils as an evasive strategy to infect macrophages. To elucidate the mechanisms of the innate immune response toC. burnetiinatural infection, SCID mice were exposed to aerosolizedC. burnetii. Surprisingly, neutrophil influx into the lungs was delayed until day 7 postinfection in both NMI- and NMII-infected mice. This result suggests that neutrophils may play a unique role in the early immune response against aerosolizedC. burnetii. Studying the interaction betweenC. burnetiiand the innate immune system can provide a model system for understanding how the bacteria evade early immune responses to cause infection.

scholarly journals Long-Term Immune Responses to Coxiella burnetii after Vaccination

2012 ◽  
Vol 20 (2) ◽  
pp. 129-133 ◽  
Author(s):  
Gilbert J. Kersh ◽  
Kelly A. Fitzpatrick ◽  
Joshua S. Self ◽  
Brad J. Biggerstaff ◽  
Robert F. Massung
Keyword(s):  
Immune Responses ◽  
Coxiella Burnetii ◽  
Cellular Immunity ◽  
Q Fever ◽  
Natural Infection ◽  
Fluorescent Antibody ◽  
Antibody Test ◽  
Content Type ◽  
Humoral And Cellular Immunity ◽  
Cellular Immune

ABSTRACTQ fever is a zoonotic disease caused by infection with the bacteriumCoxiella burnetii. Infection withC. burnetiiresults in humoral and cellular immune responses, both of which are thought to contribute to protection against subsequent infection. Whole-cell formalin-inactivated vaccines have also been shown to induce both humoral and cellular immunity and provide protection. Whether measurement of cellular or humoral immunity is a better indicator of immune protection is not known, and the duration of immunity induced by natural infection or vaccination is also poorly understood. To better understand the measurement and duration ofC. burnetiiimmunity, 16 people vaccinated against Q fever (0.2 to 10.3 years before analysis) and 29 controls with a low risk of Q fever exposure were tested for immune responses toC. burnetiiby an indirect fluorescent-antibody test (IFA) to measure circulating antibody and by a gamma interferon release assay (IGRA) to measure cellular immunity. Among vaccinated subjects, the IFA detected antibodies in 13/16, and the IGRA also detected positive responses in 13/16. All of the vaccinated subjects had a positive response in at least one of the assays, whereas 8/29 control subjects were positive in at least one assay. There was not a correlation between time since vaccination and responses in these assays. These results show that IFA and IGRA perform similarly in detection ofC. burnetiiimmune responses and that Q fever vaccination establishes long-lived immune responses toC. burnetii.

scholarly journals Coxiella burnetii Alters Cyclic AMP-Dependent Protein Kinase Signaling during Growth in Macrophages

2012 ◽  
Vol 80 (6) ◽  
pp. 1980-1986 ◽  
Author(s):  
Laura J. MacDonald ◽  
Richard C. Kurten ◽  
Daniel E. Voth
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Coxiella Burnetii ◽  
Alveolar Macrophages ◽  
Q Fever ◽  
Parasitophorous Vacuole ◽  
Dependent Protein Kinase ◽  
Content Type ◽  
Bacterial Agent ◽  
Dependent Protein

ABSTRACTCoxiella burnetiiis the bacterial agent of human Q fever, an acute, flu-like illness that can present as chronic endocarditis in immunocompromised individuals. Following aerosol-mediated transmission,C. burnetiireplicates in alveolar macrophages in a unique phagolysosome-like parasitophorous vacuole (PV) required for survival. The mechanisms ofC. burnetiiintracellular survival are poorly defined and a recent Q fever outbreak in the Netherlands emphasizes the need for better understanding this unique host-pathogen interaction. We recently demonstrated that inhibition of host cyclic AMP-dependent protein kinase (PKA) activity negatively impacts PV formation. In the current study, we confirmed PKA involvement in PV biogenesis and probed the role of PKA signaling duringC. burnetiiinfection of macrophages. Using PKA-specific inhibitors, we found the kinase was needed for biogenesis of prototypical PV andC. burnetiireplication. PKA and downstream targets were differentially phosphorylated throughout infection, suggesting prolonged regulation of the pathway. Importantly, the pathogen actively triggered PKA activation, which was also required for PV formation by virulentC. burnetiiisolates during infection of primary human alveolar macrophages. A subset of PKA-specific substrates were differentially phosphorylated duringC. burnetiiinfection, suggesting the pathogen uses PKA signaling to control distinct host cell responses. Collectively, the current results suggest a versatile role for PKA inC. burnetiiinfection and indicate virulent organisms usurp host kinase cascades for efficient intracellular growth.

scholarly journals Identification of ElpA, a Coxiella burnetii Pathotype-Specific Dot/Icm Type IV Secretion System Substrate

2015 ◽  
Vol 83 (3) ◽  
pp. 1190-1198 ◽  
Author(s):  
Joseph G. Graham ◽  
Caylin G. Winchell ◽  
Uma M. Sharma ◽  
Daniel E. Voth
Keyword(s):  
Coxiella Burnetii ◽  
Q Fever ◽  
Parasitophorous Vacuole ◽  
Secretion System ◽  
Terminal Region ◽  
Effector Proteins ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Content Type ◽  
Type Iv

Coxiella burnetiicauses human Q fever, a zoonotic disease that presents with acute flu-like symptoms and can result in chronic life-threatening endocarditis. In human alveolar macrophages,C. burnetiiuses a Dot/Icm type IV secretion system (T4SS) to generate a phagolysosome-like parasitophorous vacuole (PV) in which to replicate. The T4SS translocates effector proteins, or substrates, into the host cytosol, where they mediate critical cellular events, including interaction with autophagosomes, PV formation, and prevention of apoptosis. Over 100C. burnetiiDot/Icm substrates have been identified, but the function of most remains undefined. Here, we identified a novel Dot/Icm substrate-encoding open reading frame (CbuD1884) present in allC. burnetiiisolates except the Nine Mile reference isolate, where the gene is disrupted by a frameshift mutation, resulting in a pseudogene. The CbuD1884 protein contains two transmembrane helices (TMHs) and a coiled-coil domain predicted to mediate protein-protein interactions. The C-terminal region of the protein contains a predicted Dot/Icm translocation signal and was secreted by the T4SS, while the N-terminal portion of the protein was not secreted. When ectopically expressed in eukaryotic cells, the TMH-containing N-terminal region of the CbuD1884 protein trafficked to the endoplasmic reticulum (ER), with the C terminus dispersed nonspecifically in the host cytoplasm. This new Dot/Icm substrate is now termed ElpA (ER-localizingproteinA). Full-length ElpA triggered substantial disruption of ER structure and host cell secretory transport. These results suggest that ElpA is a pathotype-specific T4SS effector that influences ER function duringC. burnetiiinfection.

scholarly journals Characterization of a Lipopolysaccharide-Targeted Monoclonal Antibody and Its Variable Fragments as Candidates for Prophylaxis against the Obligate Intracellular Bacterial Pathogen Coxiella burnetii

2014 ◽  
Vol 82 (11) ◽  
pp. 4530-4541 ◽  
Author(s):  
Ying Peng ◽  
Laura Schoenlaub ◽  
Alexandra Elliott ◽  
William J. Mitchell ◽  
Guoquan Zhang
Keyword(s):  
Monoclonal Antibody ◽  
Coxiella Burnetii ◽  
Natural Infection ◽  
Bacterial Pathogen ◽  
Passive Transfer ◽  
Single Chain Variable Fragment ◽  
Single Chain ◽  
Fab Fragment ◽  
Content Type ◽  
Aerosol Infection

ABSTRACTOur previous study demonstrated that treatment ofCoxiella burnetiiwith the phase I lipopolysaccharide (PI-LPS)-targeted monoclonal antibody (MAb) 1E4 significantly inhibitedC. burnetiiinfection in mice, suggesting that 1E4 is a protective MAb. To determine whether passive transfer of antibodies (Abs) can provide protection againstC. burnetiinatural infection, we examined if passive transfer of 1E4 would protect SCID mice againstC. burnetiiaerosol infection. The results indicated that 1E4 conferred significant protection against aerosolizedC. burnetii, suggesting that 1E4 may be useful for preventingC. burnetiinatural infection. To further understand the mechanisms of 1E4-mediated protection and to test the possibility of using humanized 1E4 to preventC. burnetiiinfection, we examined whether the Fab fragment of 1E4 (Fab1E4), a recombinant murine single-chain variable fragment (muscFv1E4), and a humanized single-chain variable fragment (huscFv1E4) retained the ability of 1E4 to inhibitC. burnetiiinfection. The results indicated that Fab1E4, muscFv1E4, and huscFv1E4 were able to inhibitC. burnetiiinfection in mice but that their ability to inhibitC. burnetiiinfection was lower than that of 1E4. In addition, treatment ofC. burnetiiwith Fab1E4, muscFv1E4, or huscFv1E4 can blockC. burnetiiinfection of macrophages. Interestingly, treatment ofC. burnetiiwith huscFv1E4 can significantly reduceC. burnetiiinfectivity in human macrophages. This report provides the first evidence to demonstrate that the humanized variable fragments of an LPS-specific MAb can neutralizeC. burnetiiinfection and appears to be a promising step toward the potential use of a humanized MAb as emergency prophylaxis againstC. burnetiiexposure.

scholarly journals Coxiella burnetii Intratracheal Aerosol Infection Model in Mice, Guinea Pigs, and Nonhuman Primates

2019 ◽  
Vol 87 (12) ◽  
Author(s):  
A. E. Gregory ◽  
E. J. van Schaik ◽  
K. E. Russell-Lodrigue ◽  
A. P. Fratzke ◽  
J. E. Samuel
Keyword(s):  
Animal Models ◽  
Coxiella Burnetii ◽  
Guinea Pigs ◽  
Nonhuman Primates ◽  
Q Fever ◽  
Febrile Illness ◽  
Cell Vaccine ◽  
Infection Model ◽  
Atypical Pneumonia ◽  
Content Type

ABSTRACT Coxiella burnetii, the etiological agent of Q fever, is a Gram-negative bacterium transmitted to humans by inhalation of contaminated aerosols. Acute Q fever is often self-limiting, presenting as a febrile illness that can result in atypical pneumonia. In some cases, Q fever becomes chronic, leading to endocarditis that can be life threatening. The formalin-inactivated whole-cell vaccine (WCV) confers long-term protection but has significant side effects when administered to presensitized individuals. Designing new vaccines against C. burnetii remains a challenge and requires the use of clinically relevant modes of transmission in appropriate animal models. We have developed a safe and reproducible C. burnetii aerosol challenge in three different animal models to evaluate the effects of pulmonary acquired infection. Using a MicroSprayer aerosolizer, BL/6 mice and Hartley guinea pigs were infected intratracheally with C. burnetii Nine Mile phase I (NMI) and demonstrated susceptibility as determined by measuring bacterial growth in the lungs and subsequent dissemination to the spleen. Histological analysis of lung tissue showed significant pathology associated with disease, which was more severe in guinea pigs. Infection using large-particle aerosol (LPA) delivery was further confirmed in nonhuman primates, which developed fever and pneumonia. We also demonstrate that vaccinating mice and guinea pigs with WCV prior to LPA challenge is capable of eliciting protective immunity that significantly reduces splenomegaly and the bacterial burden in spleen and lung tissues. These data suggest that these models can have appreciable value in using the LPA delivery system to study pulmonary Q fever pathogenesis as well as designing vaccine countermeasures to C. burnetii aerosol transmission.

scholarly journals Lack of Small Intestinal Dysbiosis Following Long-Term Selective Inhibition of Cyclooxygenase-2 by Rofecoxib in the Rat

Cells ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 251 ◽  
Author(s):  
Bernadette Lázár ◽  
Gábor Brenner ◽  
András Makkos ◽  
Mihály Balogh ◽  
Szilvia László ◽  
...  
Keyword(s):  
Selective Inhibition ◽  
Mucosal Damage ◽  
Inhibitory Effect ◽  
Intestinal Dysbiosis ◽  
Bowel Diseases ◽  
Direct Inhibitory Effect ◽  
Cox 2 ◽  
Small Intestinal

Intestinal dysbiosis is linked to numerous gastrointestinal disorders, including inflammatory bowel diseases. It is a question of debate if coxibs, selective inhibitors of cyclooxygenase (COX)-2, cause dysbiosis. Therefore, in the present study, we aimed to determine the effect of long-term (four weeks) selective inhibition of COX-2 on the small intestinal microbiota in the rat. In order to avoid mucosal damage due to topical effects and inflammation-driven microbial alterations, rofecoxib, a nonacidic compound, was used. The direct inhibitory effect of rofecoxib on the growth of bacteria was ruled out in vitro. The mucosa-sparing effect of rofecoxib was confirmed by macroscopic and histological analysis, as well as by measuring the intestinal levels of cytokines and tight junction proteins. Deep sequencing of bacterial 16S rRNA revealed that chronic rofecoxib treatment had no significant influence on the composition and diversity of jejunal microbiota. In conclusion, this is the first demonstration that long-term selective inhibition of COX-2 by rofecoxib does not cause small intestinal dysbiosis in rats. Moreover, inhibition of COX-2 activity is not likely to be responsible per se for microbial alterations caused by some coxibs, but other drug-specific properties may contribute to it.

scholarly journals Coxiella burnetii Infects Primary Bovine Macrophages and Limits Their Host Cell Response

2016 ◽  
Vol 84 (6) ◽  
pp. 1722-1734 ◽  
Author(s):  
Katharina Sobotta ◽  
Kirstin Hillarius ◽  
Marvin Mager ◽  
Katharina Kerner ◽  
Carsten Heydel ◽  
...  
Keyword(s):  
Coxiella Burnetii ◽  
Inflammatory Responses ◽  
Q Fever ◽  
Infection Model ◽  
Target Cells ◽  
Avirulent Strain ◽  
Host Immune System ◽  
Activation Markers ◽  
Content Type ◽  
Mhc Molecules

Although domestic ruminants have long been recognized as the main source of human Q fever, little is known about the lifestyle that the obligate intracellular Gram-negative bacteriumCoxiella burnetiiadopts in its animal host. Because macrophages are considered natural target cells of the pathogen, we established primary bovine monocyte-derived macrophages (MDM) as anin vitroinfection model to study reservoir host-pathogen interactions at the cellular level. In addition, bovine alveolar macrophages were included to take cell type peculiarities at a host entry site into account. Cell cultures were inoculated with the virulent strain Nine Mile I (NMI; phase I) or the avirulent strain Nine Mile II (NMII; phase II). Macrophages from both sources internalized NMI and NMII. MDM were particularly permissive for NMI internalization, but NMI and NMII replicated with similar kinetics in these cells. MDM responded to inoculation with a general upregulation of Th1-related cytokines such as interleukin-1β (IL-1β), IL-12, and tumor necrosis factor alpha (TNF-α) early on (3 h postinfection). However, inflammatory responses rapidly declined whenC. burnetiireplication started.C. burnetiiinfection inhibited translation and release of IL-1β and vastly failed to stimulate increased expression of activation markers, such as CD40, CD80, CD86, and major histocompatibility complex (MHC) molecules. Such capability of limiting proinflammatory responses may helpCoxiellato protect itself from clearance by the host immune system. The findings provide the first detailed insight intoC. burnetii-macrophage interactions in ruminants and may serve as a basis for assessing the virulence and the host adaptation ofC. burnetiistrains.

scholarly journals Neurotransmitter System-Targeting Drugs Antagonize Growth of the Q Fever Agent, Coxiella burnetii, in Human Cells

mSphere ◽  
2021 ◽  
Author(s):  
Marissa S. Fullerton ◽  
Punsiri M. Colonne ◽  
Amanda L. Dragan ◽  
Katelynn R. Brann ◽  
Richard C. Kurten ◽  
...  
Keyword(s):  
Coxiella Burnetii ◽  
Q Fever ◽  
Human Cells ◽  
Neurotransmitter System ◽  
Content Type ◽  
Fatal Infection

Coxiella burnetii causes the debilitating disease Q fever in humans. This infection is difficult to treat with current antibiotics and can progress to long-term, potentially fatal infection in immunocompromised individuals or when treatment is delayed.

scholarly journals Dependency of Coxiella burnetii Type 4B Secretion on the Chaperone IcmS

2019 ◽  
Vol 201 (23) ◽  
Author(s):  
Charles L. Larson ◽  
Paul A. Beare ◽  
Robert A. Heinzen
Keyword(s):  
Host Cell ◽  
Coxiella Burnetii ◽  
Legionella Pneumophila ◽  
Q Fever ◽  
Secretion System ◽  
Host Cells ◽  
Growth Defect ◽  
Wild Type ◽  
Signal Sequences ◽  
Content Type

ABSTRACT Macrophage parasitism by Coxiella burnetii, the cause of human Q fever, requires the translocation of proteins with effector functions directly into the host cell cytosol via a Dot/Icm type 4B secretion system (T4BSS). Secretion by the analogous Legionella pneumophila T4BSS involves signal sequences within the C-terminal and internal domains of effector proteins. The cytoplasmic chaperone pair IcmSW promotes secretion and binds internal sites distinct from signal sequences. In the present study, we investigated requirements of C. burnetii IcmS for host cell parasitism and effector translocation. A C. burnetii icmS deletion mutant (ΔicmS) exhibited impaired replication in Vero epithelial cells, deficient formation of the Coxiella-containing vacuole, and aberrant T4BSS secretion. Three secretion phenotypes were identified from a screen of 50 Dot/Icm substrates: IcmS dependent (secreted by only wild-type bacteria), IcmS independent (secreted by both wild-type and ΔicmS bacteria), or IcmS inhibited (secreted by only ΔicmS bacteria). Secretion was assessed for N-terminal or C-terminal truncated forms of CBU0794 and CBU1525. IcmS-inhibited secretion of CBU1525 required a C-terminal secretion signal whereas IcmS-dependent secretion of CBU0794 was directed by C-terminal and internal signals. Interchange of the C-terminal 50 amino acids of CBU0794 and CBU1525 revealed that sites within the C terminus regulate IcmS dependency. Glutathione S-transferase-tagged IcmSW bound internal sequences of IcmS-dependent and -inhibited substrates. Thus, the growth defect of the C. burnetii ΔicmS strain is associated with a loss of T4BSS chaperone activity that both positively and negatively regulates effector translocation. IMPORTANCE The intracellular pathogen Coxiella burnetii employs a type 4B secretion system (T4BSS) that promotes growth by translocating effectors of eukaryotic pathways into host cells. T4BSS regulation modeled in Legionella pneumophila indicates IcmS facilitates effector translocation. Here, we characterized type 4B secretion by a Coxiella ΔicmS mutant that exhibits intracellular growth defects. T4BSS substrates demonstrated increased, equivalent, or decreased secretion by the ΔicmS mutant relative to wild-type Coxiella. Similar to the Legionella T4BSS, IcmS dependency in Coxiella was determined by C-terminal and/or internal secretion signals. However, IcmS inhibited secretion of some effectors by Coxiella that were previously shown to be translocated by Legionella. Thus, Coxiella has a unique IcmS regulatory mechanism that both positively and negatively regulates T4BSS export.

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