Q fever endocarditis of the tricuspid valve transmitted in an urban setting with no livestock exposure: Case report.

BACKGROUND: Coxiella burnetii is a bacterium with extreme tenacity and contagiousness that is mainly transmitted by inhalation of contaminated aerosols. Nevertheless, a transmission by ticks is under discussion. We report a case of Q fever in an urban environment and far away from sheep breeding that caused a rare right-sided endocarditis. CASE PRESENTATION: A 55-year-old man who was in good health before the event developed a C. burnetii -endocarditis of the tricuspid valve. He had no contact with sheep and no recent travel in a rural or even endemic area. The infection originated in a strictly urban environment, and the patient's occupation as a cemetery gardener in Berlin, coupled with the close temporal and local exposure to wild boar, made a transmission by these animals a plausible hypothesis. The infection was confirmed by the German Reference Laboratory, and the patient recovered completely after treatment with doxycycline and hydrochlorquine. CONCLUSIONS: The specialities of this case report are the right-sided endocarditis and the transmission of C. burnetii in a metropolitan area without sheep contact. We think that this case should serve to increase awareness of the potential for Q fever infection even in non-rural areas.

Divergent effects of itaconate isomers on Coxiella burnetii growth in macrophages and in axenic culture.

Aconitate decarboxylase-1 (ACOD1) is expressed by activated macrophages and generates itaconate that exerts anti-microbial and immunoregulatory effects. ACOD1-itaconate is essential for macrophage-mediated control of the intracellular pathogen Coxiella (C.) burnetii, which causes Q fever. Two isomers of itaconate, mesaconate and citraconate, have overlapping yet distinct activity on macrophage metabolism and inflammatory gene expression. Here, we found that all three isomers inhibited the growth of C. burnetii in axenic culture in ACCM-2 medium. However, only itaconate reduced C. burnetii replication efficiently in Acod1-/- macrophages. In contrast, addition of citraconate strongly increased C. burnetii replication in Acod1+/- macrophages, whereas mesaconate weakly enhanced bacterial burden in Acod1-/- macrophages. Analysis of intracellular isomers showed that exogenous citraconate and mesaconate inhibited the generation of itaconate by infected Acod1+/- macrophages. Uptake of added isomers into Acod1-/- macrophages was increased after infection for itaconate and mesaconate, but not for citraconate. Mesaconate, but not citraconate, competed with itaconate for uptake into macrophages. Taken together, inhibition of itaconate generation by macrophages and interference with the uptake of extracellular itaconate could be identified as potential mechanisms behind the divergent effects of citraconate and mesaconate on C. burnetii replication in macrophages or in axenic culture.

A case report of acute Q fever with low-read detection of Coxiella burnetii genome by next-generation metagenomic sequencing.

The case presents a 47-year-old man with sudden abdominal pain and fever, but the cause was uncertain. Through metagenomic next-generation sequencing (mNGS) and detecting Q fever antibodies in serum, along with the patient's clinical and epidemiological history, a precise diagnosis was made, enabling timely and proper treatment.

Structure based functional identification of an uncharacterized protein from Coxiella burnetii involved in adipogenesis.

Coxiella burnetii, the causative agent of Q fever, is an intracellular pathogen posing a significant global public health threat. There is a pressing need for dependable and effective treatments, alongside an urgency for further research into the molecular characterization of its genome. Within the genomic landscape of Coxiella burnetii, numerous hypothetical proteins remain unidentified, underscoring the necessity for in-depth study. In this study, we conducted comprehensive in silico analyses to identify and prioritize potential hypothetical protein of Coxiella burnetii, aiming to elucidate the structure and function of uncharacterized protein. Furthermore, we delved into the physicochemical properties, localization, and molecular dynamics and simulations, and assessed the primary, secondary, and tertiary structures employing a variety of bioinformatics tools. The in-silico analysis revealed that the uncharacterized protein contains a conserved Mth938-like domain, suggesting a role in preadipocyte differentiation and adipogenesis. Subcellular localization predictions indicated its presence in the cytoplasm, implicating a significant role in cellular processes. Virtual screening identified ligands with high binding affinities, suggesting the protein's potential as a drug target against Q fever. Molecular dynamics simulations confirmed the stability of these complexes, indicating their therapeutic relevance. The findings provide a structural and functional overview of an uncharacterized protein from C. burnetii, implicating it in adipogenesis. This study underscores the power of in-silico approaches in uncovering the biological roles of uncharacterized proteins and facilitating the discovery of new therapeutic strategies. The findings provide valuable preliminary data for further investigation into the protein's role in adipogenesis.

Coxiella burnetii inhibits nuclear translocation of TFEB, the master transcription factor for lysosomal biogenesis.

Coxiella burnetii is a highly infectious, Gram-negative, obligate intracellular bacterium and the causative agent of human Q fever. The Coxiella Containing Vacuole (CCV) is a modified phagolysosome that forms through fusion with host endosomes and lysosomes. While an initial acidic pH < 4.7 is essential to activate Coxiella metabolism, the mature, growth-permissive CCV has a luminal pH of ~5.2 that remains stable throughout infection. Inducing CCV acidification to a lysosomal pH (~4.7) causes Coxiella degradation, suggesting that Coxiella regulates CCV pH. Supporting this hypothesis, Coxiella blocks host lysosomal biogenesis, leading to fewer host lysosomes available to fuse with the CCV. Host cell lysosome biogenesis is primarily controlled by the transcription factor EB (TFEB), which binds Coordinated Lysosomal Expression And Regulation (CLEAR) motifs upstream of genes involved in lysosomal biogenesis and function. TFEB is a member of the microphthalmia/transcription factor E (MiT/TFE) protein family, which also includes MITF, TFE3, and TFEC. This study examines the roles of MiT/TFE proteins during Coxiella infection. We found that in cells lacking TFEB, both Coxiella growth and CCV size increase. Conversely, TFEB overexpression or expression in the absence of other family members leads to significantly less bacterial growth and smaller CCVs. TFE3 and MITF do not appear to play a significant role during Coxiella infection. Surprisingly, we found that Coxiella actively blocks TFEB nuclear translocation in a Type IV Secretion System-dependent manner, thus decreasing lysosomal biogenesis. Together, these results suggest that Coxiella inhibits TFEB nuclear translocation to limit lysosomal biogenesis, thus avoiding further CCV acidification through CCV-lysosomal fusion. IMPORTANCE: The obligate intracellular bacterial pathogen Coxiella burnetii causes the zoonotic disease Q fever, which is characterized by a debilitating flu-like illness in acute cases and life-threatening endocarditis in patients with chronic disease. While Coxiella survives in a unique lysosome-like vacuole called the Coxiella Containing Vacuole (CCV), the bacterium inhibits lysosome biogenesis as a mechanism to avoid increased CCV acidification. Our results establish that transcription factor EB (TFEB), a member of the microphthalmia/transcription factor E (MiT/TFE) family of transcription factors that regulate lysosomal gene expression, restricts Coxiella infection. Surprisingly, Coxiella blocks TFEB translocation from the cytoplasm to the nucleus, thus downregulating the expression of lysosomal genes. These findings reveal a novel bacterial mechanism to regulate lysosomal biogenesis.

Coxiella burnetii-containing vacuoles interact with host recycling endosomal proteins Rab11a and Rab35 for vacuolar expansion and bacterial growth.

Introduction: Coxiella burnetii is a gram-negative obligate intracellular bacterium and a zoonotic pathogen that causes human Q fever. The lack of effective antibiotics and a licensed vaccine for Coxiella in the U.S. warrants further research into Coxiella pathogenesis. Within the host cells, Coxiella replicates in an acidic phagolysosome-like vacuole termed Coxiella-containing vacuole (CCV). Previously, we have shown that the CCV pH is critical for Coxiella survival and that the Coxiella Type 4B secretion system regulates CCV pH by inhibiting the host endosomal maturation pathway. However, the trafficking pattern of the 'immature' endosomes in Coxiella- infected cells remained unclear. Methods: We transfected HeLa cells with GFP-tagged Rab proteins and subsequently infected them with mCherry-Coxiella to visualize Rab protein localization. Infected cells were immunostained with anti-Rab antibodies to confirm the Rab localization to the CCV, to quantitate Rab11a and Rab35- positive CCVs, and to quantitate total recycling endosome content of infected cells. A dual-hit siRNA mediated knockdown combined with either immunofluorescent assay or an agarose-based colony-forming unit assay were used to measure the effects of Rab11a and Rab35 knockdown on CCV area and Coxiella intracellular growth. Results: The CCV localization screen with host Rab proteins revealed that recycling endosome-associated proteins Rab11a and Rab35 localize to the CCV during infection, suggesting that CCV interacts with host recycling endosomes during maturation. Interestingly, only a subset of CCVs were Rab11a or Rab35-positive at any given time point. Quantitation of Rab11a/Rab35-positive CCVs revealed that while Rab11a interacts with the CCV more at 3 dpi, Rab35 is significantly more prevalent at CCVs at 6 dpi, suggesting that the CCV preferentially interacts with Rab11a and Rab35 depending on the stage of infection. Furthermore, we observed a significant increase in Rab11a and Rab35 fluorescent intensity in Coxiella-infected cells compared to mock, suggesting that Coxiella increases the recycling endosome content in infected cells. Finally, siRNA-mediated knockdown of Rab11a and Rab35 resulted in significantly smaller CCVs and reduced Coxiella intracellular growth, suggesting that recycling endosomal Rab proteins are essential for CCV expansion and bacterial multiplication. Discussion: Our data, for the first time, show that the CCV dynamically interacts with host recycling endosomes for Coxiella intracellular survival and potentially uncovers novel host cell factors essential for Coxiella pathogenesis.

Molecular identification of Coxiella burnetii in raw milk samples collected from farm animals in districts Kasur and Lahore of Punjab, Pakistan.

Coxiella burnetii is the worldwide zoonotic infectious agent for Q fever in humans and animals. Farm animals are the main reservoirs of C. burnetii infection, which is mainly transmitted via tick bites. In humans, oral, percutaneous, and respiratory routes are the primary sources of infection transmission. The clinical signs vary from flu-like symptoms to endocarditis for humans' acute and chronic Q fever. While it is usually asymptomatic in livestock, abortion, stillbirth, infertility, mastitis, and endometritis are its clinical consequences. Infected farm animals shed C. burnetii in birth products, milk, feces, vaginal mucus, and urine. Milk is an important source of infection among foods of animal origin. This study aimed to determine the prevalence and molecular characterization of C. burnetii in milk samples of dairy animals from two districts in Punjab, Pakistan, as it has not been reported there so far. Using a convenience sampling approach, the current study included 304 individual milk samples from different herds of cattle, buffalo, goats, and sheep present on 39 farms in 11 villages in the districts of Kasur and Lahore. PCR targeting the IS1111 gene sequence was used for its detection. Coxiella burnetii DNA was present in 19 of the 304 (6.3%) samples. The distribution was 7.2% and 5.2% in districts Kasur and Lahore, respectively. The results showed the distribution in ruminants as 3.4% in buffalo, 5.6% in cattle, 6.7% in goats, and 10.6% in sheep. From the univariable analysis, the clinical signs of infection i.e. mastitis and abortion were analyzed for the prevalence of Coxiella burnetii. The obtained sequences were identical to the previously reported sequence of a local strain in district Lahore, Sahiwal and Attock. These findings demonstrated that the prevalence of C. burnetii in raw milk samples deserves more attention from the health care system and veterinary organizations in Kasur and Lahore of Punjab, Pakistan. Future studies should include different districts and human populations, especially professionals working with animals, to estimate the prevalence of C. burnetii.

Acute Q fever pneumonia diagnosed by metagenomic next-generation sequencing.

INTRODUCTION: Q fever, a zoonotic disease caused by Coxiella burnetii (C. burnetii), presents diagnostic challenges due to its clinical and radiological nonspecificity, which often mimics community-acquired pneumonia, coupled with the limitations of traditional diagnostic methods. Metagenomic next-generation sequencing (mNGS) has become an indispensable tool in clinical diagnostics for its high-throughput pathogen identification capabilities. Herein, we detail a case of acute Q fever pneumonia diagnosed with mNGS. CASE PRESENTATION: The patient exhibited symptoms of fever, cough, expectoration, and diarrhea for three days, with the pathogen undetected in initial laboratory assessments. Bronchoscopy and bronchoalveolar lavage (BAL) were conducted, leading to the identification of C. burnetii in the lavage fluid via mNGS. Consequently, the patient was promptly initiated on a treatment regimen of 100 mg doxycycline, administered orally every 12 hours. RESULTS: Post-treatment, the patient's temperature normalized, and a full recovery was observed. The follow-up chest CT scan revealed complete resolution of the right lower lobe consolidation. CONCLUSIONS: The clinical presentation of Q fever pneumonia lacks specificity, making diagnosis based solely on symptoms and imaging challenging. mNGS offers a superior alternative for identifying elusive or rarely cultured pathogens.

Caspase-8 activity mediates TNFα production and restricts Coxiella burnetii replication during murine macrophage infection.

Coxiella burnetii is an obligate intracellular bacteria that causes the global zoonotic disease Q Fever. Treatment options for chronic infection are limited, and the development of novel therapeutic strategies requires a greater understanding of how C. burnetii interacts with immune signaling. Cell death responses are known to be manipulated by C. burnetii, but the role of caspase-8, a central regulator of multiple cell death pathways, has not been investigated. In this research, we studied bacterial manipulation of caspase-8 signaling and the significance of caspase-8 to C. burnetii infection, examining bacterial replication, cell death induction, and cytokine signaling. We measured caspase, RIPK, and MLKL activation in C. burnetii-infected tumor necrosis factor alpha (TNFα)/cycloheximide-treated THP-1 macrophage-like cells and TNFα/ZVAD-treated L929 cells to assess apoptosis and necroptosis signaling. Additionally, we measured C. burnetii replication, cell death, and TNFα induction over 12 days in RIPK1-kinase-dead, RIPK3-kinase-dead, or RIPK3-kinase-dead-caspase-8-/- bone marrow-derived macrophages (BMDMs) to understand the significance of caspase-8 and RIPK1/3 during infection. We found that caspase-8 is inhibited by C. burnetii, coinciding with inhibition of apoptosis and increased susceptibility to necroptosis. Furthermore, C. burnetii replication was increased in BMDMs lacking caspase-8, but not in those lacking RIPK1/3 kinase activity, corresponding with decreased TNFα production and reduced cell death. As TNFα is associated with the control of C. burnetii, this lack of a TNFα response may allow for the unchecked bacterial growth we saw in caspase-8-/- BMDMs. This research identifies and explores caspase-8 as a key regulator of C. burnetii infection, opening novel therapeutic doors.

Efficacy of rifapentine and other rifamycins against Coxiella burnetii in vitro.

Since 1999, doxycycline and hydroxychloroquine have been the recommended treatment for chronic Q fever, a life-threatening disease caused by the bacterial pathogen, Coxiella burnetii. Despite the duration of its use, the treatment is not ideal due to the lengthy treatment time, high mortality rate, resistant strains, and the potential for contraindicated usage. A literature search was conducted to identify studies that screened large panels of drugs against C. burnetii to identify novel targets with potential efficacy against C. burnetii. Twelve candidate antimicrobials approved for use in humans by the US Food and Drug Administration were selected and minimum inhibitory concentrations (MICs) were determined against the low virulence strain Nine Mile phase II. Rifabutin and rifaximin were the best performing antibiotics tested with MICs of ≤0.01 µg mL-1. Further screening of these top candidates was conducted alongside two drugs from the same class, rifampin, well-characterized, and rifapentine, not previously reported against C. burnetii. These were screened against virulent strains of C. burnetii representing three clinically relevant genotypes. Rifapentine was the most effective in the human monocytic leukemia cell line, THP-1, with a MIC ≤0.01 µg mL-1. In the human kidney epithelial cell line, A-498, efficacy of rifapentine, rifampin, and rifabutin varied across C. burnetii strains with MICs between ≤0.001 and 0.01 µg mL-1. Rifampin, rifabutin, and rifapentine were all bactericidal against C. burnetii; however, rifabutin and rifapentine demonstrated impressive bactericidal activity as low as 0.1 µg mL-1 and should be further explored as alternative Q fever treatments given their efficacy in vitro. IMPORTANCE: This work will help inform investigators and physicians about potential alternative antimicrobial therapies targeting the causative agent of Q fever, Coxiella burnetii. Chronic Q fever is difficult to treat, and alternative antimicrobials are needed. This manuscript explores the efficacy of rifamycin antibiotics against virulent strains of C. burnetii representing three clinically relevant genotypes in vitro. Importantly, this study determines the susceptibility of C. burnetii to rifapentine, which has not been previously reported. Evaluation of the bactericidal activity of the rifamycins reveals that rifabutin and rifapentine are bactericidal at low concentrations, which is unusual for antibiotics against C. burnetii.

Delayed diagnosis of persistent Q fever: a case series from China.

BACKGROUND: Q fever, caused by the zoonotic pathogen Coxiella burnetii, exhibits a worldwide prevalence. In China, Q fever is not recognized as a notifiable disease, and the disease is overlooked and underestimated in clinical practice, leading to diagnostic challenges. CASE PRESENTATION: We present a case series of three patients diagnosed with persistent Q fever between 2022 and 2023. The average age of our three cases was 63.33 years old, consisting of two males and one female. The medical history of the individuals included previous valve replacement, aneurysm followed by aortic stent-graft placement and prosthetic hip joint replacement. At the onset of the disease, only one case exhibited acute fever, while the remaining two cases were devoid of any acute symptoms. The etiology was initially overlooked until metagenomic next-generation sequencing test identified Coxiella burnetii from the blood or biopsy samples. Delayed diagnosis was noted, with a duration ranging from three months to one year between the onset of the disease and its confirmation. The epidemiological history uncovered that none of the three cases had direct exposure to domestic animals or consumption of unpasteurized dairy products. Case 1 and 2 resided in urban areas, while Case 3 was a rural resident engaged in farming. All patients received combination therapy of doxycycline and hydroxychloroquine, and no recurrence of the disease was observed during the follow-up period. CONCLUSION: Q fever is rarely diagnosed and reported in clinical practice in our country. We should be aware of persistent Q fever in high-risk population, even with unremarkable exposure history. Metagenomic next-generation sequencing holds great potential as a diagnostic tool for identifying rare and fastidious pathogens such as Coxiella burnetii.

Bacterial burden and molecular characterization of Coxiella burnetii in shedding pregnant and postpartum ewes from Saint Kitts.

This study aimed to evaluate the bacterial burden and perform molecular characterization of Coxiella burnetii during shedding in pregnant (vaginal, mucus and feces) and postpartum (vaginal mucus, feces and milk) ewes from Saint Kitts. Positive IS1111 DNA (n=250) for C. burnetii samples from pregnant (n=87) and postpartum (n=74) Barbados Blackbelly ewes in a previous investigation were used for this study. Vaginal mucus (n=118), feces (n=100), and milk (n=32) positive IS1111 C. burnetii-DNA were analysed by real time qPCR (icd gene). For molecular characterization of C. burnetii, selected (n=10) IS1111 qPCR positive samples were sequenced for fragments of the IS1111 element and the 16 S rRNA gene. nBLAST, phylogenetic and haplotype analyses were performed. Vaginal mucus, feces and milk had estimated equal amounts of bacterial DNA (icd copies), and super spreaders were detected within the fecal samples. C. burnetii haplotypes had moderate to high diversity, were ubiquitous worldwide and similar to previously described in ruminants and ticks and humans.

Tissue distribution of Coxiella burnetii and antibody responses in macropods co-grazing with livestock in Queensland, Australia.

Coxiella burnetii, the causative agent of Q fever, is a zoonotic bacteria of global public health significance. The organism has a complex, diverse, and relatively poorly understood animal reservoir but there is increasing evidence that macropods play some part in the epidemiology of Q fever in Australia. The aim of this cross-sectional survey was to estimate the animal- and tissue-level prevalence of coxiellosis amongst eastern grey (Macropus giganteus) and red (Osphranter rufus) kangaroos co-grazing with domestic cattle in a Q fever endemic area in Queensland. Serum, faeces and tissue samples from a range of organs were collected from 50 kangaroos. A total of 537 tissue samples were tested by real-time PCR, of which 99 specimens from 42 kangaroos (84% of animals, 95% confidence interval [CI], 71% to 93%) were positive for the C. burnetii IS1111 gene when tested in duplicate. Twenty of these specimens from 16 kangaroos (32%, 95% CI 20% to 47%) were also positive for the com1 or htpAB genes. Serum antibodies were present in 24 (57%, 95% CI 41% to 72%) of the PCR positive animals. There was no statistically significant difference in PCR positivity between organs and no single sample type consistently identified C. burnetii positive kangaroos. The results from this study identify a high apparent prevalence of C. burnetii amongst macropods in the study area, albeit seemingly with an inconsistent distribution within tissues and in relatively small quantities, often verging on the limits of detection. We recommend Q fever surveillance in macropods should involve a combination of serosurveys and molecular testing to increase chances of detection in a population, noting that a range of tissues would likely need to be sampled to confirm the diagnosis in a suspect positive animal.

Molecular and serological diagnosis of multiple bacterial zoonoses in febrile outpatients in Garissa County, north-eastern Kenya.

Bacterial zoonoses are diseases caused by bacterial pathogens that can be naturally transmitted between humans and vertebrate animals. They are important causes of non-malarial fevers in Kenya, yet their epidemiology remains unclear. We investigated brucellosis, Q-fever and leptospirosis in the venous blood of 216 malaria-negative febrile patients recruited in two health centres (98 from Ijara and 118 from Sangailu health centres) in Garissa County in north-eastern Kenya. We determined exposure to the three zoonoses using serological (Rose Bengal test for Brucella spp., ELISA for C. burnetti and microscopic agglutination test for Leptospira spp.) and real-time PCR testing and identified risk factors for exposure. We also used non-targeted metagenomic sequencing on nine selected patients to assess the presence of other possible bacterial causes of non-malarial fevers. Considerable PCR positivity was found for Brucella (19.4%, 95% confidence intervals [CI] 14.2-25.5) and Leptospira spp. (1.7%, 95% CI 0.4-4.9), and high endpoint titres were observed against leptospiral serovar Grippotyphosa from the serological testing. Patients aged 5-17 years old had 4.02 (95% CI 1.18-13.70, p-value = 0.03) and 2.42 (95% CI 1.09-5.34, p-value = 0.03) times higher odds of infection with Brucella spp. and Coxiella burnetii than those of ages 35-80. Additionally, patients who sourced water from dams/springs, and other sources (protected wells, boreholes, bottled water, and water pans) had 2.39 (95% CI 1.22-4.68, p-value = 0.01) and 2.24 (1.15-4.35, p-value = 0.02) times higher odds of exposure to C. burnetii than those who used unprotected wells. Streptococcus and Moraxella spp. were determined using metagenomic sequencing. Brucellosis, leptospirosis, Streptococcus and Moraxella infections are potentially important causes of non-malarial fevers in Garissa. This knowledge can guide routine diagnosis, thus helping lower the disease burden and ensure better health outcomes, especially in younger populations.

One Health approach to Coxiella burnetii in Brazilian indigenous communities.

Indigenous health has posted complex challenges worldwide, particularly due to historical economic, territorial, social and environmental processes, which may lead to emergence and reemergence of pathogens. In addition to few Coxiella burnetii serosurveys in vulnerable populations, especially in developing tropical countries, no comprehensive One Health approach has focused on human-animal infection along with potential environmental determinants. Accordingly, this study aimed to assess the seroprevalence of anti-C. burnetii antibodies in indigenous populations and their dogs from 10 indigenous communities distributed in southern and southeastern Brazil, along with the correspondent healthcare professionals. In overall, 8/893 (0.90%; 95% CI 0.45-1.76) indigenous and 1/406 (0.25%) dog samples were seropositive, with 7/343 (2.04%) individuals the 1/144 (0.69%) dog from the Ocoy community, located in the city of São Miguel do Iguaçu, bordering Argentina at south, and far 10 km at west from Paraguay. All 84 healthcare professionals tested seronegative.

Coxiella burnetii effector CvpE maintains biogenesis of Coxiella-containing vacuoles by suppressing lysosome tubulation through binding PI(3)P and perturbing PIKfyve activity on lysosomes.

Coxiella burnetii (C. burnetii) is the causative agent of Q fever, a zoonotic disease. Intracellular replication of C. burnetii requires the maturation of a phagolysosome-like compartment known as the replication permissive Coxiella-containing vacuole (CCV). Effector proteins secreted by the Dot/Icm secretion system are indispensable for maturation of a single large CCV by facilitating the fusion of promiscuous vesicles. However, the mechanisms of CCV maintenance and evasion of host cell clearance remain to be defined. Here, we show that C. burnetii secreted Coxiella vacuolar protein E (CvpE) contributes to CCV biogenesis by inducing lysosome-like vacuole (LLV) enlargement. LLV fission by tubulation and autolysosome degradation is impaired in CvpE-expressing cells. Subsequently, we found that CvpE suppresses lysosomal Ca2+ channel transient receptor potential channel mucolipin 1 (TRPML1) activity in an indirect manner, in which CvpE binds phosphatidylinositol 3-phosphate [PI(3)P] and perturbs PIKfyve activity in lysosomes. Finally, the agonist of TRPML1, ML-SA5, inhibits CCV biogenesis and C. burnetii replication. These results provide insight into the mechanisms of CCV maintenance by CvpE and suggest that the agonist of TRPML1 can be a novel potential treatment that does not rely on antibiotics for Q fever by enhancing Coxiella-containing vacuoles (CCVs) fission.

Occurrence of Coxiellosis in ruminants and its associated risk factors.

Coxiellosis in animals is caused by the zoonotic pathogen, Coxiella burnetii. Although the disease is of public health importance it remains underdiagnosed and underreported. The cross- sectional study was aimed to estimate the occurrence of the disease in livestock of study area and also to identify the risk factors associated with the disease in animals. Blood, serum, and vaginal swabs samples were collected from 200 ruminants (cattle, sheep, and goats), across various farms in Karnataka, India. These samples were then screened using ELISA and PCR (com1 and IS1111). A questionnaire was administered to the farm owners to collect the risk factor-related information. About 5.26 % cattle, 12.3 % sheep, and 12.5 % goats were positive by ELISA. By PCR, 9.47 % cattle, 9.3 % sheep, and 10 % goats were positive. Overall, the occurrence of 14.73 %, 18.46 % and 17.5 % was estimated in cattle, sheep and goat, respectively. PCR targeting the IS1111 gene detected higher number of samples as positive as compared to the com1 gene PCR. Higher number of vaginal swab samples were detected as positive as compared to blood. History of reproductive disorders (OR: 4.30; 95 %CI:1.95- 9.46), abortion (OR: 30.94; 95 %CI:6.30- 151.84) and repeat breeding (OR:11.36; 95 %CI:4.16- 30.99) were significantly associated with coxiellosis (p < 0.005). Multivariable analysis by logistic regression model analysis suggested retained abortion, repeat breeding and rearing of animal in semi-intensive system as factors significantly associated with the infection. Cultural identification of the PCR positive samples were cultured using embryonated egg propagation and cell culture techniques and positivity was confirmed in six samples. Phylogenetic analysis of the com1 and IS1111 gene revealed clustering based on similar geographic locations. The study estimated the occurrence of the disease in the study area and identified the potential risk factors.

Coxiella burnetii serostatus in dromedary camels (Camelus dromedarius) is associated with the presence of C. burnetii DNA in attached ticks in Laikipia County, Kenya.

AIMS: Q fever is a globally distributed, neglected zoonotic disease of conservation and public health importance, caused by the bacterium Coxiella burnetii. Coxiella burnetii normally causes subclinical infections in livestock, but may also cause reproductive pathology and spontaneous abortions in artiodactyl species. One such artiodactyl, the dromedary camel (Camelus dromedarius), is an increasingly important livestock species in semi-arid landscapes. Ticks are naturally infected with C. burnetii worldwide and are frequently found on camels in Kenya. In this study, we assessed the relationship between dromedary camels' C. burnetii serostatus and whether the camels were carrying C. burnetii PCR-positive ticks in Kenya. We hypothesized that there would be a positive association between camel seropositivity and carrying C. burnetii PCR-positive ticks. METHODS AND RESULTS: Blood was collected from camels (N = 233) from three herds, and serum was analysed using commercial ELISA antibody test kits. Ticks were collected (N = 4354), divided into pools of the same species from the same camel (N = 397) and tested for C. burnetii and Coxiella-like endosymbionts. Descriptive statistics were used to summarize seroprevalence by camel demographic and clinical variables. Univariate logistic regression analyses were used to assess relationships between serostatus (outcome) and tick PCR status, camel demographic variables, and camel clinical variables (predictors). Camel C. burnetii seroprevalence was 52%. Across tick pools, the prevalence of C. burnetii was 15% and Coxiella-like endosymbionts was 27%. Camel seropositivity was significantly associated with the presence of a C. burnetii PCR-positive tick pool (OR: 2.58; 95% CI: 1.4-5.1; p = 0.0045), increasing age class, and increasing total solids. CONCLUSIONS: The role of ticks and camels in the epidemiology of Q fever warrants further research to better understand this zoonotic disease that has potential to cause illness and reproductive losses in humans, livestock, and wildlife.

Ultraviolet C inactivation of Coxiella burnetii for production of a structurally preserved whole cell vaccine antigen.

Q fever, a worldwide-occurring zoonotic disease, can cause economic losses for public and veterinary health systems. Vaccines are not yet available worldwide and currently under development. In this regard, it is important to produce a whole cell antigen, with preserved structural and antigenic properties and free of chemical modifications. Thus, inactivation of Coxiella burnetii with ultraviolet light C (UVC) was evaluated. C. burnetii Nine Mile phase I (NMI) and phase II (NMII) were exposed to decreasing intensities in a time-dependent manner and viability was tested by rescue cultivation in axenic medium or cell culture. Effects on the cell structure were visualized by transmission electron microscopy and antigenicity of UVC-treated NMI was studied by immunization of rabbits. NMI and NMII were inactivated at UVC intensities of 250 µW/cm2 for 5 min or 100 µW/cm2 for 20 min. Reactivation by DNA repair was considered to be unlikely. No morphological changes were observed directly after UVC inactivation by transmission electron microscopy, but severe swelling and membrane degradation of bacteria with increasing severity occurred after 24 and 48 h. Immunization of rabbits resulted in a pronounced antibody response. UVC inactivation of C. burnetii resulted in a structural preserved, safe whole cell antigen and might be useful as antigen for diagnostic purposes or as vaccine candidate.