Search

Background: Q fever caused by Coxiella burnetii is transmitted to humans by inhalation of aerosols from animal birth products. Q fever in pregnancy is suspected to be a potential cause of fetal and maternal morbidity and fetal mortality but the pathogenesis is poorly understood, and even in Q fever endemic areas, the magnitude of a potential association is not established.We aimed to examine if presence of antibodies to C. burnetii during pregnancy or seroconversion were associated with adverse pregnancy outcomes., Methods: The Danish National Birth Cohort collected blood samples and interview data from 100,418 pregnant women (1996-2002). We sampled 397 pregnant women with occupational or domestic exposure to cattle or sheep and a random sample of 459 women with no animal exposure. Outcome measures were spontaneous abortion, preterm birth, birth weight and Small for Gestational Age (SGA).Blood samples collected in pregnancy were screened for antibodies against C. burnetii by enzyme-linked immunosorbent assay (ELISA). Samples positive for IgG or IgM antibodies in the ELISA were confirmed by immunofluorescence antibody test (IFA)., Results: Among the 856 women, 169 (19.7%) women were IFA positive; 147 (87%) of these had occupational or domestic contact with livestock (IFA cutoff > =1:128).Two abortions were IFA positive vs. 6 IFA negative (OR: 1.5; 95%CI: 0.3-7.6). Three preterm births were IFA positive vs. 38 IFA negative (OR: 0.4; 95% CI: 0.1-1.1). There was a significant difference in birth weight of 168 g (95% CI: 70-267 g) with IFA positive being heavier, and the risk of being SGA was not increased in the newborns of IFA positive women (OR: 0.4; 95%CI: 0.8-1.0).Most seropositive women were IgG positive indicating previous exposure. Seroconversion during pregnancy was found in 10 women; they all delivered live babies at term, but two were SGA., Conclusion: We found no increased risk of adverse pregnancy outcome in women with verified exposure to C. burnetii.To our knowledge, this is the first population-based seroepidemiologic study evaluating pregnancy outcome in women with serologically verified exposure to C. burnetii against a comparable reference group of seronegative women.

Q fever is a zoonotic disease caused by infection with the bacterium Coxiella burnetii. Infection with C. burnetii results 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 of C. burnetii immunity, 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 to C. burnetii by 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 of C. burnetii immune responses and that Q fever vaccination establishes long-lived immune responses to C. burnetii.

The circulation of the rickettsiae R.africae and C.brunetii, the causative agents of African tick-bite spotted fever and Q fever, was first ascertained throughout the territory of the Republic of Guinea. The immune stratum against R.africae among the population varied 1.1 to 25.4% or 10.6+/-0.7% on average and that among the livestock did 0.6 to 18.8% or 7.6+/-0.6% on average. The proportion of sera to C,brunettii in the population was in the rage from 0.8 to 10.5% or 2.4+/-0.3% on average; that in livestock was 3.2 to 18.7% or 8.0+/-0.6% on average. However, many aspects of the circulation of rickettsiae, the pathology and importance of these fevers in the structure of morbidity in Guinea remain still unclarified and call for further investigations, by applying the current laboratory diagnostic tests for rickettsiosial diseases.

Q fever, caused by the pathogen Coxiella burnetii, is an acute disease that can progress to become a serious chronic illness. The organism leads an obligate, intracellular lifecycle, during which it multiplies in the phagolytic compartments of the phagocytic cells of the immune system of its hosts. This characteristic makes study of the organism particularly difficult and is perhaps one of the reasons why, more than 70 y after its discovery, much remains unknown about the organism and its pathogenesis. A variety of animal species have been used to study both the acute and chronic forms of the disease. Although none of the models perfectly mimics the disease process in humans, each opens a window onto an important aspect of the pathology of the disease. We have learned that immunosuppression, overexpression of IL10, or physical damage to the heart muscle in mice and guinea pigs can induce disease that is similar to the chronic disease seen in humans, suggesting that this aspect of disease may eventually be fully understood. Models using species from mice to nonhuman primates have been used to evaluate and characterize vaccines to protect against the disease and may ultimately yield safer, less expensive vaccines.

Large outbreaks of Q fever in The Netherlands have provided a unique opportunity for studying longitudinal serum antibody responses in patients. Results are presented of a cohort of 344 patients with acute symptoms of Q fever with three or more serum samples per patient. In all these serum samples IgM and IgG against phase 1 and 2 Coxiella burnetii were measured by an immunofluorescence assay. A mathematical model of the dynamic interaction of serum antibodies and pathogens was used in a mixed model framework to quantitatively analyse responses to C. burnetii infection. Responses show strong heterogeneity, with individual serum antibody responses widely different in magnitude and shape. Features of the response, peak titre and decay rate, are used to characterize the diversity of the observed responses. Binary mixture analysis of IgG peak levels (phases 1 and 2) reveals a class of patients with high IgG peak titres that decay slowly and may represent potential chronic cases. When combining the results of mixture analysis into an odds score, it is concluded that not only high IgG phase 1 may be predictive for chronic Q fever, but also that high IgG phase 2 may aid in detecting such putative chronic cases.

Possible factors related to seropositivity and seroconversion to Coxiella burnetii were examined in a dairy herd with a high Coxiella-seroprevalence and high excretion levels of the bacterium in the bulk tank milk. Antibodies were detected by using a commercial ELISA test in 50.7% of 603 parous cows. The likelihood of C. burnetii seropositivity significantly increased by factors of 1.87 and 1.61 for cows in their first and second terms of pregnancy, respectively, compared to non-pregnant cows. In 478 cows tested twice 12 months apart, the seroconversion rate was 5%. The likelihood of C. burnetii-seroconversion was 2.27 times lower in multiparous than in primiparous cows and 6.88 times higher in cows during their first 90 days in milk than dry-off cows. Our findings indicated a higher seroprevalence in the first and second terms of pregnancy, and that seroconversion mainly occurred in primiparous cows during their first 90 days in milk., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Coxiella burnetii is a Gram-negative bacterium that causes acute and chronic Q fever in humans. Creation of a safe and effective new generation vaccine to prevent Q fever remains an important public health goal. Previous studies suggested that Ab-mediated immunity to C. burnetii phase I LPS (PI-LPS) is protective. To identify the potential peptides that can mimic the protective epitopes on PI-LPS, a PI-LPS-specific mAb 1E4 was generated, characterized, and used to screen a phage display library. Interestingly, our results indicate that 1E4 was able to inhibit C. burnetii infection in vivo, suggesting that 1E4 is a protective mAb. After three rounds of biopanning by 1E4 from the phage display library, a mimetic peptide, m1E41920, was identified, chemically synthesized, and conjugated to keyhole limpet hemocyanin (KLH) for examining its immunogenicity. The results indicate that the synthetic peptide m1E41920 was able to inhibit the binding of 1E4 to PI Ag, suggesting m1E41920 shares the same binding site of 1E4 with the epitopes of PI Ag. In addition, m1E41920-KLH elicited a specific IgG response to PI Ag, and immune sera from m1E41920-KLH-immunized mice was able to inhibit C. burnetii infection in vivo, suggesting that m1E41920 may specifically mimic the protective epitope of PI-LPS. Furthermore, m1E41920-KLH was able to confer significant protection against C. burnetii challenge. Thus, m1E41920-KLH is a protective Ag and may be useful for developing a safe and effective vaccine against Q fever. This study demonstrates the feasibility of developing a peptide mimic vaccine against Q fever.

Q fever is a zoonosis caused by Coxiella burnetii, a unique bacterium that is widespread but infrequently associated with human illness or outbreaks. We report on evidence of infection with C. burnetii in a small group of regular consumers of raw (unpasteurized) milk from the same dairy in Michigan.

The recombinant membrane-associated proteins of Coxiella burnetii, Com1, Mip and GroEL, were used in vitro to stimulate BALB/c mouse bone marrow-derived dendritic cells (BMDCs). The antigen-activated BMDCs were transferred into naïve BALB/c mice. Seven days after challenge of C. burnetii, the bacterial loads of mice receiving BMDCs activated with Com1 or Mip, but not GroEL, were significantly lower than that of mice receiving BMDCs pulsed with TrxA (Esherichia coli thioredoxin) in a quantitative polymerase chain reaction assay. After in vitro interaction with cognate antigen-pulsed BMDCs, the percentages of CD69-positive cells and TNF-α-positive cells in CD4(+) and CD8(+) T cells isolated from the spleens of mice receiving Com1-, Mip-, or GroEL-pulsed BMDCs were significantly higher than that of mice receiving mock-pulsed BMDCs in flow cytometric analysis. The percentages of IFN-γ-positive cells in CD4(+) and CD8(+) T cells from mice receiving Com1- or Mip-pulsed BMDCs were significantly greater than that of mice receiving GroEL-pulsed BMDCs. However, the percentage of IL-4-positive cells in CD4(+) T cells of mice receiving GroEL-pulsed BMDCs was obviously higher than that of mice receiving Com1- or Mip-pulsed BMDCs. Our results demonstrate that Com1 and Mip are protective antigens and strongly indicate that they favor to induce IFN-γ-producing Th1 and Tc1 cells, whereas the non-protective antigen GroEL is biased to induce a Th2 response. Therefore, Com1 and Mip are key antigens to induce a protective immune response against C. burnetii infection., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

We investigated the positive predictive value (PPV) of a solitary positive immunoglobulin M (IgM) phase II response for the serodiagnosis of acute Q fever detected with either an indirect immunofluorescence assay (IFA) or an enzyme-linked immunosorbent assay (ELISA). Initial and follow-up sera from patients suspected of acute Q fever were included if initially only IgM phase II tested positive with IFA in 2008 (n=92), or ELISA in 2009 (n=85). A seroconversion for Q fever was defined as an initial sample being IgG phase II negative but positive in the follow-up sample. The PPV of an initial isolated IgM phase II result detected by IFA or ELISA was 65% and 51%, respectively, and therefore appeared not to adequately predict acute Q fever. For this reason it cannot be used as a diagnostic criterion nor should it be included in public health notification without confirmation with other markers or a follow-up serum sample.

Effectiveness of phase 1 vaccine, combined or not with tetracycline, to control Coxiella burnetii vaginal shedding at calving in cows was assessed through a 13 months study in 22 Q fever clinically affected commercial dairy herds. Four medical strategies implemented at herd level but randomly assigned to cows (vaccination, vaccination and tetracycline, tetracycline, nothing) were compared. There was no significant interaction effect between vaccination and antibiotherapy. Tetracycline used once at drying off was associated with a lower risk of being detected shedder at calving (OR=0.40, CI 95% [0.21-0.75]), but had no significant effect on the bacterial load shed. Vaccination did not significantly prevent shedding but was significantly (OR=0.15, CI 95% [0.03-0.85]) associated with lower bacterial load shed. Thus, vaccination using a phase 1 vaccine and antibiotherapy using tetracycline is associated with a decrease in shedding in dairy cows and could contribute to reduce the bacterial load generated in the environment. To the best of our knowledge, this is the first study providing useful information for evidenced-based and rational use of medical strategy combining antibiotic and vaccination in infected dairy cattle herds., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Little is known about the effect of timing of antibiotic treatment on development of IgG antibodies following acute Q fever. We studied IgG antibody responses in symptomatic patients diagnosed either before or during development of the serologic response to Coxiella burnetii. Between 15 and 31 May 2009, 186 patients presented with acute Q fever, of which 181 were included in this retrospective study: 91 early-diagnosed (ED) acute Q fever patients, defined as negative IgM phase II enzyme-linked immunosorbent assay (ELISA) and positive PCR, and 90 late-diagnosed (LD) acute Q fever patients, defined as positive/dubious IgM phase II ELISA and positive immunofluorescence assay (IFA). Follow-up serology at 3, 6, and 12 months was performed using IFA (IgG phase I and II). High IgG antibody titers were defined as IgG phase II titers of ≥1:1,024 together with IgG phase I titers of ≥1:256. At 12 months, 28.6% of ED patients and 19.5% of LD patients had high IgG antibody titers (P = 0.17). No statistically significant differences were found in frequencies of IgG phase I and IgG phase II antibody titers at all follow-up appointments for adequately and inadequately treated patients overall, as well as for ED and LD patients analyzed separately. Additionally, no significant difference was found in frequencies of high antibody titers and between early (treatment started within 7 days after seeking medical attention) and late timing of treatment. This study indicates that early diagnosis and antibiotic treatment of acute Q fever do not prohibit development of the IgG antibody response.

The relationship between the level of antibodies in bulk tank milk (BTM) and the within-herd seroprevalence of Coxiella burnetii in cows was assessed. Blood from milking cows and BTM were sampled in 55 infected herds and tested using commercial enzyme-linked immunosorbent assay (ELISA) kits. The relationship between antibody levels and WHP, which was quantified using a general linear model, was only moderate (R(2)=0·15). Nevertheless, the lowest antibody level in BTM was associated with the lowest mean within-herd prevalence. The present finding indicates that ELISA applied to BTM could identify infected herds with quite low within-herd seroprevalence. For such herds, the vaccination of dairy cows as well as nulliparous heifers using a phase I vaccine could effectively prevent C. burnetii shedding.

The article deals with the results of study of 35 patients with Q-fever and 30 donors to determine the content of rosette-forming neutrophils, lysozyme activity of blood and saliva. On the second week of disease it was revealed the activation of compensative immune mechanisms and on third and fourth week inhibition of these mechanisms.

Q fever is an important zoonotic disease caused by Coxiella burnetii. There are few reliable data about C. burnetii infection available. The aim of this study was to assess the importance and potential infectious sources of Q fever in Hungary. A total of 215 milk samples (10 individual samples from each herd and 1 bulk tank milk sample from each cattle herd), and 400 serum samples (20 from each herd) were tested from 15 dairy cattle herds and 5 sheep flocks located in different parts of Hungary. The study found 19.3% (58/300) and 38.0% (57/150) seropositivity in cattle, and 0% (0/100) and 6.0% (3/50) seropositivity in sheep, by complement fixation test (CFT) and enzyme-linked immunosorbent assay (ELISA), respectively. C. burnetii DNA was detected by IS1111 element-based TaqMan real-time polymerase chain reaction (PCR) in 8.7% (13/150) of individual dairy cow milk samples, 4.0% (2/50) of individual sheep milk samples, and 66.7% (10/15) of dairy bulk tank milk samples. Samples taken from nine different commercially-available pasteurized cow milk products from different Hungarian producers were also tested for the presence of C. burnetii DNA, and eight of these samples were found to be positive (88.9%). The real-time PCR examination of 5402 ixodid ticks collected from different parts of the country yielded negative results. Knowledge of the true prevalence of Q fever is crucial for policymakers involved in evidence-based decision making.

In this study, we compared Coxiella burnetii IgG phase I, IgG phase II, and IgM phase II detection among a commercially available enzyme-linked immunosorbent assay (ELISA) (Virion/Serion), an indirect fluorescent antibody test (IFAT) (Focus Diagnostics), and a complement fixation test (CFT) (Virion/Serion). For this, we used a unique collection of acute- and convalescent-phase sera from 126 patients with acute Q fever diagnosed by positive Coxiella burnetii PCR of blood. We were able to establish a reliable date of onset of disease, since DNA is detectable within 2 weeks after the start of symptoms. In acute samples, at t = 0, IFAT demonstrated IgM phase II antibodies in significantly more sera than did ELISA (31.8% versus 19.7%), although the portion of solitary IgM phase II was equal for IFAT and for ELISA (18.2% and 16.7%, respectively). Twelve months after the diagnosis of acute Q fever, 83.5% and 62.2% of the sera were still positive for IgM phase II with IFAT and ELISA, respectively. At 12 months IFAT IgG phase II showed the slowest decline. Therefore, definitive serological evidence of acute Q fever cannot be based on a single serum sample in areas of epidemicity and should involve measurement of both IgM and IgG antibodies in paired serum. Based on IgG phase II antibody detection in paired samples (at 0 and 3 months) from 62 patients, IFAT confirmed more cases than ELISA and CFT, but the differences were not statically significant (100% for IFAT, 95.2% for ELISA, and 96.8% for CFT). This study demonstrated that the three serological tests are equally effective in diagnosing acute Q fever within 3 months of start of symptoms. In follow-up sera, more IgG antibodies were detected by IFAT than by ELISA or CFT, making IFAT more suitable for prevaccination screening programs.

Q fever is a zoonosis caused by Coxiella burnetii. Infection can result in severe disease. However, little is known about the risk of infection in veterinarians. In a cross-sectional study among German veterinarians, participants provided sera and completed an exposure questionnaire. We investigated predictors for seropositivity using multivariable logistic regression modelling. The 424 participants' median age was 40 (18-74) years, and 276 (65%) were female. Sera of 162 (38%) were positive for Coxiella burnetii phase II IgG antibodies (by ELISA and IFAT). Predictors for seropositivity were occupational exposure to cattle (aOR 2.83, 95% CI 1.64-4.87), occupational exposure to sheep (2.09, 1.22-3.58), male sex (1.9, 1.15-3.13), and increasing age (30-39 years: 4.91, 2.00-12.04; 40-49 years: 5.32, 2.12-13.33; >50 years: 6.70, 2.60-17.25; compared with <30 years). When investigating occupational exposure to cattle and sheep in detail in a separate model, the seroprevalence increased with increasing numbers of cattle obstetrics procedures performed per month, and with increasing numbers of individual cattle treated per week. The high antibody prevalence implies a high lifetime-risk of Q fever in veterinarians. Cattle veterinarians, especially those frequently performing obstetrics, should be counseled early in their career on the clinical picture of Q fever, and on specific risks.

In 2006, a cross-sectional survey was carried out in 206 herds in southern Belgium to estimate the proportion of herds with Q fever-seropositive bulk tank milk (BTM), i.e. herds with an intra-herd seroprevalence >10%. Of the tested herds, 119 (57.8%; 95% CI: 51.1-64.4%) were seropositive. Most had a low antibody titre. Of these herds, 50 were randomly subjected to a real time Coxiella burnetii PCR analysis. The proportion of herds excreting Coxiella in BTM was 30.0% with only 2.0% of herds having a high level of shedding. An additional questionnaire and logistical regression identified some factors which increased the risk of BTM seroconversion (in heifers, drinking water from watercourse or well water) and some which decreased it (in heifers, tie- and free-stalling, and animals of all age in the same shed; in heifers and cows, shed disinfection)., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Despite the widespread distribution of Q fever, the prevalence in humans is not accurately known, because many infected people seroconvert without symptoms or with a mild febrile disease. The aim of this study was to determine the seroprevalence of Q fever in different regions of Croatia. During a 2-year period (2008-2010), serum samples from 552 febrile patients with prolonged cough aged 1-88 were tested for the presence of Coxiella burnetii antibodies by using indirect immunofluorescent assay. Sera from 27.5% patients showed IgG antibodies. Serological evidence of C. burnetii infection was found in patients from all parts of Croatia. Seroprevalence rates significantly differed among regions from 21.5% to 41.2% (p=0.001). Men were more often seropositive (31.6%) than women (22.2%; p=0.016). According to age, a progressive increase in the IgG seropositivity rates was observed as ranging from 6.7% in children less than 10 years of age to 39.2% in patients aged 40-49 (p=0.001). Above the age of 50, the IgG seroprevalence remained stable. Patients from rural areas were more often seropositive than patients from urban areas (40.8% vs. 19%), p<0.001). Acute Q fever was confirmed in 5.8% of patients. Cases occurred throughout the year. A majority of cases were reported during summer months.

Background: The outcome of Q fever, an infectious disease caused by Coxiella burnetii, is associated with granuloma formation. Granulomas are present in patients with resolutive Q fever but are lacking in patients with chronic Q fever., Methods: Study of granuloma formation requires invasive approaches. Here, we took advantage of a recently described method that enables in vitro generation of human granulomas specific for C. burnetii., Results: Circulating mononuclear cells progressively accumulated around beads coated with C. burnetii extracts, and complete granulomas were generated in 8 days. Granuloma cells consisted of macrophages, lymphocytes, and, to a lesser extent, epithelioid cells and multinucleated giant cells. Early events that govern granuloma formation were studied using live-imaging microscopy. Monocytes migrated toward C. burnetii-coated beads independently of the presence of T lymphocytes and then recruited T lymphocytes. About 90% of patients with chronic Q fever failed to form granulomas. This deficiency was associated with defective migration of monocytes toward coated beads., Conclusions: Monocytes were involved in the early stages of granuloma formation and recruited T lymphocytes to complete granuloma formation. This article describes a direct relationship between defective granuloma formation and defective migration of monocytes.

Many animal species, including macropods, have the potential to act as atypical reservoirs of the causative agent of Q fever, Coxiella burnetii. The objective of this study was to determine the seroprevalence of C. burnetii in various macropod species in Australia. Competitive and indirect ELISAs were developed for the testing of macropod sera for antibodies to phase II and I C. burnetii antigens separately. A total of 500 macropod serum samples from selected species sampled in eastern and western coastal states of Australia were screened for the presence of anti-C. burnetii antibodies. An overall seroprevalence of 20.8% (95% CI 20.8-20.9%) was observed with 30.4% (30.2-30.9%) in northern Queensland, 13.0% (12.9-13.1%) in southern Queensland, 7.1% (7.1-8.0%) in western Queensland and 22.8% (22.7-22.9%) in south-western Western Australia. These data indicated that macropods represented a potential reservoir for zoonotic transmission of C. burnetii to domestic animals and the human population., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Coxiella burnetii, the causative agent of Q fever, is an obligatory intracellular bacterium with worldwide distribution. The aim of this study was to determine the prevalence of C. burnetii phase II antibodies in two different groups (high and low risk) of healthy human population and investigate the epidemiological characteristics of the infection in the island of Crete (southern Greece). Collection and testing by IFA of 493 sample sera for IgG and IgM antibodies against C. bumetii phase II antigen indicated a prevalence of IgG antibodies of 48.7%. Of the seropositive individuals, 34% also revealed IgM seropositive antibody titers. Analysis of 225 sample sera by IFA from high risk population presented a prevalence for C. burnetii of 62.2%. Our findings revealed that C. burnetii is highly endemic in Crete, indicating a high exposure of the population to the pathogen regardless of occupation or place of residence., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

This study, carried out in three goat herds, was aimed at describing individual responses to Q fever infection in an abortive context, focusing on both antibody and shedding levels. Seroprevalence of Coxiella burnetii (Cb) infection and vaginal shedding of 1083 goats were investigated using ELISA and realtime qPCR assays, respectively. At the end of the outbreaks, a seroprevalence of 45.0% was found, and vaginal shedding appeared massive with levels above 10(4) Cb per swab in 42.3% of the whole population and above 10(6) Cb per swab for 90.9% of aborted goats. Susceptible animals (i.e. seronegative nonshedders) were unfrequent (31.2%), most of them being kids (94.7%). Seronegative females were predominant among nonshedders and conversely seropositive ones, predominant among high shedders (above 10(6) Cb per swab). Nevertheless, at least 43.3% of seronegative goats shed bacteria confirming the need of interpreting serology on a herd scale. The subsequent farrowing period was characterized by a significant reduction in the number of clinical cases. Females that had already aborted were more often involved than others. Shedding quantities remained high, particularly for primiparous does, mainly when facing infection for the first time. Thus, Q fever control must be based on both preventive measures directed to the preherd and environmental precautions.

Chronic Q fever, which principally manifests as endocarditis, is characterized by Coxiella burnetii persistence and an impaired cell-mediated immune response. The long-term persistence of pathogens has been associated with the expansion of regulatory T cells (Tregs), the CD4(+) T-cell subset that is characterized by the expression of CD25 and Foxp3. We investigated the presence of Tregs in patients with acute Q fever (n = 17), known to exhibit an efficient immune response, patients with Q fever endocarditis (n = 54) and controls (n = 27) by flow cytometry. The proportion of CD3(+) , CD4(+) and CD8(+) T cells was similar in controls and patients with Q fever. The percentage of CD4(+) T cells that expressed CD25 was similar in controls and patients with Q fever. The population of CD4(+) T cells that expressed both CD25 and Foxp3 was significantly (P < 0.001) increased in patients with Q fever endocarditis compared with controls. Our data suggest that the expansion of Tregs may be critical for the chronic evolution of Q fever., (© 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.)

Coxiella burnetii, the causative agent of Q fever, is a zoonotic disease with potentially life-threatening complications in humans. Inhalation of low doses of Coxiella bacteria can result in infection of the host alveolar macrophage (AM). However, it is not known whether a subset of AMs within the heterogeneous population of macrophages in the infected lung is particularly susceptible to infection. We have found that lower doses of both phase I and phase II Nine Mile C. burnetii multiply and are less readily cleared from the lungs of mice compared to higher infectious doses. We have additionally identified AM resident within the lung prior to and shortly following infection, opposed to newly recruited monocytes entering the lung during infection, as being most susceptible to infection. These resident cells remain infected up to twelve days after the onset of infection, serving as a permissive niche for the maintenance of bacterial infection. A subset of infected resident AMs undergo a distinguishing phenotypic change during the progression of infection exhibiting an increase in surface integrin CD11b expression and continued expression of the surface integrin CD11c. The low rate of phase I and II Nine Mile C. burnetii growth in murine lungs may be a direct result of the limited size of the susceptible resident AM cell population.

Coxiella burnetii, the causative agent of Q fever, has evolved a wealth of mechanisms in order to persist within hosts. Two tissues, namely adipose tissue and placenta, are candidates to house C. burnetii, but the mechanisms governing C. burnetii survival in these tissues are still unknown. In contrast, monocytes and macrophages are well-known targets of C. burnetii. First, C. burnetii has developed a specific strategy of phagocytosis subversion that consists of the inhibition of integrin interplay. Second, C. burnetii persistence is associated with macrophage activation profiles. Indeed, monocytes (in which C. burnetii survives without replication) exhibit a proinflammatory M1-type response, whereas macrophages (in which C. burnetii slowly replicates) are polarized towards an M2-type. Third, interleukin-10 produced by monocytes is a main factor of the chronic development of Q fever, and murine models confirm the key role of interleukin-10 in C. burnetii persistence. Fourth, apoptotic cells may play a key role in chronic Q fever. The uptake of apoptotic cells by circulating monocytes increases C. burnetii replication by redirecting monocytes toward a non-protective M2 profile. In the presence of interferon-γ, apoptotic cell engulfment is inhibited and monocytes polarized toward an M1 program are able to kill C. burnetii; this is the situation observed in patients with uncomplicated acute Q fever. Finally, we cannot exclude that regulatory T cells may play a role in C. burnetii persistence because their number is increased in patients with chronic Q fever.

Coxiella burnetii infection is frequently unrecognized or misdiagnosed, as symptoms generally mimic an influenza-like illness. However, the disease (Q fever) may result in chronic infection, usually manifesting as potentially fatal endocarditis. The development of a chronic fatigue-like sequela may also occur. Infected ruminants are the major reservoir for infection in humans, primarily through exposure to birth products or aerosols that transmit the bacterium over wide regions. A vaccine against C. burnetii infection has been in use in Australia for abattoir and agricultural workers for many years. The possibility of adverse reactions in those with previous exposure to the agent has prevented its use elsewhere. Subunit vaccines, utilizing chemical extraction of components thought to cause adverse reactions, are in development, but none are yet licensed. Others have sought to combine immunogenic peptides with or without selected lipopolysaccharide components to produce a vaccine without the possibility of adverse reactions. Selected immunogenic proteins have been shown to induce both humoral and cellular immune responses. Although current diagnosis of infection relies on serological testing, the presentation of specific antibody occurs 7-15 days following the onset of symptoms, delaying treatment that may result in prolonged morbidity. PCR detection of DNA to specific C. burnetii antigens in the blood is possible early in infection, but PCR may become negative when PII IgG antibodies appear. PCR is useful for early diagnosis when Q fever is suspected, as in large epidemics, and shortens the delay in the identification of Q fever endocarditis. Others have combined PCR with ELISA or other methods to increase the ability to detect infection at any stage. The search for new diagnostic reagents and vaccines has utilized new methods for discovery of immunoreactive proteins. DNA analysis of the heterogeneity of C. burnetii isolates has led to a greater understanding of the diversity of isolates and a means to determine whether there is a correlation between strain and disease severity. 2-D SDS PAGE of immunogenic proteins reactive with human or animal infection sera and mass spectrometric analysis of specific secreted or outer membrane proteins have identified candidate antigens. Microarrays have allowed the analysis of peptide libraries of open reading frames to evaluate the immunogenicity of complete genomes.

The Netherlands has experienced large community outbreaks of Q fever since 2007. Sera and questionnaires containing epidemiological data from 5654 individuals were obtained in a nationwide seroprevalence survey used to evaluate the National Immunization Programme in 2006-2007. We tested these sera for IgG phase-2 antibodies against Coxiella burnetii with an ELISA to estimate the seroprevalence and to identify determinants for seropositivity before the Q fever outbreaks occurred. Overall seroprevalence was 1·5% [95% confidence interval (CI) 1·3-1·7]. Corrected for confirmation with immunofluorescence results in a subset, the estimated seroprevalence was 2·4%. Seropositivity ranged from 0·48% (95% CI 0·00-0·96) in the 0-4 years age group to 2·30% (95% CI 1·46-3·15) in the 60-79 years age group. Keeping ruminants, increasing age and being born in Turkey were independent risk factors for seropositivity. The low seroprevalence before the start of the outbreaks supports the hypothesis that The Netherlands has been confronted with a newly emerging Q fever problem since spring 2007.

Recent proteomic studies of C. burnetii, the etiological agent of Q fever, have brought a deeper insight into the pathogen's physiology and offered new possibilities in investigations of inter- or intra-species relatedness. The data generated from these studies in conjunction with the current genomic sequence databases may reveal additional identities for conserved and unique C. burnetii biomarkers and aid in creating algorithms and/or databases that could develop into diagnostic and detection tools for the pathogen. Moreover, wide scale screening and further characterization of potential C. burnetii protein antigens along with a comprehensive evaluation of the humoral immune response will be of fundamental importance towards research and development of a safe and efficacious vaccine as well as improved serodiagnostic tests for rapid and sensitive detection of the Q fever pathogen. Given these advances, proteomics may make marked contributions to the improvement of human health protection against C. burnetii in the coming years.

Coxiella burnetii is an obligate intracellular bacterium that causes a worldwide zoonotic disease, Q fever. Since C. burnetii infection could develop into severe chronic disease in humans, vaccination is the logical approach to prevent individuals at risk of natural and deliberate exposure. Although formalin-inactivated C. burnetii phase I vaccine (PIV) is effective in protecting vaccinated host against the infection in humans, widespread use of this vaccine is limited by its high incidence of adverse reactions, especially in individuals with prior immunity to the agent. Creation of a safe and effective vaccine to prevent Q fever remains an important goal for public health and international biosecurity. It is critical to clearly understand the mechanisms that involved in development of protective immunity against C. burnetii infection and to identify the key protective antigens for developing a safe and effective new generation vaccine against Q fever. This chapter describes new information related to the characterization of acquired immunity to C. burnetii vaccination and infection that will provide a fundamental understanding of the development of protective immunity against Q fever.

The diagnosis and epidemiological studies of Q fever depend on serology. Among the main methods employed are the enzyme-linked immunosorbent assay (ELISA) and the immunofluorescent assay test (IFAT). We show that two commercial assays representing the two methods with two different cut-off titres can lead to significant differences in diagnostic and seroprevalence estimates. This in turn emphasizes the need for a standardized gold method to compare the various assays; whether this standard is 'in-house' or commercially obtained.

Coxiella burnetii, the causative agent of Q fever, may cause culture-negative vascular graft infections that can be diagnosed by serology and molecular biology. We present a case of vascular graft infection detected by positron emission tomography (PET) scanner. The presence of C. burnetii was confirmed by high antibody titers and positive polymerase chain reaction specific for C. burnetii. This report emphasizes the relevance of the PET scanner in the diagnosis of infection when used in association with Q fever serology and molecular biology for the etiological identification of C. burnetii., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Acute Q fever is commonly resolved without an antibiotic regimen, but a primary infection may develop into a chronic infection in a minority of cases. Coxiella burnetii, the causative agent of Q fever, is known to infect macrophages both in vitro and in vivo. It has been observed that the intracellular survival of C. burnetii requires the subversion of the microbicidal properties of macrophages. Adaptive immunity is also essential to cure C. burnetii infection, as demonstrated by clinical studies and animal models. Indeed, the control of infection in patients with primary Q fever involves a systemic cell-mediated immune response and granuloma formation with an essential role for interferon-γ in the protection against C. burnetii. In contrast, chronic Q fever is characterized by defective cell-mediated immunity with the defective formation of granulomas and over-production of interleukin-10, an immunoregulatory cytokine. Finally, epidemiological data demonstrate that age and gender are risk factors for Q fever. The analysis of gene expression programs in mice reveals the importance of sex-related genes in C. burnetii infection because only 14% of the modulated genes are sex-independent, while the remaining 86% are differentially expressed in males and females. These results open a new field to understand how host metabolism controls C. burnetii infection in humans.

Q fever has been associated with exposure to domesticated livestock and the agricultural industry. However large population-based studies examining the relationship are lacking. This report sought to describe the association between Coxiella burnetii infection and participation in agricultural work in the 2003-2004 National Health and Nutrition Examination Survey. Adjusted logistic regression analysis showed that agricultural workers were six times more likely to have antibody evidence of C. burnetii infection than those employed in other occupations (odds ratio 6·5, 95% confidence interval 1·7-25·3). These findings suggest that agricultural workers may experience greater C. burnetii infection and emphasize an important need for more detailed study of people engaged in this work.

A lipopolysaccharide (LPS) is considered to be one of the major determinants of virulence expression and infection of virulent Coxiella burnetii. The LPSs from virulent phase I (LPS I) and from avirulent phase II (LPS II) bacteria were investigated for their chemical composition, structure and biological properties. LPS II is of rough (R) type in contrast to LPS I, which is phenotypically smooth (S) and contains a noticeable amount of two sugars virenose (Vir) and dihydrohydroxystreptose (Strep), which have not been found in other LPSs and can be considered as unique biomarkers of the bacterium. Both sugars were suggested to be located mostly in terminal positions of the O-specific chain of LPS I (O-PS I) and to be involved in the immunobiology of Q fever. There is a need to establish a more detailed chemical structure of LPS I in connection with prospective, deeper studies on mechanisms of pathogenesis and immunity of Q fever, its early and reliable diagnosis, and effective prophylaxis against the disease. This will also help to better understanding of host-pathogen interactions and contribute to improved modulation of pathological reactions which in turn are prerequisite for research and development of vaccines of new type. A fundamental understanding of C. burnetii LPS biosynthesis is still lacking. The intracellular nature of the bacterium, lack of genetic tools and its status as a selected agent have made elucidating basic physiological mechanisms challenging. The GDP-β-D-Vir biosynthetic pathway proposed most recently is an important initial step in this endeavour. The current advanced technologies providing the genetic tools necessary to screen C. burnetii mutants and propagate isogenic mutants might speed the discovery process.

Coxiella burnetii, the causative agent of Q fever, is the only known intracellular pathogenic bacterium that replicates within the acidic, degradative confines of a eukaryotic phagolysosome. It appears that the bacterium nullifies or thwarts the toxic elements of this vacuole and evades both innate and adaptive immune responses. C. burnetii is ubiquitous in its geographic distribution with the disease prevalence more widespread than previously considered. Recent molecular and cell biological advances, along with improved instrumentation, have provided unique insight into the host-parasite interrelationship and revealed previously unknown virulence strategies of C. burnetii. An example is completion of the genome sequences of several strains of C. burnetii that has improved our understanding of pathogenic mechanisms used by the organism to cause disease in mammalian hosts.

During 2007-2009, we tested serum samples from 2,004 pregnant women living in an area of high Q fever incidence in the Netherlands. Results confirmed that presence of antibodies against Coxiella burnetii is related to proximity to infected dairy goat farms. Pregnant women and patients with certain cardiovascular conditions should avoid these farms.

The aims of this study were to analyse, in high-producing dairy cows, plasma Coxiella burnetii antibody titres and seroconversion throughout gestation, along with possible factors affecting such titres. The study was performed on 65 lactating pregnant non-aborting animals in a commercial Holstein-Friesian dairy herd in northeastern Spain. Blood samples for antibody determinations were collected on days 40, 90, 120, 150, 180 and 210 of gestation. By General Linear Model (GLM) repeated measures analysis of variance, the effects of milk production and reproductive variables as well as Neospora caninum-seropositivity on C. burnetii antibody levels for all animals and for seropositive animals were established. Significant effects were observed of day of gestation, parity and N. caninum-seropositivity (between subject effects) on the C. burnetii antibody levels recorded for the whole population of animals throughout the gestation period. C. burnetii antibody levels were higher in primiparous than in multiparous cows, with titres in primiparous cows diminishing during the post-partum period. In seropositive cows, significant effects were observed of milk production and inseminating bull on gestational C. burnetii antibody levels. When the data were subjected to binary logistic regression considering C. burnetii-seropositivity as the dependent variable, the resultant odds ratios indicated that the likelihood of C. burnetii-seropositivity was lower in N. caninum-seropositive animals (OR 0.12) compared to N. caninum-seronegative animals, and in multiparous cows (OR 0.12) compared to primiparous cows. In conclusion, Coxiella-infected dams remained seropositive during the whole gestation period, though primiparous cows showed a drop in antibody titres post-partum. No seronegative cow suffered seroconversion. Presence of both, N. caninum and C. burnetii antibodies in the same animal, was associated with a decrease in antibody titres against C. burnetii, perhaps indicating some cross-protection in animals infected by both pathogens., (© 2011 Blackwell Verlag GmbH.)

Physicians often encounter patients who present with a vague clinical syndrome. A wide serological workup is often ordered, which may include tests for Coxiella burnetii in endemic areas. Often, the results of these tests pose new dilemma, with overlapping positive laboratory assays. The objective of this investigation was to characterise the serological overlap between acute Q fever and other infectious and immunological diseases. We retrospectively scanned the files of patients with a positive or equivocal immunoglobulin (Ig) M for C. burnetii phase II over a period of 8 years in a general hospital. Clinical and laboratory data, including antibodies to infectious agents and antibodies related to immunological states, were recorded. Anti-nuclear antibody (ANA), smooth muscle antibody (SMA) and rheumatoid factor were positive in 38%, 33.3% and 22.2% of the cases, respectively. In patients with acute Q fever, elevated IgM levels for Epstein-Barr Virus (EBV), cytomegalovirus (CMV), Mycoplasma pneumoniae, parvovirus, Bordetella pertussis, Rickettsia conorii and R. typhi were noted in 13.8%, 8.3%, 12.12%, 22.2%, 25%, 13% and 21.7% of cases, respectively. Acute Q fever induces a non-specific immunological arousal in a significant number of patients. This may interfere with diagnosis and delay treatment. Caution, clinical judgment and serological follow-up is warranted in such conditions.

Pooling samples may provide a valuable alternative to individual testing for pathogen surveillance purposes. We studied the reliability of measuring the level of antibodies against Coxiella burnetii in bulk-tank milk (BTM) to estimate the seroprevalence of C. burnetii in dairy sheep in 34 flocks. We then estimated the seroprevalence of C. burnetii in 154 dairy sheep flocks according to the level of antibodies in BTM. We tested for the accuracy of our estimation at the population level by comparing predicted mean C. burnetii flock seroprevalence with that obtained in another survey performed on the same population. Our findings showed that testing BTM by ELISA is a cost-effective and relatively good index of the seroprevalence of C. burnetii in dairy sheep and may be a useful tool for epidemiological surveillance at the population level.

Antigen profiling using comprehensive protein microarrays is a powerful tool for characterizing the humoral immune response to infectious pathogens. Coxiella burnetii is a CDC category B bioterrorist infectious agent with worldwide distribution. In order to assess the antibody repertoire of acute and chronic Q fever patients we have constructed a protein microarray containing 93% of the proteome of Coxiella burnetii, the causative agent of Q fever. Here we report the profile of the IgG and IgM seroreactivity in 25 acute Q fever patients in longitudinal samples. We found that both early and late time points of infection have a very consistent repertoire of IgM and IgG response, with a limited number of proteins undergoing increasing or decreasing seroreactivity. We also probed a large collection of acute and chronic Q fever patient samples and identified serological markers that can differentiate between the two disease states. In this comparative analysis we confirmed the identity of numerous IgG biomarkers of acute infection, identified novel IgG biomarkers for acute and chronic infections, and profiled for the first time the IgM antibody repertoire for both acute and chronic Q fever. Using these results we were able to devise a test that can distinguish acute from chronic Q fever. These results also provide a unique perspective on isotype switch and demonstrate the utility of protein microarrays for simultaneously examining the dynamic humoral immune response against thousands of proteins from a large number of patients. The results presented here identify novel seroreactive antigens for the development of recombinant protein-based diagnostics and subunit vaccines, and provide insight into the development of the antibody response.

Coxiella burnetii, a category B biological warfare agent, causes multiple outbreaks of the zoonotic disease Q fever world-wide, each year. The virulent phase I and avirulent phase II variants of the Nine Mile RSA 493 and 439 strains of C. burnetii were propagated in embryonated hen eggs and then purified by centrifugation through Renografin gradients. Total protein fractions were isolated from each phase and subjected to analysis by one-dimensional electrophoresis plus tandem mass spectrometry. A total of 235 and 215 non-redundant proteins were unambiguously identified from the phase I and II cells, respectively. Many of these proteins had not been previously reported in proteomic studies of C. burnetii. The newly identified proteins should provide additional insight into the pathogenesis of Q fever. Several of the identified proteins are involved in the biosynthesis and metabolism of components of the extracellular matrix. Forty-four of the proteins have been annotated as having distinct roles in the pathogenesis or survival of C. burnetii within the harsh phagolysosomal environment. We propose that nine enzymes specifically involved with lipopolysaccharide biosynthesis and metabolism, and that are distinctively present in phase I cells, are virulence-associated proteins., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Background: Coxiella burnetii is an obligate intracellular bacterium and the etiologic agent of Q fever; both coxiella outer membrane protein 1 (Com1) and heat shock protein B (HspB) are its major immunodominant antigens. It is not clear whether Com1 and HspB have the ability to mount immune responses against C. burnetii infection., Results: The recombinant proteins Com1 and HspB were applied to pulse human monocyte-derived dendritic cells (HMDCs), and the pulsed HMDCs were used to stimulate isogenic T cells. Com1-pulsed HMDCs expressed substantially higher levels of surface molecules (CD83, CD40, CD80, CD86, CD54, and CD58) and a higher level of interleukin-12 than HspB-pulsed HMDCs. Moreover, Com1-pulsed HMDCs induced high-level proliferation and activation of CD4(+) and CD8(+) cells, which expressed high levels of T-cell activation marker CD69 and inflammatory cytokines IFN-γ and TNF-α. In contrast, HspB-pulsed HMDCs were unable to induce efficient T-cell proliferation and activation., Conclusions: Our results demonstrate that Com1-pulsed HMDCs are able to induce efficient T-cell proliferation and drive T cells toward Th1 and Tc1 polarization; however, HspB-pulsed HMDCs are unable to do so. Unlike HspB, Com1 is a protective antigen, which was demonstrated by the adoptive transfer of Com1-pulsed bone marrow dendritic cells into naive BALB/c mice.

Q fever (Coxiella burnetii) is a zoonotic disease of increasing public health importance. The objective of this study was to estimate the prevalence of, and risk factors associated with, exposure to C. burnetii in cattle in the Republic of Ireland. Bulk-tank milk samples from 290 dairy herds and 1659 sera from 332 dairy and beef herds, randomly sampled, were tested by indirect ELISA to detect antibodies to C. burnetii. In total, 37·9% of bulk-milk sample herds and 1·8% of sera (from 6·9% of herds) were antibody positive. Of risk factors tested using logistic regression analysis, only large herd size (bulk-milk analysis) and dairy breed (serum analysis) significantly increased the odds of being positive for antibodies to C. burnetii. Herds with positive milk or serum samples were randomly distributed throughout the Republic of Ireland and no clustering was observed. The use of an ELISA to test bulk-milk samples collected by randomized stratified sampling is a cost-effective method by which national herd prevalence can be estimated by active surveillance.

Serological diagnosis of acute and chronic Q fever in humans relies on detection of antibodies to phase I (PhI) and II (PhII) antigens of Coxiella (C.) burnetii. Although phase-specific antigens are available, they are not yet used in ruminants as they are in humans. This study focuses on phase-specific serology as a tool for analysis of the dynamics of infection in cattle. As a prerequisite, sero-prevalence in Bavarian cattle (1) and sero-prevalences for age-groups (2) were determined by ELISA (CHEKIT Q-Fever; mix of PhI/PhII-antigen). Subsequently, phase-specific antigens were coated onto ELISA plates individually and tests were simultaneously applied in an endemically infected herd with about 90 dairy cows and 250 calves/heifers in April 2005, March 2006 and retrospectively in May and October 2004. From April 2005 onward, placentas were analysed for C. burnetii by PCR (3). (1) Sero- and herd prevalences based on 21,051 sera from 603 Bavarian dairy farms collected in 2003 were 14.8% ± 0.48% and 72.3% ± 3.6%, respectively. (2) Analysis of 3965 animals from 105 farms for which age was reported revealed a base level of sero-prevalence of less than 5% in 1-2 years old animals, it increased to 15% in 2-3 years old and reached a plateau (25-30%) in cows four years and older. (3) In May 2004 and April 2005 a peak of PhI(-)/PhII(+)-prevalence in primiparous cows (2.0-3.5 years) was observed; but not in October 2004 and March 2006. The PhI(-)/PhII(+)-pattern in primiparous cows changed to negative (one-third), PhI(+)/PhII(+) (1/3) or persisted (1/3). In contrast, sero-conversion was rare in multiparous cows (>3.5 years). If the PhI(-)/PhII(+) pattern was detected, it was due to an infection in preceding years. This pattern persisted (2/3) or changed to negative (1/3); a change to PhI(+)/PhII(+) did not occur. PhI(-)/PhII(+) in heifers (1-2 years) always changed to negative. Detection of PhII-antibodies was significantly associated with PCR-positive placentas. Remarkably, 45% of sera with the PhI(-)/PhII(+) pattern were negative for the CHEKIT Q-Fever ELISA, thus this test missed an important group of infected animals., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Background: Recent outbreaks in the Netherlands allowed for laboratory follow-up of a large series of patients with acute Q fever and for evaluation of test algorithms to detect chronic Q fever, a condition with considerable morbidity and mortality., Methods: For 686 patients with acute Q fever, IgG antibodies to Coxiella burnetii were determined using an immunofluorescence assay at 3, 6, and 12 months of follow-up. Polymerase chain reaction (PCR) was performed after 12 months and on earlier serum samples with an IgG phase I antibody titer ≥ 1:1024., Results: In 43% of patients, the IgG phase II antibody titers remained high (≥ 1:1024) at 3, 6, and 12 months of follow-up. Three months after acute Q fever, 14% of the patients had an IgG phase I titer ≥ 1:1024, which became negative later in 81%. IgG phase I antibody titers were rarely higher than phase II titers. Eleven cases of chronic Q fever were identified on the basis of serological profile, PCR results, and clinical presentation. Six of these patients were known to have clinical risk factors at the time of acute Q fever. In a comparison of various serological algorithms, IgG phase I titer ≥ 1:1024 at 6 months had the most favorable sensitivity and positive predictive value for the detection of chronic Q fever., Conclusions: The wide variation of serological and PCR results during the follow-up of acute Q fever implies that the diagnosis of chronic Q fever, necessitating long-term antibiotic treatment, must be based primarily on clinical grounds. Different serological follow-up strategies are needed for patients with and without known risk factors for chronic Q fever.

Q fever is a widespread zoonosis caused by Coxiella burnetii, an obligate intracellular Gram-negative bacterium. Current diagnostics of Q fever is based on serological testing of patient serum. Biological distinction among C. burnetii strains has been referred at the genetic level as well as in virulence in animal models of Q fever. Disclosure of strain specific antigens might show insight into the biology and pathogenesis of this query pathogen, as well as it can provide the literature with potential serodiagnostic markers. In the present study, we sought to obtain an outer membrane enriched fraction of two C. burnetii reference strains, which originate from different sources, in order to investigate the way in which their antigenic profile is differentiated against a patient serum. We systematically analyzed the sarcosyl-insoluble fraction, enriched in outer membrane proteins, of the two C. burnetii strains using doubled SDS-PAGE combined with MS/MS analysis. In total, twenty-two outer membrane proteins were identified, representing 26% of the overall 86 identified proteins. The sarcosyl-insoluble fraction was then separated on 2DE IEF/SDS-PAGE and probed with serum from an infected patient. Different immuno-reactive proteins between the two C. burnetii strains were identified and included 2 outer membrane proteins, a hypothetical protein (CBU&#95;0937) with unknown function and OmpH (CBU&#95;0612), a previously identified marker for Q fever endocarditis. This approach can be used to reveal strain-specific proteins involved in pathogenesis and new serodiagnostic markers., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Objective: To assess the presence and identity of Bartonella species in a pool of human blood samples from DRC Congo., Methods: Blood (±120μL) was collected anonymously from Congolese patients and placed on calibrated filter papers. Bartonella serology determination was performed using an indirect immunofluorescence assay (IFA) against six specific Bartonella antigens and Coxiella burnetii (C. burnetii) antigen. The end cut-off value for Bartonella sp. was a titre greater than 1:200., Results: None of the patients was positive for Bartonella elizabethae, Bartonella vinsonii subsp. vinsonii or Bartonella vinsonii subsp. arupensis nor for C. burnetti, but 4.5% of the 155 samples were positive for either Bartonella henselae, Bartonella quintana, or Bartonella clarridgeiae., Conclusions: This preliminary study presents the first report of Bartonella species in the DR Congo and the first report of antibodies to Bartonella clarridgeiae in an African human population. Although few experimental trials have established the link between fleas and Bartonella transmission, the repeated detection of similar Bartonella species in fleas and humans in several countries suggests that Bartonellosis could be another flea-borne disease which specific reservoirs are still unknown., (Copyright © 2011 Hainan Medical College. Published by Elsevier B.V. All rights reserved.)

Coxiella burnetii is a zoonotic, rickettsial pathogen which causes mild and severe diseases often referred to as Q-fever in humans, particularly those occupationally exposed. This study determined the seropositivity for Coxiella burnetii IgM immunoglobulins using the enzyme immunoassay (EIA) in livestock and abattoir workers in Trinidad and related to selected personal characteristics to seroprevalence. Overall, of the 455 humans whose serum samples were tested, 20 (4.4%) were seropositive for C. burnetii IgM immunoglobulin, comprising 13 (4.6%) out of 283 livestock workers, 4 (4.7%) out of 85 abattoir workers and 3 (3.4%) out of 87 office workers (P>0.05; Chi 2). The age, sex and race of workers were not significantly associated with the occurrence of acute Q-fever (P>0.05; Chi 2). This is considered the first documentation of Q-fever in the human population in Trinidad. It is difficult to assess the impact of the disease in the country since the disease is not routinely tested for in the local hospitals or diagnostic laboratories.