Single nucleotide polymorphisms in immune response genes in acute Q fever cases with differences in self-reported symptoms.

Genes involved in human immune response are well recognized to influence the clinical course of infection. The association of host genetics with susceptibility to and severity of clinical symptoms in acute Q fever was investigated. Single nucleotide polymorphisms (SNPs) in the IFNG (rs2430561/rs1861493), STAT1 (rs1914408), and VDR (rs2228570) genes were determined in 85 patients from the 2007 Dutch acute Q fever outbreak, and a symptom score was calculated. IFNG rs1861493 showed a significant association with the symptom score; IFNG rs2430561 showed a similar trend. These SNPs were then used to reproduce results in a 2009 outbreak population (n = 123). The median symptom score differed significantly in both populations: 2 versus 7. The significant association of IFNG rs1861493 with symptom score in the first population was not reproduced in the second population. We hypothesize that individuals in the second outbreak were exposed to a higher Coxiella burnetii dose compared to the first, which overruled the protection conferred by the A-allele of IFNG rs1861493 in the first population.

Serving the new masters - dendritic cells as hosts for stealth intracellular bacteria.

Dendritic cells (DCs) serve as the primers of adaptive immunity, which is indispensable for the control of the majority of infections. Interestingly, some pathogenic intracellular bacteria can subvert DC function and gain the advantage of an ineffective host immune reaction. This scenario appears to be the case particularly with so-called stealth pathogens, which are the causative agents of several under-diagnosed chronic diseases. However, there is no consensus how less explored stealth bacteria like Coxiella, Brucella and Francisella cross-talk with DCs. Therefore, the aim of this review was to explore the issue and to summarize the current knowledge regarding the interaction of above mentioned pathogens with DCs as crucial hosts from an infection strategy view. Evidence indicates that infected DCs are not sufficiently activated, do not undergo maturation and do not produce expected proinflammatory cytokines. In some cases, the infected DCs even display immunosuppressive behaviour that may be directly linked to the induction of tolerogenicity favouring pathogen survival and persistence.

Cytokine profiles in patients with Q fever fatigue syndrome.

BACKGROUND: Q fever fatigue syndrome (QFS) is a state of prolonged fatigue following around 20% of acute Q fever cases. It is thought that chronic inflammation plays a role in its etiology. To test this hypothesis we measured circulating cytokines and the ex-vivo cytokine production in patients with QFS and compared with various control groups. MATERIALS/METHODS: Peripheral blood mononuclear cells (PBMCs), whole blood, and serum were collected from 20 QFS patients, 19 chronic fatigue syndrome (CFS) patients, 19 Q fever seropositive controls, and 25 age- and sex-matched healthy controls. Coxiella-specific ex-vivo production of tumor necrosis factor (TNF)α, interleukin (IL)-1ß, IL-6, and interferon (IFN) was measured, together with a total of 92 circulating inflammatory proteins. RESULTS: PBMCs of QFS patients produced more IL-6 (P = 0.0001), TNFα (P = 0.0002), and IL-1ß (P = 0.0005) than the various control groups when stimulated with Coxiella antigen. QFS patients had distinct differences in circulating inflammatory markers compared to the other groups, including higher concentrations of circulating IL-6 and IFNγ. CONCLUSION: QFS patients showed signs of chronic inflammation compared to asymptomatic Q fever seropositive controls, CFS patients, and healthy controls, of which the monocyte-derived cytokines TNFα, IL-1ß, and especially IL-6, are likely crucial components.

Serologic and molecular characterization of tickborne pathogens in lions (Panthera leo) from the Fasano Safari Park, Italy.

Lions (Panthera leo) are an endangered species threatened by illegal hunting, habitat loss, and infectious diseases. Little is known about the tick-borne pathogens that infect lions and could contribute to population declines. The objective of this study was to characterize Rickettsia spp., Anaplasma phagocytophilum, and Coxiella burnetii infections in 10 lions from the Fasano Safari Park in Italy by serology, polymerase chain reaction, and sequence analysis. Although animals did not show clinical signs of tick-borne diseases, evidence of infection with C. burnetii, spotted fever group Rickettsia sp., and A. phagocytophilum were found in 50%, 20%, and 10% of the lions, respectively. One of the lions tested positive for all three pathogens. This study is the first report of molecular evidence of infection with C. burnetii, Rickettsia sp., and A. phagocytophilum in lions and provides evidence that these felids become infected and serve as hosts for tick-transmitted bacteria.

A review of the efficacy of human Q fever vaccine registered in Australia.

BACKGROUND: Q fever remains an important occupational zoonosis in rural Australia. Although Q fever vaccine is recommended in high-risk occupational groups, its availability has been limited in recent years. METHOD: A literature review of the efficacy of the human Q fever vaccine registered in Australia was conducted. RESULTS: Seven relevant vaccine efficacy studies were identified but no large double-blind, randomised, placebo-controlled studies have been conducted. Vaccine efficacy has ranged from 83-100% but limitations of study designs hamper a precise estimate of vaccine efficacy. CONCLUSION: Despite the shortcomings of efficacy studies, the Q fever vaccine available in Australia has considerable protective benefit in established high-risk environments, particularly of an occupational nature.

Q fever. A call to heighten our index of suspicion.

The prevalence of Q fever infection is probably underestimated. In Michigan, the first two reported human cases of Q fever occurred in 1984. The case-patients lived in adjacent, rural counties and had multiple exposures to goats. We conducted a serosurvey of goat owners and a reference population to compare the prevalence of Q fever antibodies in the two-county area. Goat owners were almost three times more likely to be seropositive with Q fever antibodies than the reference population (43% vs 15%). Among goat owners, individual and household seropositivity prevalences were positively correlated with the number of goats, the number of positive goats, and the number of goat births on the farm. Q fever should be considered more often in the differential diagnosis of patients with compatible illness, especially those with frequent animal contact.

Q fever endocarditis.

Despite a worldwide distribution of Coxiella burnetii, only single cases of Q fever endocarditis have been reported outside Great Britain and Australia. We present 10 patients; five were female, only four had a history of environmental exposure, and the mitral valve was involved as commonly as the aortic stenosis, and three patients had a prosthetic valve. We confirm the importance of hepatic involvement, thrombocytopenia and hypergammaglobulinemia as diagnostic features. Diagnosis was established by finding and elevated complement-fixing antibody to Phase I C. burnetii antigen. Tetracycline, with or without lincomycin or cotrimoxazole, was used in nine patients, and one patient received cotrimoxazole as as the sole antibiotic agent. Optimal duration of therapy is unknown. In one patient, relapse followed when treatment was stopped after 18 months. Valve replacement was necessary in five patients, because of hemodynamic problems. Five patients died, and the means survival is 36 months with a range of five to 66 months. We suggest that Q fever endocarditis is frequently missed, and we recommend clinicians to consider the diagnosis in all cases of culture-negative endocarditis.

An outbreak of Q fever probably due to contact with a parturient cat.

Thirty-three cases (24 definite, nine probable) of Q fever were diagnosed in Victoria County, Cape Breton, Nova Scotia from May to August, 1985. Twenty-six of the cases occurred in residents of Baddeck (population 900, attack rate 2.8 percent), and 21 of the cases occurred during the month of June. There was geographic clustering of the cases: 14 of the 33 (42 percent) lived or worked in four buildings located side by side in the center of town. A case control study revealed that 25 of 29 cases were exposed to a cat that gave birth to stillborn kittens on June 8, 1985 and had bled per vaginum for three weeks prior to delivery. The cat lived in one of the buildings where geographic clustering occurred and frequently visited the other buildings. None of the 40 control subjects was so exposed (p less than 0.001). This cat had an antibody titer of 1:512 to Coxiella burnetii phase 1 antigen and a titer of 1:1024 to phase 2 antigen. Exposure to cattle, sheep and goats, the traditional reservoirs of Q fever, was uncommon among patients and control subjects and none of eight cattle tested had antibodies to C burnetii phase I antigen. We conclude that the infected parturient cat was probably responsible for this outbreak of Q fever affecting 2.8 percent of the population of the town of Baddeck.

The immune response to phase I and phase II Coxiella burnetii antigens as measured by western immunoblotting.

To determine the utility of Western immunoblotting in distinguishing chronic Q fever from acute Q fever, we first examined serum samples from individuals who had no antibodies to Coxiella burnetii by either the indirect immunofluorescence antibody test or by the enzyme-linked immunosorbent assay. In these subjects, the IgG fraction in low dilutions of serum (1:8, 1:16) reacted with as many as 10 proteins in phase I and phase II antigens. This number of reacting bands seen in Western blots was reduced by using serum in a dilution of 1:1024. In contrast, IgA antibodies were uncommon even at low dilutions. Likewise, IgA antibodies were infrequently observed in patients with acute Q fever. However, in chronic Q fever there were many IgA antibodies to phase I and phase II proteins. Antibodies to phase I proteins were more common than those to phase II proteins. Several antigenic protein bands were recognized only by serum from chronic Q fever patients. Three of these antigens had molecular masses of, respectively, 50 kDa, 80 kDa, and 160 kDa. Serial serum samples from patients with chronic Q fever revealed that the number of antigens recognized by the IgA fraction decreased after the initiation of antibiotic therapy. The decline was faster for antibodies to phase II proteins. We conclude that immunoblotting is useful in the diagnosis of chronic Q fever.

Antigenic structure of Coxiella burnetii. A comparison of lipopolysaccharide and protein antigens as vaccines against Q fever.

The antigenic structure of Coxiella burnetii is being investigated by identifying both external and internal cellular epitopes of the morphologic cell types. Both the phase I lipopolysaccharide (LPSI) and several surface proteins are candidates for the development of subunit multivalent vaccines. The protective efficacy of purified LPSI was demonstrated in A/J mice. The purified LPSI preparations contained residual peptides detected by amino acid analysis. Therefore, the protection afforded by LPSI may be, in part, due to the presence of peptides. The purification of proteins free of LPSI must be accomplished before the protective efficacy of proteins or peptides can be established. We have identified three proteins that are both antigenic and immunogenic, as indicated by either enzyme immunoassay, radioimmunoprecipitation, immunoblot assay, or lymphocyte transformation. A 62-kDa protein antigen encoded by the htpB gene of C. burnetii was analyzed for immunogenicity. The purified protein antigen was immunogenic, as it elicited specific antibodies and performed as recall antigen in lymphocyte stimulation assays. The antigen was not detected on the surface of phase I cells but was highly represented on the surface of phase II cells. Therefore, the protein may not be a good candidate for vaccine development. The diagnostic utility of the 62-kDa protein antigen lies in the fact that convalescent and chronic Q fever sera from human patients reacted with the antigen, whereas acute sera did not. Although the 62-kDa protein is a "common antigen," specific peptide-based diagnostic reagents may be useful in the detection of Q fever disease progression. A major surface protein (P1) of roughly 29.5 kDa was purified from the phase I Nine Mile (clone 7) strain. No LPSI was detected in the P1 preparation by three different LPSI monoclonal antibodies. Monoclonal antibodies prepared against P1 were effective in localizing the protein on the cell surface, in the cell wall, and associated with the peptidoglycan of large cells of C. burnetii. Small, pressure-resistant cells did not contain P1. Mice immunized with two 25-micrograms injections of LPSI produced antibodies against LPSI and phase I whole cells. No antibody was detected against phase II whole cells. Immunization with P1 induced antibody against the LPSI fraction and phase I and phase II whole cells. P1 was more effective than LPSI in reducing the number of infectious C. burnetii in the spleens of challenged mice. The gene encoding another protein (P2) recognized by P1 monoclonal antibodies was cloned and sequenced.(ABSTRACT TRUNCATED AT 400 WORDS)

Injection of inactivated phase I Coxiella burnetii increases non-specific resistance to infection and stimulates lymphokine production in mice.

The encounter of phase I C. burnetii with the host results in seemingly disparate consequences. On the one hand, in vitro lymphocyte responses to mitogens and homologous recall antigen are suppressed. On the other, host resistance to a variety of infectious agents and to a tumor is increased. An explanation for this augmented immune response surely involves the ability of C. burnetii to stimulate cytokines, such as interferon and TNF, which enhance host immune function.

Seroepidemiology of Q fever among cats in New Brunswick and Prince Edward Island.

The indirect microimmunofluorescence test was used to determine the presence of antibodies to phase I and phase II Coxiella burnetii antigens in New Brunswick and Prince Edward Island cats. Twenty of 104 (19.2%) New Brunswick cats tested had antibodies to phase II antigen; five of these (4.8%) also had antibodies to phase I antigen. Six of 97 (6.2%) Prince Edward Island cats tested had antibodies to phase I and phase II antigens. Our data suggest that cats may be important in the epidemiology of Q fever in these provinces.

Q fever in Sokoto, Nigeria.

There is very little information available about the prevalence of Coxiella burnetii in Africa. We obtained blood from 75 Nigerians hospitalized in Sokoto for a variety of acute medical conditions. Their age range was 7 months to 50 years; there were 39 males and 36 females. Antibody titers were determined to phase I and phase II C. burnetii antigens using a microimmunofluorescence test. Thirty-three (44%) had an antibody titer of greater than or equal to 1:8 to phase II C. burnetii. We conclude on the basis of this limited survey that Q fever is common in Nigeria.

Rickettsial antibody prevalence in southern Israel: IgG antibodies to Coxiella burnetii, Rickettsia typhi, and spotted fever group rickettsiae among urban- and rural-dwelling and Bedouin women.

A retrospective serological survey was carried out using sera obtained from women at childbirth in the southern desert region of Israel to determine exposure experience to three rickettsial agents: Coxiella burnetii, Rickettsia typhi, and spotted fever group rickettsiae. Using the indirect fluorescent antibody method for determining IgG antibodies, it was found that about 40% of all sera examined demonstrated antibodies to one or more rickettsiae. Bedouin women appeared to be at greater risk of having antibodies to C. burnetii and spotted fever group rickettsiae than did Jewish residents of Beersheba, agricultural settlements, and development towns. The residents of development towns appeared to be at lower risk of developing antibodies to spotted fever group rickettsiae than did other populations sampled. Possible reasons for these differences are discussed.

Immunofluorescence serology. A tool for prognosis of Q-fever.

The indirect immunofluorescence antibody test is currently the method of choice for Q-fever laboratory diagnosis. It permits the detection of IgG-, IgM-, and IgA-specific antibodies against the two phases of Coxiella burnetii. Sera from 20 cases of C. burnetii infection have been examined. Only total IgG against phase II were detected in cryptic infections. In acute Q-fever cases, the appearance of total IgG antibodies against phase I was a sign of aggravation, while IgM titers remained low. In subacute cases of Q-fever, anti-phase-I IgG titers were equal to or higher than anti-phase-II titers, and IgM against both phases were produced over a long time. Particularly high IgM titers were found in cases of granulomatous hepatitis. IgA antibodies against phase I were found in cases of Q-fever endocarditis, although the two cases that died had few or no IgA antibodies, despite very high IgG and IgM titers.

Immunoenzymatic test for Q-fever.

An immunoenzymatic test using as antigen purified suspensions of Coxiella burnetti coated by methylglyoxal on microtiter plates was developed. Multiple testing of the same sera gave similar results: two dilutions of serum (1:400 and 1:1600) were used in routine tests. Good agreement between the immunoenzymatic and the indirect immunofluorescent antibody tests was obtained for 41 of 50 sera examined. Five sera negative by the immunofluorescent antibody test were positive by the immunoenzymatic test; this result may be due to the higher sensitivity of the latter test. On the other hand, three sera with higher titers by the indirect immunofluorescent antibody test showed a rather feeble positivity by the immunoenzymatic test. This is probably due to the different specificity of the reacting antibodies in the two methods. The indirect immunofluorescent antibody test permits better distinction of the very high titers (greater than 1:5120) than the immunoenzymatic test. The immunoenzymatic test seems to be the method of choice for seroepidemiology surveys of Q-fever; however, its use for clinical serodiagnosis needs further confirmation.

Antibody responses in acute and chronic Q fever and in subjects vaccinated against Q fever.

An analysis is made of the antibody response to Coxiella burnettii Phase-1 and Phase-2 antigens, as measured by immunofluorescence in the IgM, IgG or IgA immunoglobulin classes, or by complement-fixation, in patients with acute and chronic Q fever and in vaccinated or skin-tested subjects. In acute (primary) Q fever, IgM specific antibodies to Phase-1 antigen are present in early convalescence together with IgM, IgG, IgA and CF antibodies to Phase-2 antigen. IgM specific antibody may persist for at least 678 days after onset of the acute illness. Patients with chronic Q fever have no IgM specific antibody to Phase-1 or -2 antigens, or only at very low levels; high levels of specific antibody in the IgG and IgA classes, together with CF antibody to both antigenic phases, appear to be characteristic. The serological response in initially seronegative, vaccinated subjects is mainly to Phase-1 antigen in the IgM fraction, and to a lesser degree to Phase-2 antigen by CF and in IgM and IgG classes. Subjects who were equivocally seropositive before vaccination showed IgA and IgG specific antibody responses to Phase-1 antigen and CF and IgG class responses to Phase-2 antigen. Similar antibody profiles were observed in patients who seroconverted after a positive skin-test. Data are also presented on the suitability of C. burnettii antigens for use in immunofluorescence and on the binding of IgM specific antibody by Phase-1 antigen but its failure to fix complement.

Rickettsial antibody in southern France: antibodies to Rickettsia conorii and Coxiella burnetii among urban, suburban and semi-rural blood donors.

Three hundred and twenty-five sera from blood donors in the south of France were examined by means of the indirect fluorescent antibody test. 18% of the sera had antibodies to Rickettsia conorii, with a significantly higher prevalence (26%) in urban and suburban areas than in semi-rural areas (13 to 16%). This supports the view that in the south of France the highest prevalence of Mediterranean Spotted Fever is suburban. 5% of the sera had antibodies to Coxiella burnetti in this area, in which Q fever is endemic.

Investigation of Coxiella burneti infection as a possible cause of chronic liver disease in man.

The possible role of Coxiella burneti as a cause of chronic liver disease in man was investigated in Cyprus. Serology, using the complement fixation test and phase 1 and phase 2 antigens, was performed on 16 patients with cryptogenic cirrhosis and two patients with chronic active hepatitis. Antibody studies were also done on 106 adult Cypriot villagers and on 13 shepherds from flocks infected with C. burneti, to provide a base line for comparative purposes. No evidence was found to implicate the organism as a cause of chronic liver disease. As the number of patients investigated was small it was not possible to exclude C. burneti as an occasional pathogen, and guiding principles were formulated for future investigations.