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PubMed2000

alpha(v)beta(3) integrin and bacterial lipopolysaccharide are involved in Coxiella burnetii-stimulated production of tumor necrosis factor by human monocytes.

Coxiella burnetii, the agent of Q fever, enters human monocytes through alpha(v)beta(3) integrin and survives inside host cells. In addition, C. burnetii stimulates the synthesis of inflammatory cytokines including tumor necrosis factor (TNF) by monocytes. We studied the role of the interaction of C. burnetii with THP-1 monocytes in TNF production. TNF transcripts and TNF release reached maximum values within 4 h. Almost all monocytes bound C. burnetii after 4 h, while the percentage of phagocytosing monocytes did not exceed 20%. Cytochalasin D, which prevented the uptake of C. burnetii without interfering with its binding, did not affect the expression of TNF mRNA. Thus, bacterial adherence, but not phagocytosis, is necessary for TNF production by monocytes. The monocyte alpha(v)beta(3) integrin was involved in TNF synthesis since peptides containing RGD sequences and blocking antibodies against alpha(v)beta(3) integrin inhibited TNF transcripts induced by C. burnetii. Nevertheless, the cross-linking of alpha(v)beta(3) integrin by specific antibodies was not sufficient to induce TNF synthesis. The signal delivered by C. burnetii was triggered by bacterial lipopolysaccharide (LPS). Polymyxin B inhibited the TNF production stimulated by C. burnetii, and soluble LPS isolated from C. burnetii largely mimicked viable bacteria. On the other hand, avirulent variants of C. burnetii induced TNF production through an increased binding to monocytes rather than through the potency of their LPS. We suggest that the adherence of C. burnetii to monocytes via alpha(v)beta(3) integrin enables surface LPS to stimulate TNF production in THP-1 monocytes.

Bacterial Adhesion↗
PubMed1992

Phagolysosomes of Coxiella burnetii-infected cell lines maintain an acidic pH during persistent infection.

Coxiella burnetii, the agent of Q fever, is an obligate intracellular bacterium that multiples within vacuoles of phagolysosomal origin. Persistently infected cell lines were maintained in continuous culture for months. We studied the pH of the phagolysosomes by using two murine cell lines during early propagation of the bacteria and after establishment of persistent infection. Three strains of C. burnetii were studied because of the purported propensity of each strain to cause acute or chronic disease and to be resistant or susceptible to antibiotics. The pHs were calculated from fluorescence experiments with fluoresceinated dextran as a lysosomal probe. Phagolysosomal vacuoles maintained an acidic pH during a 36-day infection. Minimal variation of the pH occurred over the duration of the experiment with strains that caused either acute or chronic disease. Phagolysosomal pH remained stable for as long as 153 days with the Nine Mile phase II isolate. Thus, neither the course of C. burnetti infection nor the diversity of antibiotic susceptibility of the strains is related to variations in the phagolysosomal pH.

Animals↗
PubMed2006

Diagnosis of Coxiella burnetii-related abortion in Italian domestic ruminants using single-tube nested PCR.

Coxiella burnetii, an obligate intracellular parasite with a worldwide distribution, is the causative agent of acute and chronic Q fever in humans. Although infection is often unapparent in cattle, sheep and goats, there is increasing evidence that C. burnetii infection in these species is associated with abortion and stillbirth. This paper describes the introduction of a single-tube nested PCR protocol for the diagnosis of C. burnetii-related abortion in domestic ruminants in Italy. A total of 514 aborted foetuses from cattle (n = 138) and sheep and goat (n = 376), collected from 301 farms, were analyzed from January 2001 to March 2005. Ninety-seven of 514 (18.9%) animals tested PCR-positive, with 16/138 (11.6%) cattle and 81/376 (21.5%) sheep and goat. Eleven of 102 (10.8%) farms with reproductive disorders in cattle and 37/199 (18.6%) farms with reproductive disorders in sheep and goats were infected with C. burnetii. A greater incidence was observed in three of the seven investigated provinces (p < 0.01), with rates of infected farms of up to 23.8%. Data showed that almost all the C. burnetii-related abortions were recorded between October and April (p < 0.01). These findings suggest that Q fever in humans is largely underestimated in Italy, probably because its occurrence is obscured by flu-like symptoms in acute forms.

Abortion, Veterinary↗
PubMed1998

Increases in the levels of Coxiella burnetii-specific immunoglobulin G1 and G3 antibodies in acute Q fever and chronic Q fever.

A detailed analysis of the humoral response to Coxiella burnetii may provide insight into the pathogenesis of Q fever, a zoonosis caused by C. burnetii. The subclasses of C. burnetii-specific antibodies were determined by immunofluorescence in 20 patients with acute Q fever and 20 patients with chronic Q fever. Although immunoglobulin G1 (IgG1) and IgG3 antibodies were found in acute and chronic Q fever, neither IgG2 nor IgG4 was detected. The detection of IgG1 and IgG3 antibodies was not due to an increase of the IgG1 and IgG3 subclasses. Moreover, IgG1 and IgG3 antibodies were not correlated, suggesting that they may play different roles in Q fever.

Acute Disease↗
PubMed1992

Histological and immunocytochemical characterization of Coxiella burnetii-associated lesions in the murine uterus and placenta.

The fetoplacental units and the postgravid uterus of BALB/cJ (H-2d) mice inoculated intraperitoneally with Coxiella burnetii (Nine Mile isolate, phase I) on day 6 of pregnancy were examined histologically and immunocytochemically at 1 to 160 days postinoculation. Clinically, abortions, stillbirths, and perinatal deaths were observed. Histological lesions in the placenta were characterized by severe necrosis of the decidua basalis and the labyrinth, fibrinoid degeneration of decidual vessels, and microthrombosis. Pyometra and endometritis at the sites of previous placental attachment, characterized by ulceration, central necrosis, and moderate cellular infiltration consisting of neutrophils and macrophages, were observed postpartum. Pups sacrificed at the age of 9 days exhibited interstitial pneumonia with few granulomas and granulomatous hepatitis and splenitis. Immunocytochemically, antigen-bearing cells were first detected in the decidua 9 days postconception, and single immunopositive cells were detected in the fetal placenta 4 days later. Thereafter, until abortion or parturition, abundant accumulation of C. burnetii antigen was observed in the maternal and fetal compartments of the placenta. Up to 28 days postinoculation, many immunopositive cells were demonstrated at the sites of previous placental attachment, whereas the adjacent endometrium contained only a few antigen-positive cells. C. burnetii antigen was demonstrated in decidual cells, trophoblasts, and macrophages and extracellularly within the sinuses of the labyrinth and in the uterine lumen but not in granulated metrial gland cells. Fetuses in utero and aborted, stillborn, or perinatally dying offspring were immunocytochemically negative for C. burnetii antigen; however, pups killed 9 days after birth showed lesion-associated positive immunoreaction in the lung, liver, and spleen. The present study shows that infection with C. burnetii during pregnancy results in uncontrolled growth of the organism in the murine uteroplacental unit and that associated lesions are characterized by necrosis of placental tissues, fibrinoid degeneration of decidual vessels, and microthrombosis.

Animals↗
PubMed2002

Evaluation of a novel commercial enzyme-linked immunosorbent assay detecting Coxiella burnetii-specific immunoglobulin G for Q fever prevaccination screening and diagnosis.

A novel commercially available enzyme-linked immunosorbent assay (ELISA) for prevaccination screening and diagnosis of Q fever (PanBio Coxiella burnetii immunoglobulin G [IgG] ELISA) was compared to the complement fixation test (CFT), and the indirect fluorescent-antibody test (IFAT) was used to resolve discrepant results between the other two tests. A total of 214 serum samples was tested. The ELISA demonstrated a specificity of 96% (46 of 48 samples) and a sensitivity of 71% (95 of 134 samples). Of the six serum pairs showing CFT seroconversion, three pairs showed a corresponding ELISA seroconversion. No cross-reactivity was observed in the ELISA with serum samples from patients with mycoplasma, brucella, and chlamydia infections. One of the 13 patients with leptospirosis demonstrated a positive result in the ELISA but not in the CFT or the IFAT, and Legionella pneumophila serogroup 4 antibody was found in one of the two sera that were false-positive by ELISA. The results presented in this study suggest that the PanBio Q fever IgG ELISA is a specific alternative method for prevaccination testing and an aid for the diagnosis of Q fever. This test is suitable for use as a screening assay, with CFT and/or IFAT used to confirm negative results.

Antibodies, Bacterial↗
PubMed2005

Balb/c mouse model and real-time quantitative polymerase chain reaction for evaluation of the immunoprotectivity against Q fever.

The Balb/c mice were infected with Coxiella burnetii and samples of blood and major organs from the infected mice were collected on days 1 to 14 after infection. The DNAs extracted from the samples were detected by a developed real-time quantitative PCR specific for C. burnetii and high loads of C. burnetii were found in spleens, livers, and lungs, particularly in spleens. The Balb/c mice were immunized with whole cell antigen (WCA) of C. burnetii and coxiella loads in spleens of mice were assessed by the real-time quantitative PCR on day 7 after challenge with C. burnetii. The analysis suggested that phase I whole cells were excellent immunogen that elicited complete protection against coxiella infection by two-booster but not one-booster immunization. The results suggest that the combination of Balb/c model and the real-time quantitative PCR assay is a reliable and sensitive way to evaluate the efficiency of vaccines against Q fever.

Animals↗
PubMed1984

Antibody-dependent cellular cytotoxicity of Coxiella burnetii-infected J774 macrophage target cells.

Cell-mediated immunity is clearly the critical host defense mechanism against human Coxiella burnetii infection (Q fever); the role of specific antibody is unclear. By using a mouse macrophage tumor cell line, J774, persistently infected with C. burnetii phase I organisms, in a standard 51Cr-release cytotoxicity assay, we explored the possibility that antibody-dependent cellular cytotoxicity may be immune mechanism in Q fever. After 16 h of incubation in the presence of immune sera from Q fever hepatitis or endocarditis patients, nonimmune human peripheral blood effector cells specifically lysed infected J774 target cells; no 51Cr release was seen in the presence of nonimmune sera or uninfected target cells. An effector/target ratio of at least 5:1 was required, and monocytes were more efficient effector cells than lymphocytes. Cytotoxicity was blocked by preincubation of effector cells with purified aggregated human immunoglobulin G, indicating the role of Fc receptor-bearing effector cells. Two nonphagocytic lymphoid tumor cell targets, passively coated with C. burnetii, did not induce substantial immune-specific cytolysis, suggesting that bystander lysis does not explain the observation of specific lysis. Although antibody-dependent cellular cytotoxicity may participate in primary defense, alternatively, it may facilitate the dissemination of C. burnetii or surreptitiously participate in granuloma formation.

Animals↗
PubMed1987

Antigen-specific circulating immune complexes in Coxiella burnetii-infected guinea pigs.

An antigen-specific conglutinin-binding assay was developed with artificial immune complexes of Coxiella burnetii and an enzyme-linked immunosorbent assay for the detection of circulating immune complexes. Sera from guinea pigs infected with C. burnetii were examined by this assay, and the percentages of infected guinea pigs with C. burnetii antigen-specific circulating immune complexes were 71, 93, 74, 65, 49, and 27%, respectively, from the first to sixth week after infection. C. burnetii antigen eluted from circulating immune complexes by acid dissociation was detected by counterimmunoelectrophoresis. The antigen-specific conglutinin binding assay was specific, sensitive, and reproducible for assay of circulating immune complexes.

Animals↗
PubMed1989

[Experience in vaccinating farm animals for preventing Q fever in humans].

Vaccination of animals is indicated for cattle and sheep to prevent human infections deriving from these animals and inhibit the infertility in livestock. Both phase I and phase II are available. Vaccination is successful only when animals had been vaccinated as noninfected young, i. e. calves or lambs. Corpuscular vaccines are prevalent in immunoprophylaxis of domestic animals against coxiellosis. Such vaccines consist of formalin--inactivated, purified corpuscules Coxiella burnetii in phase I or phase II suspended in isotonic saline. But only complete composition of particles Coxiella burnetii secures their immunogenicity. We assume that any vaccine prepared from phase II Coxiella burnetii can not be equivalent to a vaccine prepared from phase I Coxiella burnetii. We tried to ascertain the optimal dose of Q-fever vaccine Coxiella burnetii, strain Nine Mile phase I, for the immunization of cattle. The vaccine is called BODIBION and it is commercially produced by BIOVETA in Nitra, Czechoslovakia. It is recommended to vaccinate by Coxiella--free herds of cattle the heifers from the age of 3 months with a dose of 200 micrograms of vaccine with the possibility either to revaccinate with the same dose, i. e. 200 micrograms 3-4 weeks after the first dose, or to vaccinate with only a single dose, i. e. 200 micrograms, but with the addition of adjuvans. In Q-fever infested herds it is recommended to vaccinate with 500 micrograms of vaccine with the possibility of either to revaccinate after 3-4 weeks with a lower dose, i. e. 200 micrograms of vaccine, or to vaccinate with a single dose of 500 micrograms vaccine with the addition of adjuvans. The administration of adjuvans in the vaccination process seems to be perspective in the development of vaccines against coxiellosis in domestic animals. Its involvement may lower the recently used vaccination dose and may avoid the revaccination.

Animals↗
PubMed1998

[Fever, negative blood culture findings and absence of response to antibiotic therapy in a patient after a second aortic valve prosthesis].

HISTORY AND CLINICAL FINDINGS: A 53-year-old patient had a prosthetic valve (St. Jude Medical 25) 9 years ago because of a Staphylococcus aureus endocarditis with severe aortic regurgitation. An initially mild, progressively more severe, aortic regurgitation then developed as a result of an empty paravalvular abscess cavity, requiring another valve replacement. Fever started on the 3rd postoperative day and persisted despite combined treatment with beta-lactam antibiotics and aminoglycoside. INVESTIGATIONS: At first no infectious focus could be identified radiologically or by echocardiography. But transoesophageal echocardiography revealed vegetations in the old abscess cavity. Several blood cultures were negative, while serological tests gave markedly raised antibody titers against Coxiella burnetii. DIAGNOSIS, TREATMENT AND COURSE: Assuming Coxiella burnetii endocarditis the patient was given doxycycline, 2 x 100 mg daily and cotrimoxazole, 1 x 960 mg daily. The fever subsided and the vegetations had disappeared after four weeks. Because of the high risk of recurrence the antibiotic treatment was to be continued for two years. CONCLUSION: Coxiella burnetii should be considered as a possible cause of fever of unknown origin, especially in patients with existing or operated cardiac valvar defects, when endocarditic vegetations have been demonstrated and several blood cultures have been negative.

Amoxicillin-Potassium Clavulanate Combination↗
PubMed2001

[Attempt of estimation of Q fever endocarditis frequency in Poland].

Up to now no Q fever endocarditis (caused by rickettsia Coxiella burnetii) has been diagnosed in Poland. Potential endocarditis caused by Coxiella burnetii strains can be related to a group of strains present in Poland or sensitivity of Polish Population. The aim of the study was to estimate frequency of Q fever endocarditis is patients of National Institute of Cardiology and to characterize Coxiella burnetii strains and correlation between frequency of Q fever endocarditis and the group of strains. In all patients infective endocarditis and valvular heart disease were diagnosed. In all cases vegetations on TTE or TEE and negative blood cultures were confirmed. No fungal antigens or elevated anti-Candida and anti-Aspergillus antibodies were found. Serological investigations as far as it concerns C. burnetii antibodies were negative in all cases. No Coxiella burnetii infection were found in patients with infective endocarditis and negative blood cultures in the National Institute of Cardiology. However due to high probability of occurrence of such an infection in Poland further investigations in other centers would be useful.

Antibodies, Bacterial↗