Survival of Mycobacterium avium and Mycobacterium tuberculosis in acidified vacuoles of murine macrophages. (1/167)

Despite the antimicrobial mechanisms of vertebrate phagocytes, mycobacteria can survive within the phagosomes of these cells. These organisms use various strategies to evade destruction, including inhibition of acidification of the phagosome and inhibition of phagosome-lysosome fusion. In contrast to mycobacteria, Coxiella burnetii, the etiologic agent of Q fever, inhabits a spacious acidified intracellular vacuole which is prone to fusion with other vacuoles of the host cell, including phagosomes containing mycobacteria. The Coxiella-infected cell thus provides a unique model for investigating the survival of mycobacteria in an acidified phagosome-like compartment. In the present study, murine bone marrow-derived macrophages were infected with either Mycobacterium avium or Mycobacterium tuberculosis and then coinfected with C. burnetii. We observed that the majority of phagocytosed mycobacteria colocalized to the C. burnetii-containing vacuole, which maintained its acidic properties. In coinfected macrophages, the growth of M. avium was not impaired following fusion with the acidified vacuole. In contrast, the growth rate of M. tuberculosis was reduced in acidified vacuoles. These results suggest that although both species of mycobacteria inhibit phagosome-lysosome fusion, they may be differentially susceptible to the toxic effects of the acidic environment in the mature phagolysosome.  (+info)

Infectivity, transmission and 16S rRNA sequencing of a rickettsia, Coxiella cheraxi sp. nov., from the freshwater crayfish Cherax quadricarinatus. (2/167)

A rickettsia-like organism isolated from infected, farm-reared Cherax quadricarinatus was cultured in the yolk sac of developing chicken eggs, but could not be cultured in 3 continuous cell lines, bluegill fry (BF-2), fathead minnow (FHM), and Spodoptera frugiperda (Sf-9). The organism was confirmed by fulfilling Koch's postulates as the aetiological agent of mortalities amongst C. quadricarinatus. When C. quadricarinatus was inoculated with the organism, mortality was 100% at 28 degrees C and 80% at an ambient temperature of 24 degrees C. Horizontal transmission with food and via the waterborne route was demonstrated, but mortalities were lower at 30 and 10% respectively over a 4 wk period. The 16S rRNA sequence of 1325 base pairs of the Gram-negative, obligate intracellular organism was 95.6% homologous to Coxiella burnetii. Of 18 species compared to this rickettsia, the next most closely related bacterium was Legionella pneumophila at 86.7%. The suggested classification of this organism is Order Rickettsiales, family Rickettsiaceae, tribe Rickettsieae, within the genus Coxiella. We suggest it should be named Coxiella cheraxi sp. nov.  (+info)

Detection of long-term cellular immunity to Coxiella burneti as assayed by lymphocyte transformation. (3/167)

Delayed hypersensitivity to the antigens of Coxiella burneti, Nine Mile strain, was demonstrated in human subjects with various past histories of exposure to the organism by using lymphocyte transformation assays. Individuals with histories indicating exposure to C. burneti up to 8 years before the study demonstrated marked lymphocyte transformation in vitro to whole-cell antigens consisting of formalin-killed C. burneti phase I and phase II. These individuals also demonstrated a marked lymphocyte response to the trichloracetic acid-soluable phase I antigen. One individual who acquired Q fever during the study and one individual who received an experimental Q fever vaccine 4 years earlier were also evaluated by the lymphocyte transformation assay. It was also found that phase I trichloroacetic acid-soluble material was capable of acting as an antigen in the assay, whereas the phase II trichloroacetic acid-soluble material did not contain any antigenic material capable of causing lymphocyte transformation. The complete phase I trichloroacetic acid-soluble antigen, which was found to consist of protein and carbohydrate, was chemically fractionated into monospecific fractions. The fraction treated to eliminate carbohydrate was the only fraction found to elicit an in vitro response.  (+info)

Changes in buoyant density relationships of two cell types of Coxiella burneti phase I. (4/167)

Coxiella burneti phase I, purified from a formalin-inactivated yolk-sac vaccine, was separated into two bands of morphologically distinct cell types when subjected to sucrose gradient centrifugation. Recycling of the less dense, rod-shaped cells in unbuffered sucrose gradients (pH 5.5 to 6.0) resulted in the formation of bands having the location and appearance of the original two bands. Recycling of the denser band of larger ovoid-shaped cells yielded a single band, suggesting that the larger cell type arose from the smaller cell. In contrast to vaccine-derived rickettsiae, live, cell culture-propagated phase I organisms formed a single band in unbuffered sucrose gradients, at the same density as the upper band of the vaccine preparation. Centrifugation of cell culture-derived rickettsiae for 26 to 48 h in sucrose gradients of pH 5.5 resulted in the formation of a second band, at the same density as the lower band of the vaccine preparation. This did not occur in gradients of pH 7.0. Treatment of cell culture-propagated rickettsiae with formalin or germicidal ultraviolet radiation induced a total shift of the less dense cell population to a zone of higher density when centrifuged isopycnically in CsC1 gradients. This density change did not occur in sucrose gradients, suggesting a difference in the effect of these treatments on the permeability of the cell membrane to sucrose and CsC1.  (+info)

Glomerulonephritis associated with Coxiella burnetii endocarditis. (5/167)

A patient with endocarditis associated with chronic Coxiella burnetii infection is described in whom glomerulonephritis developed with granular deposits containing immunoglobulins and complement in the glomeruli. The serum was notable for the variety of circulating antibodies detected, which included antibodies directed against native DNA.  (+info)

Studies on the physiology of Rickettsiae. IV. Folic acids of Coxiella burnetii. (6/167)

Mattheis, Martha S. (University of Kansas, Lawrence), M. Silverman, and D. Paretsky. Studies on the physiology of rickettsiae. IV. Folic acids of Coxiella burnetii. J. Bacteriol. 85:37-41. 1963.-Yolk, yolk sac, and embryo tissues of uninfected eggs, and those infected with Coxiella burnetii, were analyzed for folic acid derivatives by employing diethylaminoethyl (DEAE)-cellulose column chromatography. Infected tissues contained quantitatively less folate, but the elution profiles of both infected and uninfected tissues were identical. Purified C. burnetii contained some types of folate apparently unique to these rickettsiae, and not found in infected tissue. The major folate fraction of C. burnetii was partially characterized by (i) elution position from DEAE columns; (ii) treatment with conjugase; (iii) growth response by Lactobacillus casei, Streptococcus faecalis R, and Pediococcus cerevisiae; and (iv) response to oxidation, reduction, and formylation.  (+info)

CONVERSION OF THE PHASE I ANTIGEN OF COXIELLA BURNETII TO HAPTEN BY PHENOL TREATMENT. (7/167)

Anacker, R. L. (Rocky Mountain Laboratory, Hamilton, Mont.), W. T. Haskins, D. B. Lackman, E. Ribi, and E. G. Pickens. Conversion of the phase I antigen of Coxiella burnetii to hapten by phenol treatment. J. Bacteriol. 85:1165-1170. 1963.-Trichloroacetic acid extracts of Coxiella burnetii are converted to hapten by treatment with phenol. Such extracts react, like the original trichloroacetic acid extract, at high dilution in the complement-fixation test and produce zones of precipitate with specific antibody in gel diffusion tests; but, unlike the parent extract, injection of the phenol-treated extract neither induces resistance to challenge in guinea pigs nor antibody formation in guinea pigs, rabbits, or mice. This loss of antigenicity is correlated with removal of protein from the original product.  (+info)

STUDIES ON THE PHYSIOLOGY OF RICKETTSIAE. V. METABOLISM OF CARBAMYL PHOSPHATE BY COXIELLA BURNETII. (8/167)

Mallavia, L. (University of Kansas, Lawrence) and D. Paretsky. Studies on the physiology of rickettsiae. V. Metabolism of carbamyl phosphate by Coxiella burnetii. J. Bacteriol. 86:232-238. 1963.-Preparations of disrupted Coxiella burnetii catalyze synthesis of citrulline from ornithine and carbamyl phosphate at an optimal pH of 7.0 to 7.5. Rickettsial synthesis of the pyrimidine precursor, ureidosuccinate, is demonstrated and confirmed by isolating C(14)-labeled ureidosuccinate from reaction mixtures of carbamyl phosphate and labeled aspartate. The data suggest a further rickettsial synthesis of orotate and imply rickettsial competence for host-independent pyrimidine synthesis.  (+info)

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10