Ribosomes and ribonucleic acids of Coxiella burneti

This report describes the direct isolation and characterization of rickettsial ribosomes. Ribosomes from the rickettsia Coxiella burneti were isolated and partially characterized. The ribosomes had a sedimentation constant of about 70S and could be dissociated into 50 and 30S subunits. Electron microscopy revealed ribosomal particles with dimensions similar to those reported for other procaryotic organisms. Ribonucleic acid (RNA) species (23 and 16S) were isolated from the ribosomal particles. The nucleotide compositions of the ribosomal RNAs were found to be similar to those reported for bacterial ribosomal RNA. In addition to the high-molecular-weight ribosomal RNA, 5S RNA was also extracted from the organism.     

Preparation of Purified Suspensions of Coxiella burneti by Genetron Extraction Followed by Continuous-Flow Ultracentrifugation

A method for the preparation of purified suspensions of Coxiella burneti by Genetron extraction followed by continuous-flow density gradient ultracentrifugation is described. Both phases of the Henzerling strain of C. burneti were found in a zone between 53 and 65% (w/w) sucrose. Based on chemical assays, the Genetron zonal rickettsial suspensions were found to be as pure as the rickettsial suspensions which were prepared by the ether extraction method currently in use for producing Q fever vaccines for human use.     

Passive Cutaneous Anaphylaxis with Antigens from Coxiella burneti

Passive cutaneous anaphylaxis (PCA) was produced in guinea pigs sensitized with guinea pig Coxiella burneti phase I–II antiserum and challenged with dimethylsulfoxide- or trichloroacetic acid-soluble extracts from phase I cells. The PCA reaction could not be induced by whole or mechanically disrupted phase I or phase II C. burneti cells or by extracted cells or extracts of phase II cells. The antibody responsible for PCA was in the 7Sγ₁ (fast γ) globulin. Sensitization of the skin by 7Sγ₁ antibody could be blocked nonspecifically by 7Sγ₁ globulin from normal serum or from phase II antiserum. The 7Sγ₂ (slow γ) globulin antibody inhibited the reaction specifically. Some antiserum pools containing high agglutinin and complement-fixing titers to phase I C. burneti cells failed to initiate the PCA reaction, perhaps due to an imbalanced ratio of γ₁ to γ₂ specific globulins or to an imbalance in the ratio of specific to nonspecific γ₁ globulins. Agglutinins to phase I cells were found in both γ₁ and γ₂ antibody globulins. Complement-fixing antibodies were found in the γ₂ globulin fraction.     

Host response to infection by Coxiella burneti.

A host response to infection by Coxiella burneti was investigated. Infectedyolk sacs were harvested from embryonated eggs and assayed for glycolytic activity. Assays of glycolytic enzymes included glucose isomerase, aldolase, phosphofructokinase,fructose-1,6-diphoshatase, glyceraldehyde-3-phosphate dehydrogenase, enolase, and pyruvate kinase. No significant differences in enzymatic activity between normal and infected tissues through the 12th day was observed. From the 13th day through the 16thday, the glycolytic activity of normal tissues decreased. Glycolytic activity of infected tissues did not decrease, but showed a gradual increase during this same time period. Embryos from infected eggs demonstrated a gradual decrease in total weight fromthe 12th day until death occurred on the 16th day.     

Isolation and Characterization of Two Cell Types of Coxiella burneti Phase I

Two morphologically distinct cell types of Coxiella burneti phase I have been separated on the basis of unique buoyant densities. When centrifuged to equilibrium in cesium chloride or density gradients of sucrose or Renografin, the cells band in two zones. Electron micrographs of ultrathin sections of the two cesium chloride-separated cell types indicate a considerable number of morphological differences. The lower-density cells are small, compact, and rodshaped and have very dense nucleoids. The cell type of highest density is larger, rounded, and more pleomorphic, and the nucleoid filaments are more dispersed. The two cell types are nearly identical in sedimentation rates, and both infect chick yolk sac cells and are lethal to chick embryos. They convert to a mixture of cell types when cultured separately. Treatment with Formalin induces all cells to band at the same position when centrifuged to equilibrium in cesium chloride. The cell type variance was found to be independent of the antigenic phase phenomenon of C. burneti.     

Preparation of highly purified F-actin-depolymerizing factor of human serum

F-actin depolymerizing factor (ADF) of human serum was purified 250-400-fold to more than 98% purity with high reproducibility. The purification included (1) 30-50% (NH4)2SO4 precipitation, (2) ion-exchange chromatography on DEAE-Sepharose, (3) chromatofocusing on Polybuffer exchanger 94 and (4) affinity chromatography on ConA-Sepharose. The recovery of ADF was estimated to be 20-30% whereas the ADF activity yield was 5-17%. The lower activity yield was thought to be due-partly to proteolysis and partly to destabilization of highly purified ADF.