Latent viral infection of cells in tissue culture. IV. Latent infection of L cells with psittacosis virus. (49/396)

By maintaining L cells in a balanced salt solution of inorganic salts and glucose (BSS) for 2 days or more, they are rendered incapable of supporting the growth of psittacosis virus (6BC), though it infects such cells and is present intracellularly for as long as 3 days in a non-infectious phase. The addition of an enriched medium to such a culture of cells at any time up to 4 days after infection results in the appearance of infectious virus within these cells, which multiplies and is released from the cells, providing the entire period of exposure of such cells to the BSS does not exceed 6 days, following which the cells die. A latent infection with psittacosis virus in a non-infectious phase has been established in a pure line of cells which possess properties of malignancy.  (+info)

Latent viral infection of cells in tissue culture. VI. Role of amino acids, glutamine, and glucose in psittacosis virus propagation in L cells. (50/396)

Mouse fibroblasts (L cells) fail to support the growth of psittacosis virus (6BC strain) if they are maintained on a medium containing only inorganic salts and glucose for 2 days prior to infection. Virus propagation can be stimulated by the addition of a synthetic medium containing amino acids, water-soluble vitamins, glutamine, glucose, and inorganic salts. By omitting single amino acids from the complete synthetic medium, tyrosine, threonine, methionine, isoleucine, phenylalanine, tryptophan, leucine, valine, and cysteine or cystine were found to be essential for stimulation, while lysine, arginine, histidine, hydroxyproline, proline, glutamic acid, aspartic acid, serine, alanine, and glycine were not essential. The cells on deficient media showed varying degrees of degenerative changes, but there was little correlation between ability to support psittacosis virus growth and morphologic condition of the cells. Glucose is also an essential component of the medium for viral growth, but the absence of glutamine had no effect on stimulation of virus propagation. L cell cultures maintained on media deficient in phenylalanine or tryptophan for 2 days before infection were also found to be incapable of supporting virus growth. The implications of this study in latent viral infections are discussed.  (+info)

Latent viral infection of cells in tissue culture. VII. Role of water-soluble vitamins in psittacosis virus propagation in L cells. (51/396)

A study of the metabolic requirements for the growth of psittacosis virus in L cells has been extended to the water-soluble vitamins. In a system in which a balanced salt solution was used to deplete the cells of their vitamin constituents, only thiamine was essential for psittacosis virus production. Extended depletion of cells with media deficient in specific vitamins demonstrated that pantothenate, niacin (niacinamide), pyridoxine (pyridoxal), and choline, in addition to thiamine, were essential for maximal growth of psittacosis virus. No requirement for biotin, inositol, folic acid, or riboflavin was demonstrated, although the possibility of incomplete vitamin depletion of the cells has not been eliminated. In most cases in which a specific vitamin requirement was shown the decreased yield of virus was correlated with a delay in the cytopathic effects produced in the cell cultures by psittacosis virus.  (+info)

Effect of alkali on the structure of cell envelopes of Chlamydia psittaci elementary bodies. (52/396)

Suspensions of isolated cell envelopes of infectious elementary bodies (EB) of Chlamydia psittaci at alkaline pH showed a rapid, extensive decrease in absorbance, accompanied by the release of a cell envelope component in a sedimentable form. This phenomenon was observed both at 0 C and with envelopes which had been previously heated to 100 C. Monovalent and divalent cations effectively inhibited the turbidity loss, whereas ethylenediaminetetraacetate (EDTA) caused an accelerated decrease in turbidity. The turbidity loss observed after incubation of the envelopes at alkaline pH could be reversed to the level of the initial value by dialysis against distilled water containing Mg2+. Thin-section electron photomicrographs of purified EB exposed to alkaline buffer with EDTA revealed the loss of the internal contents of cells, but these cells still maintained their round shapes. The cell surface of treated EB appeared pitted in negatively stained preparations, whereas intact EB had a smooth surface. Electron microscopic studies on negatively stained preparations of the clear supernatant obtained after the treatment of the envelope with alkaline buffer containing EDTA demonstrated the presence of spherical particles, approximately 6 to 7 nm in diameter, and rodlike particles, which appeared to be made up of two or more spherical particles.  (+info)

Protein-carbohydrate-lipid complex isolated from the cell envelopes of Chlamydia psittaci in alkaline buffer and ethylenediaminetetraacetate. (53/396)

Exposure of isolated cell envelopes from purified infectious elementary (EB) of Chlamydia psittaci to sodium carbonate-bicarbonate buffer at pH 10 plus ethylenediaminetetraacetate (EDTA) results in partial solubilization of the total protein. The released materials represent 20% of the dry weight, 16% of the total protein, 40% of the total carbohydrate, and 9% of the total lipid of the cell envelopes. Sucrose density gradient centrifugation, and Sephadex G-200, Sepharose 4B, or diethylaminoethyl-cellulose column chromatography, reveal a protein-carbohydrate-lipid complex of several hundred thousand molecular weight that contains 50% protein. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the isolated EB cell envelopes reveals two major protein bands, A and B, with estimated molecular masses of approximately 85,000 and 53,000, respectively, both of which also stain for the presence of carbohydrate and lipid. Gel electrophoresis of the protein-carbohydrate-lipid complex reveals two protein bands, C and D, with estimated molecular weights of approximately 17,000 and 13,000, respectively, which contain lipid and a small amount of carbohydrate; bands A and B are not present in the complex. Gel electrophoresis of the cell envelope residues after extraction of the complex with alkali and EDTA shows a single main band, corresponding to the position of band B, which contains protein, carbohydrate, and lipid; band A is completely missing. B and A is believed to be a component of the complex, which is split into two subunits on alkali solubilization.  (+info)

Growth and lethal effects of the psittacosis agent in chicken embryos of different ages. (54/396)

Stewart, Robert B. (University of Rochester, Rochester, N. Y.). Growth and lethal effects of the psittacosis agent in chicken embryos of different ages. J. Bacteriol. 83:423-428. 1962.-Inoculation of the psittacosis agent (strain 6BC) into the yolk sacs of chicken eggs in different stages of embryonic development resulted in a steady decrease in ld(50) titer as the embryos increased in age from 7 to 10 days. Correlated with the decreased ld(50) titers in older eggs was the finding that the titers of the organism were lower in the yolk-sac tissues of the older eggs. The embryos themselves also gained appreciably in resistance with increase in age, since comparable titers of psittacosis organisms were found in embryonic tissues of differing ages at the time of inoculation but the mortality of older embryos was considerably less. This resistance of older embryos to the lethal effects of the psittacosis agent could not be demonstrated when the organism was introduced intravenously instead of into the yolk sac.  (+info)

Effect of p-fluorophenylalanine of psittacosis virus in tissue cultures. (55/396)

Tanami, Yoh (University of Texas Medical Branch, Galveston) and Morris Pollard. Effect of p-fluorophenylalanine on psittacosis virus in tissue cultures. J. Bacteriol. 83:437-442. 1962.-The inhibitory effect of p-fluorophenylalanine (FPA) on maturation of psittacosis virus was investigated, with attention to the time sequence of viral protein synthesis. Extracellular virus particles were not inactivated by FPA at a concentration of 100 mug per ml, at which level it interfered with maturation of intracellular virus. When FPA was added to infected tissue cultures earlier than 15 hr after infection, intracellular virus maturation was suppressed. However, when FPA was added after 15 hr, infective virus was produced, which indicates that the synthesis of a FPA-sensitive virus precursor (presumably viral protein) had already occurred. A latent ("dormant") infection of psittacosis virus, established in a medium deficient in phenylalanine and tyrosine, was also investigated.  (+info)

DIAMINOPIMELIC ACID DECARBOXYLASE OF THE AGENT OF MENINGOPNEUMONITIS. (56/396)

Moulder, James W. (University of Chicago, Chicago, Ill.), Dorothy L. Novosel, and Ilse C. Tribby. Diaminopimelic acid decarboxylase of the agent of meningopneumonitis. J. Bacteriol. 85:701-706. 1963.-Evidence is presented for the presence in meningopneumonitis particles and extracts of an enzyme decarboxylating alpha, epsilon-diaminopimelic acid to lysine and for the absence of a corresponding enzyme in the uninfected host. Properties of the enzyme are described and compared with those of bacterial diaminopimelic acid decarboxylases. The significance of these observations with respect to the mode of lysine biosynthesis in the psittacosis group and to its phylogenetic origin is pointed out.  (+info)