Comparative studies of the Smith and Raynaud strains of murine cytomegalovirus

A number of the biological, biophysical, and immunological parameters of the Smith and Raynaud strains of murine cytomegalovirus were compared. The two strains were found to be indistinguishable.

Chemical characterization of organisms isolated from leprosy patients

CHEMICAL ANALYSES OF THE CELL WALLS OF ORGANISMS ISOLATED IN VARIOUS PARTS OF THE WORLD FROM CASES OF LEPROMATOUS AND TUBERCULOID LEPROSY MAKE POSSIBLE THEIR ASSIGNMENT TO ONE OF THE THREE GENERA: Corynebacterium, Mycobacterium, or Propionibacterium. One, bacterium 22M, remains unassigned. The combined chemical and enzymatic properties attributed to leprosy bacilli freshly harvested from lepromata are found collectively, but not individually, in these three genera.

Influence of complement on the neutralization of murine cytomegalovirus by rabbit antibody

Antiserum against murine cytomegalovirus produced in the rabbit contained complement (C')-requiring neutralizing (CRN) antibody. The proportion of CRN was extremely high (up to 98%) during the early portion of an immunization procedure, whereas the antisera produced late had a much lower proportion that required C'. The antiserum produced was specific for MCMV with or without C'.

Abortive infection of human diploid cells by murine cytomegalovirus

Inoculation of human diploid cells (WI-38) with murine cytomegalovirus (MCMV) did not result in the synthesis of any infectious virions. However, morphological changes typical of the cytopathic effects (CPE) of MCMV were detectable within 12 hr of infection. The CPE included rounding, swelling, and detachment of cells. The nuclei of infected cells were enlarged, and intranuclear inclusions were visible by May Grunwald-Giemsa staining and by the indirect fluorescent-antibody test. All cells infected at a multiplicity of infection of 3 showed CPE, and these cells could not be passaged successfully. Cell lysates and exhausted media from infected WI-38 cultures did not produce any CPE in WI-38 cells. The virus absorbed to WI-38 cells with the same efficiency as to mouse embryo fibroblast cells (MEF). Samples of MCMV in which virus infectivity for MEF cells had been inactivated by ultraviolet irradiation or by exposure to 56 C failed to produce any of the above signs. MCMV-specific CPE did not occur in the presence of actinomycin D (1 mug/ml) or puromycin (20 mug/ml), but 5'-fluoro-2'-deoxyuridine at 1 x 10(-4)m did not prevent CPE or the development of intranuclear inclusions.

Factors affecting interaction of staphylococcal alpha toxin with membranes

Staphylococcal alpha toxin interacts not only with membranes of erythrocytes but also with membranes of other kinds of mammalian cells (platelets, hepatocytes, and lysosomes from polymorphonuclear leukocytes) with the formation of characteristic ring-like structures that can be seen by electron microscopy. Such structures are not observed when alpha toxin is added to membranes derived from various bacteria. The rings seen on mammalian cell membranes tend to be either randomly disposed or in square array. The frequency with which square arrays are seen is influenced by the presence of staphylococcal delta toxin, by the negative staining agent, and by the kind of cell from which the membrane is derived. Synthetic membranes in the form of liposomes, prepared individually from phosphatidyl choline, phosphatidyl serine, phosphatidyl inositol, and cardiolipin, produced randomly disposed rings upon addition of alpha toxin. Liposomes made from phosphatidyl ethanolamine did not yield rings. Alpha toxin-treated liposomes prepared from chloroform-methanol extracts of brain white matter consistently showed rings that were rectangularly ordered. Ordered rings on membranes derived from toxin-treated platelets and those on toxin-treated brain extract liposomes were seen in freeze-etched as well as in negatively stained preparations.

Detection of cholesterol in cell membranes by use of bacterial toxins

A method is described for the detection of cholesterol in membranes from erythrocytes, mycoplasmas, and bacterial cells by a ferritin-labeling technique. Membranes treated with cereolysin, a bacterial hemolysin which specifically binds to cholesterol, and then treated with ferritin-antitetanolysin, were specifically ferritin-labeled for cholesterol. A similar antigen-antibody system, streptolysin O-ferritin-antistreptolysin, was also used successfully with erythrocyte membranes. There was an uneven distribution of ferritin in erythrocyte membranes suggesting that the distribution of cholesterol may not be entirely random. Mycoplasma gallisepticum was intensely labeled, but Acholeplasma laidlawii with or without cholesterol in the membranes was not labeled, suggesting an unusual location for cholesterol in A. laidlawii membranes. As controls, two of three species of bacterial membranes lacking cholesterol were not ferritin-labeled.

Amino acids of the cell wall of Nocardia rubra

Two classes of preparations of cell walls of Nocardia rubra strain 721-A, digested by trypsin and pepsin with or without subsequent extraction in alkaline ethanol, when examined by electron microscope and analyzed quantitatively for amino acid content differ in ultrastructure and constituent amino acids. Evidence suggests that the lipid-associated amino acids (as peptide or protein) occupy a location superficial to the basal peptido-glycan layer of this nocardia. Their removal is associated with the loss of a characteristic pattern of the outer envelope.

Growth of murine cytomegalovirus in various cell lines

Murine cytomegalovirus (MCMV) was capable of infecting and replicating in both primary and continuous cell lines obtained from various species. In African green monkey kidney (BSC-1) cells, primary rabbit kidney cells, and baby hamster kidney (BHK-21) cells, there were cytopathic effects (CPE) and virus replication upon initial exposure of cells to virus. In primary fetal sheep brain (FSB) cells, L cells, and rabbit kidney (RK-13) cells, it was necessary to subculture the infected cells one or more times before appearance of CPE and replication of virus. In the case of the infected FSB cultures, it was found that the virus effect could be induced if subculturing were accomplished by trypsinization but did not occur if cells were subcultured by scraping. FSB-grown virus replicated better in FSB than in mouse embryo fibroblast (MEF) cells. The CPE produced in all of the above cell lines was similar to that observed in MEF infected with MCMV. The virus grown in different cell lines was completely neutralized when mixed with several reference sera prepared in rabbits or mice. The populations of virions released from infected MEF and FSB cells were compared by isopycnic centrifugation in potassium tartrate, and no differences were revealed in the buoyant densities of the populations. Human embryonic brain cells, human embryonic kidney cells, a human lung fibroblast cell strain (WI-38), HeLa, and Hep-2 were not susceptible to MCMV.