Maurice C. Davies

THE ELECTRON MICROSCOPY OF RABIES VIRUS IN CULTURES OF CHICKEN EMBRYO TISSUES.

Abstract Cultures of chicken embryo tissue infected with the HEP Flury strain of rabies have been studied with the electron microscope. Sections of infected cells reveal within the cytoplasm round and elongated particles associated with masses of homogeneous material. Similar particles can also be seen budding from the cell membranes and free in extracellular space. Round and elongated particles were also seen in pellets from infected tissue culture fluid both by sectioning and by negative staining. The round forms have a wide size range and by negative staining sometimes show a fringed outer surface resembling myxoviruses. This structure has not been seen on the elongated particles. The particles described were not seen in uninfected cultures, and their appearance could be prevented by adding rabies immune serum to the inoculum. It has not been possible so far to correlate infectivity with one or both types of particles.

Antagonistic Action of Certain Neurotropic Viruses Toward a Lymphoid Tumor in Chickens with Resulting Immunity.

Conclusions 1. RPL-12, a transplantable lymphoid tumor of chickens, can be caused to regress, without any apparent damage to the host, by superimposed inoculations of Russian Spring-Summer, West Nile, Japanese B encephalitis, St. Louis encephalitis or louping-ill viruses. 2. Chickens which have been inoculated with the RPL-12 tumor followed by a superimposed infection with any of the 5 viral agents are rendered immune, as a rule, to challenge by homologous tumor even though the original inoculation with tumor may not have produced a palpable tumor. 3. The infective titer of RSS virus in infected tumor tissue is equal to that of infected mouse brain. 4. RSS virus obtained from infected mouse brain has a high oncolytic action when introduced into the tumor area but is less effective when it is introduced at a distance from the tumor. 5. RSS virus obtained from infected RPL-12 tumor has a high oncolytic action when introduced either in the tumor area or at a distance from the tumor.

Electron Microscopy of Staphylococcus aureus Treated with Tetracycline

After exposure to tetracycline, Staphylococcus aureus was fixed with formaldehyde and osmium tetroxide, thin-sectioned, and examined with the electron microscope. Compared with control cells, the tetracycline-treated cells had no transvers septa, were larger, had a greater electron density, and had thicker cell walls.

GAL virus: Its growth cycle in tissue culture and some of its properties

Abstract The GAL virus growth cycle has been determined by plaque assay and correlated with electron microscope observations of infected cells. The virus was found to have a long latent period and growth cycle, to be produced only within the cell nucleus, and to accumulate there. It also was found to be polyhedral in shape and ether stable and to resemble adenovirus in its intranuclear site of development, its morphology, and its ether stability. Data concerning its stability under various conditions of storage are included.

Correlation of structure with infectivity of influenza virus.

Abstract Using the technique of phosphotungstic acid negative contrast, standard productions of high titer influenza virus in embryonated eggs have been compared with “incomplete virus,” produced both by the von Magnus procedure of undiluted passage and by the procedure of Fazekas de St. Groth and Graham, who pretreated the embryos with potassium periodate. Most of the particles found in the third undiluted passage virus, with a titer of 106 ID50/ml in eggs, differed markedly from those found in a standard preparation with a titer of 109. These different particles were void of dense internal bodies and varied greatly in shape and size. In preparations grown in embryonated eggs pretreated with potassium periodate, where both the infectivity and hemagglutinin titers were low, the particles were mostly of a bizarre form without dense internal bodies and with sparsely spaced spines in their external coats. A combination of negative staining and metal shadowing indicated that particles not possessing the dense internal body were flat empty bags. Even the preparations with highest infectivity titers contained a considerable proportion of the baglike spiny structures. The nature of the internal dense granule has not been revealed, but tentative possibilities are discussed.

The interaction of corticotropin with bovine albumin

Abstract The presence of serum albumin in the diluent medium has been shown to have a marked effect on the Sayers assay for corticotropin. The binding of corticotropin by serum albumin has been demonstrated by measuring constituent sedimentation constants in the ultracentrifuge by means of the synthetic boundary cell.

Propagation of mouse polyoma virus in a strain of mouse mammary tumor cells in vitro.

Summary 1) An established cell line originating from a spontaneous mouse mammary tumor is a convenient host in which to propagate and to assay polyoma virus in vitro. Cytopathic effects of the virus were first observed in cultures 6 days after infection and progressed to complete destruction of all cells by 12th day. Increasing cell destruction was accompanied by rise in tissue culture infectivity and hemagglutination titers. 2) Observations with electron microscope revealed presence of virus in infected cells beginning 6th day after infection. Virus particles were observed in the nucleus and occasionally in the cytoplasm. Particles averaged 30 mμ in diameter and did not show an internal structure.

Some observations on influenza hemagglutination inhibitor of allantoic fluid.

Summary Treatment of the hemagglutination inhibitor from allantoic fluid with 90% phenol did not result in a low molecular weight active substance. After acetone precipitation, adsorption on indicator virus and ultrafiltration, the partially purified inhibitor was active at 0.5 p.g and the active principle had a sedimentation constant of 15.