A LABILE INTRANUCLEAR RNA ASSOCIATED WITH THE DEVELOPMENT OF ADENOVIRUSES

Experimental adenovirus infection of the mouse adrenal gland. II. Electron microscopic observations

A strain of mouse adenovirus, found to have a striking tropism for the weanling mouse adrenal gland, enabled electron microscopic examination of adrenals in various stages of infection. Nucleolar hypertrophy and the successive formation of three types of inclusion bodies in association with nucleoli preceded virion production. Angular crystals of virions formed in the affected nuclei. Virus was released by lysis of nuclear membranes; rapid degeneration of cytoplasmic organelles followed. Rupture of external cell membranes released virus into the extracellular spaces where virions crossed vascular basement membranes to enter endothelial cells. Virions were also phagocytized by inflammatory cells which reentered vascular sinusoids, and by adrenal parenchymal cells. Disruption of virus-laden phagocytic vacuoles in parenchymal cells released virions into the cytoplasm. Typical viral inclusion bodies also formed in vascular endothelial cells and in inflammatory cells, but virion replication was not detected. The possibility that virus directly entered parenchymal cells through the external cell membrane without phagocytosis is discussed.

Effects of a pathogenic canine herpesvirus on established thyroid adenocarcinoma cell cultures

The effects of a pathogenic canine herpesvirus were studied sequentially in established canine thyroid adenocarcinoma tissue culture cells. The lesions were defined as early, middle, and late manifestations of viral effects based on the time a lesion first appeared. The early phase (3 to 10 hours) consisted of nucleolar swelling followed by disruption. The nucleolar changes were characterized by loss of RNA as determined with acridine orange and segregation of the nucleolar components as demonstrated by electron microscopy. The middle phase (10 to 34 hours) was characterized by the appearance of three types of eosinophilic intranuclear inclusions. One type of inclusion appeared to transform progressively into another. The appearance of viral antigen in the nucleus as demonstrated by immunofluorescence, correlated with ultrastructural evidence of viral replication. The late phase (34 to 72 hours) was manifested by cellular degeneration and viral release into the cytoplasm.

Ultrastructural alterations of tissue cultures infected with a pathogenic porcine adenovirus

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Histological study of adenovirus type 14 development in cell cultures

By means of the fluorescent antibody method and of acridine orange staining experimental infection with adenovirus type 14 has been investigated in KB and MK cell cultures. Intracellular changes could be shown to precede the appearance of the cytopathic effect.

Thus, progressive stages in the development of adenovirus at this level could be separated both by the demonstration of the specific antigen and by the appearance of an altered DNA.

Both methods have proved to be equally useful for the detection of virus multiplication and of the histochemical changes induced in the cells.

No significant differences have been found to exist with respect to the cell line used.