Electron microscopy of cytoplasmic inclusion bodies in cells infected with rinderpest virus

Immunohistological localisation of rinderpest virus in formalin-fixed, paraffin-embedded tissues from experimentally infected cattle

Six Freesian steers were subcutaneously inoculated with the virulent rinderpest virus strain Kabete "0" and sacrificed at the height of fever. Sections of formalin-fixed, paraffin-embedded tissues were stained according to the peroxidase anti-peroxidase (PAP) technique. Labelling of viral antigen, both in the cytoplasm and in the nuclei of infected cells, was observed in the epithelial cells of the upper and lower alimentary tract and in lymphoid organs, i.e. spleen, lymph nodes, pharyngeal tonsils, Peyer's patches and thymus. Electron microscopy studies confirmed the results.

Morphology of the Warthin-Finkeldey giant cells in monkeys with experimentally induced measles

The lymphoid tissues of 9 monkeys infected experimentally with wild type measles virus were examined by light and electron microscopy. Multi-nucleated giant cells of the Warthin-Finkeldey type were found 7 to 11 days after virus inoculation. The giant cells occurred mostly in the germinal center of lymphatic follicles, where they underwent degeneration and disappeared rapidly. Lymphoid and reticular types of giant cells were recognized. The ultrastructural evidence suggested that some of the nuclei contained in giant cells were formed by an aberrant nuclear cleavage. The majority of giant cells, however, were postulated to arise from virus-mediated cell fusion, although direct evidence of cell fusion was not seen. Peculiar nuclear changes, in which some nuclei and fragments of the outer nuclear membrane were contained in a common outer membrane of the nuclear envelope, were observed in all lymphoid giant cells. Both cytoplasmic and intranuclear inclusions were seen to be composed of viral nucleoprotein strands. The former were detected in all giant cells of both types, and the latter in occasional nuclei, providing the direct evidence that giant cell formation resulted from replication of the virus.