抄録
Variola virus (Yamamoto strain) was shown to multiply in culture of HeLa cells, causing cytopathogenic effects. In succeeding passages, the effects appeared sooner and infectivity titer of intracellular virus increased. It was found that their occurred a drop in infectivity in the first few hours, followed by an increase in infectivity after 11 hours. The maximum yield of variola virus in a infected HeLa cell was about 20 infectious units per cell.
Intracytoplasmic inclusion bodies were observed. The inclusions were stained red with the Giemsa stain, blue or bluigh red with hematoxylin eosin stain. Electron microscopy of the infected cells revealed that they had so-called matrix type inclusions, which contained nothing associated with viral component in early stage of infection, but became contain several kinds of developmental form after 10-hour-infection. In the matrix a membrane-double membrane seemed progressively to enclose a pre-existing viroplasmic component.
