Differences in the morphology of herpes simplex virus infected cells. II. Type specific membrane alterations of HSV-1 and HSV-2 infected cells.

The two types of herpes simplex virus (HSV-1, HSV-2) induced significantly different alterations in the morphology and permeability of infected cells. HEp-2 cells infected with HSV-1 (strain THEA) were characterized by the formation of polynuclear syncytia. In contrast, after infection with HSV-2 (strain D316, DD), the cells were rounded up. The HSV-1 strains KOS and LS5039 and the HSV-2 strain 196 induced both types of cytopathic effect. As shown by comparative scanning and transmission electron microscopy newly synthesized virus particles of the various strains of HSV-1 were generally found to be restricted to smooth areas of the cell surface. In these areas the number of microvilli was reduced in comparison to uninfected cells. However, the progeny viruses of the strains of HSV-2 were mainly connected with protrusions of the cell membrane (microvilli and filopodia). The morphological changes in cells infected with either type of HSV were associated with different functional alterations of the cell membrane. The membranes of HEp-w cells became more stable after infection with HSV-1. This is characterized by a reduced permeability for 51Cr as well as by a decreased sensitivity to the detergent Triton-X-100. HSV-2 induced opposite effects on the stability of the membrane in infected cells. In contrast to these findings with HEp-2 cells, opposite results were obtained with primary chick embryo fibroblasts: Infection with HSV-1 rendered the cell membrane more permeable for 51Cr and a reduction of the 51Cr-release was achieved by infection with HSV-2. The results show that HSV-cell interactions depend on the type of the virus as well as on the type of the infected cell.