No abstract

Cytopathological effects by vesicular stomatitis virus (VSV) infection were studied in several cell lines. Marked polykaryocyte formation was observed in monolayers of certain strains of BHK-21 cells infected with VSV. The BHK-21-KB cells were found to be the most susceptible to virus-induced cell fusion. This type of cell fusion was related to intracellular growth of the viruses, and strong cytolytic changes were found to occur following the development of large multinucleated giant cells. The cell-fusing activity was associated with the infectivity of VSV and was neutralized by anti-VSV immune serum. The viruses irradiated for 20 minutes or heated at 60 degrees C for 10 minutes lost completely both infectivity and cell-fusing activity. These experimental results indicate that virus replication was responsible for fusion of BHK cells.

The effect of certain metabolic inhibitors on the fusion of BHK-21 cells induced by vesicular stomatitis virus (VSV) was studied. The polykaryocyte formation in infected cells and virus growth were inhibited by 2-deoxy-D-glucose and Vesicular stomatitis virus (VSV) grows rapidly and is highly cytopathic to several lines of mammalian cell culture (17). Recently it has been reported that marked polykaryocyte formation was observed in monolayers of some cell lines infected with VSV and that the virus replication caused cell fusion (3, 10, 15). These virus-cell interactions provided an excellent means for a detailed understanding of the fusion process and cytopathogenicity by using various anti-metabolites (13). The experiments were undertaken to analyse the fusion process that occurred during virus multiplication. MATERIALS AND METHODSCell cultures. Two strains of baby hamster kidney (BHK-21-KB and BHK-21-B) cells were grown in Eagle's minimum essential medium (MEM) containing 0.03% L-glutamine and 5% inactivated calf serum. The medium without glucose was used for studying the effect of 2-deoxy-D-glucose. The BHK-21-KB cells were most sensitive to VSV-induced cell fusion and BHK-21-B cells were less sensitive (15).

During continuous culture of neural PC12 cells, we obtained a drug-hypersensitive PC12 mutant cell that showed high stimulation of neurite outgrowth by various drugs. When several Chinese medicines such as shu-jing-huo-xie-tang and Wu-Ling-San were provided to these PC12 mutant cells, the frequency of nerve growth factor (NGF)-induced neurite outgrowth increased approximately 30-fold compared to NGF alone. Neurite outgrowth induced by NGF in PC12 cells is accompanied by sustained activation of mitogen-activated protein kinase (MAPK); however, these Chinese medicines did not induce MAPK activity. The findings thus indicate that certain Chinese medicines may induce neurite outgrowth by a novel mechanism which is distinct from the NGF-activated pathway in PC12 mutant cells.

Interferon (IF) induction and antiviral activity by purified spherical (S) or filamentous (F) virus-like particles and S-derived RNA was studied. A single administration of S particles prior to virus challenge reduced significantly the mortality of mice infected with western equine encephalitis (WEE) virus.