Oncosis in MA104 cells is induced by rotavirus infection through an increase in intracellular Ca2+ concentration

Rotavirus infection modifies the metabolism and ionic homeostasis of the ho st cell. First, there is an induction of viral synthesis with a parallel sh utoff of cell protein production, followed by an increase of plasma membran e Ca2+ permeability, thereby inducing an increase of free cytoplasmic and s equestered Ca2+ concentrations. Cell death follows at a later stage. We stu died the role of the increase in Ca2+ concentration in cell death. An eleva tion of extracellular Ca2+ concentration during infection induced an increa se in [Ca2+](i) and potentiated cell death. Buffering the increases in [Ca2 +](i) with BAPTA added at 6 h p.i. reduced the cytopathic effect without in hibiting viral protein synthesis and infectious particle production. Metoxy verapamil (D600), a Ca2+ channel inhibitor, added at 1 h p.i. reduced Ca2permeability, the increases in [Ca2+](i), and cell death produced by infect ion without modifying Viral protein synthesis and infectious titer. Thapsig argin, the inhibitor of Ca2+-ATPase of endoplasmic reticulum, potentiated t he increase of [Ca2+](i) and accelerated the time course of cell death. Dou ble staining with fluorescein diacetate and ethidium bromide or acridine or ange and ethidium bromide showed that infected MA104 cells had lost plasma membrane integrity without DNA fragmentation or formation of apoptotic bodi es. These results support the hypothesis that the increase in [Ca2+](i) due to a product of viral protein synthesis triggers the chain of events that leads to cell death by oncosis. (C) 1998 Academic Press.