ENHANCED INTRACELLULAR CALCIUM-CONCENTRATION DURING POLIOVIRUS INFECTION

The infection of human fibroblasts by poliovirus leads to a notable increase in the intracellular calcium concentration, [Ca2+](i), measured by microfluorimetry or by flow cytometry. [Ca2+](i) increases from 2 to 3 h postinfection, and by the fifth hour there is a 5- to 10-fold increase in [Ca2+](i), At this time postinfection there is active viral protein synthesis. The modifications in [Ca2+](i), are not observed in the presence of cycloheximide, guanidine, or Ro 09-0179, indicating that virus gene expression is required for the increase in [Ca2+](i). Attempts to identify the source of the intracellular Ca2+ by using different inhibitors of calcium fluxes suggest that calcium enters from the culture medium through voltage-sensitive calcium channels.