Alteration of the Intracellular Energetic and Ionic Conditions by Mengovirus Infection of Ehrlich Ascites Tumor Cells and Its Influence on Protein Synthesis in the Midphase of Infection

Mengovirus infection of Ehrlich ascites tumor cells caused a change of the intracellular ATP concentration. It increased by 35% within the first 3 h postinfection and then declined to zero within the next 5 h. The decrease in the ATP concentration was due, at least in part, to leakage of ATP into the medium, where it could be demonstrated by the luciferin-luciferase assay. Gross leakage of ATP was observed at 4.5 h postinfection, concomitant with the production of the first intracellular, infectious virus particles. A similar concentration decrease was detected for Mg(2+), the polyamines, and K(+), whereas an increase in the Na(+) concentration was observed. The intracellular Mg(2+) concentration varied synchronously with the ATP level, rising by 16% during the first 3 h postinfection and then progressively falling to lower values in the late period of the infectious cycle. After an initial slight enhancement, the putrescine, spermidine, and spermine concentrations declined at about 1.5 h postinfection. Wherease the intracellular K(+) concentration increased by 17% during the first hour postinfection, the Na(+) concentration diminished by the same value within the same time period, leaving the internal ionic strength unchanged early in infection. Three hours after the beginning of virus infection, there was a rapid decline of K(+) and enhancement of Na(+) within the cell. These alterations of the intracellular energetic and ionic conditions seem to be, at least in part, responsible for the cessation of virus-specific protein synthesis in mengovirus-infected Ehrlich ascites tumor cells commencing 3 to 3.5 h postinfection.