U_L38 expression is sufficient to drive metabolic activation.

After 24h incubation, conditioned serum free medium from confluent MRC5 cells transduced with an empty vector or UL38 was harvested for analysis. (A) Western blot analysis of UL38 expression in EV and UL38 transduced cells compared to mock and HCMV infected cells (MRC5 cells infected at MOI = 3 and harvested at 53hpi). (B-D) Changes in metabolic intermediates present in the conditioned medium were measured. Values are means ± SE (n = 3). (*pL38 protein (UL38) were cultured in serum free media for 24h. Cells were then quenched and extracted for analysis. Absolute intracellular metabolite concentrations were determined by LC-MS/MS and normalized to protein levels. Values are means ± SE (n = 6). (*p<0.05, **p<0.01).