Protein synthesis in pseudorabies virus-infected cells: decreased expression of protein kinase PKR, and effects of 2-aminopurine and adenine.

The impact of pseudorabies virus (PRV) infection on the synthesis of host cell proteins was studied. By metabolic labeling of protein synthesis with [35S]methionine, it was observed that the translation of cellular proteins was inhibited globally in the late phase of infection and viral proteins became the dominating products. Furthermore, immunoblot analysis showed that the total protein levels of two genes involved in translational regulation, namely the dsRNA-dependent protein kinase (PKR) and extracellular signal-regulated kinase 2 (ERK2), decreased during late time of infection. Using [32P]orthophosphate labeling, it was observed that PRV infection also caused a decrease in the phosphorylation of intracellular PKR. Finally, using 2-aminopurine (2-AP, an inhibitor of serine/threonine protein kinase) or adenine (an isomer of 2-AP) to treat PRV-infected cells, we found that the inhibition of host protein synthesis by PRV was partially prevented by these two drugs, suggesting that 2-AP and adenine may share a same target and pathway to manifest the effect.