Protein synthesis in Semliki Forest virus-infected cells is not controlled by permeability changes.

The uptake of the GTP analogue guanylyl(beta,gamma-methylene)diphosphonate (GppCH2p) is the same in Semliki Forest virus (SFV)-infected BHK cells as in mock-infected cells, in spite of the fact that protein synthesis is inhibited by GppCH2p more markedly in SFV-infected cells than in control cells. A possible explanation for this difference is that infected cells have a lower concentration of GTP and a lower ratio of GTP:GDP than uninfected cells, and the analogue may thus be a more effective competitive inhibitor of translation. We conclude that in this system, the difference between infected and uninfected cells lies not at the plasma membrane but within the cytoplasm.