Interaction of eukaryotic initiation factor eIF4B with the internal ribosome entry site of foot-and-mouth disease virus is independent of the polypyrimidine tract-binding protein

Eukaryotic translation initiation factor 4B (eIF4B) binds directly to the i nternal ribosome entry site (IRES) of foot-and-mouth disease virus (FMDV). Mutations in all three subdomains of the IRES stem-loop 4 reduce binding of eIF4B and translation efficiency in parallel, indicating that eIF4B is fun ctionally involved in FMDV translation initiation. In reticulocyte lysate d evoid of polypyrimidine tract-binding protein (PTB), eIF4B still bound well to the wild-type IRES, even after removal of the major PTB-binding site. I n conclusion, the interaction of eIF4B with the FMDV IRES is essential for IRES function but independent of PTB.