Plant viral diseases affect a significant number of food crops world-wide and can have severe impact on both economic conditions and food supply. Protein synthesis is a key step in viral infection, however the mechanism is not well understood. Biophysical studies have provided insight into the mechanism of this process and how viruses compete for host cell machinery to synthesize viral proteins. We have recently gained new insight into the role of the potyvirus genome-linked protein, VPg in wheat germ in vitro translation. Addition of VPg to wheat germ extracts leads to enhancement of uncapped (viral) RNA translation and inhibition of capped (host) RNA translation. To understand the molecular basis of these effects, we characterized the interaction of VPg with eIF4F, eIFiso4F, and a structured RNA derived from tobacco etch virus. When VPg formed a complex with eIF4F the affinity for TEV RNA increased more than 4-fold compared with eIF4F alone. The binding of eIF4F to TEV RNA correlates with translational efficiency. Viral RNA which is generally translated less efficiently than capped RNA, must compete for available cell components for translation. In the presence of both capped and uncapped mRNA, VPg competes with eIF4F and eIFiso4F for cap binding. Formation of a VPg-eIFiso4F complex leads to a non-productive complex that reduces host cell translation. In contrast, an eIF4F-VPg complex binds more tightly to viral RNA and enhances its translation. These complementary functions provide a significant competitive advantage for viral RNA.