Here we investigate the relationships between the thermodynamic stability of the HIV type 1 (HIV-1) RNA frameshift site stem-loop, frameshift efficiency, and infectivity, using pseudotyped HIV-1 and HEK293T cells.  The data reveal a strong correlation between frameshift efficiency and local, but not overall, RNA thermodynamic stability.  Thus, frameshift efficiency is determined by the strength of the thermodynamic barrier encountered by the ribosome.  Here, we utilized a panel of mutant HIV strains to demonstrate that in cells, frameshifting efficiency is correlated with the stability of the local thermodynamic barrier to ribosomal translocation. 
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