RNA was synthesized from a template obtained by polymerase chain reaction (PCR) from bases 3821 to 628 of the pBR322 DNA plasmid, where the frameshifting RNA signal from HIV-1 was cloned into the EcoRI and HindIII restriction sites and a T7 promoter was appended to the template in the course of the PCR reaction (42) . The DNA components of the handles were prepared by PCR from pBR322. Handle A (pBR322 bases 3821 to 3) was biotinylated, and one of the primers used to amplify handle B (pBR322 bases 30 to 628) was purchased with a 5 0 digoxigenin group.