For in vitro eEF1A-repRNA co-purification, DI-72(+) repRNA was biotin-labeled in standard T7 transcription reaction in the presence of 20 mM Biotin-16-UTP (Roche). After the T7 transcription, the unincorporated biotin-UTP was removed on a Bio-Rad mini gel filtration column. The biotinylated RNA was immobilized on a column containing Streptavidin MagneSphere Paramagnetic Particles (SA-PMPs). Briefly, a 30-ml suspension of SA-PMPs (Promega) was washed three times with 1 ml of water and re-suspended in 16 Phosphate Buffered Saline (PBS). Biotinylated DI-72(+) RNA (5 mg) was then added to the suspension of SA-PMPs, followed by 30 min incubation at 4uC with gentle rotation. The SA-PMPs were collected on the side of the tube in a magnetic stand and washed 3 times with 16 PBS buffer. eEF1A was translated in vitro and labeled with 35 In vitro TCV p88C RdRp assay