Since it is known that eEF1A can bind to the 39-UTR of TBSV (+)RNA as well as to the tombusvirus replication proteins [25] and to the TCV RdRp ( Fig. S2A) , we wanted to test if the above stimulating activity of eEF1A in the in vitro RdRp assay was due to binding of eEF1A to the (+)RNA template and/or to the TCV RdRp protein.