Studies of the FCV signal have indicated a role for eIF3 in termination-reinitiation as, for example, addition of supplementary eIF3 to RRL is able to specifically stimulate synthesis of the ORF3 reinitiation product [17] . Furthermore, greater stimulation is observed with mRNAs that show a partial defect in reinitiation in the absence of eIF3, suggesting that the increase in eIF3 concentration may rescue the negative phenotype, perhaps by allowing increased binding of eIF3 to the mRNA [17] . To analyse whether the same is true of reinitiation on the BM2 ORF, we examined the effect of exogenous eIF3 on reinitiation on mRNAs containing a fully functional signal (BM2wt, BM2-204), or mutants by AONs are shown above the sequence, colour coded to match the relevant AON sequence. The BM2wt RNA was translated as above in the presence of increasing AON concentrations as indicated above each autoradiograph. doi:10.1371/journal.pone.0016822.g002 defective by virtue of a deletion (BM2-207, BM2-210, described in [11] ) or a substitution in motif 1 (BM2-AG, BM2-AC). To focus specifically on the effect of eIF3 on termination-reinitiation rather than 59-dependent initiation, the BM2 sequences were sub-cloned such that the rlucM1 ORF would initiate on an alanine codon provided as part of the CrPV IRES. As can be seen in Figure 7 , exogenous eIF3 specifically stimulated synthesis of the BM2fluc reinitiation product with all of the mRNAs tested, including those mutants that were essentially inactive (BM2-210 and BM2-AC; most evident in long exposures, see right panel, Figure 7) . Importantly, the addition of an unrelated, similarly purified protein had no effect on reinitiation in any of the RNAs described above (Figure S1 ), further highlighting the specificity of eIF39s effect on reinitiation.