FIG. 4.

Vitamin B₁₂ inhibits pCSFV1-3/HCV4- and GBV-B IRES-directed translation. The effect of vitamin B₁₂ on translation directed by these IRES elements was examined by incubating vitamin B₁₂ with the RNA for 10 min at room temperature prior to translation in a RRL. RNA with the same volume of water represented the control. pHCV-IRES-CAT and pCSFV-IRES-CAT translations in the presence and absence of vitamin B₁₂ represented positive and negative controls for inhibition by vitamin B₁₂ (A). The predicted structure of the GBV-B IRES is similar to that of the HCV IRES, including domain IV (B). (C) The effect of vitamin B₁₂ on GBV-B IRES-directed translation.