Advances on IRES Element of Picornavirus mRNA

Unlike most Eukaryotic mRNAs, FMDV RNA is not capped at 5′end but has a small viral coded protein (VPg) covalently attached to the terminal 5′uridine residue. Translation initiation of Picornavirus RNA is dependent on the presence of an internal ribosome entry site (IRES) element at the 5′end of genome RNA, and it is different from that of most eucaryotic cell that initiate at a cap element. Foot and Mouth disease virus (FMDV), a member of the genus Aphthoviridae of the Picornavirus family, cause a highly contagious viral disease of cloven hooved animals and it is of paramout economic importance. Entire viral particles are composed of a single stranded positive sense RNA about 8500 nucleotides (nt), capsid proteins and a little un structural proteins and actins carried secretly during encapsidation. Up to now, it has been testified that IRES is a unique element directing the translation initiation in FMDV RNA. The sequences and secondary structures of IRES are compared. Interaction between IRES and translation initiation factors and relation with virulence of FMDV is summarized.