Polycistronic viral genomes

The inability of mammalian ribosomes to translate efficiently all but the 5 P3 oximal cistrons of a polycistronic mENA raises problems in the expression of viral genomes. With many viruses these problems are solved at the stages of transcription, processing and splicing of the mENA. This is obviously applicable to viruses... 

Certain eukaryotic RNA viruses (e.g., picornaviruses) contain a single-stranded genomic RNA (—7.5 kb) that functions as a polycistronic mRNA. The 5 ends of the picornaviral RNAs are not capped, but are covalently linked to a small viral protein, VPg. In contrast to the average of 55-nt-Iong 5 UTR in yeast and higher eukaryotic mRNAs, the 5 UTRs of picornaviruses are over 700 bases long and contain extensive stem—loop structures. The particular 5 UTR structures of picornaviruses by no means fit the widely accepted scanning mechanism of... 

---