About

Picornaviruses are viruses with naked, icosahedral capsids and small diameters of 30nm. VP1, VP2, and VP3 are the proteins that form the outer surface of the virus capsid. The genome is a single positive-stranded RNA molecule. The viral RNA is infectious because it is translated on entry into the cell to produce all the viral proteins required for viral replication. Picornavirus genomic RNA is unique because it is covalently linked at the 5′ end to a protein called VPg.  In addition to the genome-linked protein VPg at the 5′ end, the genome also commonly includes has a 5′ region containing the IRES, the protein coding region, the 3′ region containing a pseudoknot, and the poly(A) tail. The pseudo-knot is not always present but it plays a role in controlling viral RNA synthesis. Biochemical studies have also shown the presence of a single, long, open reading frame (ORF) on the viral RNA that is processed to form individual viral proteins. The polyprotein is cleaved during translation.