ABSTRACT
The picornaviruses represent an important group of eukaryotic pathogens, the intracellular life cycles of which are characterized by several unique macromolecular/biosynthetic events. Poliovirus is a member of the enterovirus group of the Picornaviridae and perhaps best exemplifies the unique aspects of the Picornavirus group. The coding region of the polio genome contains a single, long, open-reading frame that encodes 2209 consecutive amino acids that would give rise to a polyprotein having a molecular weight of 247,000 daltons. The overall genome structures and polyprotein organization of all picornaviruses are roughly equivalent. The viral RNAs uniformly possess a 5'-linked VPg protein and a 3' polyadenylate tract. The crude and partially purified RNA replication complexes from extracts of virus-infected HeLa cells are associated with numerous host-cell proteins. Poliovirus RNA synthesis occurs primarily in a membranous environment. In vitro RNA synthesis assays using a crude membrane fraction from infected cells demonstrated that the membrane fraction is responsible for the majority of virus-specific RNA synthesis.
