Replication of the Viral RNA
In the cytoplasm of an uninfected mammalian host cell, so far no enzymes have been detected that synthesize RNA on an RNA template. The incoming poliovirus contains a plus strand RNA but does not carry an RNA-replicase. Formation of replicase(s) is a prerequisite for the synthesis of viral progeny RNA. Therefore, the parental RNA which encodes for replicase protein(s) has first to function as mRNA. Replication of the viral RNA then proceeds in two distinct steps. First, the parental RNA serves as template for the synthesis of complementary RNA, then the minus strand serves as template for the synthesis of new viral RNA chains with the same polarity as the parental RNA (plus-strand RNA). This newly formed + RNA has three potential fates: a) it can again act as template for the synthesis of cRNA, b) it may function as mRNA, or c) it may become incorporated into progeny virus particles. Figure 94 (p. 374–375) shows a schematic overview of the principle steps in poliovirus RNA replication.
KeywordsReplication Complex Minus Strand cRNA Synthesis Poliovirus Infected Cell vRNA Synthesis
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