Replication of a Positive + Sense Strand of Lytic RNA PhagE

Viruses are differentiated based on how they reproduce within a cell. There are several types including singled-stranded positive-sense RNA viruses (ss+RNA), single-stranded negative-sense RNA viruses, double-stranded RNA viruses, retroviruses, and double-stranded DNA viruses. The animation shows reproduction of ss+RNA viruses within a cell.

In the first step of viral replication, early proteins are made. An example of an early protein is viral replicase. This is an RNA-dependent RNA polymerase (RdRp), meaning that it uses RNA as a template to make more RNA. In step 2, the RdRp copies the original positive-sense RNA strand to make a double-stranded RNA replicative complex. The newly made negative-sense RNA strand is used as a guide to make more single strands of positive-sense RNA (step 3). These single strands of positive-sense RNA can be used as mRNA to make the structural proteins (step 4) or will be packaged into the final virions. Step 5 shows that the structural proteins and the positive-sense single strands of RNA are packaged together (as indicated by the dotted green arrow) to bud out or exit the cell when it lyses (explodes).