Replication of RNA viruses
RNA viruses cannot use enzymes present in the host cell to replicate the genome because no host cells replicate RNA under normal conditions.
RNA viruses either carry or code for enzymes that allow their RNA to be replicated in the host cell.
RNA-dependent RNA polymerase (RdRp) allows RNA to be replicated directly.
- Positive strand RNA encodes RdRp in the genome. It is then translated (the enzyme is synthesised) once inside the host, allowing replication of the viral genome.
- Negative strand RNA viruses carry pre-made RdRp which is used to replicate the RNA.