At this stage, the virus uses the proteins of the cell to replicate its genome. This particular stage is different in different types of viruses:
Single strand DNA viruses: the strand of viral DNA goes to the nucleus because DNA replication proteins are located there. The nuclear proteins make the second strand of viral DNA, and an intermediate double strand viral DNA is formed. It is used for two purposes:
- to produce RNA needed for viral proteins synthesis;
- to produce new single strand DNA genomes for new viruses;
Double strand DNA viruses: The double strand viral DNA also goes to the nucleus after uncoating. There, the nuclear protein can make new viral DNAs, as well as RNA “messages” for viral proteins.
As far as the RNA viruses go, they undergo a different process-they replicate in the cytoplasm:
- Single strand RNA viruses: The viral genome replicates in the cytoplasm. Also, the viral RNA can be directly used for the production of the new viral proteins.
- Double strand RNA viruses: The double-stranded RNA genome of the virus is used both for production of single RNA strands needed for protein synthesis, as well as for production of new complete RNA genomes made of two strands.
- RNA retroviruses: This is a unique group of viruses. While they have a genome made from the single strand of RNA, they reproduce quite differently:
- A special enzyme called RNA-dependent DNA polymerase, or revertase, uses this single strand to make a strand of DNA.
- Based on this new strand of DNA, a second strand is formed.
- The double strand viral DNA enters the nucleus and inserts itself into the genome of the host.
- The viral DNA can replicate together with the host DNA when the cell divides.
- The viral DNA region is used for making proteins and new viral genomes.
[…] We’ve found that viruses are everywhere, in us, around us, all over. We even learned they evolve when they inject their DNA or RNA into the host cell be it a bacteria or a mammal cell the host cell automatically copies their DNA or RNA and the […]