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babar90 t1_jc2aokw wrote

For coronaviruses the genome is translated into a big polyprotein which is cleaved in a dozen of proteins by a protease it includes. That dozen of proteins somehow self assemble into a replication complex which also makes the (lipid) ER membrane bubble. Into such a bubble the viral polymerase of the replication complex replicates the genome many times and also makes many subgenomic mRNA coding for the structural proteins. Eventually the bubble bursts and frees the many copies of the genome and the many subgenomic mRNA, those are translated and flood the environment with viral structural proteins. Together with the copied genomes all this mess self assemble into new virions. Both the bubbling and the natural cellular transport of membrane anchored proteins help the new virions to egress the cell.

Hope this helps your understanding of the standard strategy for virus replication.

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not_my_usual_name OP t1_jc3gw7y wrote

This is interesting. My understanding was always that the viral RNA is seen as RNA coming from the cell's DNA, and the cell's protein assembling machinery would assemble a virus according to the virus' RNA. You're saying that the virus' RNA actually has the cell's machinery assemble a virus factory "replication complex"?

Presumably in the replication complex, there's some molecule producing viral RNA. Does it do that by looking at and copying the original strand of RNA (or copies)? If not, then was the RNA production machine built "knowing" how to make the viral RNA? I'd think that involves some compression, which is what I'm most curious about.

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babar90 t1_jc3jiw3 wrote

All the translation (making of proteins) is done by the cell's ribosomes (this for almost every viruses) from mRNA strands as the cells do everydays to make proteins.

But the replication and transcription (making copies of the full length RNA genome and some mRNA copied from parts of it) is achieved by a viral polymerase, a RdRp.

This is for RNA viruses. Many DNA viruses do something along the same lines, but some do not and make their genome enter the cell nucleus to exploit either its DNA replication machinery or its DNA->RNA transcription machinery, or both.

Retroviruses are some kind of hybrid between the two strategies.

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