If one cell is having SG RNA without having structural genes so how that RNA is transferred from one cell to other if it does not form whole virus which lyse one cell and attack other cell .
It is possible that RNAs can be incorporated in exosomes, secreted and then uptaken by other cells. However, I don't know whether sgRNA can be secreted by this way but it would be interesting to study this research issue.
As I was in search of getting the right answer for the above asked question, I came up with the answer that as the cell divides the subgenomic replicons transfer from one cell to another as they are present in the cytoplasm of the cell. and for their efficient replication inside cells, they have viral promoters.