Question

12. Describe how (-) ssRNA and dsRNA viruses switch from mRNA to genome RNA synthesis.

Answer 1

In the case of positive-stranded viruses, the genomic RNA act as a template for both process translation and RNA replication. An RNA structure at the 5′ end of the viral genome carries signals that are responsible to control both viral translation and RNA synthesis or transcription. The RNA structure interacts with the cellular factor PCBP to regulates viral translation.

The genomes of positive-stranded RNA viruses act as mRNAs to direct the synthesis of viral translation; this also serves as templates for genome replication.   the movement of ribosomes with the viral RNA in the 5′ to 3′ direction responsible to the polymerase action and initiates replication at the 3′ end of the RNA to synthesize a positive-strand vice versa for complementary negative strand.

the repression of viral translation confirms that all viral proteins required for the replication of RNA. each individual polypeptide present in equal concentrations and, act as a translation shut-off factor. Shine–Dalgarno sequences use to control the translation of the core protein.