Question

How do each of the following viruses deal with issues and problems related to translation initiation, expression of downstream cistrons and fine-tuning of gene expression?

TMV

Brome Mosaic Virus

Poliovirus

Answer 1

TMV :

For translation issues, TMV's replication protein binds with host genome RNA in its 5' UTR for successful translation and uses bicistronic RNA

BMV:

In BMV, tRNA like structures plays a major role in translation initaiation.They trick the host ribosomes into the translational initiation site. BMV , being a tripartite genomic Virus, uses its 3rd part, RNA3 and expresses sgRNA due to the location of downstream Cistron.

Polio Virus:

The internal entry of ribosome is mediated by the active participation of trans- acting factors.In a recent study, it is proven that Smad5, a human morphonegenic gene, has interanal RNa entry site in its 5' UTR, and this is used for expression of downstream cistron.