Question

​Why is the RNA genome of poliovirus by itself "infectious" when transfected into a host cell? EXPLAIN thoroughly!

Answer 1

Poliovirus causes poliomyelitis in humans and has single-stranded positive RNA as a genome. It belongs to the Picornaviridae family and each virion particle composed of VP1, VP2, VP3, and VP4 capsid proteins. The single-stranded positive-sense RNA of the Poliovirus is made up of 7500 nucleotides and polyadenylated at 3’ end. The 5’ end of RNA associated with the VPg protein which increases the half-life of RNA. The genome of Poliovirus directly acts as a mRNA, when it is entered into the cell immediately take control of host cellular machinery and synthesis the new copies of the genome and viral proteins. These two associate and form new virion particles. The negative sense RNA of RNA congaing viruses is itself not infectious, to become infectious negative RNA must be converted Into positive sense RNA. In poliovirus the positive sense RNA highly infectious because it directly acts as mRNA and synthesizes all types of proteins which required for the production of new virion particles.