Question

Why must (-)ssRNA be converted to (+)ssRNA with RNA viruses? In other words, why must the (-)ssRNA from the virus be converted to (+)ssRNA and then back to (-)ssRNA in the host?

a) (+)ssRNA is the active form of the virus in the host
b) (-)ssRNA is unstable and needs conversion for stability
c) The host immune system recognizes only (+)ssRNA
d) Conversion to (+)ssRNA facilitates viral replication

Answer 1

(-)ssRNA viruses must convert their RNA to (+)ssRNA, since host ribosomes can only directly translate (+)ssRNA into viral proteins. RNA-dependent RNA polymerase (RdRP) is responsible for this conversion, which is necessary for viral replication.

Step-by-step explanation:

The reason why (-)ssRNA must be converted to (+)ssRNA in RNA viruses is that (-)ssRNA is not immediately usable by the host ribosomes to create viral proteins. This sequence is complementary to the mRNA and must be transcribed into (+)ssRNA, which acts like cellular mRNA and can be directly translated by the host's ribosomes. The process involves an enzyme called RNA-dependent RNA polymerase (RdRP) that comes with the virus. This enzyme synthesizes the (+)ssRNA from the original (-)ssRNA genome. After (+)ssRNA is used to produce viral proteins, it can also serve as a template for the production of more (-)ssRNA, completing the cycle for viral replication. In summary, the conversion to (+)ssRNA facilitates viral replication.