Functional role of the positive strand in dsRNA viruses: Among the two strands, what is the primary function served by the positive-sense RNA inside host cells?

Introduction / Context:Viral replication depends on converting genetic information into proteins. For dsRNA viruses, understanding which strand can act directly in translation clarifies early steps of infection.

Given Data / Assumptions:

• Genome is double-stranded RNA.
• One strand is positive-sense (same polarity as mRNA).
• We seek the function of that positive strand.

Concept / Approach:The positive-sense RNA strand corresponds to mRNA. When accessible, it can be translated by host ribosomes to produce viral proteins. Ribosomes themselves are complex ribonucleoprotein machines assembled by the cell; viruses do not produce ribosomes de novo.

Step-by-Step Solution: Define positive-sense RNA: has the same polarity as mRNA. Translation: ribosomes read mRNA to synthesize proteins. Apply to dsRNA viruses: the + strand serves as the coding template for protein synthesis once separated. Therefore, its function is protein synthesis, not ribosome production.

Verification / Alternative check:In vitro translation of purified +RNA generates viral proteins; ribosome biogenesis uses host nucleolar pathways, independent of viral RNA sense.

Why Other Options Are Wrong:

• Production of ribosomes: a host nuclear/nucleolar process; viruses do not encode complete ribosome assembly.
• Both (a) and (b): incorrect because only (a) applies.
• None of these: incorrect because (a) is true.

Common Pitfalls:Assuming any viral RNA can create cellular organelles; viral RNAs program protein synthesis, not organelle biogenesis.

Final Answer:Synthesis of protein