Which one of the following steps does NOT occur during the multiplication of a picornavirus?

• A. Synthesis of a DNA intermediate
• B. Attachment of the virus to host cell receptors
• C. Replication of viral RNA in the cytoplasm
• D. Translation of viral RNA into a polyprotein

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the nature of picornaviruses. Picornaviruses are positive-sense single-stranded RNA viruses, meaning their genome can directly serve as mRNA for protein synthesis.
2. Step 2: Review the typical steps in picornavirus multiplication: attachment to host cell receptors, entry, uncoating, translation of viral RNA into a polyprotein, replication of viral RNA in the cytoplasm, assembly, and release.
3. Step 3: Recognize that because picornaviruses have RNA genomes, they do not require a DNA intermediate for replication. DNA intermediates are characteristic of retroviruses or DNA viruses, not RNA viruses like picornaviruses.
4. Step 4: Confirm that attachment to host cell receptors is an essential first step for viral entry, and translation of viral RNA into a polyprotein occurs immediately after uncoating in the cytoplasm.
5. Step 5: Conclude that the step 'Synthesis of a DNA intermediate' does NOT occur during picornavirus multiplication, as their replication cycle involves RNA replication directly in the cytoplasm without a DNA stage.