Host cell macromolecules during infection – Identify the exception: Virulent and nonvirulent (attenuated) viruses typically do all of the following during infection, except which one?

Introduction:
Many viruses reprogram host biosynthesis to favor viral replication. Common outcomes include inhibition of host DNA, RNA, and protein synthesis—collectively called host shutoff. Distinguishing typical inhibitory effects from atypical stimulation clarifies how viruses commandeer cellular resources. This question asks for the option that is generally not a feature shared by virulent and nonvirulent strains.

Given Data / Assumptions:

• Viruses commonly suppress host transcription and translation to prioritize viral gene expression.
• Some lytic infections degrade host DNA.
• Nonvirulent (attenuated) strains can still impose host shutoff mechanisms, though often less aggressively.

Concept / Approach:
Evaluate which action contradicts the typical viral strategy. While degrees vary by virus, stimulation of global host macromolecule synthesis is not a common shared feature; instead, viruses usually inhibit host macromolecular processes and redirect them toward viral synthesis.

Step-by-Step Solution:
Step 1: List common viral effects: inhibit host DNA replication, suppress host mRNA production, and shut off host translation.Step 2: Recognize some viruses encode nucleases or trigger pathways that degrade host DNA or mRNA.Step 3: Compare with “stimulate host macromolecule synthesis,” which runs counter to conserved host-shutoff strategies.Step 4: Select stimulation as the exception (i.e., what they may not do).

Verification / Alternative check:
Examples include poliovirus cleavage of eIF4G (translation shutoff), herpesviruses’ host shutoff proteins, and influenza endonuclease/NS1 activities—all reducing host macromolecular synthesis rather than increasing it.

Why Other Options Are Wrong:

• Inhibit DNA/RNA synthesis: widely documented across diverse viruses.
• Degrade host DNA: observed in several lytic infections.
• Shut off translation: a recurring strategy to privilege viral mRNAs.

Common Pitfalls:
Interpreting “nonvirulent” as “non-replicating”; many attenuated strains still induce host shutoff to some degree.

Final Answer:
Stimulate host cell macromolecule synthesis.