Cytopathic effect (CPE): what is the term for virus-induced deterioration of host cell structure? Choose the correct term used in cell culture virology for visible structural changes caused by viral replication.

Introduction / Context:
When viruses replicate in cultured cells, they often produce characteristic morphological changes observable under the microscope. Recognizing and naming these changes is fundamental in diagnostic and research virology.

Given Data / Assumptions:

• Virus replication can cause rounding, shrinkage, syncytia, inclusion bodies, and lysis.
• These changes can be virus- and cell line-specific.
• The question asks for the standard term describing this overall deterioration.

Concept / Approach:
“Cytopathic effect” (CPE) is the umbrella term for structural alterations in host cells due to viral invasion. CPE patterns (for example, ballooning, syncytium formation, focal degeneration) are used to suggest etiologic agents prior to confirmatory tests.

Step-by-Step Solution:
Recall definition: CPE = morphological cell damage from viral replication.Map examples: HSV causes multinucleated giant cells; paramyxoviruses cause syncytia; adenovirus causes rounding and clustering.Choose “Cytopathic effect” as the correct term.

Verification / Alternative check:
Cell culture manuals and diagnostic algorithms begin with CPE observation before antigen detection, PCR, or sequencing, confirming the terminology.

Why Other Options Are Wrong:

• Aneuploidy: abnormal chromosome number, not a general term for virus-induced morphology.
• Protopathic effect: not the accepted term in virology for culture changes.
• Cytotonic effect: used in toxin pharmacology for nonlethal morphological changes; not the standard virology term.
• None of these: incorrect because CPE is correct and widely used.

Common Pitfalls:
Assuming all viruses cause identical CPE. Patterns vary; hence, CPE guides, but does not by itself prove, a specific diagnosis.

Final Answer:
Cytopathic effect.