Core roles of the viral capsid: Which statement best describes the functions served by a virus capsid?

Introduction / Context:
The capsid is the protein shell enclosing viral nucleic acid. Beyond passive containment, its design underpins stability, host recognition, and environmental survival, making a comprehensive view of capsid functions essential for understanding infection biology and vaccine design.

Given Data / Assumptions:

• Capsid subunits (capsomeres) self-assemble into icosahedral, helical, or complex forms.
• Viruses must protect their genome outside the host and then locate and enter susceptible cells.
• Transmission between hosts often occurs in harsh environments (desiccation, enzymes, UV).

Concept / Approach:
Capsids are multifunctional. They physically protect RNA/DNA from shear, pH, and nucleases; they present receptor-binding motifs or, in enveloped viruses, underlie and organize glycoproteins that mediate attachment and entry; and they stabilize virions during environmental transit, enabling efficient host-to-host spread.

Step-by-Step Solution:
Evaluate option A: true—capsids shield the genome from physical/enzymatic damage.Evaluate option B: true—capsid or associated proteins contribute to receptor binding and tropism.Evaluate option C: true—capsids create a robust particle for transmission.Therefore, the inclusive answer is “all of the above.”

Verification / Alternative check:
Nonenveloped enteric viruses (e.g., poliovirus) illustrate extreme capsid robustness and receptor specificity.

Why Other Options Are Wrong:
Each single-function option is incomplete; the capsid performs all listed roles.

Common Pitfalls:
Assuming only enveloped viruses have receptor-binding proteins; in many nonenveloped viruses, the capsid itself carries the attachment determinants.

Final Answer:
all of the above