Which of the following is most likely to be present on the surface of a skin epithelial cell that has been infected by a virus?

• A. Viroid RNA fragments
• B. Bacterial lipopolysaccharides
• C. Prion proteins
• D. Viral antigens

Answer: (D)

Verified step by step guidance

1. Understand the context: When a skin epithelial cell is infected by a virus, the virus uses the cell's machinery to replicate and produce viral components.
2. Recall that viral antigens are viral proteins expressed on the surface of the infected host cell, which can be recognized by the immune system.
3. Eliminate options that are unlikely to be present on the surface of a virus-infected cell: Viroid RNA fragments are infectious RNA molecules that do not produce proteins and typically infect plants, not animal cells; bacterial lipopolysaccharides are components of bacterial outer membranes, not viral infections; prion proteins are misfolded proteins associated with certain neurodegenerative diseases, unrelated to viral infection.
4. Conclude that the most likely molecules present on the surface of a virus-infected skin epithelial cell are viral antigens, as these are produced during viral replication and displayed on the cell membrane.
5. Therefore, the correct answer is viral antigens because they serve as markers of infection and trigger immune responses.