The outermost layer of a virion fulfills which of the following functions of the virus?

• A. Synthesis of viral proteins
• B. Production of host cell enzymes
• C. Replication of viral nucleic acid
• D. Protection of the viral genome and facilitation of host cell attachment

Answer: (D)

Verified step by step guidance

1. Identify the components of a virion, which typically include the nucleic acid (genome), capsid (protein coat), and sometimes an outer envelope.
2. Understand the role of the outermost layer, which can be either the capsid or an envelope derived from the host cell membrane.
3. Recognize that the outermost layer does not participate in synthesis of viral proteins, production of host enzymes, or replication of viral nucleic acid, as these processes occur inside the host cell after infection.
4. Focus on the protective function of the outermost layer, which shields the viral genome from environmental damage and enzymatic degradation.
5. Note that the outermost layer also contains structures (such as glycoprotein spikes) that facilitate attachment to specific receptors on the host cell surface, enabling viral entry.