A retrovirus _____.

• A. Is a DNA virus.
• B. Integrates viral DNA into the host chromosome.
• C. Requires the viral protein replicase to replicate its genome.
• D. All of the above.

Answer: (B)

Verified step by step guidance

1. Understand what a retrovirus is: Retroviruses are a type of virus that have RNA as their genetic material. They are unique because they use an enzyme called reverse transcriptase to convert their RNA into DNA after infecting a host cell.
2. Identify the key characteristic of retroviruses: One of the defining features of retroviruses is their ability to integrate their viral DNA into the host cell's chromosome. This integration is facilitated by the enzyme integrase, which is encoded by the virus.
3. Evaluate the given options: The first option states that a retrovirus is a DNA virus, which is incorrect because retroviruses are RNA viruses that convert their RNA into DNA. The second option correctly describes the integration of viral DNA into the host chromosome, which is a hallmark of retroviral infection.
4. Consider the role of viral proteins: The third option mentions the viral protein replicase, which is not typically associated with retroviruses. Retroviruses use reverse transcriptase, not replicase, to replicate their genome.
5. Determine the correct answer: Based on the understanding of retroviruses, the correct answer is the option that states 'Integrates viral DNA into the host chromosome,' as this is a key process in the retroviral life cycle.