Which of the following statements about viruses, retroviruses, and HIV is correct?

Introduction / Context:
Viruses show great diversity in their genetic material and replication strategies. Retroviruses are a special group that use reverse transcriptase to copy RNA into DNA. This question tests your understanding of what characterizes retroviruses and the human immunodeficiency virus (HIV) in particular. It also checks whether you can distinguish correct statements from incorrect generalizations about RNA viruses.

Given Data / Assumptions:
• HIV is known as a retrovirus. • Retroviruses have RNA genomes and use reverse transcriptase. • Not all RNA viruses are retroviruses.

Concept / Approach:
Retroviruses are enveloped viruses with single stranded RNA genomes. They carry an enzyme called reverse transcriptase, which converts their RNA genome into complementary DNA (cDNA) after infection of a host cell. This DNA is then integrated into the host genome. HIV is a classic example of a retrovirus, so it contains reverse transcriptase and has RNA as its genetic material. On the other hand, many other RNA viruses do not use reverse transcriptase and are not classified as retroviruses. Therefore, the statement that all RNA containing viruses are retroviruses is incorrect.

Step-by-Step Solution:
Step 1: Evaluate statement A: HIV contains reverse transcriptase. As HIV is a retrovirus that converts RNA to DNA in host cells, this statement is correct. Step 2: Evaluate statement B: A retrovirus contains RNA as its genetic material. Retroviruses are defined by having RNA genomes, so this statement is also correct. Step 3: Evaluate statement D: All RNA containing viruses are retroviruses. This is false because many RNA viruses (such as influenza viruses) are not retroviruses. Step 4: Since both A and B are correct and D is false, the best option is the one that states both A and B are correct.

Verification / Alternative check:
Reference descriptions of retroviruses consistently state that they use reverse transcriptase and have RNA genomes. HIV is always classified as a retrovirus and its life cycle diagrams show reverse transcription from RNA to DNA. In contrast, virology texts classify many RNA viruses, such as picornaviruses and flaviviruses, under different families and not as retroviruses. This confirms that only statements A and B are correct together.

Why Other Options Are Wrong:
Option A alone: While statement A is correct, option C captures both correct statements A and B, making option A incomplete. Option B alone: Statement B is also correct, but again option C, which combines both, is more complete. Option D: Incorrect because many RNA viruses do not use reverse transcriptase and are not retroviruses. Option E: Incorrect because both A and B are in fact correct statements.

Common Pitfalls:
Students sometimes assume that any virus with RNA must follow the retrovirus pattern, leading to the false conclusion that all RNA viruses are retroviruses. Another pitfall is to think that reverse transcriptase is present in all viruses, when in reality it is specific to retroviruses and some related elements. To avoid confusion, remember that retroviruses are defined by both their RNA genome and their use of reverse transcriptase to integrate into host DNA.

Final Answer:
The correct choice is that both statement A and statement B are correct, meaning HIV contains reverse transcriptase and a retrovirus contains RNA as its genetic material.