Question

Which of the following is the best technique for detecting HIV:

• A. \( \text{Widal test} \)
• B. \( \text{Real-time PCR} \)
• C. \( \text{Polymerase chain reaction} \)
• D. \( \text{Reverse transcriptase-PCR} \)

Hint:

HIV testing methods include: 1. ELISA: For initial screening. 2. Western blot: For confirmation. 3. RT-PCR: Highly sensitive for detecting viral RNA, especially in early stages of infection.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
HIV is a retrovirus, meaning its genetic material is RNA, and the right detection method must be built to work with an RNA genome.

Step 2: Key Formula or Approach:
Check whether each technique can directly handle RNA or whether it needs an extra conversion step first, since a DNA only method cannot detect an RNA virus on its own.

Step 3: Detailed Explanation:
The Widal test detects antibodies against Salmonella and has no connection to viral genetic material at all.
Standard PCR and real time PCR both amplify existing DNA sequences, but HIV does not naturally have a DNA genome, so neither method can start directly from the virus's RNA.
Reverse transcriptase-PCR solves this gap by first using the enzyme reverse transcriptase to copy the viral RNA into complementary DNA. Once this DNA copy exists, the PCR step can amplify it to detectable levels, allowing sensitive and specific identification of the virus.

Step 4: Final Answer:
Because reverse transcriptase-PCR is the only method here that can first convert HIV's RNA into DNA before amplification, it is the best technique for detecting HIV among the options.