Question

A screen test for detection of human immunodeficiency virus (HIV) reveals a positive ELISA test. Which test will be used to confirm the diagnosis of HIV? A. Radioimmunoprecipitation assay (RIPA) test B. p24 levels C. Lymphocyte count D. Indirect immunofluorescence assay (IFA)

Short answer

Answer: The indirect immunofluorescence assay (IFA) test is commonly used to confirm the diagnosis of HIV after a positive ELISA test.

Step-by-step solution

Understand ELISA and its role in HIV detection

The enzyme-linked immunosorbent assay (ELISA) is a widely used method for detecting the presence of specific antibodies or antigens in a patient's blood sample. In HIV detection, the ELISA test is used to detect the presence of HIV-specific antibodies. A positive ELISA test means that HIV antibodies have been detected in the patient's blood, but it does not confirm the diagnosis of HIV. A confirmatory test is needed to ensure accuracy and to rule out false-positive results.

Review the given test options

A. Radioimmunoprecipitation assay (RIPA) test: RIPA is an immunoprecipitation technique that involves the use of radioactively labeled antigens to detect specific antibodies in a sample. It can be used as a confirmatory test for HIV, but it is not the most commonly used method. B. p24 levels: p24 is a protein found in the HIV virus. Measuring p24 levels can be helpful in detecting early-stage HIV infection, but it is not a confirmatory test for HIV diagnosis. C. Lymphocyte count: A decrease in lymphocyte count can be a sign of HIV infection since the virus attacks the immune system. However, this is not a specific test for HIV diagnosis, and it cannot be used as a confirmatory test. D. Indirect immunofluorescence assay (IFA): IFA is a method that uses fluorescently labeled antibodies to detect the presence of specific antigens in a sample. In the context of HIV, IFA can detect HIV-specific antibodies and can be used as a confirmatory test for HIV diagnosis.

Identify the best confirmatory test for HIV diagnosis

Based on the explanations above, the best test to confirm the diagnosis of HIV after a positive ELISA test is the indirect immunofluorescence assay (IFA), which is option D. This method specifically detects HIV antibodies and is widely used as a confirmatory test for HIV diagnosis. In conclusion, the correct answer to this question is option D. Indirect immunofluorescence assay (IFA).