🧪 What is HIV Western Blot Test?

The HIV Western Blot is a confirmatory blood test used to detect specific antibodies to HIV proteins (antigens) following a positive screening test (such as ELISA or rapid test).

• It separates HIV proteins using gel electrophoresis, then probes the patient's serum for specific antibodies.
• It is highly specific, helping to confirm or rule out false positives from earlier tests.

Note: In many modern guidelines, Western Blot is being replaced by HIV-1/2 differentiation assays and HIV RNA PCR due to higher sensitivity and faster turnaround.

❓ Why is the Test Done?

To:

• Confirm HIV infection after a reactive ELISA/rapid test
• Distinguish between true positive and false positive results
• Provide definitive diagnosis in prenatal screening or medico-legal settings

🔬 How It Works

• HIV proteins (e.g., gp160, gp120, gp41, p24, p31) are immobilized on a strip
• Patient serum is applied
• Presence of antibodies against these proteins produces visible bands

📊 Interpretation of Results

Western blot is less sensitive during early (window period) infection – hence may be negative even if HIV is present in very early stage.

🧠 Associated Organs & Conditions

🔄 Related / Follow-Up Tests

• HIV Antibody/Antigen Combo (4th Gen ELISA) – Initial screening
• HIV RNA PCR / Viral Load – Confirms and monitors infection
• CD4 Count – Evaluates immune status
• HIV-1/2 Differentiation Immunoassay – Modern confirmatory test
• HIV Drug Resistance Test – Before ART initiation
• STD Panel – Syphilis, Hep B/C, chlamydia, gonorrhea, etc.

✅ Fasting Required?

📝 Summary Table