Western blotting is the confirmatory test for HIV. In the standard interpretation, which combination of bands constitutes a reactive (positive) result per WHO/CDC criteria?
- A Two or more bands from: p24, gp41, gp120/gp160 (CDC 1993 criteria) — or any 2 of p24, gp41 and gp120/160 (WHO criteria) ✓
- B Any single reactive band is sufficient for positive interpretation
- C Presence of p17 band alone is sufficient as it is the most specific band
- D All 9 standard bands (p17, p24, p31, gp41, p51, p55, p66, gp120, gp160) must be reactive
Explanation
Western blot (WB) for HIV-1 detects antibodies against specific viral proteins separated by electrophoresis. Interpretation criteria for positive WB: CDC 1988 criteria — any 2 of p24, gp41, gp120/gp160; WHO criteria — 2 or more envelope bands (gp41 and/or gp120/gp160), or gp41/gp120/gp160 alone is sufficient in some WHO interpretations; CRPN criteria (France) — p24, gp41 and gp120 all reactive. An indeterminate WB has bands present but insufficient to meet positive criteria and requires repeat testing in 4–6 weeks. The gp120/gp160 envelope glycoproteins are the most specific bands.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
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