Which marker is used to detect HIV-1 antibodies in donor testing?

• A. NAT
• B. ELISA
• C. Western blot
• D. PCR

Answer: (B)

ELISA detects HIV-1 antibodies in donor testing. In this assay, HIV-1 antigens are bound to a solid surface; if a donor’s blood contains antibodies to HIV-1, they attach to these antigens. A secondary enzyme‑conjugated antibody that recognizes human antibodies is added, and the enzyme’s reaction produces a color change that signals a positive result. This high-sensitivity screening approach is used to catch antibodies during seroconversion. If reactive, results are typically confirmed with a more specific test like Western blot. Others in the list detect viral nucleic acids rather than antibodies (NAT, PCR), or are used for confirmation rather than initial screening.