Q:

What is the significance of an HIV Western blot indeterminate result?

A:

The diagnosis of human immunodeficiency virus (HIV-1) infection is based primarily on tests that detect HIV-1 antibodies. The primary screening test is the enzyme immunoassay (EIA). All repeatedly reactive EIA tests must be confirmed by Western blot. The cardinal bands are p24, gp41, and gp120/gp160. For gp120/gp160 to be considered cardinal, both must be present. A positive HIV-1 Western blot must have at least two cardinal bands. Negative HIV-1 Western blots have no antibody bands. All other interpretations are indeterminate. An indeterminate result may represent cross reacting antibodies (often to p24 antigen), early infection, or severe AIDS. Western blot testing should be repeated in 4–6 weeks to catch seroconversion in early infection. The CDC recommends retesting at 6 months. If still indeterminate, testing is considered negative. Seroconversion almost always occurs within 3 months.