Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1383 page)

   Indeterminate results may occur due to partial seroconversion during acute HIV infection, advanced HIV infection with decreased titers of p24 antibodies, or infection with HIV-2.

   Other causes for an indeterminate test result in persons who are not infected with HIV include

   Cross-reacting alloantibodies from pregnancy

   Autoantibodies (collagen–vascular diseases, autoimmune diseases, and malignancy)

   Receipt of an experimental HIV-1 vaccine

   Influenza vaccination

Suggested Reading

CLSI.
Criteria for Laboratory Testing and Diagnosis of Human Immunodeficiency Virus Infection; Approved Guideline
. CLSI document M53-A. Wayne, PA: Clinical and Laboratory Standards Institute; 2011.

HUMAN IMMUNODEFICIENCY VIRUS (HIV-1) CONFIRMATORY WESTERN BLOT ASSAY

   Definition

   The Western blot (WB) assay is a method in which individual proteins of an HIV-1 lysate or recombinant HIV proteins allow the determination of antigenic specificity of the antibodies in the patients’ serum. This is considered a confirmation test for HIV serology.

   Western blot assays are specific for different HIV species and subtypes.

   HIV-1 antibodies present in the specimen bind to HIV-1 antigens (p15, p17, p24, p31, gp41, p51, p66, p55, gp120, gp160).

   Alternative confirmation testing algorithms have been described, including use of a second, different EIA, IFA, line immunoassay, or nucleic acid amplification test.

   Use

   The Western blot is used for confirmation of repeatedly reactive HIV antibody screen or rapid HIV antibody results.