Lab

HIV Western Blot

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HIV Western Blot, HIV Confirmatory Test

  • Indication
  1. Previously used to confirm positive HIV EIA (HIV Screening Test)
  2. Replaced by
    1. HIV-1/HIV2 Discriminatory Assay (Multispot)
    2. HIV-1 RNA Nucleic Acid Amplification Test (NAT or NAAT) for HIV RNA Viral Activity
  • Mechanism
  1. Direct visualization of antibodies to HIV components
    1. Components: Env, Gag, Pol
    2. Antibodies: p24, gp41, gp120, gp160
    3. Band forms if Antibody present to that component
  2. Positive Test
    1. Two or more bands from p24, gp41, gp120 or qp160
  • Efficacy
  1. Reliably identifies HIV-1
  2. False negative causes
    1. Group O protein (10% False Negative Rate)
    2. HIV-2 (20% False Negative Rate)
    3. Early seroconversion (less sensitive than HIV ELISA)
  3. False positive causes
    1. Hyperbilirubinemia
    2. Connective Tissue Disorder
    3. Polyclonal Gammopathy
  • Follow-Up evaluation for indeterminate or negative test
  1. Repeat Western blot in 1-3 months
  2. Consider Western blot for HIV-2
  • References
  1. Demeter in Mandell (2000) Infectious Disease, p. 1371