title: HIV-1 western blot: development and assessment of testing to resolve indeterminate reactivity.
abstract: OBJECTIVE
  To reduce the number of HIV-1 Western blot (WB)-indeterminates requiring follow-up and the time taken to provide a clear positive or negative result.
  
  
  METHODS
  In the first of two stages, a testing and follow-up strategy was developed to resolve anti-HIV-1 status of WB-indeterminates. In the second stage, implementation of this strategy was assessed.
  
  
  METHODS
  After dividing indeterminates into four groups according to WB profile, samples were tested for anti-HIV-1, anti-HIV-2, anti-HTLV-I antibodies, and HIV-1 antigen using the most sensitive assays available. When testing failed to clarify anti-HIV-1 status, follow-up samples were taken to monitor changes in antibody status.
  
  
  RESULTS
  Samples in two out of the four indeterminate groups were negative for anti-HIV-1. The other two groups required additional testing and/or follow-up to distinguish reactivity caused by anti-HIV-1 from cross-reactivity.
  
  
  CONCLUSIONS
  Grouping HIV-1 WB-indeterminates according to profile allows a significant percentage to be reported as anti-HIV-1-negative, while additional testing may allow others to be reported as anti-HIV-1-positive. The remainder require a maximum of 3 months' follow-up to resolve anti-HIV-1 status.
authors.affiliation: National HIV Reference Laboratory, Fairfield Hospital, Victoria, Australia.
authors.forename: D S
authors.initials: DS
authors.lastname: Healey
authors.forename: W J
authors.initials: WJ
authors.lastname: Maskill
authors.forename: T S
authors.initials: TS
authors.lastname: Howard
authors.forename: V A
authors.initials: VA
authors.lastname: Armstrong
authors.forename: W V
authors.initials: WV
authors.lastname: Bolton
authors.forename: G J
authors.initials: GJ
authors.lastname: Cooper
authors.forename: J C
authors.initials: JC
authors.lastname: Downie
authors.forename: L A
authors.initials: LA
authors.lastname: Hiley
authors.forename: A A
authors.initials: AA
authors.lastname: Imrie
authors.forename: S
authors.initials: S
authors.lastname: Johnson
mesh_terms: D015492:AIDS Serodiagnosis / Q000379:methods*; D000937:Antigen-Antibody Reactions; D001315:Australia / Q000453:epidemiology; D015153:Blotting, Western / Q000379:methods*; D005500:Follow-Up Studies; D015488:HIV Antigens / Q000276:immunology; D015658:HIV Infections / Q000175:diagnosis* / Q000453:epidemiology; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D015166:Monitoring, Immunologic; D011446:Prospective Studies; D012680:Sensitivity and Specificity
chemical_list: D015488:HIV Antigens