HIV-1 Western blot: Development and assessment of testing to resolve indeterminate reactivity

D. S. Healey, W. J. Maskill, T. S. Howard, V. A. Armstrong, W. V. Bolton, G. J. Cooper, J. C. Downie, L. A. Hiley, A. A. Imrie, S. Johnson, P. W. Robertson, S. Schepetiuk

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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. Design: 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-1 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. Conclusion: 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.

Original languageEnglish
Pages (from-to)629-633
Number of pages5
Issue number7
Publication statusPublished - 1 Jan 1992
Externally publishedYes


  • HIV-1
  • Indeterminate
  • Testing strategy
  • Western blot

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