HIV-1 western blot: development and assessment of testing to resolve indeterminate reactivity.
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.
Healey
D S
DS
National HIV Reference Laboratory, Fairfield Hospital, Victoria, Australia.
Maskill
W J
WJ
Howard
T S
TS
Armstrong
V A
VA
Bolton
W V
WV
Cooper
G J
GJ
Downie
J C
JC
Hiley
L A
LA
Imrie
A A
AA
Johnson
S
S
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
D015488:HIV Antigens