Background: Used as a supplemental assay, new anti-human immunodeficiency virus (HIV) immunoblots, employing recombinant and synthetic antigens, appeared to resolve the majority of samples with false-reactive Western blot results. Would it be possible to completely replace the Western blot by an immunoblot for confirmation and exclusion of HIV infection?
Study design and methods: The sensitivity of the new LiaTek HIV III immunoblot assay (Organon Teknika, Turnhout, Belgium) was tested on 416 Western-blot positive samples (386 HIV-1, 22 HIV-2, 1 HIV-1/2, and 7 HIV-O) and on 45 HIV-1 seroconversion samples. The specificity was tested on 146 samples from noninfected donors with false-positive results on a HIV screening test.
Results: All Western-blot-positive samples tested positive in the immunoblot (sensitivity: 100%). The immunoblot could not discriminate between HIV-1 and HIV-2 infection in 22 of 416 (5%) samples. The LiaTek assay showed reactivity in 28 of 45 seroconversion samples, whereas the Western blot reacted in 30 of 45 seroconversion samples. With false-positive donor samples, the immunoblot was indeterminate in 10 of 146 samples (specificity: 93%), and the Western blot was indeterminate in 44 of 146 samples (specificity: 70%).
Conclusion: Like the Western blot, the immunoblot runs the risk of missing samples that are reactive by enzyme immunoassay during the early stage of HIV infection. Nevertheless, considering its superior specificity on false-positive donor samples, it appears that the immunoblot offers a cost-effective alternative to the Western blot assay for confirmation and exclusion of HIV infection.