Background: Two new anti-human immunodeficiency virus type 1 and 2 (HIV-1/2) immunoblot assays, which use recombinant and synthetic antigens for antibody detection have become available. These assays might be able to resolve indeterminate anti-HIV Western blot results.
Study design and methods: The new anti-HIV immunoblot assays were used to test 67 samples from 31 HIV infected and 24 noninfected persons showing various anti-HIV Western blot patterns.
Results: The immunoblots correctly identified eight HIV-2-positive samples and five late-stage HIV-1-positive samples. After 30 samples from 18 seroconverting persons were tested, the Western blot showed reactivity in 24 of 30 samples and the immunoblots showed reactivity in 21 of 30 samples (difference not significant). In 16 of 30 seroconversion samples, both immunoblot assays produced HIV-1-positive results. In accordance with various criteria for interpretation, the number of positive Western blot results was as follows: Centers for Disease Control and Prevention, 16 of 30 and World Health Organization, 13 of 30. When samples from non-HIV-infected persons were tested, both immunoblot assays resolved 20 (83%) of 24 samples showing indeterminate Western blot reactivity.
Conclusion: Although the sensitivity of the immunoblot assays should be validation in larger studies, the mere specificity of these assays makes them valuable for the exclusion of HIV infection in Western blot-indeterminate, HIV p24 antigen-negative samples.