APPARENT HIV-1 GLYCOPROTEIN REACTIVITY ON WESTERN-BLOT IN UNINFECTED BLOOD-DONORS

Objective: To investigate samples with 'false-positive' reactivity to HIV-1 glycoproteins on Western blot (WB). Design: Samples from 13 blood donors with glycoprotein reactivity were examined for serological evidence of HIV infection and followed-up where possible. Methods: Samples were tested for anti-HIV-1, HIV-1 p24 antigen, anti-HIV-2 and anti-HTLV-I. Reactivity to multimeric, monomeric, and deglycosylated gp41 was determined, as was the ability of recombinant gp160 (rgp160) to inhibit reactivity to multimeric gp41. Results: Serology and follow-up failed to confirm HIV infection in any of the donors. All samples reacted to multimeric gp41, and eight out of the 13 reacted to deglycosylated gp41. Reactivity on a commercial WB was inhibited by rgp160. Conclusion: Apparent reactivity to HIV-1 glycoprotein may occur in individuals with no other serological evidence of HIV infection. Reactivity to different forms of gp41 and inhibition by rgp160 suggested that the observed WB reactivity may be due to cross-reactivity with gp41 rather than to a co-migrating contaminant.