Antibodies against human IFN-α and -β recognized the immunosuppressive domain of HIV-1 gp41 and inhibit gp41-binding to the putative cellular receptor protein p45

Abstract

Sequence-comparison indicates existing sequence-similarity between receptor-binding regions of human type 1 IFNs (IFN-α, -β and -ω) and HIV-1 gp41. Previous findings had suggested that the increased levels of antibodies against human IFN-α and -β in HIV-1-infected individuals are associated with a common epitope on gp41, IFN-α and -β. To clarify the relationship between human type I interferon and HIV-1 gp41 and the protective mechanism of an IFN-α-vaccine, we prepared antisera against human IFN-α, -β and HIV-1 gp41, and examined crossreaction of these antisera and their inhibition of gp41 binding to its binding protein p45. Mouse antisera against IFN-α and -β could recognize HIV-1 recombinant soluble (aa539–684) and gp41 immunosuppressive peptide (ISP, aa583–599), while normal mouse sera (pre-immune sera) did not. Mouse antisera to rsgp41 crossreacted with IFN-α and -β. Besides, mouse antisera to IFN-α and β, like mouse anti-rsgp41 antiserum, could inhibit gp41-binding to its putative cellular receptor protein p45, while normal mouse serum did not. These results indicate that antibodies crossreacting with gp41 ISP, IFN-α and -β, could be induced by this common immunological epitope in vivo.