Antigenic Domains of the HIV-1 vif Protein as Recognized by Human Sera and Murine Monoclonal Antibodies

To analyze the vif antibody response in individuals infected with the human immunodeficiency virus type 1 (HIV-1) and to determine antigenic epitopes on the vif protein, 104 HIV-1⁺ sera were screened for reactivity with a recombinant vif protein; 30 (28.8%) of these sera recognized the recombinant vif protein in immunoblot and were employed, together with 17 HIV-1/vif-negative control sera, in an enzyme immunoassay (EIA)-based epitope scanning assay with 183 overlapping decapeptides that covered the complete amino acid sequence of the HIV-1 vif protein (strain BH10). Of the 30 HIV-l/vif ⁺ sera, 87% reacted with decapeptides comprising the two following epitopes: IEWRKKRY (vif amino acids 87-94) or DRWNKPQ (vif amino acids 172-178). The two epitopes were 89% and 100% conserved among different HIV-1 strains and their antigenicity could be confirmed by computer-assisted predictions of vif antigenic determinants. All the sera reactive with recombinant vif protein and with vif peptides originated from patients in CDC stages III or IV. Two murine anti-vif monoclonal antibodies reacted only with the seven C-terminal amino acids of the vif protein (SHTMNGH), which were not recognized by any of the human sera. Our results may be useful for further studies of vif seroreactivity and for the production of anti-vif mono-or polyclonal antibodies using vif peptides.