Abstract
Immunoreactive regions of human immunodeficiency virus type 1 (HIV-1) gp41 were mapped by reacting HIV-1 antibody-positive human sera with overlapping synthetic peptides which covered the transmembrane protein. Three immunoreactive domains were identified, and five different and partially overlapping epitopes recognized by HIV-1-positive human sera were found within one immunodominant region. The effect on antibody recognition after single amino acid substitutions within one defined epitope was also studied. The reactivity of various HIV-1-positive sera to synthetic peptides with amino acid substitutions representing known isolates suggests an important substitution in the major epitope of African HIV-1 strains.