Epitope mapping of twelve monoclonal antibodies against the phenolic glycolipid-I of M. leprae.

Epitope mapping of 12 monoclonal antibodies (MAbs) directed to the trisaccharide part of the phenolic glycolipid-I (PGL-I) of Mycobacterium leprae was carried out by using the set of chemically synthesized sugar-BSA conjugates. The results can be summarized as follows: mAb (1-21), mAb (1-24) and mAb (1-25) recognized the outer (nonreducing end) monosaccharide of the trisaccharide chain of PGL-I. However, the affinity of these MAbs to the outer monosaccharide was weak. They required the contributions of some parts of the second sugar for enough affinity. MAbs ml 6A12, ml 8A2, ml 8B2, and PG2 B8F recognized the outer disaccharide. MAb F47-21-3 recognized the outer disaccharide and some parts of the third sugar. MAb SF 1 recognized the trisaccharide of PGL-I. MAb 3D1-A9 recognized the phenol group and the structure around the branching point on the carrier protein in addition to the trisaccharide. MAbs DZ 1 and 2G3-A8 had unique characters which recognized the inner part of the sugar chain. MAb DZ 1 recognized the inner (reducing end) disaccharide. MAb 2G3-A8 recognized the inner monosaccharide, phenol group and the structure around the branching point on the carrier protein. All of the MAbs tested, except for ml 6A12, recognized the anomeric configurations in the sugar parts they recognized; ml 6A12 recognized the anomeric configuration only within the outer disaccharide. This set of MAbs, which were well defined on their binding specificity, promises to be an effective tool for the immunological study of PGL-I and the clinical assessment of leprosy.