Evaluation of four semi-synthetic Mycobacterium leprae antigens with sera from healthy populations in endemic and non-endemic areas.

tested, by an indir ect IgM ELISA, for the presence of antibodies rea cting with four semisynth etic antigens based on the phenolic gly colipid I antig en of M. leprae: ND-O-BSA (natural disaccharide with octyl lin kage to bovine serum albumin), NT-O-BSA (natural trisaccharide with octyl linka ge to BSA), ND-P-BSA (natural disaccharide with phenolic ring linka ge to BSA) and NT-P- BSA (natural trisaccharide with phenolic ring linka ge to BSA). Using an OD read ing ;;. 0·16 as positive, the antigen with the lowest background serorea ctivity was ND-O-BSA, which reacted with 5/398 (1' 3%) sera from Cebu, and 3/426 (0,7 %) sera from Chicago . A total of 10 (2'5 %) of 398 sera from the endemic area reacted with at least one antigen and 5 (1' 3%) sera reacted with all four semisynthetic antig ens. Of the 426 sera from Chicago, 12 (2,8 %) were reactive with at least one antigen and 3 (0'7 %) were reactive with all four semisynthetic antig ens. Mean ELISA values for the 22 posit ive sera for each antig en rang ed from 0·17 to O· 3 OD units, while the mean values for all sera in