Evaluation of four semi-syntheticMycobacterium lepraeantigens with sera from healthy populations in endemic and non-endemic areas

Abstract

In order to determine the frequency of occurrence of antibodies to semisynthetic antigens of My cobacterium leprae in clinically healthy nonpatient populations and to establish a 'baseline' for comparison with antibody frequen cies in both patients with a history of leprosy and their contacts, ELISAs were conducted using representative sera from two areas: a leprosy endemic area, Cebu City, Philippines and a nonendemic area for leprosy Chicago, Illinois, USA. These sera were tested, by an indirect IgM ELISA, for the presence of antibodies reacting with fo ur semisynthetic antigens based on the phenolic glycolipid I antigen of M. leprae: ND-O-BSA (natural disaccharide with octyl linkage to bovine serum albumin), NT-O-BSA (natural trisaccharide with octyl linkage to BSA), ND-P-BSA (natural disaccharide with phenolic ring linkage to BSA) and NT-P-BSA (natural trisaccharide with phenolic ring linkage to BSA). Using an OD reading ;;. 0•16 as positive, the antigen with the lowest background seroreactivity 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 antigens. Of the 426 sera fr om Chicago, 12 (2,8%) were reactive with at least one antigen and 3 (0'7%) were reactive with all four semisynthetic antigens. Mean ELISA values for the 22 positive sera for each antigen ranged from 0• 17 to O• 3 OD units, while the mean values for all sera in

Production and characterization of peptide mimotopes of phenolic glycolipid-I ofMycobacterium leprae

“…Since early studies showed that the carbohydrates of the PGL‐I antigen are critical for its binding to antibodies, a series of neoglycoconjugate antigens containing carbohydrate epitopes of PGL‐I were prepared and were found to give a strong correlation with the native antigen in terms of detecting antibodies [12–14]. Currently, neoglycoconjugate antigens such as ND‐ O ‐BSA and ND‐ P ‐BSA are widely used for detecting anti‐PGL‐I antibodies [13,15]. Organic synthesis of the terminal disaccharides, 3,6‐di‐ O ‐Me‐Glc‐(1→ 4)‐2,3‐di‐ O ‐Me‐Rha, and the linking of this sugar to BSA carrier protein is, however, a tedious process requiring more than 20 steps [13].…”