title: Evaluation of recombinant serine-rich 45-kDa antigen (ML0411) for detection of antibodies in leprosy patients.
abstract: The potential of the recombinant serine-rich 45-kDa antigen (ML0411) of Mycobacterium leprae to aid in detecting M. leprae-specific serum antibodies was assessed by an enzyme-linked immunosorbent assay (ELISA) in leprosy patients and controls comprising of tuberculosis patients, other unrelated skin-diseased patients and healthy individuals from India. All 18 multibacillary (MB) and 18/38 (47.4%) of the paucibacillary (PB) leprosy patients were found positive. None of the controls was positive, yielding complete (0/49) specificity in the series tested here. On the other hand, an anti-phenolic glycolipid-1 (PGL-I) antibody-detecting assay yielded detectable responses in 94.4% (17/18) of MB and 36.8% (14/38) of PB leprosy patients. Only two of 49 (4.1%) controls were positive, giving a specificity of 95.9%. Further, there was a good concordance (agreement of 83.8%; chi(2) = 40.3, P < 0.001; kappa = 0.63) between the two assays. Thus, the 45-kDa-based assay was slightly better than anti-PGL-I antibody-detecting assay. Interestingly, when combining the results of both the assays together for all leprosy patients (MB + PB), the combined sensitivity was significantly higher than that of the anti-PGL-I antibody-detecting ELISA alone (73.2% versus 55.4%; P < 0.05), but not (P > 0.05) compared with the 45-kDa antigen-based assay alone. Similarly, in case of PB patients, using both assays in combination, the sensitivity was significantly higher compared with anti-PGL-I antibody-detecting assay alone (60.5% versus 36.8%; P < 0.05). While adopting the combinatorial approach, the specificity remained invariably high (>95%). In conclusion, the results of the present study indicate that the M. leprae 45-kDa protein is a potent B-cell antigen and may be a useful serodiagnostic reagent.
authors.affiliation: National JALMA Institute for Leprosy and other Mycobacterial Diseases, TajGanj, Agra 1, India.
authors.forename: O
authors.initials: O
authors.lastname: Parkash
authors.forename: A
authors.initials: A
authors.lastname: Kumar
authors.forename: A
authors.initials: A
authors.lastname: Nigam
authors.forename: K L M C
authors.initials: KL
authors.lastname: Franken
authors.forename: T H M
authors.initials: TH
authors.lastname: Ottenhoff
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood*; D000942:Antigens, Bacterial / Q000276:immunology* / Q000378:metabolism; D001402:B-Lymphocytes / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D006017:Glycolipids / Q000276:immunology; D006801:Humans; D007918:Leprosy / Q000097:blood / Q000175:diagnosis / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology; D008970:Molecular Weight; D009166:Mycobacterium leprae / Q000235:genetics / Q000276:immunology*; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D012680:Sensitivity and Specificity; D012694:Serine / Q000378:metabolism*
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D006017:Glycolipids; C455919:Mycobacterium leprae 45 kDa antigen; D011994:Recombinant Proteins; C045169:phenolic glycolipid I, Mycobacterium leprae; D012694:Serine