Sensitivity of Anti-PGL-1 Elisa test using mixed antigens (disaccharide and trisaccharide) for the diagnosis and epidemiological surveillance of leprosy

Introduction: The development of immunological and molecular diagnostic tests for leprosy has advanced substantially in the past decade, although such advances have not yet been effective in reducing the burden of leprosy in endemic countries.
Objective: To assess the performance of anti-PGL-1 IgM ELISA Mycobacterium leprae test using trisaccharide antigen compared to using mixed antigens (MIX).
Results: The average levels of anti-PGL-1 antibodies in multibacillary (MB) patients for NT-P-BSA antigen was 0·494 and the MIX antigens, 0·985; in paucibacillary (PB) patients for NT-P-BSA, 0·06 and the MIX, 0·113; in contacts (CON) the average for NT-P-BSA was 0·088 and the MIX 0·155. Among PB patients, 14% (7/50) were negative for NT-P-BSA and positive for the MIX antigens; among CON 18% (14/78) were negative for NT-P-BSA and positive for the MIX antigens. Analysis of variance showed that the levels of anti-PGL-1 antibodies are significantly higher for the MIX antigens compared to NT-P-BSA.
Conclusions: These findings suggest that a test using the mixed antigens to the three classes of immunoglobulins (IgM, IgA and IgG), could represent a more sensitive test for the diagnosis and monitoring of leprosy in endemic countries.