Serological detection of leprosy employing Mycobacterium leprae derived serine-rich 45 kDa, ESAT-6, CFP-10 and PGL-I: a compilation of data from studies in Indian populations

This article is a compilation of our findings recorded in the recent past where we have investigated the serological performance of Mycobacterium leprae antigens like-serine-rich 45 kDa protein (45 kD), early secretary antigenic target-6 (ESAT-6), culture filtrate protein-10 (CFP-10) and phenolic glycolipid-I (PGL-I) for detection (employing antibody detecting ELISA) of leprosy patients, particularly those belonging to the paucibacillary (PB) group. All of these antigens were capable of detecting, by themselves the majority (82-100%) of multibacillary (MB) patients. However, with respect to PB patients, only 18-47% (i.e. less than half) of the cases could be detected. Based on the results of serological assays for each of the four antigens separately a combinatorial approach was performed for these antigens, which increased the sensitivity for detection of PB patients to 73%, giving 36% improvement over conventional PGL-I based ELISA. Thus, the multi-antigenic serological approach is worthwhile for its establishment for detection of leprosy patients. Since ESAT-6 and CFP-10 are secreted proteins by nature, antibodies against them are worth exploring for detection of early infections and for monitoring of treatment efficiency. Nevertheless, efforts towards identification of more new antigens with serological potential are still desirable in order to further improve the detection rate of leprosy.