Identifcation of new antigen targets for leprosy serodiagnosis

Mycobacterium leprae , a non-cultivable bacteria, is the causative agent of leprosy. Despite huge effort from WHO leprosy remains a public health problems in some parts of the world. One of the principal goals of leprosy research is to develop serological tests that will allow identification and early treatment of leprosy patients. In this work, M. habana a cultivable non-pathogenic mycobacterium and candidate vaccine for leprosy, was used to obtain soluble antigenic extracts (MHSE). By Western blot (WB) analysis MHSE proteins were reacted with sera form lepromatous leprosy patients (LL), active tuberculosis patients (TB) and healthy donors (H) from an endemic leprosy area. LL sera diluted 1:2,000 showed reactivity with a 28-30 KDa doublet antigen in MHSE. No reactivity with these bands was observed at 1:2,000 or lower sera dilutions of TB or H donors. After performing two dimension PAGE and WB analysis with the same sera, the doublet band was shown to have several spots. Further characterization was done using Tandem Mass Spectrometry (LC/ESI-MS/MS) and two proteins were identified: enoyl- coenzyme A hydratase (lipid metabolism) and antigen 85B (Ag85B, mycolyltransferase). These proteins represent promising candidates for the design of a reliable tool for the serodiagnosis of the infectious form of leprosy.