Silent transmission of Mycobacterium leprae, as evidenced by stable
leprosy incidence rates in various countries, remains a health challenge despite the implementation of multidrug
therapy worldwide. Therefore, the development of tools for the early diagnosis of M. leprae
infection should be emphasised in
leprosy research. As part of the continuing effort to identify
antigens that have diagnostic potential, unique M. leprae
peptides derived from predicted virulence-associated
proteins (group IV.A) were identified using advanced genome pattern programs and bioinformatics. Based on
human leukocyte antigen (HLA)-binding motifs, we selected 21
peptides that were predicted to be promiscuous HLA-class I
T-cell epitopes and eight
peptides that were predicted to be HLA-class II restricted
T-cell epitopes for field-testing in Brazil, Ethiopia and Nepal. High levels of
interferon (IFN)-γ were induced when peripheral blood mononuclear cells (PBMCs) from
tuberculoid/borderline tuberculoid leprosy patients located in Brazil and Ethiopia were stimulated with the ML2055 p35
peptide. PBMCs that were isolated from healthy endemic controls living in areas with high
leprosy prevalence (EChigh) in Ethiopia also responded to the ML2055 p35
peptide. The Brazilian EChigh group recognised the ML1358 p20 and ML1358 p24
peptides. None of the
peptides were recognised by PBMCs from healthy controls living in non-endemic region. In Nepal, mixtures of these
peptides induced the production of IFN-γ by the PBMCs of
leprosy patients and EChigh. Therefore, the M. leprae virulence-associated
peptides identified in this study may be useful for identifying exposure to M. leprae in population with differing HLA polymorphisms.