Immune profiling of leprosy and tuberculosis patients to 15‐mer peptides of Mycobacterium leprae and M. tuberculosis GroES in a BCG vaccinated area: implications for development of vaccine and diagnostic reagents

Abstract

SUMMARYMycobacterium leprae (ML) GroES has been shown to induce strong T cell responses in tuberculoid as well as in exposed healthy contacts of leprosy patients, and therefore this antigen has been the focus of study as a potential vaccine candidate. Paradoxically, we have shown that ML GroES also induces extremely high titres of IgG1 antibody in leprosy patients across the disease spectrum, a response associated with disease progression. IgG1 antibodies in leprosy also show a negative association with interferon-g, a critical T cell cytokine responsible for macrophage activation and intracellular killing of mycobacteria. We therefore queried if antibody and T cell responses were being evoked by different epitopes in ML GroES proteins. To address the issue of epitope recognition in mycobacterial diseases, we have analysed 16 peptides (15-mer peptides) spanning the entire ML and M. tuberculosis GroES protein in leprosy (n 19) and tuberculosis (n 9) patients and healthy endemic controls (n 8). Our analysis demonstrates clearly that the dominant peptides evokingT cell and IgG subclass antibodies were different. The target of both T and B cell responses were cross-reactive epitopes in all groups. Differences in disease and healthy states related to the strength (mean intensity) of the T cell and antibody response. IgG1 and IgG3 antibodies were associated with disseminated disease and IgG 2 and IgG4 with disease limitation. Such comprehensive immune pro®ling of antigen-speci®c responses is critical to understanding the disease pathogenesis and also if these reagents are to be exploited for either diagnostic or vaccine purposes.

Proteomic analysis of purified protein derivative of Mycobacterium tuberculosis

“…Our results are correlating with earlier publications and many of the proteins identified in the PPD of M. tuberculosis , have already been analyzed for their potential as a diagnostic markers. Some of the hits we have found are GroES [52,53], GroEL [54,55], protein EsxB (EsxB) [56] heat shock protein HspX (HspX) [57], hypothetical protein (TB15.3), hypothetical protien (TB16.3) [58], 50S ribosomal protein L7/L12 (RplL) [59], hypothetical protein (EsxA) [60], immunogenic protein Mpt63 (Mpt63) [61], Mpt64 [62], ESAT-6 like protein EsxJ (EsxJ), and ESAT-6 like protein EsxO (EsxO) [63]. Based on these observations, many more M. tuberculosis PPD can be analyzed and the abundant antigens be evaluated for their potential as diagnostics biomarkers.…”

Immunodiagnosis of Tuberculosis: a Dynamic View of Biomarker Discovery

“…Tumor necrosis factor alpha (TNF-␣), a proinflammatory cytokine, is also required for control of the infection, as shown by the increased incidence of TB reactivation in individuals receiving anti-TNF-␣ antibody treatment for unrelated disease. Other examples of proinflammatory responses are the production of IL-2, which is involved in the clonal expansion of antigen-specific T cells (125), and of the chemokine CXCL10 (IP-10), which is important in trafficking monocytes and Th1 cells to the site of (90) (32,67,140). For example, the presence of IFN-␥ favors IgG2, IL-4 and IL-13 favor IgG4, while IL-10 favors IgG1 and IgG3.…”

Gene Expression Profile and Immunological Evaluation of Unique Hypothetical Unknown Proteins of Mycobacterium leprae by Using Quantitative Real-Time PCR

“…The literature and our study show that the low sensitivity of IGRA to current peptide antigens may be attributable to low antigen availability and poor T cell recognition of the parent proteins by the host immune system. A number of well-known M. leprae antigens (MMPI, MMPII, GroES, ML0049, and ML0050) induce strong cell-mediated and humoral immune responses in leprosy patients (24,(34)(35)(36)(37)(38). Araoz et al (6,7) showed that a few of the recombinant hypothetical unknown proteins can be recognized by circulating antibodies in sera of leprosy patients but also induce M. leprae-specific T cell responses in leprosy and endemic control populations.…”