Antigen 85B (Ag85B/MPT59) is a major secreted protein from Mycobacterium tuberculosis which is a promising candidate antigen for inclusion in novel subunit vaccines against tuberculosis (TB). The present study was undertaken to map naturally derived T-cell epitopes from M. tuberculosis Ag85B in relation to major histocompatibility complex (

MPB70 is a secreted protein ofTuberculosis (TB) is a chronic infectious disease of worldwide importance. In 1993 the World Health Organization declared TB a global emergency, and according to the latest survey conducted by this organization TB still exists at an alarming level, with about one-third of the world population infected with Mycobacterium tuberculosis, 8 million people developing the disease, and 2 million to 3 million people dying of TB each year (6). Control and eventual eradication of TB require protective vaccines. However, the protection induced by the currently available Mycobacterium bovis BCG vaccine against pulmonary TB varies tremendously in different parts of the world, and the efficacy ranges from 0 to 80% (7). In addition, BCG vaccination induces a positive response to the purified protein derivative (PPD) of M. tuberculosis, thereby compromising the diagnostic value of PPD. Moreover, use of the BCG vaccine, which consists of attenuated live organisms, is contraindicated in AIDS patients, who are at high risk of developing TB. The present situation calls for identification and characterization of M. tuberculosis antigens and peptides that might be used to develop universally efficacious and safer vaccines against TB.Although infection with M. tuberculosis induces both humoral immunity and cell-mediated immunity, only cell-mediated immunity responses mediated primarily by gamma interferon (IFN-␥)-producing Th1 cells are relevant to protection (4, 16). Thus, identification of antigens and peptides that induce Th1 cell responses could be useful for designing new vaccines to protect against TB. Secreted proteins of M. tuberculosis have been the focus of extensive research on the development of subunit vaccines because these proteins are considered to be important targets of recognition by the immune system (1, 31).MPB70 is a major secreted protein of M. bovis, and small quantities of this protein are expressed by M. tuberculosis. M. bovis BCG strains can be divided into strains that produce high levels of MPB70 and strains that produce low levels of MPB70 (9,18,34,58). There are no differences between M. bovis and M. tuberculosis (H37Rv and CDC1551) in terms of the sequences of the expressed proteins encoded by the mpb70 and mpt70 genes, respectively (17; http://www.ncbi.nlm.nih.gov /BLAST). MPB70 is an M. tuberculosis complex-specific nonglycosylated protein with a signal peptide consisting of 30 amino acids (aa) and a mature protein sequence consisting of 163 aa with a deduced molecular mass of 16.3 kDa (53). The mature MPB70 protein stimulates both cellular and humoral immune responses during infection with bovine and human tubercle bacilli (4,10,16, 28,47,49,36).The present work was carried out to identify dominant and natural Th1 cell epitopes of MPB70 which can be recognized by humans in the context of multiple HLA molecules. Peripheral blood mononuclear cells (PBMC) from healthy donors

Comparative genomics has identified several regions of differences (RDs) between the infectious Mycobacterium tuberculosis and the vaccine strains of Mycobacterium bovis BCG. We aimed to evaluate the cellular immune responses induced by antigens encoded by genes predicted in 11 RDs. Synthetic peptides covering the sequences of RD1, RD4 to RD7, RD9 to RD13, and RD15 were tested for antigen-induced proliferation and secretion of Th1 cytokine, gamma interferon (IFN-␥), by peripheral blood mononuclear cells (PBMC) obtained from culture-proven pulmonary tuberculosis (TB) patients and M. bovis BCG-vaccinated healthy subjects. Among the peptide pools, RD1 induced the best responses in both donor groups and in both assays. In addition, testing of TB patients' PBMC for secretion of proinflammatory cytokines (tumor necrosis factor alpha Mycobacterium tuberculosis is among the most successful human pathogens and is the primary cause of human tuberculosis (TB) in the world. Globally, about 2 billion people are infected with M. tuberculosis, 8 to 10 million develop active disease, and 2 million die from TB every year (53). An overwhelming majority of TB patients reside in the developing countries, which suffer from marked poverty, lack of healthy living conditions, and inadequate medical facilities (53).The global control of TB requires effective vaccines and reagents for specific diagnosis. The only vaccine currently available for humans is Mycobacterium bovis bacillus CalmetteGuérin (BCG), a live attenuated strain of M. bovis. In spite of being the most used vaccine in the world, with proven efficacy against childhood TB meningitis and miliary TB (41, 49), BCG has failed to reduce the global burden of TB (43). The efficacy of BCG against pulmonary TB in adults has varied between 0 and 80% (16). Furthermore, vaccination with M. bovis BCG faces two additional problems. First, it induces a delayed-type hypersensitivity response that cannot be distinguished from infection with M. tuberculosis, and therefore, it compromises the use of purified protein derivative (PPD) of M. tuberculosis in skin tests for diagnostic or epidemiological purposes (25,26). Second, M. bovis BCG, as a live vaccine, is contraindicated in human immunodeficiency virus-infected patients for fear of causing disease (11). PPD, the commonly used diagnostic reagent, is nonspecific because of the presence of antigens crossreactive with M. bovis BCG and environmental mycobacteria (14, 25). Thus, there is a need to identify M. tuberculosisspecific antigens to develop new protective vaccines and specific diagnostic reagents against TB.Comparative genome analyses of the M. tuberculosis genome and M. bovis BCG have shown that 16 genomic regions of M. tuberculosis are deleted or lacking in some or all strains of M. bovis and/or M. bovis BCG (9). Among these regions of differences (RDs), 11 regions (RD1, RD4 to RD7, RD9 to RD13, and RD15) covering 89 open reading frames (ORFs) of M. tuberculosis H37Rv are absent in all M. bovis BCG substrains currently used as vaccin...

Tuberculosis (TB) is among the most important diseases of worldwide distribution with respect to both morbidity and mortality. Annually, TB afflicts about 9 million people with 2 million deaths (18). The rapid spread of TB in developing countries of Africa and Asia is accelerated by the human immunodeficiency virus epidemic and the spread of multi-and extra-drug-resistant TB (46). To protect against TB, vaccination with Mycobacterium bovis BCG has been used for more than 70 years, but its efficacy varies tremendously in different parts of the world (49). In addition, the diagnostic value of the presently used skin test reagent, the purified protein derivative (PPD) of M. tuberculosis, is low due to cross-reactivity with environmental mycobacteria and the vaccine strains of M. bovis BCG (14). Furthermore, vaccination with M. bovis BCG is contraindicated in immunocompromised subjects, including AIDS patients who are usually at a very high risk of developing TB (19). Identification of M. tuberculosis antigens useful for diagnosis and development of new vaccines is therefore an important goal in TB research.The protection against TB requires cellular immune responses mediated by T helper 1 (Th1)-type cells that secrete large quantities of gamma interferon (IFN-␥) (2, 13, 15), and therefore a primary criterion for selecting candidate antigens for vaccine design has been their ability to induce IFN-␥ responses (reviewed in reference 27). M. tuberculosis is rich in antigens that induce IFN-␥ secretion, and the presence of such antigens has been reported in purified cell walls, the cytosolic fraction, and short-term culture filtrates (ST-CF) (reviewed in reference 25). However, several studies have suggested that antigens present in ST-CF are the primary inducers of IFN-␥ secretion and provide protection against TB in mice and guinea pigs (reviewed in reference 26). It has been previously shown that two M. tuberculosis-specific antigens present in ST-CF, i.e., ESAT6 and CFP10, are frequently recognized by human Th1 cells after natural infection and therefore are important in the specific diagnosis of active and latent TB (29,31,47). Interestingly, ESAT6 and CFP10, when tested together in IFN-␥ assays, have been shown to improve the diagnostic efficacy of TB compared to results with each antigen separately (20). In addition, vaccination with ESAT6 and CFP10 has been shown to provide protection against challenge with M. tuberculosis in animal models of TB (50). However, ESAT6 and CFP10 can be used either as vaccines or as diagnostic reagents but not as both. This necessitates the identification of additional M. tuberculosis antigens, some of which could be reserved for diagnosis and others for the development of new vaccines against TB.The analysis of the M. tuberculosis genome sequence has shown that genes encoding ESAT6 and CFP10 are located in region of difference 1 (RD1) that is deleted in all vaccine strains of M. bovis BCG but present in all of the tested strains and isolates of pathogenic M. tuberculosis and M. bov...

SummaryPatients with diabetes mellitus are more susceptible to tuberculosis (TB), and the clinical conditions of diabetic TB patients deteriorate faster than nondiabetic TB patients, but the immunological basis for this phenomenon is not understood clearly. Given the role of cell-mediated immunity (CMI) in providing protection against TB, we investigated whether CMI responses in diabetic TB patients are compromised.