Secretory proteins of Mycobacterium habana induce a protective immune response against experimental tuberculosis

Enoyl-coenzyme A hydratase and antigen 85B of Mycobacterium habana are specifically recognized by antibodies in sera from leprosy patients

Leprosy is an infectious disease caused by Mycobacterium leprae, which is a noncultivable bacterium. One of the principal goals of leprosy research is to develop serological tests that will allow identification and early treatment of leprosy patients. M. habana is a cultivable nonpathogenic mycobacterium and candidate vaccine for leprosy, and several antigens that cross-react between M. leprae and M. habana have been discovered. The aim of the present study was to extend the identification of cross-reactive antigens by identifying M. habana proteins that reacted by immunoblotting with antibodies in serum samples from leprosy patients but not with antibodies in sera from tuberculosis (TB) patients or healthy donors (HDs). A 28-kDa antigen that specifically reacted with sera from leprosy patients was identified. To further characterize this antigen, protein spots were aligned in two-dimensional polyacrylamide gels and Western blots. Spots cut out from the gels were then analyzed by mass spectrometry. Two proteins were identified: enoyl-coenzyme A hydratase (lipid metabolism; ML2498) and antigen 85B (Ag85B; mycolyltransferase; ML2028). These proteins represent promising candidates for the design of a reliable tool for the serodiagnosis of lepromatous leprosy, which is the most frequent form in Mexico.

Identification of immunoreactive extracellular proteins of Streptococcus agalactiae in bovine mastitis

Streptococcus agalactiae is a common pathogen that causes bovine mastitis. The aims of this study were to evaluate the antibody response against S. agalactiae extracellular proteins in the whey and serum of naturally infected bovines and to identify possible immunodominant extracellular antigens. IgG1 antibodies against S. agalactiae extracellular proteins were elevated in the whey and serum of naturally infected bovines. In the whey, the levels of IgG1 specific for S. agalactiae extracellular proteins were similar in infected and noninfected milk quarters from the same cow, and the production of antibodies specific for S. agalactiae extracellular proteins was induced only by infection with this bacterium. The immunoreactivity of extracellular proteins with bovine whey was clearly different in infected versus control animals. Group B protective surface protein and 5'-nucleotidase family protein were 2 major immunoreactive proteins that were detected only in the whey of infected cows, suggesting that these proteins may be important in the pathogenesis of S. agalactiae-induced mastitis. This information could be used to diagnose S. agalactiae infection. In addition, these antigens may be useful as carrier proteins for serotype-specific polysaccharides in conjugate vaccines.

Lipids of ‘Mycobacterium habana’, a synonym of Mycobacterium simiae with vaccine potential

'Mycobacterium habana' was proposed as a distinct species within the genus Mycobacterium; however, it is actually a synonym of Mycobacterium simiae and included in the serotype I of this species. The potential use of 'M. habana' as a vaccine in both leprosy and tuberculosis has led to the analysis of its lipid composition in an attempt to define distinctive markers that could be used in the quality control of true strains of this bacterium. Lipids of taxonomic value (fatty and mycolic acids) are similar in 'M. habana' and M. simiae; nevertheless, they clearly differ on the basis of glycopeptidolipid (GPL) composition. Thus, contrary to M. simiae, most strains of 'M. habana' can be defined by the presence of three polar compounds, designated GPL-I, GPL-II and GPL-III, easily determined by thin-layer chromatography, and characterized, respectively, by the content of l-fucose, 2,4-di-O-Me-d-glucuronic acid, and 4-O-Me-d-glucuronic acid, as epitopes.

Evaluation of integral membrane antigens of Mycobacterium habana for serodiagnosis of extrapulmonary tuberculosis: association between levels of antibodies and Mycobacterium tuberculosis antigens

The performance of integral membrane antigens (IMAs) of Mycobacterium habana TMC 5135 in detecting antimycobacterial antibodies in serum and body fluids of patients mainly of extrapulmonary tuberculosis was evaluated. The IMAs were recovered from the detergent phase during Triton X-114 treatment of the plasma membrane of M. habana. Antimycobacterial antibodies were detected by ELISA using IMAs in serum and body fluids of 42 patients and 62 control subjects. As authentic adjunct Mycobacterium tuberculosis antigens were also detected (by ELISA) in body fluids and circulating immune complexes using anti-M. tuberculosis H37Ra antibodies. Anti-M. habana IMA antibody detection increased the positivity rate from 26.% (11/42) and 10% (4/42) obtained by culture and smear microscopy, respectively, to 86% (36/42). M. tuberculosis antigens were also found in 29 out of 36 anti-M. habana IMA antibody-positive cases. Interestingly, all 11 culture-positive cases were also positive for anti-M. habana IMA antibodies. The mean antigen titres in 23 cases, positive for antigens in body fluids, were 2.34 times higher in those who were also positive for anti-IMA antibodies in serum than in those negative for these antibodies. M. habana IMAs may be promising non-tubercular candidate antigens in ELISA-based serodiagnosis of extrapulmonary tuberculosis with substantial sensitivity, specificity and safety.