Characterisation of a lipoprotein in Mycobacterium bovis (BCG) with sequence similarity to the secreted protein MPB70

Vosloo, Wilna; Tippoo, Patrick; Hughes, Jane; Harriman, Natalie; Emms, M.; Beatty, Dave W; Zappe, Harold; Steyn, Lafras M.

doi:10.1016/s0378-1119(96)00806-2

Cited by 26 publications

(31 citation statements)

References 26 publications

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“…The gene for MPB70 is present in M. bovis BCG but expressed to greater or lesser extents in different strains (i.e., lower expression in Glaxo and Pasteur strains than in Tokyo or virulent M. bovis) (64,67). Evidence for a smaller gene of 4.6 kb in M. kansasii that hybridizes to a MPB83 gene probe has also been obtained using Southern blotting (65). The mpt70 gene is also present in M. tuberculosis; although expression is not observed in bacterial cultures, it may be up-regulated during infection in vivo, based on increased T-cell responses in tuberculosis patients compared to BCG vaccinees (48).…”

Section: Discussionmentioning

confidence: 90%

Gamma Interferon Responses Induced by a Panel of Recombinant and Purified Mycobacterial Antigens in Healthy, Non-Mycobacterium bovisBCG-Vaccinated Malawian Young Adults

Black

Weir

Chaguluka

et al. 2003

Clin Vaccine Immunol

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We have previously shown that young adults living in a rural area of northern Malawi showed greater gamma interferon (IFN-␥) responses to purified protein derivatives (PPD) prepared from environmental mycobacteria than to PPD from Mycobacterium tuberculosis. In order to define the mycobacterial species to which individuals living in a rural African population have been exposed and sensitized, we tested T-cell recognition of recombinant and purified antigens from M. tuberculosis (38 kDa, MPT64, and ESAT-6), M. bovis There is great variation in the protection that Mycobacterium bovis BCG vaccines can provide against tuberculosis in different locations (17). In two large randomized controlled studies of BCG vaccination in Malawi and the United Kingdom, we have shown that prior to the vaccination of previously unvaccinated young adults in Malawi, over 60% of individuals show gamma interferon (IFN-␥) responses to purified protein derivative (PPD) from M. tuberculosis and that BCG vaccination provides only a moderate increase in this T-cell response (8). When PPDs from a number of nontuberculous environmental (atypical) mycobacteria were used to stimulate whole-blood cultures from the same subjects, PPDs from members of the M. avium-M. intracellulare-M. scrofulaceum complex induced stronger IFN-␥ responses than PPD from M. tuberculosis (6). To further define the mycobacterial species to which these subjects had been exposed, we have now used a panel of recombinant and purified antigens, with known species distributions, to test IFN-␥ responses, as a measure of the type 1 T-cell response induced by mycobacterial antigens, in day 6 supernatants from diluted whole-blood cultures. We have also assessed the potential of these recombinant antigens for identifying infection with M. tuberculosis and M. leprae, by studying the association between the IFN-␥ response to these antigens and the skin test response to M. tuberculosis PPD.Most studies of T-cell recognition of individual mycobacterial antigens have used patients infected with pathogenic mycobacteria or the contacts of these patients. Our study is unusual in that non-BCG-vaccinated, human immunodeficiency virus-negative, healthy individuals living in a rural area of northern Malawi have been tested for their ability to make a type 1 cytokine response to a panel of seven recombinant mycobacterial antigens and one purified native mycobacterial antigen. These subjects were clinically well at the time of testing and were recruited in their villages and homes.

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Section: Discussionmentioning

confidence: 90%

Gamma Interferon Responses Induced by a Panel of Recombinant and Purified Mycobacterial Antigens in Healthy, Non-Mycobacterium bovisBCG-Vaccinated Malawian Young Adults

Black

Weir

Chaguluka

et al. 2003

Clin Vaccine Immunol

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“…Lesions in M. kansasii-infected reindeer closely resemble those seen from M. bovis-inoculated reindeer (13). Antigens traditionally considered specific for the M. tuberculosis complex (e.g., ESAT-6, CFP10, and MPB83) are also produced by M. kansasii and have been shown to elicit an immune response in M. kansasii-sensitized/infected cattle, humans, nonhuman primates, and guinea pigs (6,7,8,9,30; W. R. Waters and K. P. Lyashchenko, unpublished observations). In the present study, the only other mycobacterium isolated was Mycobacterium duvalii from a sample of kidney.…”

Section: Discussionmentioning

confidence: 99%

Antibody Responses in Reindeer (Rangifer tarandus) Infected withMycobacterium bovis

Waters

Palmer

Bannantine

et al. 2005

Clin Vaccine Immunol

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Despite having a very low incidence of disease, reindeer (Rangifer tarandus) are subject to tuberculosis (TB) testing requirements for interstate shipment and herd accreditation in the United States. Improved TB tests are desperately needed, as many reindeer are falsely classified as reactors by current testing procedures. Sera collected sequentially from 11 (experimentally) Mycobacterium bovis-infected reindeer and 4 noninfected reindeer were evaluated by enzyme-linked immunosorbent assay (ELISA), immunoblotting, and multiantigen print immunoassay (MAPIA) for antibody specific to M. bovis antigens. Specific antibody was detected as early as 4 weeks after challenge with M. bovis. By MAPIA, sera were tested with 12 native and recombinant antigens, which were used to coat nitrocellulose. All M. bovis-infected reindeer developed responses to MPB83 and a fusion protein, Acr1/MPB83, and 9/11 had responses to MPB70. Other antigens less commonly recognized included MPB59, ESAT-6, and CFP10. Administration of purified protein derivatives for skin testing boosted serum antibody responses, as detected by each of the assays. Of the noninfected reindeer, 2/4 had responses that were detectable immediately following skin testing, which correlated with pathological findings (i.e., presence of granulomatous lesions yet the absence of acid-fast bacteria). The levels of specific antibody produced by infected reindeer appeared to be associated with disease progression but not with cell-mediated immunity. These findings indicate that M. bovis infection of reindeer elicits an antibody response to multiple antigens that can be boosted by skin testing. Serological tests using carefully selected specific antigens have potential for early detection of infections in reindeer.Mycobacterium bovis infection of reindeer (Rangifer tarandus) is rare, especially in North America, where there are no published reports of the occurrence of tuberculosis (TB) in this species. Despite the low incidence of disease, reindeer are subject to regulations in the United States Department of Agriculture (USDA) Bovine Tuberculosis Eradication Uniform Methods and Rules (29), requiring testing for interstate movement and herd accreditation. For TB surveillance of reindeer within the United States, a single cervical test (a measure of delayed-type hypersensitivity) is the primary test and the comparative cervical skin test (CCT) is used to confirm infection. Although exact numbers are difficult to ascertain, many reindeer have tested positive by skin testing for TB surveillance. Strains of Mycobacterium bovis or other Mycobacterium spp. within the Mycobacterium tuberculosis complex, however, have not been isolated from these reindeer upon necropsy. Reasons for the high rate of false-positive reactions elicited by skin testing are unclear, although it may be due to unusual exposure to nontuberculous Mycobacterium spp. or an exaggerated cellular immune response to mycobacterial antigens. Therefore, improved TB tests are urgently needed to avoid the unnecessary sla...

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“…From a minimal module of mpt83-rskA-sigK, a gene duplication first resulted in two MPT70/83 paralogues. Of these, MPT83 shares a membrane lipid anchor with a number of protein from other Actinomycetales, unlike MPT70, which lacks this feature and is secreted (32). As another example of how this regulon has evolved, the addition of dipZ is interesting on a number of counts.…”

Section: Discussionmentioning

confidence: 99%

Evolution of the Mycobacterial SigK Regulon

2008

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Previous studies have established that members of the Mycobacterium tuberculosis complex exhibit variable production of the antigenic proteins MPT70 and MPT83 due to mutations in their positive regulator, SigK (sigma factor K), and their negative regulator, RskA (regulator of sigma K). To further understand this highly specific SigK-controlled regulon, we have undertaken evolutionary studies to determine the presence of homologues of SigK-regulated genes in other organisms and to predict its transcriptional network. Evolutionary analysis indicates that the positive and negative regulators are conserved across many organisms, but that the genes under their control are variable. Moreover, the addition, loss, and movement of various genes in the mpt70/83 locus suggest that these genes are unlikely to be cotranscribed. To test predictions from sequence analysis, we have used promoter luciferase fusions and Northern blots to show that the majority of genes in this locus have their own promoters, of which a subset are SigK regulated (mpt83, dipZ, mpt70, and Rv0449c). Next, we have shown that the intracellular inducibility of mpt70 and mpt83 is a conserved property, shared between M. tuberculosis and Mycobacterium marinum. In addition, we have shown that SigK and RskA from an environmental mycobacterium isolate (M. gilvum PYR-GCK) complemented the regulatory activity of M. tuberculosis ⌬sigK rskA. Together, our data indicate that the regulatory system SigK/RskA is conserved across the Mycobacterium genus, whereas the regulon under its control varies considerably across species.Mycobacterium tuberculosis is an extremely successful pathogen of humans, infecting an estimated one-third of the world's population. This capacity to persist in the host, despite the dynamic alterations effected by the host immune response, testifies to an evolved capacity of the organism to regulate its genetic expression to the conditions encountered during infection. Indeed, a number of studies have demonstrated that disruption of M. tuberculosis regulatory elements, such as sigma factors, results in reduced virulence in experimental models (21,28,30).The determination of genomic sequences for a number of nonpathogenic mycobacteria has revealed that homologues of many genes, including regulatory elements, are often present in organisms that are not virulent to humans. For instance, comparative analysis has demonstrated conservation of biochemical pathways and a secretory system important for full virulence of M. tuberculosis (7,10). This indicates that genetic elements and the proteins they encode that exist in other mycobacteria either serve an important function in M. tuberculosis pathogenicity or have evolved a specific role in M. tuberculosis complex organisms. As a number of predicted regulatory elements are also conserved between environmental mycobacteria and M. tuberculosis, it follows that an evolutionary analysis may guide predictions about the origins of such elements, the transcriptional networks they control, and the stimuli that...

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Characterisation of a lipoprotein in Mycobacterium bovis (BCG) with sequence similarity to the secreted protein MPB70

Cited by 26 publications

References 26 publications

Gamma Interferon Responses Induced by a Panel of Recombinant and Purified Mycobacterial Antigens in Healthy, Non-Mycobacterium bovisBCG-Vaccinated Malawian Young Adults

Gamma Interferon Responses Induced by a Panel of Recombinant and Purified Mycobacterial Antigens in Healthy, Non-Mycobacterium bovisBCG-Vaccinated Malawian Young Adults

Antibody Responses in Reindeer (Rangifer tarandus) Infected withMycobacterium bovis

Evolution of the Mycobacterial SigK Regulon

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