The Potential of the ESAT-6 Antigen Secreted by Virulent Mycobacteria for Specific Diagnosis of Tuberculosis

Pollock, J.M.; Andersen, Peter

doi:10.1086/593686

Cited by 170 publications

(130 citation statements)

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“…Proteins encoded within the ESAT-6 gene cluster (including ESAT-6 and CFP-10) of tuberculous mycobacteria evoke potent T-cell responses that have been utilized in TB diagnostic tests (2,3,4,20,21,27). In particular, use of these antigens can enhance the specificity of IFN-␥-based tests over that achieved when standard PPDs are used as the eliciting agent.…”

Section: Discussionmentioning

confidence: 99%

“…Recently, recombinant antigens specific for virulent tubercle bacilli (e.g., early secretory antigenic target 6 [ESAT-6], culture filtrate protein 10 [CFP-10], MPB-59, MPB-64, and MPB-70) have been evaluated for use in tests that discriminate between M. avium-exposed, M. bovis BCGvaccinated, and tuberculous cattle (4,5,13,27,29). These antigens have demonstrated utility for both in vitro (i.e., IFN-␥ test) and in vivo (i.e., skin test) use (7,14,20,21,26,32). ESAT-6 and CFP-10 are particularly robust inducers of recall IFN-␥ responses by infected cattle.…”

Section: Mycobacterium Bovis Infection Of Reindeer (Rangifer Tarandus)mentioning

confidence: 99%

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Diagnostic Implications of Antigen-Induced Gamma Interferon Production by Blood Leukocytes from Mycobacterium bovis -Infected Reindeer ( Rangifer tarandus )

Waters

Palmer

Slaughter³

et al. 2006

Clin Vaccine Immunol

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The only approved method of tuberculosis (TB) surveillance of reindeer within the United States is tuberculin skin testing; however, skin testing has an apparent lack of specificity, since numerous reindeer are classified as reactors, yet Mycobacterium bovis is not isolated from tissues upon necropsy. The objective of this study was to evaluate the ability of an in vitro assay (the Cervigam assay) to detect gamma interferon (IFN-␥) produced by blood leukocytes in response to mycobacterial antigens from M. bovis-infected reindeer. Thirteen male reindeer ϳ9 months of age were inoculated with 10 5 CFU M. bovis in their tonsillar crypts. Stimulation of whole-blood cultures with a mitogen resulted in significant production of IFN-␥ compared to that by nonstimulated samples. Responses by infected reindeer to M. bovis purified protein derivative (PPD) were as much as 3.5-fold higher than those by noninfected reindeer (n ‫؍‬ 4). Despite differences in responses to PPD by the two groups, reindeer within the noninfected group had responses of >0.1 change in optical density (⌬OD) (a level generally considered positive) to PPD. Mean responses by infected reindeer to a rESAT-6-CFP-10 fusion protein (Mycobacterium tuberculosis complex specific) were as much as 20-fold higher than respective responses by noninfected reindeer at all time points. Additionally, responses by 3/4 noninfected reindeer were <0.1 ⌬OD (considered negative) at each time point. To further evaluate the specificity of the assay, samples were collected from reindeer in a TB-free herd. All reindeer had responses to mitogen; however, only 1 of 38 had a response to PPD, and none of the reindeer responded to rESAT-6-CFP-10. Together, these findings indicate that IFN-␥-based tests may prove useful for TB surveillance of reindeer. Mycobacterium bovis infection of reindeer (Rangifer tarandus)is rare, especially in North America, where there are no published reports of tuberculosis occurring in reindeer. Despite the low incidence of disease, reindeer are subject to regulations in the USDA Uniform Methods and Rules for the Eradication of Bovine Tuberculosis (TB) (Animal and Plant Health Inspection Service [APHIS] circular 91-45-011) (25) requiring TB testing for interstate movement and herd accreditation. For reindeer within the United States, the single cervical test (SCT), a measure of delayed-type hypersensitivity, is the primary approved test for tuberculosis. The SCT relies on in vivo reactivity to M. bovis purified protein derivative (PPD) injected intradermally into the mid-cervical region. Reindeer classified as reactors or suspect with this test are often retested using the comparative cervical skin test (CCT), in which M. bovis PPD is injected at one site and Mycobacterium avium PPD at a separate site. In principle, the CCT provides an added ability to distinguish M. avium responders from M. bovis responders. Although exact numbers are difficult to ascertain, many reindeer have tested positive upon skin testing for TB surveillance. Neither Mycobacterium bo...

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Section: Discussionmentioning

confidence: 99%

Section: Mycobacterium Bovis Infection Of Reindeer (Rangifer Tarandus)mentioning

confidence: 99%

Diagnostic Implications of Antigen-Induced Gamma Interferon Production by Blood Leukocytes from Mycobacterium bovis -Infected Reindeer ( Rangifer tarandus )

Waters

Palmer

Slaughter³

et al. 2006

Clin Vaccine Immunol

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“…Such tests promise to improve the detection of latent M. tuberculosis infection and could help with the rapid diagnosis of active TB in low-prevalence regions. Like the TST, T-cell-based tests do not distinguish between active TB and latent M. tuberculosis infection, so their diagnostic utility for active TB would be limited in populations with a high prevalence of latent infection.By screening eluted fractions of antigens from M. tuberculosis and M. bovis culture filtrates for recognition by T cells from infected humans and cattle, respectively, Andersen and coworkers identified several low-molecular-mass antigens that are major targets of CMI responses (2,12,32,33). Subtractive DNA hybridization of pathogenic M. bovis and BCG (27) and comparative genome-wide DNA microarray analysis of M. tuberculosis H37Rv and BCG (9) identified several regions of difference, designated RD1 to RD16, between M. tuberculosis and M. bovis on the one hand and BCG on the other (9).…”

mentioning

confidence: 99%

“…By screening eluted fractions of antigens from M. tuberculosis and M. bovis culture filtrates for recognition by T cells from infected humans and cattle, respectively, Andersen and coworkers identified several low-molecular-mass antigens that are major targets of CMI responses (2,12,32,33). Subtractive DNA hybridization of pathogenic M. bovis and BCG (27) and comparative genome-wide DNA microarray analysis of M. tuberculosis H37Rv and BCG (9) identified several regions of difference, designated RD1 to RD16, between M. tuberculosis and M. bovis on the one hand and BCG on the other (9).…”

mentioning

confidence: 99%

“…Two of the low-molecular-mass potent T-cell antigens identified by Andersen and colleagues, early secretory antigen target 6 (ESAT-6) and culture filtrate protein 10 (CFP10), are encoded in RD1 (2, 10) and have been intensively investigated in animal models and humans over the last few years (4,7,15,16,26,30,32,33,36,40). Studies using several different assays, including lymphoproliferation, gamma interferon (IFN-␥) enzyme-linked immunosorbent assay (ELISA), and IFN-␥ enzyme-linked immunospot (ELISPOT) assay, have shown that they are strong targets of the cellular immune response in animal models, TB patients, and contacts (4,11,24,28,30,35,(37)(38)(39).…”

mentioning

confidence: 99%

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Evaluation of T-Cell Responses to Novel RD1- and RD2-EncodedMycobacterium tuberculosisGene Products for Specific Detection of Human Tuberculosis Infection

et al. 2004

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The tuberculin skin test for diagnosing Mycobacterium tuberculosis infection suffers from antigenic crossreactivity of purified protein derivative with BCG, resulting in poor specificity in BCG-vaccinated populations. Comparative genomics has identified several genetic regions in M. tuberculosis and M. bovis that are deleted in M. bovis BCG. Proteins encoded in these regions will form the basis of new specific T-cell-based blood tests that do not cross-react with BCG, but only two, early secretory antigen target 6 and culture filtrate protein 10, have been studied in detail in humans. We investigated four novel gene products, encoded by RD2 (Rv1989c) and RD1 (Rv3873, Rv3878, and Rv3879c), that are absent from most or all of the vaccine strains of BCG, respectively. Sixty-seven overlapping peptides were tested in ex vivo gamma interferon enzyme-linked immunospot assays in 49 patients with culture-confirmed tuberculosis and 38 healthy BCG-vaccinated donors. Forty-five percent (95% confidence interval [CI], 31 to 57%) and 53% (95% CI, 39 to 67%) of the tuberculosis patients responded to Rv3879c and Rv3873, respectively, identifying these proteins as major M. tuberculosis T-cell antigens in humans, while 35 and 25% of the patients responded to Rv3878 and Rv1989c, respectively. Of the 38 BCG-vaccinated donors, 1 (2.6%) responded to peptides from Rv3878 and Rv3879c, 3 (7.9%) responded to Rv3873, and none responded to Rv1989c. Exclusion of cross-reactive peptides encoded in conserved motifs of Rv3873, a PPE family member, increased its specificity to 97.4%. The high specificity of Rv3879c peptides and nonconserved Rv3873 sequences, together with their moderate sensitivity in tuberculosis patients, identifies these peptides as candidates for inclusion in new T-cell-based tests for M. tuberculosis infection.Accurate diagnosis of tuberculosis (TB) infection is essential for the treatment, prevention, and control of this resurgent disease (1). Since Mycobacterium tuberculosis is often difficult to culture from patients with active TB, and impossible to culture from healthy latently infected people, an immunebased diagnostic test indicating the presence or absence of M. tuberculosis infection would be very useful for the diagnosis of active TB and screening for latent M. tuberculosis infection. The only widely used test is the century-old tuberculin skin test (TST), which has many drawbacks. Foremost among these is its poor specificity (21). This results from the broad antigenic cross-reactivity of purified protein derivative (PPD), a crude mixture of more than 200 M. tuberculosis proteins widely shared among M. tuberculosis, M. bovis Bacillus CalmetteGuérin (BCG), and most environmental mycobacteria (22). Hence, false-positive results are common in people with environmental mycobacterial exposure and previous BCG vaccination. Since most of the world's population is BCG vaccinated and since the confounding effect of BCG persists for up to 15 years after vaccination (41), this is a significant problem. Thus, there has been a...

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Immunodiagnosis of Mycobacterial Infection

et al. 1999

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The Potential of the ESAT-6 Antigen Secreted by Virulent Mycobacteria for Specific Diagnosis of Tuberculosis

Cited by 170 publications

References 14 publications

Diagnostic Implications of Antigen-Induced Gamma Interferon Production by Blood Leukocytes from Mycobacterium bovis -Infected Reindeer ( Rangifer tarandus )

Diagnostic Implications of Antigen-Induced Gamma Interferon Production by Blood Leukocytes from Mycobacterium bovis -Infected Reindeer ( Rangifer tarandus )

Evaluation of T-Cell Responses to Novel RD1- and RD2-EncodedMycobacterium tuberculosisGene Products for Specific Detection of Human Tuberculosis Infection

Immunodiagnosis of Mycobacterial Infection

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