Immunological Characterization of Antigens Encoded by the RD1 Region of the <i>Mycobacterium tuberculosis</i> Genome

Brusasca, PierNatale; Colangeli, Roberto; Lyashchenko, Konstantin P.; Zhao, Xin; Vogelstein, M.; Spencer, John S.; McMurray, David N.; Gennaro, Maria Laura

doi:10.1046/j.1365-3083.2001.00975.x

Cited by 65 publications

(65 citation statements)

References 26 publications

(44 reference statements)

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“…The high specificity of the Rv3879c peptides (97.4%), together with the fact that they are recognized in the IFN-␥ ELISPOT assay by almost half of TB patients, identifies this molecule as a potentially useful T-cell antigen for inclusion in novel T-cellbased diagnostic tests of M. tuberculosis infection. Antibody responses to Rv3873 and Rv3878 have previously been studied in humans (14). Of 75 TB patients, none (0%) had antibodies to Rv3873 and only 5 (6.7%) had detectable antibody responses to Rv3878 (14), considerably lower than the rates of response to these antigens of our series of 49 culture-confirmed TB patients in IFN-␥ ELISPOT assays.…”

Section: Vol 72 2004 T-cell Responses To Novel M Tuberculosis Genementioning

confidence: 58%

“…Antibody responses to Rv3873 and Rv3878 have previously been studied in humans (14). Of 75 TB patients, none (0%) had antibodies to Rv3873 and only 5 (6.7%) had detectable antibody responses to Rv3878 (14), considerably lower than the rates of response to these antigens of our series of 49 culture-confirmed TB patients in IFN-␥ ELISPOT assays. Thus, the potential of these two RD1-encoded gene products to contribute to an improved diagnostic test for TB could only be recognized by evaluation of T-cell responses in TB patients.…”

Section: Vol 72 2004 T-cell Responses To Novel M Tuberculosis Genementioning

confidence: 58%

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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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Section: Vol 72 2004 T-cell Responses To Novel M Tuberculosis Genementioning

confidence: 58%

Section: Vol 72 2004 T-cell Responses To Novel M Tuberculosis Genementioning

confidence: 58%

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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“…In mice it has been shown that the ESAT-6 1-15 epitope was recognized by as much as 25-35% of the total mycobacteria-reactive T cell repertoire recruited to the site of infection in the first phase of a recall response in C57BL/6J mice (9). The immunodominance of this epitope may be a consequence of the high expression of ESAT-6 during infection (32), as well as easy proteolytic access to the protruding part of the ESAT-6 molecule containing this epitope (33). However, it is known from viral studies that epitope dominance cannot only be explained in terms of peptide loading and affinity for MHC (34), and there are data to suggest that T cells responding to one Ag can actively interfere with T cells responding to another (35,36).…”

Section: Discussionmentioning

confidence: 99%

“…2). No IFN-␥ release was found in response to the control peptide (ESAT-6 [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] ). In addition to the immunodominant P1 (ESAT-6 [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] ) epitope, the analysis of peptides covering the full sequence of ESAT-6 revealed two additional subdominant epitopes to which T cells are not primed during the natural infection.…”

Section: Identification Of Subdominant Epitopes In Esat-6mentioning

confidence: 99%

Quality and Vaccine Efficacy of CD4+ T Cell Responses Directed to Dominant and Subdominant Epitopes in ESAT-6 from Mycobacterium tuberculosis

Aagaard

Hoang²,

Vingsbo‐Lundberg³

et al. 2009

The Journal of Immunology

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The ESAT-6 (early secretory antigenic target) molecule is a very important target for T cell recognition during infection with Mycobacterium tuberculosis. Although ESAT-6 contains numerous potential T cell epitopes, the immune response during infection is often focused toward a few immunodominant epitopes. By immunization with individual overlapping synthetic peptides in cationic liposomes (cationic adjuvant formulation, CAF01) we demonstrate that the ESAT-6 molecule contains several subdominant epitopes that are not recognized in H-2d/b mice either during tuberculosis infection or after immunization with ESAT-6/CAF01. Immunization with a truncated ESAT-6 molecule (Δ15ESAT-6) that lacks the immunodominant ESAT-61–15 epitope refocuses the response to include T cells directed to these subdominant epitopes. After aerosol infection of immunized mice, T cells directed to both dominant (ESAT-6-immunized) and subdominant epitopes (Δ15ESAT-6-immunized) proliferate and are recruited to the lung. The vaccine-promoted response consists mainly of double- (TNF-α and IL-2) or triple-positive (IFN-γ, TNF-α, and IL-2) polyfunctional T cells. This polyfunctional quality of the CD4+ T cell response is maintained unchanged even during the later stages of infection, whereas the naturally occurring infection stimulates a response to the ESAT-61–15 epitope that consist almost exclusively of CD4+ effector T cells. ESAT-6 and Δ15ESAT-6 both give significant protection against aerosol challenge with tuberculosis, but the most efficient protection against pulmonary infection is mediated by the subdominant T cell repertoire primed by Δ15ESAT-6.

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“…PBS is a common biological buffer because it is isotonic (with similar osmolarity to the body) and non-toxic to cells. 202 Intra-dermal injections of PBS alone have been used as controls in studies 203,204 with reported histology of moderate dermal oedema and blood vessel dilation without inflammation in human skin. 205 Similarly previous experiments involving human skin demonstrated redness and swelling at 10 and 30 minutes associated with needle trauma, followed by mild or no inflammatory reaction 48 hours after intra-dermal saline injections.…”

Section: Limitations Of Experimental Protocols In the Main Studymentioning

confidence: 99%

The mode of action of intra-dermal sodium lauryl sulfate (SLS) as a chemical alternative to mulesing in sheep

Lee¹

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Sheep blowfly strike imposes significant economic costs of $260 million annually from disruptions to farm management operations 1, 2 associated with high labour cost of controlling flystrike, 3 sheep morbidity and mortality, and loss of wool productivity. 4 Mulesing, the surgical removal of skin from the breech which minimises soiling and reduces susceptibility to flystrike, is performed without anaesthetic and is therefore perceived as cruel and painful as reflected by physiological and behavioural alterations in affected lambs. 5,6 Intra-dermal sodium lauryl sulfate (SLS) was trialled in this study as a potential chemical alternative to mulesing. A sound mulesing alternative would ideally provide efficient wound healing and hairless scar formation which increases the bare area of the breech while causing minimal discomfort to the animal.In a sighting study, 3 Merino wethers were given intra-dermal injections of SLS at specific sites on the flank which were biopsied at different time points over 28 days. Assessments were made on gross and histological changes of wound healing as well as early behavioural indicators of pain.Based on the results of the sighting study, the following protocol refinements were made for the main study which used 6 Merino wethers, to:1) reduce biopsy frequency with concentration around specimens of histopathologic interest;2) expand lesion parameters and sharpen the grading process;3) improve SLS delivery using a pressurized needleless applicator; 4) incorporate analysis of SLS's mode of action at the ultrastructural level; 5) improve the approach for pain assessment.Treated sheep showed minimal behavioural or postural indicators of pain or discomfort, their appetite was normal and there was a net gain in body weight, when compared with their untreated cohorts. Gross appearance of the treatment site consisted of initial swelling which subsided by day 14 leaving a firm, slightly raised, crust. At day 21, the treated area was depressed and covered by a scab (eschar) which partially sloughed off by day 28.Histological examination revealed necrosis of soft tissue structures (including hair bulbs, collagen, vessels and nerves) in the subcutis and deep dermis at 2 minutes after treatment, followed by subsequent additional ischaemic necrosis of the superficial dermis and epidermis with progressive inflammation, proliferation and remodelling of the wound. Fibroplasia and angiogenesis were accompanied with reepithelialisation starting at day 7, subjacent to areas of full dermal-epidermal

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Immunological Characterization of Antigens Encoded by the RD1 Region of the Mycobacterium tuberculosis Genome

Cited by 65 publications

References 26 publications

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

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

Quality and Vaccine Efficacy of CD4+ T Cell Responses Directed to Dominant and Subdominant Epitopes in ESAT-6 from Mycobacterium tuberculosis

The mode of action of intra-dermal sodium lauryl sulfate (SLS) as a chemical alternative to mulesing in sheep

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