Mycobacterium tuberculosis may escape helper T cell recognition by infecting human fibroblasts

ABSTRACTTheMycobacterium tuberculosisgenome includes the large family ofpe_pgrsgenes, whose functions are unknown. Because of precedents in other pathogens in which gene families showing high sequence variation are involved in antigenic variation, a similar role has been proposed for thepe_pgrsgenes. However, the impact of immune selection onpe_pgrsgenes has not been examined. Here, we sequenced 27pe_pgrsgenes in 94 clinical strains from five phylogenetic lineages of theM. tuberculosiscomplex (MTBC). We found thatpe_pgrsgenes were overall more diverse than the remainder of the MTBC genome, but individual members of the family varied widely in their nucleotide diversity and insertion/deletion (indel) content: some were more, and others were much less, diverse than the genome average. Individualpe_pgrsgenes also differed in the ratio of nonsynonymous to synonymous mutations, suggesting that different selection pressures act on individualpe_pgrsgenes. Using bioinformatic methods, we tested whether sequence diversity inpe_pgrsgenes might be selected by human T cell recognition, the major mechanism of adaptive immunity to MTBC. We found that the large majority of predicted human T cell epitopes were confined to the conserved PE domain and experimentally confirmed the antigenicity of this domain in tuberculosis patients. In contrast, despite being genetically diverse, the PGRS domains harbored few predicted T cell epitopes. These results indicate that human T cell recognition is not a significant force driving sequence diversity inpe_pgrsgenes, which is consistent with the previously reported conservation of human T cell epitopes in the MTBC.IMPORTANCERecognition ofMycobacterium tuberculosisantigens by T lymphocytes is known to be important for immune protection against tuberculosis, but it is unclear whether human T cell recognition drives antigenic variation inM. tuberculosis. We previously discovered that the known human T cell epitopes in theM. tuberculosiscomplex are highly conserved, but we hypothesized that undiscovered epitopes with naturally occurring sequence variants might exist. To test this hypothesis, we examined thepe_pgrsgenes, a large family of genes that has been proposed to function in immune evasion byM. tuberculosis. We found that thepe_pgrsgenes exhibit considerable sequence variation, but the regions containing T cell epitopes and the regions of variation are distinct. These findings confirm that the majority of human T cell epitopes ofM. tuberculosisare highly conserved and indicate that selection forces other than T cell recognition drive sequence variation in thepe_pgrsgenes.

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Helper T Cell Recognition of Respiratory Syncytial Virus in Mice

Journal of General Virology ◽

10.1099/0022-1317-69-2-305 ◽

1988 ◽

Vol 69 (2) ◽

pp. 305-312 ◽

Cited By ~ 28

Author(s):

P. J. M. Openshaw ◽

R. M. Pemberton ◽

L. A. Ball ◽

G. W. Wertz ◽

B. A. Askonas

Keyword(s):

Respiratory Syncytial Virus ◽

T Cell ◽

Cell Recognition ◽

Helper T Cell ◽

T Cell Recognition ◽

Syncytial Virus

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Cellular and genetic control of antibody responses. V. Helper T-cell recognition of H-2 determinants on accessory cells but not B cells.

Journal of Experimental Medicine ◽

10.1084/jem.149.5.1208 ◽

1979 ◽

Vol 149 (5) ◽

pp. 1208-1226 ◽

Cited By ~ 70

Author(s):

A Singer ◽

K S Hathcock ◽

R J Hodes

Keyword(s):

T Cells ◽

T Cell ◽

B Cells ◽

Helper T Cells ◽

Cell Recognition ◽

Helper T Cell ◽

T Cell Recognition ◽

Accessory Cells

Requirements for helper T-cell recognition of H-2 determinants expressed on adherent accessory cells and on B cells was individually assessed in the anti-hapten PFC responses to TNP-KLH. Complicating allogeneic effects were minimized or avoided by the use of helper T cells from normal F1 hybrids, parent leads to F1 chimeras, and F1 leads to parent chimeras. The results of both in vitro and in vivo experiments demonstrated that: (a) helper T cells are not required to recognize the identical H-2 determinants on both accessory cells and B cells; (b) helper T cells are required to recognize K or I-A region-encoded determinants expressed on accessory cells; (c) no requirement was observed in vitro or in vivo for helper T-cell recognition of B-cell-expressed H-2 determinants; and (d) no requirement was observed for H-2 homology between accessory cells and B cells. The absence of required helper T-cell recognition of the identical H-2 determinants on both accessory cells and B cells was demonstrated in two ways: (a) naive of KLH-primed (A x B)F1 hybrid helper T cells collaborated equally well with B cells from either parentA or parentB in the presence of accessory cells from either parent; (b) A leads to (A x B)F1 chimeric spleen cells depleted of accessory cells collaborated equally well with accessory cells from either parentA or parentB, even though the B cells only expressed the H-2 determinants of parentA. A requirement for helper T-cell recognition of K or I-A region-encoded H-2 determinants on accessory cells was also demonstrated in two ways: (a) (A x B)F1 leads to parentA chimeric spleen cells depleted of accessory cells collaborated with accessory cells from parentA but not parentB; and (b) (A x B)F1 leads to parentA chimeric helper T cells collaborated with normal F1 B cells only in the presence of parental or recombinant accessory cells that expressed the K or I-A region-encoded determinants of parentA. Although restricted in their ability to recognize H-2 determinants on accessory cells, it was demonstrated both in vitro and in vivo that (A x B)F1 leads to parentA chimeric helper T cells were able to collaborate with B cells from either parentA or parentB. In vitro in the presence of accessory cells from parentA, (A x B)F1 leads to parentA chimeric helper T cells collaborated equally well with B cells from either parent. In addition, the inability of (A x B)F1 leads to parentA chimeric helper T cells to collaborate with (B + accessory) cells from parentB was successfully reversed by the addition of parentA SAC as added accessory cells. In vivo, upon the addition of parentA accessory cells, (A x B)F1 leads to parentA chimeric helper T cells collaborated with parentB B cells in short-term adoptive transfer experiments.

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T-cell recognition of iron-regulated culture filtrate proteins of Mycobacterium tuberculosis in tuberculosis patients and endemic normal controls

Indian Journal of Medical Microbiology ◽

10.4103/0255-0857.99495 ◽

2012 ◽

Vol 30 (3) ◽

pp. 323

Author(s):

M Sritharan ◽

K Venu ◽

S Duggirala ◽

K Subhakar

Keyword(s):

Mycobacterium Tuberculosis ◽

T Cell ◽

Culture Filtrate ◽

Cell Recognition ◽

Tuberculosis Patients ◽

T Cell Recognition ◽

Culture Filtrate Proteins ◽

Normal Controls ◽

Endemic Normal

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Analysis of the T Cell Recognition System Using (T,G)-A--L Specific Helper T Cell Lines

Ir Genes ◽

10.1007/978-1-4612-5633-5_77 ◽

1983 ◽

pp. 541-546

Author(s):

Edna Mozes ◽

Ruth Lifshitz ◽

Ron N. Apte

Keyword(s):

T Cell ◽

Cell Lines ◽

Recognition System ◽

Cell Recognition ◽

Helper T Cell ◽

T Cell Recognition ◽

T Cell Lines

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T-Cell Recognition of the HspX Protein of Mycobacterium tuberculosis Correlates with Latent M. tuberculosis Infection but Not with M. bovis BCG Vaccination

Infection and Immunity ◽

10.1128/iai.01990-06 ◽

2007 ◽

Vol 75 (6) ◽

pp. 2914-2921 ◽

Cited By ~ 78

Author(s):

Annemieke Geluk ◽

May Young Lin ◽

Krista E. van Meijgaarden ◽

Eliane M. S. Leyten ◽

Kees L. M. C. Franken ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

T Cell ◽

T Cell Responses ◽

Cell Recognition ◽

T Cell Epitopes ◽

Bcg Vaccination ◽

T Cell Recognition ◽

Cell Responses

ABSTRACT During stationary growth or in vitro conditions mimicking relevant aspects of latency, the HspX protein (Rv2031c) is specifically upregulated by Mycobacterium tuberculosis. In this study we compared T-cell responses against HspX and the secreted M. tuberculosis protein Ag85B (Rv1886c) in tuberculosis (TB) patients, tuberculin skin test-positive individuals, M. bovis BCG-vaccinated individuals, and healthy negative controls. Gamma interferon responses to HspX were significantly higher in M. tuberculosis-exposed individuals than in M. tuberculosis-unexposed BCG vaccinees. In contrast, no such differences were found with respect to T-cell responses against Ag85B. Therefore, BCG-based vaccines containing relevant fragments of HspX may induce improved responses against this TB latency antigen. To identify relevant major histocompatibility complex class I- and class II-restricted HspX-specific T-cell epitopes, we immunized HLA-A2/Kb and HLA-DR3.Ab0 transgenic (tg) mice with HspX. Two new T-cell epitopes were identified, p91-105 and p31-50, restricted via HLA-A*0201 and HLA-DRB1*0301, respectively. These epitopes were recognized by human T cells as well, underlining the relevance of HspX T-cell recognition both in vivo and in vitro. In line with the data in humans, BCG immunization of both tg strains did not lead to T-cell responses against HspX-derived epitopes, whereas nonlatency antigens were efficiently recognized. These data support the notion that BCG vaccination per se does not induce T-cell responses against the latency antigen, HspX. Thus, we suggest that subunit vaccines incorporating HspX and/or other latency antigens, as well as recombinant BCG strains expressing latency antigens need to be considered as new vaccines against TB.

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Differential T-Cell Recognition of Native and Recombinant Mycobacterium tuberculosis GroES

Infection and Immunity ◽

10.1128/iai.67.11.5552-5558.1999 ◽

1999 ◽

Vol 67 (11) ◽

pp. 5552-5558 ◽

Cited By ~ 18

Author(s):

Ida Rosenkrands ◽

Karin Weldingh ◽

Pernille Ravn ◽

Lise Brandt ◽

Peter Højrup ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

T Cell ◽

Recombinant Protein ◽

Culture Filtrate ◽

Binding Protein ◽

Maltose Binding Protein ◽

Mass Spectrometry Analysis ◽

Cell Recognition ◽

T Cell Recognition ◽

Immunological Recognition

ABSTRACT Mycobacterium tuberculosis GroES was purified from culture filtrate, and its identity was confirmed by immunoblot analysis and N-terminal sequencing. Comparing the immunological recognition of native and recombinant GroES, we found that whereas native GroES elicited a strong proliferative response and release of gamma interferon-γ by peripheral blood mononuclear cells from healthy tuberculin reactors, the recombinant protein failed to do so. The same difference in immunological recognition was observed in a mouse model of TB infection. Both the native and recombinant preparations were recognized by mice immunized with the recombinant protein. Biochemical characterization including sodium dodecyl sulfate-polyacrylamide gel electrophoresis, two-dimensional electrophoresis, and mass spectrometry analysis of both proteins demonstrated no differences between the native and recombinant forms of GroES except for the eight additional N-terminal amino acids derived from the fusion partner in recombinant GroES. The recombinant fusion protein, still tagged with the maltose binding protein, was recognized by T cells isolated from TB-infected mice if mixed with culture filtrate before affinity purification on an amylose column. The maltose binding protein treated in the same manner as a control preparation was not recognized. Based on the data presented, we suggest that the association of biologically active molecules from culture filtrate with the chaperone GroES may be responsible for the observed T-cell recognition of the native preparation.

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