T cell recognition of Mycobacterium tuberculosis peptides presented by HLA-E derived from infected human cells

McMurtrey, Curtis P.; Harriff, Melanie J.; Swarbrick, Gwendolyn; Duncan, Amanda; Cansler, Meghan; Null, Megan; Bardet, Wilfried; Jackson, Kenneth W.; Lewinsohn, Deborah A.; Hildebrand, William H.; Lewinsohn, David

doi:10.1371/journal.pone.0188288

Cited by 42 publications

(54 citation statements)

References 36 publications

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“…Many efforts have been made for vaccine development against TB and presently, there are 12 vaccine candidates for TB at different stages of clinical trials for the development of new vaccine candidate against pulmonary TB . It has been proven that stimulation of cell‐mediated immune mechanisms, including γδ T cells, CD4+ T cells, CD8+ T cells, and CD1‐restricted and HLA‐E‐restricted T cells, have the potential to kill the mycobacterium . Some of the most promising antigens of MTB that could be used for subunit vaccine development are: ESAT‐6, MTB72F, Ag85B, and LiPY .…”

Section: Introductionmentioning

confidence: 99%

Expression of ESAT‐6 antigen from Mycobacterium tuberculosis in broccoli: An edible plant

Saba

Sameeullah

Asghar

et al. 2020

Biotech and App Biochem

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Tuberculosis (TB) is one of the major infectious diseases caused by Mycobacterium tuberculosis. The development of an effective and economical vaccine for controlling TB is essential especially for developing countries. Edible plants can serve as biofactories to produce vaccine antigens. In this study, 6 kDa early secretory antigenic target (ESAT‐6) of M. tuberculosis was expressed in Brassica oleracea var. italica via Agrobacterium‐mediated transformation to facilitate oral delivery of antigen. ESAT‐6 gene was cloned using Gateway® cloning strategy. Transformation and presence of transgene was confirmed through PCR. Expression level of transgene was calculated via quantitative real‐time PCR (qRT‐PCR) and the maximum integrated transgene number was two. Maximum amount of total soluble fraction of ESAT‐6 was evaluated by immunoblotting, estimated to accumulate up to 0.5% of total soluble protein. The recombinant ESAT‐6 protein was further purified and detected using silver staining and Western blotting. ESAT‐6 protein induced humoral immune response in mice immunized orally and subcutaneously. The expression of M. tuberculosis antigen in edible plants could aid in the development of cost‐effective and oral delivery of an antigen‐based subunit vaccine against TB. To the best our knowledge, it is the first report of expression of a vaccine antigen in broccoli.

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Section: Introductionmentioning

confidence: 99%

Expression of ESAT‐6 antigen from Mycobacterium tuberculosis in broccoli: An edible plant

Saba

Sameeullah

Asghar

et al. 2020

Biotech and App Biochem

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“…Intriguingly a number of key epitopes against which HLA-E-restricted CD8 + T cell responses have previously been identified did not exhibit definitive HLA-E binding in this assay. For example, the Mtbderived EK11 which comprises residues 19-29 of the conserved hypothetical protein Rv0634A (EIEVDDDLIQK), demonstrated an immunodominant profile with HLA-E-restricted responses detected in 81% of tested donors with active or latent Mtb infection 21 . However, in the peptide exchange ELISA assay EK11 generated an average absorbance reading below the 'no-rescue' peptide-free background signal, and produced the lowest signal of any peptide tested ( Supplementary Table 2).…”

Section: Discussionmentioning

confidence: 99%

“…A panel of Mycobacterial peptides eluted from Mtb-infected cells 21 was screened in the improved assay system ( Figure 5, A). As these peptides were eluted from HLA-E, they were not subject to the algorithmic biases that dictate previously described HLA-E-restricted peptide sequence motifs.…”

Section: Screening Of Mtb-derived Peptides Predicted To Bind Hla-ementioning

confidence: 99%

Detailed and atypical HLA-E peptide binding motifs revealed by a novel peptide exchange binding assay

Walters

McMichael

Gillespie

2020

Preprint

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Diverse SIV epitopes that bind the rhesus homologue of HLA-E, Mamu-E, have recently been identified in SIV-vaccine studies using a recombinant Rhesus cytomegalovirus (RhCMV 68-1) vector, where unprecedented protection against SIV challenge was achieved. Additionally, several Mycobacterial peptides identified both algorithmically and following elution from infected cells, are presented to CD8 + T cells by HLA-E in humans. Yet, a comparative and comprehensive analysis of relative HLA-E peptide binding strength via a reliable, high throughput in vitro assay is currently lacking. To address this we developed and optimised a novel, highly sensitive peptide exchange ELISA-based assay that relatively quantitates peptide binding to HLA-E. Using this approach we screened multiple peptides, including peptide panels derived from HIV, SIV and Mtb predicted to bind HLA-E. Our results indicate that although HLA-E preferentially accommodates canonical MHC class I leader peptides, many noncanonical, sequence diverse, pathogen-derived peptides also bind HLA-E, albeit generally with lower relative binding strength. Additionally, our screens demonstrate that the majority of peptides tested, including some key Mtb and SIV epitopes which have been shown to elicit strong Mamu-E-restricted T cell responses, either bind HLA-E extremely weakly or give signals that are indistinguishable from the negative, peptide-free controls.Given the identification of a large number of non-VL9 pathogen-and self-derived HLA-E-binding peptides, we recognised the need to develop an assay to reliably and comparatively assess the HLA-E peptidome. We therefore designed and optimised a new in vitro peptide exchange ELISA-based assay to validate and relatively quantitate peptide binding to HLA-E. Although we previously validated HLA-E peptide binding 17 using a micro-refolding ELISA-based assay, originally developed to determine peptide binding affinity to classical MHC class I molecules 7 22 , this assay suffered from variability between biological repeats, so that very large numbers of replicate assays were required to achieve statistically robust results. The variability was likely caused by assay-to-assay fluctuations in protein refolding in addition to unusually high background signals, due to partial HLA-E-b2M refolding in the absence of added peptide 20 . To improve the system we adopted a new UV peptide exchange ELISAbased assay 23 . In this assay, HLA-E heavy chain and β2M are pre-refolded with a UV-labile HLA-E binding peptide based on the VL9 sequence in which the solvent exposed Arg at position 5 of VL9 was replaced with a photo-cleavable, unnatural 2-nitrophenylamino acid residue 20 23 . Such conditional peptide ligand technology was originally developed for HLA-A*02:01 23 and subsequently adapted to facilitate peptide exchange in HLA-A*1, -A*3, -A*11, -B*7 and -B*57 molecules 24 25 . Specifically, the nitrophenyl moiety within the substituted beta amino acid is sensitive to UV illumination at >350nm. This results in peptide cleavage and successiv...

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“…Multiple peptides within the Mtb genome can be presented (including peptides from p49 and Mtb44 proteins, Table 2) [61,72,74]. Their varying amino acid length implies that HLA-E has higher peptide binding plasticity than solely the VL9 peptide [75]. These non-canonical T cells contribute to the majority of T cells present during active Mtb infection [77], and overshadow T cells restricted by canonical HLA class Ia epitope presentation [78,79].…”

Section: Mycobacterium Tuberculosismentioning

confidence: 99%

“…In humans and mice, CD4 + and CD8 + T cells are vital for control of Mtb infection [75]. Unusually, for any known pathogen, there is a large population of CD8 + T cells restricted by HLA-E induced by infection [76], possibly enhanced by the up-regulation of HLA-E on the surface of Mtb-infected phagosomes [65,70].…”

Section: Mycobacterium Tuberculosismentioning

confidence: 99%

HLA-E: exploiting pathogen-host interactions for vaccine development

Sharpe

Bowyer

Brackenridge

et al. 2019

Clinical and Experimental Immunology

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Summary Viruses, when used as vectors for vaccine antigen delivery, can induce strong cellular and humoral responses against target epitopes. Recent work by Hansen et al. describes the use of a cytomegalovirus‐vectored vaccine, which is able to generate a stable effector‐memory T cell population at the sites of vaccination in rhesus macaques. This vaccine, targeted towards multiple epitopes in simian immunodeficiency virus (SIV), did not induce classical CD8+ T cells. However, non‐canonical CD8+ T cell induction occurred via major histocompatibility complex (MHC) class II and MHC‐E. The MHC‐E‐restricted T cells could recognize broad epitopes across the SIV peptides, and conferred protection against viral challenge to 55% of vaccinated macaques. The human homologue, human leucocyte antigen (HLA)‐E, is now being targeted as a new avenue for vaccine development. In humans, HLA‐E is an unusually oligomorphic class Ib MHC molecule, in comparison to highly polymorphic MHC class Ia. Whereas MHC class Ia presents peptides derived from pathogens to T cells, HLA‐E classically binds defined leader peptides from class Ia MHC peptides and down‐regulates NK cell cytolytic activity when presented on the cell surface. HLA‐E can also restrict non‐canonical CD8+ T cells during natural infection with various pathogens, although the extent to which they are involved in pathogen control is mostly unknown. In this review, an overview is provided of HLA‐E and its ability to interact with NK cells and non‐canonical T cells. Also discussed are the unforeseen beneficial effects of vaccination, including trained immunity of NK cells from bacille Calmette–Guérin (BCG) vaccination, and the broad restriction of non‐canonical CD8+ T cells by cytomegalovirus (CMV)‐vectored vaccines in pre‐clinical trials.

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T cell recognition of Mycobacterium tuberculosis peptides presented by HLA-E derived from infected human cells

Cited by 42 publications

References 36 publications

Expression of ESAT‐6 antigen from Mycobacterium tuberculosis in broccoli: An edible plant

Expression of ESAT‐6 antigen from Mycobacterium tuberculosis in broccoli: An edible plant

Detailed and atypical HLA-E peptide binding motifs revealed by a novel peptide exchange binding assay

HLA-E: exploiting pathogen-host interactions for vaccine development

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