scholarly journals B cells immortalized by a mini–Epstein-Barr virus encoding a foreign antigen efficiently reactivate specific cytotoxic T cells

Blood ◽  
2002 ◽  
Vol 100 (5) ◽  
pp. 1755-1764 ◽  
Author(s):  
Andreas Moosmann ◽  
Naeem Khan ◽  
Mark Cobbold ◽  
Caroline Zentz ◽  
Henri-Jacques Delecluse ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Cell Lines ◽  
Cell Cultures ◽  
Epstein Barr Virus ◽  
Large Fraction ◽  
Barr Virus ◽  
Epstein Barr

Lymphoblastoid cell lines (LCLs) are human B cells latently infected and immortalized by Epstein-Barr virus (EBV). Presenting viral antigens, they efficiently induce EBV-specific T-cell responses in vitro. Analogous ways to generate T-cell cultures specific for other antigens of interest are highly desirable. Previously, we constructed a mini-EBV plasmid that consists of less than half the EBV genome, is unable to cause virus production, but still immortalizes B cells in vitro. Mini-EBV–immortalized B-cell lines (mini-LCLs) are efficiently produced by infection of B cells with viruslike particles carrying only mini-EBV DNA. Mini-EBV plasmids can be engineered to express an additional gene in immortalized B cells. Here we present a mini-EBV coding for a potent CD8+ T-cell antigen, the matrix phosphoprotein pp65 of human cytomegalovirus (CMV). By means of this pp65 mini-EBV, pp65-expressing mini-LCLs could be readily established from healthy donors in a one-step procedure. We used these pp65 mini-LCLs to reactivate and expand effector T cells from autologous peripheral blood cells in vitro. When generated from cytomegalovirus (CMV)–seropositive donors, these effector T-cell cultures displayed strong pp65-specific HLA-restricted cytotoxicity. A large fraction of CD8+ T cells with pp65 epitope specificity was present in such cultures, as demonstrated by direct staining with HLA/peptide tetramers. We conclude that the pp65 mini-EBV is an attractive tool for CMV-specific adoptive immunotherapy. Mini-EBVs could also facilitate the generation of T cells specific for various other antigens of interest.

scholarly journals CD4+ T-Cell Effectors Inhibit Epstein-Barr Virus-Induced B-Cell Proliferation

2001 ◽  
Vol 75 (8) ◽  
pp. 3740-3752 ◽  
Author(s):  
Sarah Nikiforow ◽  
Kim Bottomly ◽  
George Miller
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Lines ◽  
Epstein Barr Virus ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACT In immunodeficient hosts, Epstein-Barr virus (EBV) often induces extensive B-cell lymphoproliferative disease and lymphoma. Without effective in vitro immune surveillance, B cells infected by the virus readily form immortalized cell lines. In the regression assay, memory T cells inhibit the formation of foci of EBV-transformed B cells that follows recent in vitro infection by EBV. No one has yet addressed which T cell regulates the early proliferative phase of B cells newly infected by EBV. Using new quantitative methods, we analyzed T-cell surveillance of EBV-mediated B-cell proliferation. We found that CD4+ T cells play a significant role in limiting proliferation of newly infected, activated CD23+ B cells. In the absence of T cells, EBV-infected CD23+ B cells divided rapidly during the first 3 weeks after infection. Removal of CD4+ but not CD8+ T cells also abrogated immune control. Purified CD4+ T cells eliminated outgrowth when added to EBV-infected B cells. Thus, unlike the killing of EBV-infected lymphoblastoid cell lines, in which CD8+ cytolytic T cells play an essential role, prevention of early-phase EBV-induced B-cell proliferation requires CD4+ effector T cells.

scholarly journals Epstein-Barr Virus Induces Adhesion Receptor CD226 (DNAM-1) Expression during Primary B-Cell Transformation into Lymphoblastoid Cell Lines

mSphere ◽  
2017 ◽  
Vol 2 (6) ◽  
Author(s):  
Lisa Grossman ◽  
Chris Chang ◽  
Joanne Dai ◽  
Pavel A. Nikitin ◽  
Dereje D. Jima ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Lines ◽  
Epstein Barr Virus ◽  
Human Herpesvirus ◽  
Barr Virus ◽  
Ebv Infection ◽  
Cellular Aggregation ◽  
Epstein Barr

ABSTRACT Epstein-Barr virus (EBV) is a common human herpesvirus that establishes latency in B cells. While EBV infection is asymptomatic for most individuals, immune-suppressed individuals are at significantly higher risk of a form of EBV latent infection in which infected B cells are reactivated, grow unchecked, and generate lymphomas. This form of latency is modeled in the laboratory by infecting B cells from the blood of normal human donors in vitro. In this model, we identified a protein called CD226 that is induced by EBV but is not normally expressed on B cells. Rather, it is known to play a role in aggregation and survival signaling of non-B cells in the immune system. Cultures of EBV-infected cells adhere to one another in “clumps,” and while the proteins that are responsible for this cellular aggregation are not fully understood, we hypothesized that this form of cellular aggregation may provide a survival advantage. In this article, we characterize the mechanism by which EBV induces this protein and its expression on lymphoma tissue and cell lines and characterize EBV-infected cell lines in which CD226 has been knocked out. Epstein-Barr virus (EBV), an oncogenic herpesvirus, infects and transforms primary B cells into immortal lymphoblastoid cell lines (LCLs), providing a model for EBV-mediated tumorigenesis. EBV transformation stimulates robust homotypic aggregation, indicating that EBV induces molecules that mediate cell-cell adhesion. We report that EBV potently induced expression of the adhesion molecule CD226, which is not normally expressed on B cells. We found that early after infection of primary B cells, EBV promoted an increase in CD226 mRNA and protein expression. CD226 levels increased further from early proliferating EBV-positive B cells to LCLs. We found that CD226 expression on B cells was independent of B-cell activation as CpG DNA failed to induce CD226 to the extent of EBV infection. CD226 expression was high in EBV-infected B cells expressing the latency III growth program, but low in EBV-negative and EBV latency I-infected B-lymphoma cell lines. We validated this correlation by demonstrating that the latency III characteristic EBV NF-κB activator, latent membrane protein 1 (LMP1), was sufficient for CD226 upregulation and that CD226 was more highly expressed in lymphomas with increased NF-κB activity. Finally, we found that CD226 was not important for LCL steady-state growth, survival in response to apoptotic stress, homotypic aggregation, or adhesion to activated endothelial cells. These findings collectively suggest that EBV induces expression of a cell adhesion molecule on primary B cells that may play a role in the tumor microenvironment of EBV-associated B-cell malignancies or facilitate adhesion in the establishment of latency in vivo. IMPORTANCE Epstein-Barr virus (EBV) is a common human herpesvirus that establishes latency in B cells. While EBV infection is asymptomatic for most individuals, immune-suppressed individuals are at significantly higher risk of a form of EBV latent infection in which infected B cells are reactivated, grow unchecked, and generate lymphomas. This form of latency is modeled in the laboratory by infecting B cells from the blood of normal human donors in vitro. In this model, we identified a protein called CD226 that is induced by EBV but is not normally expressed on B cells. Rather, it is known to play a role in aggregation and survival signaling of non-B cells in the immune system. Cultures of EBV-infected cells adhere to one another in “clumps,” and while the proteins that are responsible for this cellular aggregation are not fully understood, we hypothesized that this form of cellular aggregation may provide a survival advantage. In this article, we characterize the mechanism by which EBV induces this protein and its expression on lymphoma tissue and cell lines and characterize EBV-infected cell lines in which CD226 has been knocked out.

scholarly journals Analysis of the defects responsible for the impaired regulation of Epstein-Barr virus-induced B cell proliferation by rheumatoid arthritis lymphocytes. I. Diminished gamma interferon production in response to autologous stimulation.

1983 ◽  
Vol 157 (1) ◽  
pp. 173-188 ◽  
Author(s):  
F Hasler ◽  
H G Bluestein ◽  
N J Zvaifler ◽  
L B Epstein
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
B Cell ◽  
Epstein Barr Virus ◽  
Gamma Interferon ◽  
Barr Virus ◽  
T Cell Regulation ◽  
Epstein Barr

T cells of patients with rheumatoid arthritis (RA) do not control the rate of B lymphoblast transformation induced by Epstein-Barr virus (EBV) as efficiently as T cells from healthy individuals; thus, lymphoblast cell lines are established more readily in RA lymphocytes in vitro after EBV infection. In the present experiments, we have asked whether this T cell regulation can be reproduced by lymphocytes. We found that normal T cells, activated in allogeneic or autologous mixed leukocyte reactions (MLR), produce lymphokines that inhibit in vitro EBV-induced B cell proliferation. Allogeneic MLR supernatants inhibited EBV-induced DNA synthesis 62 +/- 4% (mean +/- SE) at 10 d post-infection, whereas autologous MLR supernatants suppressed it 50 +/- 3%. RA T cell supernatants produced in an allogeneic MLR suppressed as well as normal T cell supernatants (64 +/- 5% inhibition). In contrast, supernatants from RA autologous MLR had little inhibitory activity. EBV-induced DNA synthesis at 10 d was reduced only 8 +/- 3%, compared with the 50 +/- 3% suppressive activity of normal autologous MLR supernatants. The magnitude of the proliferative responses in the autologous MLR regenerating the lymphokines was similar in the normal and RA populations. After depletion of adherent cells from the RA auto-MLR stimulators, supernatant inhibitory activities increased to normal levels (from 11 +/- 6 [SE] to 52 +/- 6% [SE]). The inhibitory factor involved in the regulation of in vitro EBV infection is a protein with a molecular weight of approximately 50,000. Its activity is eliminated by hearing at 56 degrees C and by exposure to acid at pH 2. The inhibitory activity is blocked by mixing the MLR supernatants with a polyvalent antisera or monoclonal antibodies specific for human gamma interferon. Gamma interferon produced by activating T cells in allo- or auto-MLR can reproduce T cell-mediated regulation of EBV-induced B cell proliferation, and the failure of RA auto-MLR to generate that lymphokine parallels the defective T cell regulation of EBV-induced B cell proliferation characteristic of RA lymphoid cells.

scholarly journals Epstein-Barr virus transformation of human pre-B cells.

1983 ◽  
Vol 158 (2) ◽  
pp. 616-622 ◽  
Author(s):  
M Hansson ◽  
K Falk ◽  
I Ernberg
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
B Cell ◽  
Cell Lines ◽  
Epstein Barr Virus ◽  
Bone Marrow Cells ◽  
Fetal Bone ◽  
Barr Virus ◽  
Epstein Barr

In vitro infection of human B lymphocytes with Epstein-Barr virus (EBV) results in establishment of B lymphoblastoid cell lines that reflect normal B cell phenotypes. In this study we have investigated whether immature B cells from fetal bone marrow and liver can serve as targets for EBV. The fetal bone marrow cells were readily transformed by EBV. Among the resulting cell lines, five were surface Ig (sIg)-negative. Three B cell-associated antigens defined by monoclonal antibodies were expressed to the same extent on the fetal cell lines, whether they belonged to the sIg- or sIg+ group. The various differentiation stages that these cell lines may represent are discussed.

scholarly journals Repertoire and frequency of immune cells reactive to Epstein-Barr virus–derived autologous lymphoblastoid cell lines

Blood ◽  
2008 ◽  
Vol 111 (3) ◽  
pp. 1334-1343 ◽  
Author(s):  
Sumita Bhaduri-McIntosh ◽  
Marisa J. Rotenberg ◽  
Benjamin Gardner ◽  
Marie Robert ◽  
George Miller
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Lines ◽  
Immune Cells ◽  
Epstein Barr Virus ◽  
Ex Vivo ◽  
Lymphoblastoid Cell Lines ◽  
Barr Virus ◽  
Different Types ◽  
Epstein Barr

AbstractAnswers to questions about frequency and repertoire of immune cells, relative contributions made by different types of immune cells toward the total Epstein-Barr virus (EBV)–directed response and the variation of such responses in healthy persons have been elusive because of disparities in assays, antigen presenting cells, and antigenic sources used in previous experiments. In this study, we addressed these questions using an assay that allowed direct comparison of responses generated by different types of cells of the immune system. This short-term (20-hour) ex vivo assay measured interferon-γ production by blood cells in response to autologous EBV-transformed lymphoblastoid cell lines (LCLs). Our experiments defined the variation in responses among persons and clearly distinguished 10 healthy EBV-immune from 10 healthy EBV-naive persons. In EBV-immune persons, 33% of responding cells were CD4+, 43.3% were CD8+, and 12.9% were γ-δ T cells. LCL-reactive CD8+ T cells were only 1.7-fold more frequent than similarly reactive CD4+T cells. Responses by γ-δ T cells were 6-fold higher in seropositive than in seronegative persons. Our findings emphasize the importance of CD4+ and γ-δ T-cell responses and have implications for immunotherapy and for identifying defects in T-cell populations that might predispose to development of EBV-associated lymphomas.

scholarly journals Standardized and Highly Efficient Expansion of Epstein-Barr Virus-Specific CD4+ T Cells by Using Virus-Like Particles

2008 ◽  
Vol 82 (8) ◽  
pp. 3903-3911 ◽  
Author(s):  
Dinesh Adhikary ◽  
Uta Behrends ◽  
Regina Feederle ◽  
Henri-Jacques Delecluse ◽  
Josef Mautner
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Lines ◽  
Clinical Efficacy ◽  
Epstein Barr Virus ◽  
Transplant Recipients ◽  
Virus Like Particles ◽  
Barr Virus ◽  
Epstein Barr ◽  
T Cell Lines

ABSTRACT Epstein-Barr virus (EBV)-specific T-cell lines generated by repeated stimulation with EBV-immortalized lymphoblastoid B-cell lines (LCL) have been successfully used to treat EBV-associated posttransplant lymphoproliferative disease (PTLD) in hematopoietic stem cell transplant recipients. However, PTLD in solid-organ transplant recipients and other EBV-associated malignancies respond less efficiently to this adoptive T-cell therapy. LCL-stimulated T-cell preparations are polyclonal and contain CD4+ and CD8+ T cells, but the composition varies greatly between lines. Because T-cell lines with higher CD4+ T-cell proportions show improved clinical efficacy, we assessed which factors might compromise the expansion of this T-cell population. Here we show that spontaneous virus production by LCL and, hence, the presentation of viral antigens varies intra- and interindividually and is further impaired by acyclovir treatment of LCL. Moreover, the stimulation of T cells with LCL grown in medium supplemented with fetal calf serum (FCS) caused the expansion of FCS-reactive CD4+ T cells, whereas human serum from EBV-seropositive donors diminished viral antigen presentation. To overcome these limitations, we used peripheral blood mononuclear cells pulsed with nontransforming virus-like particles as antigen-presenting cells. This strategy facilitated the specific and rapid expansion of EBV-specific CD4+ T cells and, thus, might contribute to the development of standardized protocols for the generation of T-cell lines with improved clinical efficacy.

scholarly journals CAR-T cells and TRUCKs that recognize an EBNA-3C-derived epitope presented on HLA-B*35 control Epstein-Barr virus-associated lymphoproliferation

2020 ◽  
Vol 8 (2) ◽  
pp. e000736
Author(s):  
Anna Christina Dragon ◽  
Katharina Zimmermann ◽  
Thomas Nerreter ◽  
Deborah Sandfort ◽  
Julia Lahrberg ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Immune Cells ◽  
Epstein Barr Virus ◽  
Target Cells ◽  
Barr Virus ◽  
Car T Cells ◽  
Car T ◽  
Epstein Barr

BackgroundImmunosuppressive therapy or T-cell depletion in transplant patients can cause uncontrolled growth of Epstein-Barr virus (EBV)-infected B cells resulting in post-transplant lymphoproliferative disease (PTLD). Current treatment options do not distinguish between healthy and malignant B cells and are thereby often limited by severe side effects in the already immunocompromised patients. To specifically target EBV-infected B cells, we developed a novel peptide-selective chimeric antigen receptor (CAR) based on the monoclonal antibody TÜ165 which recognizes an Epstein-Barr nuclear antigen (EBNA)−3C-derived peptide in HLA-B*35 context in a T-cell receptor (TCR)-like manner. In order to attract additional immune cells to proximity of PTLD cells, based on the TÜ165 CAR, we moreover generated T cells redirected for universal cytokine-mediated killing (TRUCKs), which induce interleukin (IL)-12 release on target contact.MethodsTÜ165-based CAR-T cells (CAR-Ts) and TRUCKs with inducible IL-12 expression in an all-in-one construct were generated. Functionality of the engineered cells was assessed in co-cultures with EBNA-3C-peptide-loaded, HLA-B*35-expressing K562 cells and EBV-infected B cells as PTLD model. IL-12, secreted by TRUCKs on target contact, was further tested for its chemoattractive and activating potential towards monocytes and natural killer (NK) cells.ResultsAfter co-cultivation with EBV target cells, TÜ165 CAR-Ts and TRUCKs showed an increased activation marker expression (CD137, CD25) and release of proinflammatory cytokines (interferon-γ and tumor necrosis factor-α). Moreover, TÜ165 CAR-Ts and TRUCKs released apoptosis-inducing mediators (granzyme B and perforin) and were capable to specifically lyse EBV-positive target cells. Live cell imaging revealed a specific attraction of TÜ165 CAR-Ts around EBNA-3C-peptide-loaded target cells. Of note, TÜ165 TRUCKs with inducible IL-12 showed highly improved effector functions and additionally led to recruitment of monocyte and NK cell lines.ConclusionsOur results demonstrate that TÜ165 CAR-Ts recognize EBV peptide/HLA complexes in a TCR-like manner and thereby allow for recognizing an intracellular EBV target. TÜ165 TRUCKs equipped with inducible IL-12 expression responded even more effectively and released IL-12 recruited additional immune cells which are generally missing in proximity of lymphoproliferation in immunocompromised PTLD patients. This suggests a new and promising strategy to specifically target EBV-infected cells while sparing and mobilizing healthy immune cells and thereby enable control of EBV-associated lymphoproliferation.

Epstein-Barr Virus (EBV) LMP2A induces alterations in gene transcription similar to those observed in Reed-Sternberg cells of Hodgkin lymphoma

Blood ◽  
2003 ◽  
Vol 102 (12) ◽  
pp. 4166-4178 ◽  
Author(s):  
Toni Portis ◽  
Patricia Dyck ◽  
Richard Longnecker
Keyword(s):  
B Cells ◽  
B Cell ◽  
Hodgkin Lymphoma ◽  
Cell Lines ◽  
Gene Transcription ◽  
Epstein Barr Virus ◽  
Barr Virus ◽  
Expression Of Genes ◽  
Epstein Barr

AbstractEpstein-Barr virus (EBV) is associated with the development of a variety of malignancies, including Hodgkin lymphoma. One of the few viral transcripts expressed in EBV-positive Hodgkin/Reed-Sternberg (HRS) cells of Hodgkin lymphoma is latent membrane protein 2A (LMP2A). This viral protein blocks B-cell receptor (BCR)-signaling in vitro. Furthermore, expression of LMP2A in developing B cells in vivo induces a global down-regulation of genes necessary for proper B-cell development. In this study we have analyzed gene transcription in primary B cells from LMP2A transgenic mice, LMP2A-expressing human B-cell lines, and LMP2A-positive and -negative EBV-infected lymphoblastoid cell lines (LCLs). We demonstrate that LMP2A increases the expression of genes associated with cell cycle induction and inhibition of apoptosis, alters the expression of genes involved in DNA and RNA metabolism, and decreases the expression of B-cell-specific factors and genes associated with immunity. Furthermore, many alterations in gene expression induced by LMP2A are similar to those recently described in HRS cells of Hodgkin lymphoma and activated, proliferating germinal center centroblasts/centrocytes. These correlations suggest that LMP2A expression in EBV-infected B cells may lead to the induction and maintenance of an activated, proliferative state that could ultimately result in the development of Hodgkin lymphoma. (Blood. 2003;102: 4166-4178)

CD4+ T-cell clones recognizing human lymphoma-associated antigens: generation by in vitro stimulation with autologous Epstein-Barr virus–transformed B cells

Blood ◽  
2009 ◽  
Vol 114 (4) ◽  
pp. 807-815 ◽  
Author(s):  
Heather M. Long ◽  
Jianmin Zuo ◽  
Alison M. Leese ◽  
Nancy H. Gudgeon ◽  
Hui Jia ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Epstein Barr Virus ◽  
Hla Class Ii ◽  
Cd4 T Cell ◽  
T Cell Clones ◽  
Barr Virus ◽  
Cell Clones ◽  
Epstein Barr

Abstract Epstein-Barr virus (EBV)–specific T-cell preparations, generated by stimulating immune donor lymphocytes with the autologous virus-transformed B-lymphoblastoid cell line (LCL) in vitro, can be used to target EBV-positive malignancies. Although these preparations are enriched for EBV antigen–specific CD8+ T cells, most also contain a CD4+ T-cell population whose specificity is unknown. Here, we show that, although CD4+ T-cell clones derived from such cultures recognize HLA class II–matched LCLs but not mitogen-activated B lymphoblasts, many (1) do not map to any known EBV antigen, (2) can be raised from EBV-naive as well as EBV-immune persons, and (3) can recognize a broad range of human B lymphoma–derived cell lines irrespective of EBV genome status, providing those lines to express the relevant HLA class II–restricting allele. Importantly, such CD4+ clones not only produce IFNγ but are also cytotoxic and can control the outgrowth of HLA-matched lymphoma cells in cocultivation assays. We infer that such CD4+ T cells recognize cellular antigens that are preferentially up-regulated in EBV-transformed but not mitogen-activated B lymphoblasts and that are also expressed in a range of B-cell malignancies. Such antigens are therefore of potential value as targets for CD4+ T cell–based immunotherapy.

scholarly journals Epstein-Barr virus (EBV)-carrying and -expressing T-cell lines established from severe chronic active EBV infection

Blood ◽  
1996 ◽  
Vol 87 (4) ◽  
pp. 1446-1457 ◽  
Author(s):  
S Imai ◽  
M Sugiura ◽  
O Oikawa ◽  
S Koizumi ◽  
M Hirao ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Lines ◽  
Epstein Barr Virus ◽  
Gene Rearrangement ◽  
Barr Virus ◽  
Ebv Infection ◽  
Epstein Barr ◽  
T Cell Lines

Four novel Epstein-Barr virus (EBV)-carrying T-cell lines, designated SIS, AIK-T8, AIK-T4, and SKN, were established from peripheral blood lymphocytes (PBL) of patients with severe chronic active EBV infection, in the presence of interleukin-2 and 4-deoxyphorbol ester. AIK-T8 and - T4 were derived from a single patient. Cell marker and genotype analyses showed that SIS, AIK-T8, and AIK-T4 had mature T-cell phenotypes with clonally rearranged T-cell receptor (TCR) genes, whereas SKN had an immature T-cell phenotype without TCR gene rearrangement. None of the cell lines expressed B, natural killer, or myeloid antigens or had Ig gene rearrangement. All lines carried EBV genomes in a single episomal form. SIS, AIK-T8, and SKN showed the same phenotype, TCR gene configuration, and/or EBV clonotype as their source or biopsied materials; therefore, they represented EBV-infected T cells proliferating in the patients. TCR gene and EBV episomal structures similar to those of AIK-T4 were not found in its source PBL, probably due to the few parental clones in vivo. All lines expressed EBV-encoded small RNA (EBER) 1, nuclear antigen (EBNA) 1, and latent membrane protein (LMP) 1, -2A, and -2B, but not other EBNAs that could be recognized by EBV-specific immune T cells. EBV replicative antigens were rarely expressed or induced. Such EBV latency reflects the in vivo situation, in which the T cells may evade immune surveillance and be insensitive to antiherpesvirus drugs. Collectively, the data suggest that EBV can target and latently infect T cells at any stage of differentiation in vivo, thus potentially causing uncontrolled T-cell proliferation. These cell lines will facilitate further analyses of possible EBV-induced oncogenicity in T cells.

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