Vaccine strategies against Epstein-Barr virus-associated diseases: lessons from studies on cytotoxic T-cell-mediated immune regulation

Immunotherapy for recurrent or metastatic nasopharyngeal carcinoma

Immunotherapy, particularly immune checkpoint inhibitors (ICIs), such as anti-programmed death 1/programmed death-ligand 1 (PD-1/PD-L1) therapy, has emerged as a pivotal treatment modality for solid tumors, including recurrent or metastatic nasopharyngeal carcinoma (R/M-NPC). Despite the advancements in the utilization of ICIs, there is still room for further improving patient outcomes. Another promising approach to immunotherapy for R/M-NPC involves adoptive cell therapy (ACT), which aims to stimulate systemic anti-tumor immunity. However, individual agent therapies targeting dendritic cells (DCs) appear to still be in the clinical trial phase. This current review underscores the potential of immunotherapy as a valuable adjunct to the treatment paradigm for R/M-NPC patients. Further research is warranted to enhance the efficacy of immunotherapy through the implementation of strategies such as combination therapies and overcoming immune suppression. Additionally, the development of a biomarker-based scoring system is essential for identifying suitable candidates for precision immunotherapy.

Lymph node targeted multi-epitope subunit vaccine promotes effective immunity to EBV in HLA-expressing mice

The recent emergence of a causal link between Epstein-Barr virus (EBV) and multiple sclerosis has generated considerable interest in the development of an effective vaccine against EBV. Here we describe a vaccine formulation based on a lymph node targeting Amphiphile vaccine adjuvant, Amphiphile-CpG, admixed with EBV gp350 glycoprotein and an engineered EBV polyepitope protein that includes 20 CD8+ T cell epitopes from EBV latent and lytic antigens. Potent gp350-specific IgG responses are induced in mice with titers >100,000 in Amphiphile-CpG vaccinated mice. Immunization including Amphiphile-CpG also induces high frequencies of polyfunctional gp350-specific CD4+ T cells and EBV-specific CD8+ T cells that are 2-fold greater than soluble CpG and are maintained for >7 months post immunization. This combination of broad humoral and cellular immunity against multiple viral determinants is likely to provide better protection against primary infection and control of latently infected B cells leading to protection against the development of EBV-associated diseases.

Variances in Antiviral Memory T-Cell Repertoire of CD45RA- and CD62L-Depleted Lymphocyte Products Reflect the Need of Individual T-Cell Selection Strategies to Reduce the Risk of GvHD while Preserving Antiviral Immunity in Adoptive T-Cell Therapy

<b><i>Introduction:</i></b> Viral infections and reactivations still remain a cause of morbidity and mortality after hematopoietic stem cell transplantation due to immunodeficiency and immunosuppression. Transfer of unmanipulated donor-derived lymphocytes (DLI) represents a promising strategy for improving cellular immunity but carries the risk of graft versus host disease (GvHD). Depleting alloreactive naïve T cells (T_N) from DLIs was implemented to reduce the risk of GvHD induction while preserving antiviral memory T-cell activity. Here, we compared two T_N depletion strategies via CD45RA and CD62L expression and investigated the presence of antiviral memory T cells against human adenovirus (AdV) and Epstein-Barr virus (EBV) in the depleted fractions in relation to their functional and immunophenotypic characteristics. <b><i>Methods:</i></b> T-cell responses against ppEBV_EBNA1, ppEBV_Consensus and ppAdV_Hexon within T_N-depleted (CD45RA⁻/CD62L⁻) and T_N-enriched (CD45RA⁺/CD62L⁺) fractions were quantified by interferon-gamma (IFN-γ) ELISpot assay after short- and long-term <i>in vitro</i> stimulation. T-cell frequencies and immunophenotypic composition were assessed in all fractions by flow cytometry. Moreover, alloimmune T-cell responses were evaluated by mixed lymphocyte reaction. <b><i>Results:</i></b> According to differences in the phenotype composition, antigen-specific T-cell responses in CD45RA⁻ fraction were up to 2 times higher than those in the CD62L⁻ fraction, with the highest increase (up to 4-fold) observed after 7 days for ppEBV_EBNA1-specific T cells. The CD4⁺ effector memory T cells (T_EM) were mainly responsible for EBV_EBNA1- and AdV_Hexon-specific T-cell responses, whereas the main functionally active T cells against ppEBV_Consensus were CD8⁺ central memory T cells (T_CM) and T_EM. Moreover, comparison of both depletion strategies indicated that alloreactivity in CD45RA⁻ was lower than that in CD62L⁻ fraction. <b><i>Conclusion:</i></b> Taken together, our results indicate that CD45RA depletion is a more suitable strategy for generating T_N-depleted products consisting of memory T cells against ppEBV_EBNA1 and ppAdV_Hexon than CD62L in terms of depletion effectiveness, T-cell functionality and alloreactivity. To maximally exploit the beneficial effects mediated by antiviral memory T cells in T_N-depleted products, depletion methods should be selected individually according to phenotype composition and CD4/CD8 antigen restriction. T_N-depleted DLIs may improve the clinical outcome in terms of infections, GvHD, and disease relapse if selection of pathogen-specific donor T cells is not available.

Human NF-κB1 Haploinsufficiency and Epstein-Barr Virus-Induced Disease-Molecular Mechanisms and Consequences

Nuclear factor kappa-light-chain-enhancer of activated B cells 1 (NF-κB1)-related human primary immune deficiencies have initially been characterized as defining a subgroup of common variable immunodeficiencies (CVIDs), representing intrinsic B-cell disorders with antibody deficiency and recurrent infections of various kind. Recent evidence indicates that NF-κB1 haploinsufficiency underlies a variable type of combined immunodeficiency (CID) affecting both B and T lymphocyte compartments, with a broadened spectrum of disease manifestations, including Epstein–Barr virus (EBV)-induced lymphoproliferative disease and immediate life-threatening consequences. As part of this review series focused on EBV-related primary immunodeficiencies, we discuss the current clinical and molecular understanding of monoallelic NFKB1 germline mutations with special focus on the emerging context of EBV-associated disease. We outline mechanistic implications of dysfunctional NF-κB1 in B and T cells and discuss the fatal relation of impaired T-cell function with the inability to clear EBV infections. Finally, we compare common and suggested treatment angles in the context of this complex disease.

Personalized adoptive immunotherapy for patients with EBV-associated tumors and complications: Evaluation of novel naturally processed and presented EBV-derived T-cell epitopes

Morbidity and mortality of immunocompromised patients are increased by primary infection with or reactivation of Epstein-Barr virus (EBV), possibly triggering EBV⁺ post-transplant lymphoproliferative disease (PTLD). Adoptive transfer of EBV-specific cytotoxic T cells (EBV-CTLs) promises a non-toxic immunotherapy to effectively prevent or treat these complications. To improve immunotherapy and immunomonitoring this study aimed at identifying and evaluating naturally processed and presented HLA-A*03:01-restricted EBV-CTL epitopes as immunodominant targets. More than 15000 peptides were sequenced from EBV-immortalized B cells transduced with soluble HLA-A*03:01, sorted using different epitope prediction tools and eleven candidates were preselected. T2 and Flex-T peptide-binding and dissociation assays confirmed the stability of peptide-MHC complexes. Their immunogenicity and clinical relevance were evaluated by assessing the frequencies and functionality of EBV-CTLs in healthy donors (n > 10) and EBV⁺ PTLD-patients (n = 5) by multimer staining, Eli- and FluoroSpot assays. All eleven peptides elicited EBV-CTL responses in the donors. Their clinical applicability was determined by small-scale T-cell enrichment using Cytokine Secretion Assay and immunophenotyping. Mixtures of these peptides when added to the EBV Consensus pool revealed enhanced stimulation and enrichment efficacy. These EBV-specific epitopes broadening the repertoire of known targets will improve manufacturing of clinically applicable EBV-CTLs and monitoring of EBV-specific T-cell responses in patients.

Comparative analysis of 22 Epstein-Barr virus genomes from diseased and healthy individuals

Epstein-Barr virus (EBV) infects most of the world's population and is causally associated with several human cancers, but little is known about how EBV genetic variations might influence EBV-associated diseases and their geographical patterns. In the present study, 22 EBV whole-genome sequences from diseased and healthy individuals were analysed to explore EBV sequence variations at the whole-genome level. We found that the 22 EBV genomes were generally highly similar to each other at the genome level. However, varying degrees of genetic diversity were detected across the entire genome, especially in the latent genes. In contrast, the sequences of promoters and non-coding RNAs were strictly conserved. These findings suggested that both latent genes and non-coding RNAs play important roles in the EBV life cycle. When we investigated changes in known T-cell epitopes in some latent and lytic proteins, we observed that some T-cell epitopes were changed, while others were conserved. These findings indicate that the effect of EBV variations in protein sequences that seem to have been selected by the host immune system should be considered when conducting EBV-targeted immunotherapy. Taken together, our results provide a global view of EBV genome sequence variation, which not only is important for designing vaccines and immunotherapy for EBV but also adds to the understanding of EBV biology and the relationships between viral sequence variation and EBV-associated diseases.

The Development of Prophylactic and Therapeutic EBV Vaccines

Over the last century, the development of effective vaccine approaches to treat a number of viral infections has provided the impetus for the continual development of vaccine platforms for other viral infections, including Epstein-Barr virus (EBV). The clinical manifestations associated with EBV infection occur either following primary infection, such as infectious mononucleosis, or following an extended period of latency, primarily the EBV-associated malignancies and potentially including a number of autoimmune disorders, such as multiple sclerosis. As a consequence, two independent vaccine approaches are under development to prevent or control EBV-associated diseases. The first approach, which has been widely successful against other viral infections, is aimed at inducing a viral neutralisation antibody response to prevent primary infection. The second approach focuses upon the induction of cell-mediated immunity to control latent infected cells in persistently infected individuals. Early clinical studies have offered some insight into the potential efficacy of both of these approaches.

Epstein-Barr Virus Strain Variation

What is wild-type Epstein-Barr virus and are there genetic differences in EBV strains that contribute to some of the EBV-associated diseases? Recent progress in DNA sequencing has resulted in many new Epstein-Barr virus (EBV) genome sequences becoming available. EBV isolates worldwide can be grouped into type 1 and type 2, a classification based on the EBNA2 gene sequence. Type 1 transforms human B cells into lymphoblastoid cell lines much more efficiently than type 2 EBV and molecular mechanisms that may account for this difference in cell transformation are now becoming understood. Study of geographic variation of EBV strains independent of the type 1/type 2 classification and systematic investigation of the relationship between viral strains, infection and disease are now becoming possible. So we should consider more directly whether viral sequence variation might play a role in the incidence of some EBV-associated diseases.

EBV genome carrying B lymphocytes that express the nuclear protein EBNA-2 but not LMP-1: Type IIb latency

The potentially oncogenic Epstein-Barr virus (EBV) is carried by almost all humans in a well equilibrated coexistence. The phenotype of the cells that carry EBV genomes is determined by virally-encoded and cellular proteins. B lymphocyte is the main target of the virus and latent infection of this cell induces proliferation. Nine virus-encoded genes participate in the “growth program” that is expressed in a narrow differentiation window of the B cell. Such cells have the potential to develop malignant proliferations. However, several control mechanism eliminate this danger and the general chronic virus carrier state is most often asymptomatic. One mechanism exploits the normal regulation in the immune system, the T cell mediated modulation of the B cell differentiation state. Another is based on cognate recognition and elimination of the infected cells. The expression of EBV encoded genes in B lymphocytes can be also “restricted,” they do not express all components of the viral growth program. Here, we discuss a rare viral expression in B cells that has not been connected with malignant transformation yet.

Recent advances in the understanding of infectious mononucleosis: are prospects improved for treatment or control?

Symptomatic primary Epstein-Barr virus infection is known more commonly as infectious mononucleosis, an illness known for afflicting adolescents and younger adults as a febrile illness accompanied by pharyngitis and lymphadenopathy. Historically believed to be generally benign, infectious mononucleosis has been linked more recently to increased risks of developing Hodgkin's lymphoma and multiple sclerosis. Advances in the understanding of host immune responses to Epstein-Barr virus have begun to elucidate the reasons why younger children typically experience subclinical infection whereas older individuals develop infectious mononucleosis. This review will highlight recent advances in the understanding of primary Epstein-Barr virus infection, and whether prospective treatments or vaccine strategies may affect native infection and its sequelae.

Epstein-barr virus sequence variation-biology and disease

Some key questions in Epstein-Barr virus (EBV) biology center on whether naturally occurring sequence differences in the virus affect infection or EBV associated diseases. Understanding the pattern of EBV sequence variation is also important for possible development of EBV vaccines. At present EBV isolates worldwide can be grouped into Type 1 and Type 2, a classification based on the EBNA2 gene sequence. Type 1 EBV is the most prevalent worldwide but Type 2 is common in parts of Africa. Type 1 transforms human B cells into lymphoblastoid cell lines much more efficiently than Type 2 EBV. Molecular mechanisms that may account for this difference in cell transformation are now becoming clearer. Advances in sequencing technology will greatly increase the amount of whole EBV genome data for EBV isolated from different parts of the world. Study of regional variation of EBV strains independent of the Type 1/Type 2 classification and systematic investigation of the relationship between viral strains, infection and disease will become possible. The recent discovery that specific mutation of the EBV EBNA3B gene may be linked to development of diffuse large B cell lymphoma illustrates the importance that mutations in the virus genome may have in infection and human disease.

Sequence variations of latent membrane protein 2A in Epstein-Barr virus-associated gastric carcinomas from Guangzhou, southern China

Latent membrane protein 2A (LMP2A), expressed in most Epstein-Barr virus (EBV)-associated malignancies, has been demonstrated to be responsible for the maintenance of latent infection and epithelial cell transformation. Besides, it could also act as the target for a CTL-based therapy for EBV-associated malignancies. In the present study, sequence variations of LMP2A in EBV-associated gastric carcinoma (EBVaGC) and healthy EBV carriers from Guangzhou, southern China, where nasopharyngeal carcinoma (NPC) is endemic, were investigated. Widespread sequence variations in the LMP2A gene were found, with no sequence identical to the B95.8 prototype. No consistent mutation was detected in all isolates. The immunoreceptor tyrosine-based activation motif (ITAM) and PY motifs in the amino terminus of LMP2A were strictly conserved, suggesting their important roles in virus infection; while 8 of the 17 identified CTL epitopes in the transmembrane region of LMP2A were affected by at least one point mutation, which may implicate that the effect of LMP2A polymorphisms should be considered when LMP2A-targeted immunotherapy is conducted. The polymorphisms of LMP2A in EBVaGC in gastric remnant carcinoma (GRC) were for the first time investigated in the world. The LMP2A sequence variations in EBVaGC in GRC were somewhat different from those in EBVaGC in conventional gastric carcinoma. The sequence variations of LMP2A in EBVaGC were similar to those in throat washing of healthy EBV carriers, indicating that these variations are due to geographic-associated polymorphisms rather than EBVaGC-associated mutations. This, to our best knowledge, is the first detailed investigation of LMP2A polymorphisms in EBVaGC in Guangzhou, southern China, where NPC is endemic.

Exploiting the interplay between innate and adaptive immunity to improve immunotherapeutic strategies for Epstein-Barr-virus-driven disorders

The recent demonstration that immunotherapeutic approaches may be clinically effective for cancer patients has renewed the interest for this strategy of intervention. In particular, clinical trials using adoptive T-cell therapies disclosed encouraging results, particularly in the context of Epstein-Barr-virus- (EBV-) related tumors. Nevertheless, the rate of complete clinical responses is still limited, thus stimulating the development of more effective therapeutic protocols. Considering the relevance of innate immunity in controlling both infections and cancers, innovative immunotherapeutic approaches should take into account also this compartment to improve clinical efficacy. Evidence accumulated so far indicates that innate immunity effectors, particularly NK cells, can be exploited with therapeutic purposes and new targets have been recently identified. We herein review the complex interactions between EBV and innate immunity and summarize the therapeutic strategies involving both adaptive and innate immune system, in the light of a fruitful integration between these immunotherapeutic modalities for a better control of EBV-driven tumors.

Generation of a multipathogen-specific T-cell product for adoptive immunotherapy based on activation-dependent expression of CD154

Viral and fungal infections remain a leading cause of mortality in patients after hematopoietic stem cell transplantation (HSCT). Adoptive transfer of multipathogen-specific T cells is promising in restoring immunity and thereby preventing and treating infections, but approaches are currently limited because of time-consuming and laborious procedures. Therefore, we investigated a new strategy to simultaneously select T cells specific for viral and fungal pathogens based on activation-dependent expression of CD154. Single- and multipathogen-specific T-cell lines with high specificity for adenovirus (AdV), Epstein-Barr virus (EBV), cytomegalovirus (CMV), Candida albicans, and/or Aspergillus fumigatus could be readily generated within 14 days irrespective of the precursor frequency. The T-cell lines responded reproducibly to endogenously processed antigen and specifically proliferated upon antigenic stimulation. Although isolation based on CD154 favors enrichment of CD4+ T cells, AdV-, EBV- and CMV-specific CD8+ T cells could be expanded and demonstrated lysis of target cells. Conversely, T cell–mediated alloreactivity was almost abrogated compared with the starting fraction. This selection and/or expansion strategy may form the basis for future adoptive immunotherapy trials in patients at risk for multiple infections and may be translated to other antigens.

Widespread sequence variation in the Epstein-Barr virus latent membrane protein 2A gene among northern Chinese isolates

Latent membrane protein 2A (LMP2A) is expressed in most Epstein-Barr virus (EBV)-associated malignancies. Besides its roles in the maintenance of latent infection and epithelial-cell transformation, LMP2A could also act as the target for a CTL-based therapy for EBV-associated malignancies. In the present study, sequence polymorphisms in LMP2A from northern Chinese EBV-associated gastric carcinoma patients, nasopharyngeal carcinoma patients and healthy donors were identified and compared with the prototype B95-8 strain. Four consistent mutations were detected in all isolates. Frequent mutations in the analysed sequences distinguished two and seven types of sequence variation in exon 1 and exons 2-8, respectively, with no consistent association shown between the genotyping of the two gene fragments. The immunoreceptor tyrosine-based activation motif and PY motif in the amino terminus were strictly conserved. Nine of the 16 identified CTL epitopes were affected by at least one point mutation, which may confer complexity to proposed immunotherapeutic approaches for EBV-associated malignancies. Most changed epitopes showed higher mutation rates in tumour isolates than in throat-washing samples from healthy donors, in accordance with the idea that virus strains can evade immune surveillance by altering amino acids within LMP epitopes. This first detailed investigation of sequence variations in the LMP2A gene reveals classifiable sequence polymorphisms in exon 1 and exons 2-8, and encourages further work on the impact of viral gene variations on tumour persistence and CTL-based immunotherapy.

Vaccines to prevent infections by oncoviruses

It has been estimated that viruses are etiological agents in approximately 12% of human cancers. Most of these cancers can be attributed to infections by human papillomavirus (HPV), hepatitis B virus (HBV), hepatitis C virus (HCV), Epstein-Barr virus (EBV), and Kaposi's sarcoma-associated herpesvirus (KSHV). Prophylactic vaccines against other pathogenic viruses have an excellent record as public health interventions in terms of safety, effectiveness, and ability to reach economically disadvantaged populations. These considerations should prompt efforts to develop and implement vaccines against oncoviruses. Safe and effective HBV and HPV vaccines, based on virus-like particles, are commercially available, and the major focus is now on vaccine delivery, especially to low-resource settings. HCV and EBV vaccines are under active development, but few clinical trials have been conducted, and none of the candidate vaccines has proven to be sufficiently effective to warrant commercialization. Efforts to develop KSHV vaccines have been more limited.

Characterization of an human leucocyte antigen A2-restricted Epstein-Barr virus nuclear antigen-1-derived cytotoxic T-lymphocyte epitope

The Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1) is regularly expressed in all proliferating virus-infected cells and is therefore an interesting target for immunotherapy. Alleles of the human leucocyte antigen (HLA) -A2 family are dominantly expressed in Caucasians so we sought to identify EBNA1-specific cytotoxic T-lymphocyte (CTL) responses restricted through this allele. We report on the characterization of the LQTHIFAEV (LQT) epitope. LQT-specific memory CTL responses were reactivated in three of 14 healthy EBV seropositive donors (21%) whereas responses to HLA-A2-restricted epitopes, two derived from LMP2 and one from EBNA3A, were detected in 93%, 71% and 42% of the donors, respectively. The LQT-specific CTL clones did not lyse EBV-carrying lymphoblastoid cell lines and Burkitt's lymphoma cell lines nor EBNA1-transfected Burkitt's lymphoma cells but specifically released interferon-gamma upon stimulation with HLA-matched EBNA1-expressing cells and this response was enhanced by deletion of the Gly-Ala repeat domain that inhibits proteasomal degradation. The poor presentation of the endogenously expressed LQT epitope was not affected by inhibition of peptidases that trim antigenic peptides in the cytosol but full presentation was achieved in cells expressing a trojan antigen construct that releases the epitope directly into the endoplasmic reticulum. Hence, inefficient proteasomal processing appears to be mainly responsible for the poor presentation of this epitope.

Adoptive Immunotherapy for EBV-associated Malignancies

Latent Epstein-Barr virus (EBV) infection is associated with a diverse group of malignancies including Burkitt's lymphoma, Hodgkin's disease, nasopharyngeal carcinoma (NPC), and lymphoproliferative disease (LPD). EBV proteins expressed in these malignancies provide targets for the adoptive immunotherapy with antigen-specific cytotoxic T cells (CTL) and EBV-specific CTL have been used successfully for the prophylaxis and treatment of EBV-LPD post hematopoietic stem cell transplantation (HSCT). The clinical experience with EBV-specific CTL for other EBV-associated malignancies such as Hodgkin's disease and NPC is limited and the results obtained so far indicate that EBV-specific CTL are less effective than for EBV-LPD post HSCT. Decreased CTL efficacy most likely reflect immune evasion strategies by tumor cells such as down regulation of immunodominant EBV proteins and secretion of inhibitory cytokines. To overcome these immune evasion strategies a number of approaches have been developed including targeting CTL to subdominant EBV antigens and genetically modifying CTL to increase their potency.

The curious case of the tumour virus: 50 years of Burkitt's lymphoma

Burkitt's lymphoma (BL) was first described 50 years ago, and the first human tumour virus Epstein-Barr virus (EBV) was discovered in BL tumours soon after. Since then, the role of EBV in the development of BL has become more and more enigmatic. Only recently have we finally begun to understand, at the cellular and molecular levels, the complex and interesting interaction of EBV with B cells that creates a predisposition for the development of BL. Here, we discuss the intertwined histories of EBV and BL and their relationship to the cofactors in BL pathogenesis: malaria and the MYC translocation.

Antibodies against Epstein-Barr virus gp78 antigen: a novel marker for serological diagnosis of nasopharyngeal carcinoma detected by xMAP technology

Immunoglobulin (Ig) A and/or IgG reactivities to several Epstein-Barr virus (EBV) antigens have been used to facilitate diagnosis of nasopharyngeal carcinoma (NPC). However, antibodies against gp78, an EBV membrane glycoprotein, have not been examined to this day. In this study, we utilized Luminex multi-analyte profiling (xMAP) technology to analyse antibody responses to a synthetic peptide of gp78 in sera samples from 95 NPC patients and 91 healthy controls. Our results showed the sensitivity and specificity of IgA-gp78 for NPC diagnosis were 79 and 71 %, respectively, while those of IgG-gp78 were 74 and 73 %, respectively. The IgA and IgG responses to different EBV antigens were not identical within an individual and IgA-gp78 and IgG-gp78 could be complementary to antibodies against viral capsid antigen (VCA), the diffused early antigen (EA-D) and the nuclear antigen EBNA1 for NPC diagnosis. When the six EBV parameters for NPC prediction, i.e. IgA-gp78, IgG-gp78, IgA-VCA, IgA-EBNA1, IgA-EA-D and IgG-EA-D, are combined, the combined predictors were able to reach overall sensitivity and specificity of 91 and 95 %, respectively. Thus, simultaneous detection of these EBV serological markers could improve the predictive values of NPC using xMAP technology.

A virtual look at Epstein-Barr virus infection: simulation mechanism

Epstein-Barr virus (EBV) is an important human pathogen that establishes a life-long persistent infection and for which no precise animal model exists. In this paper, we describe in detail an agent-based model and computer simulation of EBV infection. Agents representing EBV and sets of B and T lymphocytes move and interact on a three-dimensional grid approximating Waldeyer's ring, together with abstract compartments for lymph and blood. The simulation allows us to explore the development and resolution of virtual infections in a manner not possible in actual human experiments. Specifically, we identify parameters capable of inducing clearance, persistent infection, or death.

The management of posttransplant lymphoproliferative disorder

Posttransplant lymphoproliferative disorder (PTLD) is a life-threatening complication of allogeneic hematopoietic stem cell and solid organ transplantation. Most cases are EBV-positive B-cell neoplasms, which occur in the setting of pharmacologically impaired cellular immunity. Several different treatment strategies including cytotoxic antitumor therapy, anti-B-cell monoclonal antibody therapy, antiviral therapy, and modalities aimed at restoration of EBV-specific cellular immunity have been employed. In addition, efforts to identify patients at high risk for PTLD have resulted in attempts at prophylactic and preemptive therapies. In this review we discuss the available literature on differing approaches to PTLD management, identify areas in need of further investigation, and, when possible, make general recommendations. Reduction of immunosuppression remains the mainstay of first-line treatment. Accumulating evidence supports the role of rituximab as second-line therapy with cytotoxic chemotherapy reserved for specific circumstances. Further investigations are needed to better define the role of more novel and less widely available therapies such as the adoptive transfer of EBV-specific T cells and optimization of antiviral therapies.

GlaxoSmithKline Adjuvant Systems in vaccines: concepts, achievements and perspectives

The need for potentiating immune responses to recombinant or subunit antigens has prompted GlaxoSmithKline (GSK) Biologicals to develop various Adjuvant Systems for the design of prophylactic and therapeutic vaccines. Adjuvant Systems are formulations of classical adjuvants mixed with immunomodulators, specifically adapted to the antigen and the target population. They can activate the appropriate innate immune system and subsequently impact on adaptive immune responses. AS04 is an Adjuvant System that has demonstrated significant achievements in several vaccines against viral diseases. AS02, another Adjuvant System, is being evaluated in various contexts, where a strong T-cell response is needed to afford protection. Likewise, AS01 has been developed for vaccines where the induction of a yet stronger T-cell-mediated immune response is required. Altogether, the promising clinical results strongly support the concept of Adjuvant Systems and allow for further development of new vaccines, best adapted to the target population and the immune mechanisms of protection.

The poor contribution of chimpanzee experiments to biomedical progress

Biomedical research on captive chimpanzees incurs substantial nonhuman animal welfare, ethical, and financial costs that advocates claim resultin substantial advancements in biomedical knowledge. However, demonstrating minimal contribution toward the advancement of biomedical knowledge generally, subsequent papers did not cite 49.5% (47/95), of 95 experiments randomly selected from a population of 749 published worldwide between 1995 and 2004. Only 14.7% (14/95) were cited by 27 papers that abstracts indicated described well-developed methods for combating human diseases. However, detailed examination of these medical papers revealed that in vitrostudies, human clinical and epidemiological studies, molecular assays and methods, and genomic studies contributed most to their development. No chimpanzee study made an essential contribution, or, in most cases, a significant contribution of any kind, to the development of the medical method described. The approval of these experiments indicates a failure of the ethics committee system. The demonstrable lack of benefit of most chimpanzee experimentation and its profound animal welfare and bioethical costs indicate that a ban is warranted in those remaining countries - notably the United States - that continue to conduct it.

A virtual look at Epstein-Barr virus infection: biological interpretations

The possibility of using computer simulation and mathematical modeling to gain insight into biological and other complex systems is receiving increased attention. However, it is as yet unclear to what extent these techniques will provide useful biological insights or even what the best approach is. Epstein–Barr virus (EBV) provides a good candidate to address these issues. It persistently infects most humans and is associated with several important diseases. In addition, a detailed biological model has been developed that provides an intricate understanding of EBV infection in the naturally infected human host and accounts for most of the virus' diverse and peculiar properties. We have developed an agent-based computer model/simulation (PathSim, Pathogen Simulation) of this biological model. The simulation is performed on a virtual grid that represents the anatomy of the tonsils of the nasopharyngeal cavity (Waldeyer ring) and the peripheral circulation—the sites of EBV infection and persistence. The simulation is presented via a user friendly visual interface and reproduces quantitative and qualitative aspects of acute and persistent EBV infection. The simulation also had predictive power in validation experiments involving certain aspects of viral infection dynamics. Moreover, it allows us to identify switch points in the infection process that direct the disease course towards the end points of persistence, clearance, or death. Lastly, we were able to identify parameter sets that reproduced aspects of EBV-associated diseases. These investigations indicate that such simulations, combined with laboratory and clinical studies and animal models, will provide a powerful approach to investigating and controlling EBV infection, including the design of targeted anti-viral therapies.

The possibility of using computer simulation and mathematical modeling to gain insight into biological systems is receiving increased attention. However, it is as yet unclear to what extent these techniques will provide useful biological insights or even what the best approach is. Epstein–Barr virus (EBV) provides a good candidate to address these issues. It persistently infects most humans and is associated with several important diseases, including cancer. We have developed an agent-based computer model/simulation (PathSim, Pathogen Simulation) of EBV infection. The simulation is performed on a virtual grid that represents the anatomy where EBV infects and persists. The simulation is presented on a computer screen in a form that resembles a computer game. This makes it readily accessible to investigators who are not well versed in computer technology. The simulation allows us to identify switch points in the infection process that direct the disease course towards the end points of persistence, clearance, or death, and identify conditions that reproduce aspects of EBV-associated diseases. Such simulations, combined with laboratory and clinical studies and animal models, provide a powerful approach to investigating and controlling EBV infection, including the design of targeted anti-viral therapies.

Phase I/II studies to evaluate safety and immunogenicity of a recombinant gp350 Epstein–Barr virus vaccine in healthy adults

Two double-blind randomised controlled studies (phase I and I/II) were performed to assess for the first time the safety and immunogenicity of a recombinant subunit gp350 Epstein-Barr virus (EBV) vaccine in 148 healthy adult volunteers. All candidate vaccine formulations had a good safety profile and were well tolerated, with the incidence of solicited and unsolicited symptoms within a clinically acceptable range. One serious adverse event was reported in the phase I trial which was considered to be of suspected relationship to vaccination. The gp350 vaccine formulations were immunogenic and induced gp350-specific antibody responses (including neutralising antibodies).

Presentation and early detection of post-transplant lymphoproliferative disorder after solid organ transplantation

Post-transplant lymphoproliferative disorder (PTLD) is a serious and still frequently observed complication of solid organ transplantation. Despite the recent introduction of anti B-cell monoclonal antibody therapy (rituximab) for treatment of PTLD, mortality rates remain high. Because PTLD often presents in a nonspecific way in clinically unsuspected patients, it is a major challenge to diagnose PTLD at an early stage. Epstein-Barr virus (EBV)-DNA load monitoring is a promising tool for the identification of patients at risk for PTLD development. However, there are some limitations of this method, and not all patients at risk for PTLD can be identified by EBV-DNA measurements alone. Therefore, it is of major importance to recognize early clinical signs and symptoms of PTLD. In this review, risk factors for PTLD development, disease presentation, and methods for early detection will be discussed. Special attention is given to allograft and digestive tract localization and the relation with time of onset of PTLD. The value and pitfalls of EBV-DNA load monitoring are discussed. In addition, because fluorodeoxyglucose (FDG)-positron emission tomography (PET) has shown to be a powerful tool for staging and response evaluation of malignant lymphoma, the role of FDG-PET for early diagnosis and staging of PTLD is addressed.

Successful in vitro priming of EBV-specific CD8+ T cells endowed with strong cytotoxic function from T cells of EBV-seronegative children

Epstein-Barr virus (EBV)-seronegative transplant recipients are at high risk of developing EBV-associated post-transplant lymphoproliferative disorder (PTLD), and would maximally benefit from an EBV-directed T-cell therapy for prevention or treatment of PTLD. So far, efforts to activate CD8+ EBV-specific cytotoxic T lymphocytes (CTL) endowed with high specific cytotoxicity from EBV-seronegative children have failed. We compared the CD8+ CTL priming efficiency of three different modified activation protocols, based on lymphoblastoid cell lines (LCL) stimulation potentially enhanced by either LCL presentation through dendritic cells, or selection of IFN-gamma+ cultured cells, or culture in the presence of rhIL-12 and rhIL-7, according to the standard protocol for reactivation of EBV-specific CTL. We found that only specific LCL stimulation in the presence of rhIL-12 and rhIL-7 was able to reproducibly expand EBV-specific CD8+ CTL endowed with strong cytotoxic activity from truly EBV-seronegative children. The lines thus activated, which included specificities toward EBV latent and lytic proteins, showed high percentage CD8+ T cells, with <10% naïve CD8+/CCR7+/CD45RA+ cells. Overall, the total number of CD8+ central memory cells, and of CCR7 T-cell effectors was comparable to that observed in healthy EBV-seropositive controls. In conclusion, it is feasible to activate EBV-specific CD8+ CTL with suitable characteristics for in vivo employment from EBV-seronegative children.

CMV-IVIG for prevention of Epstein Barr virus disease and posttransplant lymphoproliferative disease in pediatric liver transplant recipients

A randomized controlled trial of CMV-IVIG (cytomegalovirus-intravenous immunoglobulin) for prevention of Epstein Barr virus (EBV) posttransplant lymphoproliferative disease (PTLD) in pediatric liver transplantation (PLTx) recipients was begun in Pittsburgh and subsequently expanded to four additional sites. Protocol EB viral loads were obtained in a blinded fashion; additional loads could be obtained for clinical indications. Patients were followed for 2 years post-LTx. Eighty-two evaluable patients (39 CMV-IVIG, 43 placebo) developed 18 episodes of EBV disease (7 CMV-IVIG, 11 placebo) including nine cases of PTLD (three CMV-IVIG, six placebo). No significant differences were seen in the adjusted 2-year EBV disease-free rate (CMV-IVIG 79%, placebo 71%) and PTLD-free rate (CMV-IVIG 91%, placebo 84%) between treatment and placebo groups at 2 years (p > 0.20). The absence of significant effect of CMV-IVIG may be explained by a lack of efficacy of the drug or limitations of sample size.

Selection of Epstein-Barr virus specific cytotoxic T lymphocytes can be performed with B lymphoblastoid cell lines created in serum-free media

Epstein-Barr Virus (EBV)-transformed B lymphoblastoid cell lines (BLCL) are currently used for numerous applications in cellular immunology. Where protocols destined for clinical application are concerned, the final choice of assay is made according to a risk/benefit ratio analysis. In this balance the use of xenogenic or allogenic serum has always been a major concern, as it carries both an infectious and an immunological risk. So far, it is unknown whether serum can be omitted from the entire BLCL selection procedure. In addition, as BLCL have been described as heterogeneous, serum deprivation may affect their antigen-presenting capacity. In the present study, BLCL were generated in the absence or presence of fetal calf serum (referred to as BLCL0 or BLCL(FCS), respectively). Next, in order to assess the antigen-presenting capacity of these cells, we compared the ability of BLCL0 and BLCL(FCS) cells to stimulate the EBV-specific repertoire of the corresponding donor's peripheral blood mononuclear cells in vitro. Our results showed that addition of serum was not essential for BLCL infection and culture, and that as far as we could determine, BLCL0 cells were as effective as BLCL(FCS) in reactivating the EBV-specific T-cell repertoire in vitro. Notably, FCS-specific T-lymphocytes can be detected among the BLCL(FCS)-specific CD4+-CTL. Not only was this latter observation unexpected for an EBV-seropositive donor, but it implied that the BLCL had captured and processed the corresponding FCS-derived solubles antigens; taken together our results emphasized the interest of the possibility to generate BLCL0, both for research and for clinical applications.

Characterization of Epstein-Barr virus Type I variants based on linked polymorphism among EBNA3A, -3B, and -3C genes

Latent Epstein-Barr virus (EBV) nuclear antigens (EBNA)-3A, -3B, and -3C are involved in transcription regulation of both viral and cellular genes. In the present study, we chose functionally important regions within EBNA3A, -3B, and -3C genes with putative tumorigenic potential to investigate natural sequence variations among EBV Type I strains circulating in Europe. Based on the identification of linked EBNA3A, -3B, and -3C sequence patterns, we defined five EBNA3 variants in addition to the B95.8 prototype sequence. Phylogenetic analysis revealed that EBNA3 variant 5, the most diverged from the B95.8 sequence, showed an evolutionary history of intertypic recombination events occurring upstream and downstream of the C-terminus of EBNA3A. The frequency of occurrence of the five newly defined EBNA3 variants was similar for strains causing EBV primary infection or reactivation and was also similar within two of the European areas investigated. In addition, preferential linkages of certain EBNA3 variants to distinct latent membrane protein 1 (LMP1) groups were found to exist. Thus, a combination of more than one polymorphic site in the EBV genome might be involved in determining disease characteristics.

Cell Therapy of Stage IV Nasopharyngeal Carcinoma With Autologous Epstein-Barr Virus–Targeted Cytotoxic T Lymphocytes

Purpose

Nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus (EBV) –related malignancy expressing EBV antigens that are possible targets of cell therapy, including latent membrane protein 2 (LMP2). We conducted a clinical trial of EBV-targeted cell therapy with autologous virus-specific cytotoxic T lymphocytes (CTLs) for NPC refractory to conventional treatments.

Patients and Methods

Ten patients with EBV-related stage IV NPC in progression after conventional radiotherapy and chemotherapy received intravenously autologous EBV-specific CTLs reactivated and expanded ex vivo from peripheral blood lymphocytes through stimulation with EBV-transformed autologous B-lymphoblastoid cell lines (LCL). Toxicity, specific cellular immune responses, and clinical tumor responses were evaluated.

Results

EBV-specific CTLs could be generated in all patients and were predominantly CD3+/CD8+ T lymphocytes displaying specific killing of autologous EBV-LCL, autologous NPC cells as well as autologous targets bearing the EBV antigen LMP2. Patients received two to 23 infusions of EBV-specific CTLs that were well tolerated with the exception of grade 1 to 2 inflammatory reactions at the tumor site in two cases. Control of disease progression was obtained in six of 10 patients (two with partial response and four with stable disease). Analysis of interferon-γ–producing cells demonstrated an increased frequency of EBV-specific immunity, with appearance of LMP2-specific responses in four patients, of whom three had clinical benefit.

Conclusion

Cell therapy with EBV-targeted autologous CTLs is safe, induces LMP-2-specific immunologic responses, and is associated with objective responses and control of disease progression in patients with stage IV NPC resistant to conventional treatments.

Epstein-Barr virus: the impact of scientific advances on clinical practice

Epstein-Barr virus (EBV) is a tumorigenic herpes virus that infects and persists in B lymphocytes in the majority of humans, generally without causing disease. However, in a few individuals the virus is associated with significant pathology, particularly benign and malignant lymphoproliferations. Recently acquired knowledge on the mechanisms of EBV persistence, immune control of primary and persistent infection, and disease pathogenesis is now being translated into the clinic with novel methods of diagnosis, prevention and treatment contributing to improved patient care. This review concentrates on these recent advances in the field of hematology/oncology.

EBV and systemic lupus erythematosus: a new perspective

We have proposed that EBV uses mature B cell biology to access memory B cells as a site of persistent infection. A central feature of this model is that EBV adapts its gene expression profile to the state of the B cell it resides in and that the level of infection is stable over time. This led us to question whether changes in the behavior or regulation of mature B cells would alter the state of EBV persistence. To investigate this, we studied the impact of systemic lupus erythematosus (SLE), a disease characterized by immune dysfunction, on EBV infection. We show that patients with SLE have abnormally high frequencies of EBV-infected cells in their blood, and this is associated with the occurrence of SLE disease flares. Although patients with SLE have frequencies of infected cells comparable to those seen in immunosuppressed patients, in SLE the effect was independent of immunosuppressive therapy. Aberrant expression of viral lytic (BZLF1) and latency (latency membrane proteins 1 and 2a) genes was also detected in the blood of SLE patients. We conclude that the abnormal regulation of EBV infection in SLE patients reflects the sensitivity of the virus to perturbation of the immune system.

EBV-specific memory CD8+ T cell phenotype and function in stable solid organ transplant patients

Immune responses to EBV in immunosuppressed (IS) solid organ transplant (SOTx) recipients have not been well characterized. Here we evaluate the phenotype and function of EBV-specific CD8+ T cells in peripheral blood isolated from "stable" IS SOTx recipients. The EBV-specific CD8+ T cell memory subset distribution in the peripheral blood of patients was examined by flow cytometric analysis using HLA-A2 tetramers incorporating BMLF1 (lytic), and LMP2 and EBNA3A (latent)-derived peptides, in conjunction with mAbs against the CD45RO, CD45RA, and CD62L markers. The ability of CD8+ T cells to produce IFN-gamma in response to the same EBV-derived peptides was measured by ELISPOT assay. Patients and healthy normal donors exhibited similar anti-EBV CD8+ T cell frequencies and specificities against the EBV epitopes evaluated. When compared to healthy normal donors, an overall significant expansion of the CD8+ T cell "effector memory" (CD45RO+/CD62L-) pool, including that of EBV "latent" (LMP2 and EBNA3A)-specific CD8+ T cells was detected in IS SOTx patients. However, the patients' EBV-specific CD8+ T cells showed decreased IFN-gamma production to the EBV-peptide stimulation. These results indicate that the impairment of EBV-specific CD8+ T cell activity is not due to clonal depletion, but is mainly due to impaired functional activation.

New Developments in the Diagnosis and Management of Posttransplantation Lymphoproliferative Disorders in Solid Organ Transplant Recipients

Posttransplantation lymphoproliferative disorders (PTLDs) have emerged as important causes of morbidity and mortality in solid organ transplant recipients. Epstein-Barr virus (EBV) plays a major pathophysiologic role in the development of many, if not most, of the highly diverse disease states, which span the spectrum from infection to malignancy, encompassed by the term "PTLD." Clinical presentation and biological behavior associated with PTLD are highly variable; patients experiencing primary EBV infection in the immediate posttransplantation period are most vulnerable. New insights into PTLD pathogenesis provide exciting opportunities for rational and targeted approaches to the diagnosis, prevention, and treatment of PTLD. This article highlights some of these developments and outlines unresolved and controversial issues in PTLD management.

Critical role of EBNA1-specific CD4+ T cells in the control of mouse Burkitt lymphoma in vivo

CD4+ T cells play important roles in orchestrating host immune responses against cancer and infectious diseases. Although EBV-encoded nuclear antigen 1-specific (EBNA1-specific) CD4+ T cells have been implicated in controlling the growth of EBV-associated tumors such as Burkitt lymphoma (BL) in vitro, direct evidence for their in vivo function remains elusive due to the lack of an appropriate experimental BL model. Here, we describe the development of a mouse EBNA1-expressing BL tumor model and the identification of 2 novel MHC H-2I-A(b)-restricted T cell epitopes derived from EBNA1. Using our murine BL tumor model and the relevant peptides, we show that vaccination of mice with EBNA1 peptide-loaded DCs can elicit CD4+ T cell responses. These EBNA1-specific CD4+ T cells recognized peptide-pulsed targets as well as EBNA1-expressing tumor cells and were necessary and sufficient for suppressing tumor growth in vivo. By contrast, EBNA1 peptide-reactive CD8+ T cells failed to recognize tumor cells and did not contribute to protective immunity. These studies represent what we believe to be the first demonstration that EBNA1-specific CD4+ T cells can suppress tumor growth in vivo, which suggests that CD4+ T cells play an important role in generating protective immunity against EBV-associated cancer.

Vaccination with inactivated murine gammaherpesvirus 68 strongly limits viral replication and latency and protects type I IFN receptor knockout mice from a lethal infection

Human gammaherpesviruses such as Epstein-Barr virus (EBV) cause lifelong infections and associated diseases, including malignancies, and the development of an effective vaccine against this class of viral infections is of considerable interest. The murine herpesvirus 68 (MHV-68) model provides a useful experimental setting to investigate the immune response to gammaherpesvirus infections and to evaluate the efficacy of vaccination strategies. In this study, we tested a heat-inactivated MHV-68 vaccine in immunocompetent mice as well as in B cell-deficient or type I IFN receptor knockout mice. Vaccination with heat-inactivated MHV-68 protected immunocompetent mice from the acute MHV-68 infection in the lung and strongly reduced the expansion of latently infected cells in the spleen and the development of splenomegaly. A similar inhibition of the acute viral replication in the lung was also observed in vaccinated B cell-deficient mice. Of note, the inactivated MHV-68 vaccine completely protected type I IFN receptor knockout mice from the infection with a lethal dose of MHV-68.

Epstein-Barr Virus and Breast Cancer: State of the Evidence for Viral Carcinogenesis

As the etiology and progression of breast cancer remain incompletely understood, novel routes of disease pathogenesis are important to consider. Viral pathogens have not been much explored, but recent interest has focused on Epstein-Barr virus (EBV). Studies of an association of this ubiquitous herpesvirus with breast cancer have had notably inconsistent results, marked by varying EBV presence (from 0% to 50% of tumors) and the absence of certain viral characteristics found in other EBV-related malignancies. The research has been plagued by the technical challenges of localizing EBV to tumor cells and by a tendency to overlook epidemiological cofactors, shown in all other EBV-related cancers to impact the EBV association. Breast cancer studies to date have used several viral detection methods of varying or uncertain sensitivity and specificity; most have involved small and/or poorly characterized case series and paid insufficient attention to epidemiological cofactors relevant to breast cancer and to EBV-related malignancies. Given these limitations and the established complexity of the connection of EBV with other cancers, a definitive judgment regarding the presence of this virus in breast cancer cannot yet be rendered. Recent advances in laboratory methodologies should help overcome the challenges of EBV detection in breast cancers. Further research is warranted, given the potential for an EBV association to inform not only breast cancer etiology but also early detection, treatment, and prevention.

Induction of therapeutic T-cell responses to subdominant tumor-associated viral oncogene after immunization with replication-incompetent polyepitope adenovirus vaccine

The EBV-encoded latent membrane proteins (LMP1 and LMP2), which are expressed in various EBV-associated malignancies have been proposed as a potential target for CTL-based therapy. However, the precursor frequency for LMP-specific CTL is generally low, and immunotherapy based on these antigens is often compromised by the poor immunogenicity and potential threat from their oncogenic potential. Here we have developed a replication- incompetent adenoviral vaccine that encodes multiple HLA class I-restricted CTL epitopes from LMP1 and LMP2 as a polyepitope. Immunization with this polyepitope vaccine consistently generated strong LMP-specific CTL responses in HLA A2/K(b) mice, which can be readily detected by both ex vivo and in vivo T-cell assays. Furthermore, a human CTL response to LMP antigens can be rapidly expanded after stimulation with this recombinant polyepitope vector. These expanded T cells displayed strong lysis of autologous target cells sensitized with LMP1 and/or LMP2 CTL epitopes. More importantly, this adenoviral vaccine was also successfully used to reverse the outgrowth of LMP1-expressing tumors in HLA A2/K(b) mice. These studies demonstrate that a replication-incompetent adenovirus polyepitope vaccine is an excellent tool for the induction of a protective CTL response directed toward multiple LMP CTL epitopes restricted through common HLA class I alleles prevalent in different ethnic groups where EBV-associated malignancies are endemic.

Evidence for the presentation of major histocompatibility complex class I-restricted Epstein-Barr virus nuclear antigen 1 peptides to CD8+ T lymphocytes

The Epstein-Barr virus (EBV)-encoded nuclear antigen 1 (EBNA1) is expressed in all EBV-associated tumors, making it an important target for immunotherapy. However, evidence for major histocompatibility complex (MHC) class I–restricted EBNA1 peptides endogenously presented by EBV-transformed B and tumor cells remains elusive. Here we describe for the first time the identification of an endogenously processed human histocompatibility leukocyte antigen (HLA)-B8–restricted EBNA1 peptide that is recognized by CD8⁺ T cells. T cell recognition could be inhibited by the treatment of target cells with proteasome inhibitors that block the MHC class I antigen processing pathway, but not by an inhibitor (chloroquine) of MHC class II antigen processing. We also demonstrate that new protein synthesis is required for the generation of the HLA-B8 epitope for T cell recognition, suggesting that defective ribosomal products (DRiPs) are the major source of T cell epitopes. Experiments with protease inhibitors indicate that some serine proteases may participate in the degradation of EBNA1 DRiPs before they are further processed by proteasomes. These findings not only provide the first evidence of the presentation of an MHC class I–restricted EBNA1 epitope to CD8⁺ T cells, but also offer new insight into the molecular mechanisms involved in the processing and presentation of EBNA1.

Ex vivo priming of naïve T cells into EBV-specific Th1/Tc1 effector cells by mature autologous DC loaded with apoptotic/necrotic LCL

Posttransplant lymphoproliferative disorders (PTLDs) represent life-threatening complications of bone marrow and solid organ transplantation (SOTx). These are B-cell malignancies triggered by Epstein-Barr Virus (EBV) infection in chronically immunosuppressed (IS) recipients. Immunosuppressed EBV seronegative (EBV(-)) organ recipients are at highest risk of developing PTLD owing to the lack of anti-EBV memory T cells to control subsequent EBV challenges. Our aim is to establish effective anti-EBV T-cell generation protocols for prevention or treatment of PTLD encountered in SOTx. We have used autologous dendritic cells (DCs) loaded with apoptotic/necrotic lymphoblastoid cell lines (LCLs) to evaluate the ability of such an approach to activate naïve T cells in vitro. In EBV(-) individuals, both CD8+ and CD4+ T-cell responses were amplified by this approach, as detected by IFN-gamma ELISPOT and cytotoxicity assays. The CD8+ T cells were poly-specific anti-EBNA3 A, -LMP2 and -BMLF1, with uniform reversion to a CD45RO+/RA-phenotype, decreased CD62L expression, and up-regulation of the activation markers CD28 and CD69. Addition of rhIL-12 improved anti-viral T-cell responses and reduced the functional differences observed between EBV(+) and EBV(-) responders. In conclusion, the DC/LCL method promotes cross-presentation of EBV-associated epitopes and may serve as an effective protocol for the adoptive immunotherapy of PTLD in EBV(-) SOTx patients.