EBV in T-/NK-Cell Tumorigenesis

A differential diagnosis method for systemic CAEBV and the prospect of EBV-related immune cell markers via flow cytometry

Chronic active Epstein-Barr virus (CAEBV) infection of the T-cell or Natural killer (NK)-cell type, systemic form (systemic CAEBV or sCAEBV) was defined by the WHO in 2017 as an EBV-related lymphoproliferative disorder and is listed as an EBV-positive T-cell and NK-cell proliferation. The clinical manifestations and prognoses are heterogeneous. This makes systemic CAEBV indistinguishable from other EBV-positive T-cell and NK-cell proliferations. Early diagnosis of systemic CAEBV and early hematopoietic stem cell transplantation can improve patient prognosis. At present, the diagnosis of systemic CAEBV relies mainly on age, clinical manifestations, and cell lineage, incurring missed diagnosis, misdiagnosis, long diagnosis time, and inability to identify high-risk systemic CAEBV early. The diagnostic methods for systemic CAEBV are complicated and lack systematic description. The recent development of diagnostic procedures, including molecular biological and immunological techniques such as flow cytometry, has provided us with the ability to better understand the proliferation of other EBV-positive T cells and NK cells, but there is no definitive review of their value in diagnosing systemic CAEBV. This article summarizes the recent progress in systemic CAEBV differential diagnosis and the prospects of flow cytometry.

Predictive value of pre-treatment T lymphocyte subsets in patients with extranodal natural killer/T-cell lymphoma

Although the host immune response is likely to be important for the prognosis of ENKTL, detailed information on the pre-treatment T lymphocyte subsets in ENKTL is lacking. To improve risk stratification for ENKTL patients, it is essential to look at the prognostic relevance of absolute CD3 + T cell counts (ACD3C), CD4 + T cell counts (ACD4C), and CD8 + T cell counts (ACD8C) for ENKTL. We retrospectively analyzed 46 ENKTL patients in the First Affiliated Hospital of Wenzhou Medical University between December 2016 and June 2022. Kaplan-Meier curves and log-rank tests were used to compare survival rates between groups according to the cut-off values of pre-treatment T lymphocyte subsets. Independent prognostic factors for survival were analyzed by Cox regression. ACD3C, ACD4C, and ACD8C were related to overall survival (OS) and progression-free survival (PFS) in ENKTL patients. Multivariate analyses identified pre-treatment ACD3C, ACD4C, and ACD8C as independent prognostic factors of survival, independent of the International Prognostic Index (IPI), prognostic index of natural killer lymphoma (PINK), and nomogram-revised risk index (NRI). The prognostic models incorporating pre-treatment T lymphocyte subsets and serum lactate dehydrogenase (LDH) could be used to stratify ENKTL patients into different prognostic groups with significantly different survivals. When superimposed on the IPI, PINK, or NRI categories, the ACD3C-LDH, ACD4C-LDH, and ACD8C-LDH models could better identify high-risk patients in the low-risk IPI, PINK, or NRI categories. In conclusion, the pre-treatment ACD3C, ACD4C, and ACD8C are effective prognostic survival indicators in ENKTL patients. When combined with LDH, they could better identify high-risk ENKTL patients.

Therapeutic challenges in peripheral T-cell lymphoma

Peripheral T-cell lymphoma (PTCL) is a rare and heterogeneous group of hematological malignancies. Compared to our knowledge of B-cell tumors, our understanding of T-cell leukemia and lymphoma remains less advanced, and a significant number of patients are diagnosed with advanced stages of the disease. Unfortunately, the development of drug resistance in tumors leads to relapsed or refractory peripheral T-Cell Lymphomas (r/r PTCL), resulting in highly unsatisfactory treatment outcomes for these patients. This review provides an overview of potential mechanisms contributing to PTCL treatment resistance, encompassing aspects such as tumor heterogeneity, tumor microenvironment, and abnormal signaling pathways in PTCL development. The existing drugs aimed at overcoming PTCL resistance and their potential resistance mechanisms are also discussed. Furthermore, a summary of ongoing clinical trials related to PTCL is presented, with the aim of aiding clinicians in making informed treatment decisions.

EBV and MS: The evidence is growing stronger

Autoimmune cross-reaction of specific antibodies to Epstein-Barr virus (EBV) has been associated with development of multiple sclerosis (MS). In this issue of Cell, Vietzen et al. identify additional immunological regulatory mechanisms that protect against autoimmunity in healthy people but are reduced in MS cases. The results confirm the link between EBV and MS.

EBV Reactivation and Lymphomagenesis: More Questions than Answers

PURPOSE OF REVIEW

Epstein-Barr Virus (EBV) is a ubiquitous herpesvirus that affects almost all humans and establishes lifelong infections by infecting B-lymphocytes leading to their immortalization. EBV has a discrete life cycle with latency and lytic reactivation phases. EBV can reactivate and cause lymphoproliferation in both immunocompetent and immunocompromised individuals. There is sparse literature on monitoring protocols for EBV reactivation and no standardized treatment protocols to treat EBV-driven lymphoproliferation.

RECENT FINDINGS

While there are no FDA-approved therapies to treat EBV, there are several strategies to inhibit EBV replication. These include immunosuppression reduction, nucleoside analogs, HDAC inhibitors, EBV-specific cytotoxic T-lymphocytes (CTLs), and monoclonal antibodies, such as rituximab. There is currently an open clinic trial combining the use of a HDAC inhibitor, nanatinostat, and ganciclovir to treat refractory/relapsed EBV lymphomas. Another novel therapy includes tabelecleucel, which is an allogenic EBV-directed T-cell immunotherapy that was approved by the European Medicines Agency, but is currently only available in the US for limited use in relapsed or refractory EBV-positive PTLD. Further research is needed to establish EBV monitoring protocols in high-risk populations, such as those with autoimmune disease, cancer, HIV, or receiving immunosuppressive therapy. Additionally, standardized treatments for both the prevention of EBV reactivation in high-risk populations and treatment of EBV reactivation and lymphoproliferation need to be established.

Updated guidelines for chronic active Epstein-Barr virus disease

Chronic active Epstein-Barr virus disease (CAEBV), formerly named chronic active Epstein-Barr virus infection, is characterized by systemic inflammation and clonal proliferation of Epstein-Barr virus (EBV)-infected T or NK cells. As CAEBV is a potentially life-threatening illness, appropriate diagnosis and therapeutic interventions are necessary for favorable clinical outcomes. Substantial evidence regarding the pathogenesis and treatment of CAEBV has been accumulated since previous guidelines for the diagnosis of CAEBV were proposed. To reflect this evidence, we updated the guidelines for the diagnosis and treatment of CAEBV to improve clinical management of the disease. The details of the updated guidelines are presented in this report. Diagnosis of CAEBV now requires confirmation of a high copy number of EBV genome and EBV-infected T or NK cells. An EBV DNA load ≥ 10,000 IU/mL in whole blood is proposed as the diagnostic cutoff value for CAEBV in this updated guideline. A standard treatment approach for CAEBV has not been established, and hematopoietic stem cell transplantation (HSCT) is considered the only curative treatment. Chemotherapy can be administered to control disease activity before HSCT.

"Sandwich" protocol based on modified SMILE regimen for children with newly extranodal NK/T cell lymphoma, nasal type: a single-arm, single-center clinical study

Extranodal NK/T-cell lymphoma, nasal type (ENKTL), which is a rare form of mature T/NK cell lymphoma in children, currently lacks a standardized first-line treatment approach. However, a treatment protocol known as the "sandwich" regimen has been used in children newly diagnosed with ENKTL. This protocol combines the administration of methotrexate, ifosfamide, etoposide, pegaspargase, and dexamethasone (referred to as SMILE) with the addition of radiotherapy (RT). From September 2017 to December 2020, a total of five patients were included in the study, consisting of three males and two females. The median age of onset was 10.6 years (range, 9.8 to 14.0 years). Among the patients, four had nasal/nasopharyngeal disease at stage II, while one patient had extra nasal disease involving the skin at stage IV. The median EBV-DNA level in plasma was 1.68 × 103 copies/ml (range, 0.44 to 21.1 × 103copies/ml). All the patients had good overall response after 2 cycles of chemotherapy and radiotherapy, including 4 of the patients who had a complete response and 1 of the patients with partial remission. The patient with stage IV received allogeneic hematopoietic stem cell transplantation after the EBV-DNA level was elevated again during treatment. One patient in the low-risk group experienced grade 4 oral mucositis, while no other severe complications or treatment-related deaths were observed. The median follow-up period was 22 months (range, 5 to 57 months). All five patients successfully completed their treatment, with four patients achieving event-free survival, and one patient was lost to follow-up. The median OS time and EFS time was 33 months (range: 18-57 months) and 20 months (range: 5-47 months), respectively. The sandwich protocol has demonstrated a high response rate, good tolerance to chemotherapy, and no treatment-related fatalities. However, further confirmation is necessary through additional clinical studies involving larger sample sizes. Clinical trial registration number: Due to modified SMILE regimens with sandwiched radiotherapy yielded promising outcomes in children ENKTL, we have carried out a phase II multicenter clinical trial (ChiCTR220005954) for children ENKTL in China to further verify the efficacy and safety.

Extranodal lymphoma: pathogenesis, diagnosis and treatment

Approximately 30% of lymphomas occur outside the lymph nodes, spleen, or bone marrow, and the incidence of extranodal lymphoma has been rising in the past decade. While traditional chemotherapy and radiation therapy can improve survival outcomes for certain patients, the prognosis for extranodal lymphoma patients remains unsatisfactory. Extranodal lymphomas in different anatomical sites often have distinct cellular origins, pathogenic mechanisms, and clinical manifestations, significantly influencing their diagnosis and treatment. Therefore, it is necessary to provide a comprehensive summary of the pathogenesis, diagnosis, and treatment progress of extranodal lymphoma overall and specifically for different anatomical sites. This review summarizes the current progress in the common key signaling pathways in the development of extranodal lymphomas and intervention therapy. Furthermore, it provides insights into the pathogenesis, diagnosis, and treatment strategies of common extranodal lymphomas, including gastric mucosa-associated lymphoid tissue (MALT) lymphoma, mycosis fungoides (MF), natural killer/T-cell lymphoma (nasal type, NKTCL-NT), and primary central nervous system lymphoma (PCNSL). Additionally, as PCNSL is one of the extranodal lymphomas with the worst prognosis, this review specifically summarizes prognostic indicators and discusses the challenges and opportunities related to its clinical applications. The aim of this review is to assist clinical physicians and researchers in understanding the current status of extranodal lymphomas, enabling them to make informed clinical decisions that contribute to improving patient prognosis.

E3 Ubiquitin Ligases in Gammaherpesviruses and HIV: A Review of Virus Adaptation and Exploitation

For productive infection and replication to occur, viruses must control cellular machinery and counteract restriction factors and antiviral proteins. Viruses can accomplish this, in part, via the regulation of cellular gene expression and post-transcriptional and post-translational control. Many viruses co-opt and counteract cellular processes via modulation of the host post-translational modification machinery and encoding or hijacking kinases, SUMO ligases, deubiquitinases, and ubiquitin ligases, in addition to other modifiers. In this review, we focus on three oncoviruses, Epstein-Barr virus (EBV), Kaposi's sarcoma herpesvirus (KSHV), and human immunodeficiency virus (HIV) and their interactions with the ubiquitin-proteasome system via viral-encoded or cellular E3 ubiquitin ligase activity.

Targeting Bcl-xL is a potential therapeutic strategy for extranodal NK/T cell lymphoma

Extranodal natural killer/T cell lymphoma, nasal type (ENKTL) is an aggressive lymphoid malignancy with a poor prognosis and lacks standard treatment. Targeted therapies are urgently needed. Here we systematically investigated the druggable mechanisms through chemogenomic screening and identified that Bcl-xL-specific BH3 mimetics effectively induced ENKTL cell apoptosis. Notably, the specific accumulation of Bcl-xL, but not other Bcl-2 family members, was verified in ENKTL cell lines and patient tissues. Furthermore, Bcl-xL high expression was shown to be closely associated with worse patient survival. The critical role of Bcl-xL in ENKTL cell survival was demonstrated utilizing selective inhibitors, genetic silencing, and a specific degrader. Additionally, the IL2-JAK1/3-STAT5 signaling was implicated in Bcl-xL dysregulation. In vivo, Bcl-xL inhibition reduced tumor burden, increased apoptosis, and prolonged survival in ENKTL cell line xenograft and patient-derived xenograft models. Our study indicates Bcl-xL as a promising therapeutic target for ENKTL, warranting monitoring in ongoing clinical trials by targeting Bcl-xL.

Extranodal NK-/T-cell lymphoma, nasal type: what advances have been made in the last decade?

Extranodal NK-/T-cell lymphoma (ENKTCL) is a rare and highly aggressive malignancy with significant racial and geographic variations worldwide. In addition to the formerly "nasal-type" initial description, these lymphomas are predominantly extranodal in origin and typically cause vascular damage and tissue destruction, and although not fully understood, Epstein-Barr virus (EBV) has an important role in its pathogenesis. Initial assessment must include a hematopathology review of representative and viable tumor areas without necrosis for adequate immunohistochemistry studies, including EBV-encoded small RNA (EBER) in situ hybridization (ISH). Positron emission tomography with 18-fluorodeoxyglucose (¹⁸F-FDG-PET/CT) for accurate staging is essential, and most patients will have localized disease (IE/IIE) at diagnosis. Apart from other T-cell malignancies, the best treatment even for localized cases is combined modality therapy (chemotherapy plus radiotherapy) with non-anthracycline-based regimens. For advanced-stage disease, l-asparaginase-containing regimens have shown improved survival, but relapsed and refractory cases have very poor outcomes. Nowadays, even with a better understanding of pathogenic pathways, up-front therapy is completely based on chemotherapy and radiotherapy, and treatment-related mortality is not low. Future strategies targeting signaling pathways and immunotherapy are evolving, but we need to better identify those patients with dismal outcomes in a pre-emptive way. Given the rarity of the disease, international collaborations are urgently needed, and clinical trials are the way to change the future.

Advancing therapeutic strategies for Epstein-Barr virus-associated malignancies through lytic reactivation

Epstein-Barr virus (EBV) is a widespread human herpes virus associated with lymphomas and epithelial cell cancers. It establishes two separate infection phases, latent and lytic, in the host. Upon infection of a new host cell, the virus activates several pathways, to induce the expression of lytic EBV antigens and the production of infectious virus particles. Although the carcinogenic role of latent EBV infection has been established, recent research suggests that lytic reactivation also plays a significant role in carcinogenesis. In this review, we summarize the mechanism of EBV reactivation and recent findings about the role of viral lytic antigens in tumor formation. In addition, we discuss the treatment of EBV-associated tumors with lytic activators and the targets that may be therapeutically effective in the future.

An update on genetic aberrations in T-cell neoplasms

T-cell neoplasms are a highly heterogeneous group of leukaemias and lymphomas that represent 10-15% of all lymphoid neoplasms. Traditionally, our understanding of T-cell leukaemias and lymphomas has lagged behind that of B-cell neoplasms, in part due to their rarity. However, recent advances in our understanding of T-cell differentiation, based on gene expression and mutation profiling and other high throughput methods, have better elucidated the pathogenetic mechanisms of T-cell leukaemias and lymphomas. In this review, we provide an overview of many of the molecular abnormalities that occur in various types of T-cell leukaemia and lymphoma. Much of this knowledge has been used to refine diagnostic criteria that has been included in the fifth edition of the World Health Organization. This knowledge is also being used to improve prognostication and identify novel therapeutic targets, and we expect this progress will continue, eventually resulting in improved outcomes for patients with T-cell leukaemias and lymphomas.

Is There an Association between Concurrent Epstein-Barr Virus Infection and Sudden Hearing Loss?-A Case-Control Study in an East Asian Population

Viral infection serves as the crucial etiology for the development of sudden sensorineural hearing loss (SSNHL). We aimed to investigate whether there is an association between concurrent Epstein-Barr virus (EBV) infection and SSNHL in an East Asian population. Patients who were older than 18 years of age and met the criteria of sudden hearing loss without an identifiable etiology were enrolled from July 2021 until June 2022, followed by the serological testing of IgA antibody responses against EBV-specific early antigen (EA) and viral capsid antigen (VCA) with an indirect hemagglutination assay (IHA) and real-time quantitative polymerase chain reaction (qPCR) of EBV DNA in serum before the treatment was initiated. After the treatment for SSNHL, post-treatment audiometry was performed to record the treatment response and degree of recovery. Among the 29 patients included during enrollment, 3 (10.3%) had a positive qPCR result for EBV. In addition, a trend of poor recovery of hearing thresholds was noted for those patients with a higher viral PCR titer. This is the first study to use real-time PCR to detect possible concurrent EBV infection in SSNHL. Our study demonstrated that approximately one-tenth of the enrolled SSNHL patients had evidence of concurrent EBV infection, as reflected by the positive qPCR test results, and a negative trend between hearing gain and the viral DNA PCR level was found within the affected cohort after steroid therapy. These findings indicate a possible role for EBV infection in East Asian patients with SSNHL. Further larger-scale research is needed to better understand the potential role and underlying mechanism of viral infection in the etiology of SSNHL.

Characteristics of Extranodal NK/T-Cell Lymphoma, Nasal Type, Compared with Nasal Diffuse Large B-cell Lymphoma

Background

Extranodal NK/T-cell lymphoma, nasal type (ENKL), is an aggressive tumour with poor prognosis. Its early diagnosis may improve the prognosis of patients; however, it is often overlooked in many cases and misdiagnosed as an inflammatory sinus disease during its initial stage. Identifying the clinical characteristics of ENKL may aid otorhinolaryngologists in indicating cases early for a pathologic examination. In this study, we aimed to investigate the clinical characteristics of ENKL compared with that of diffuse large B-cell lymphoma (DLBCL), which is the most common nasal malignant lymphoma.

Methods

The backgrounds, clinical symptoms, blood test results, and computed tomography images of patients with nasal/paranasal malignant lymphoma in our hospital between 2012 and 2017 were investigated. The characteristics of ENKL and nasal DLBCL were compared to differentiate them.

Results

A total of 27 patients with nasal cavity and/or paranasal sinus lymphoma were included. Extranodal NK/T-cell lymphoma, nasal type, was diagnosed in 10 patients, while DLBCL was diagnosed in 17 patients. The median age of patients with ENKL was significantly lower than that of patients with DLBCL. All patients with ENKL had a unilateral lesion in the nasal cavity, with most located at the inferior turbinate. They also experienced nasal symptoms with significantly higher incidence of nasal obstruction and tendency of bleeding.

Conclusion

ENKL was often unilateral and caused nasal obstruction, unlike DLBCL. Those who are younger in age and have sinonasal tumour with unilateral nasal obstruction and bleeding should be considered for early and repeated biopsies at multiple sites, with ENKL taken into consideration.

How EBV Infects: The Tropism and Underlying Molecular Mechanism for Viral Infection

The Epstein-Barr virus (EBV) is associated with a variety of human malignancies, including Burkitt's lymphoma, Hodgkin's disease, nasopharyngeal carcinoma and gastric cancers. EBV infection is crucial for the oncogenesis of its host cells. The prerequisite for the establishment of infection is the virus entry. Interactions of viral membrane glycoproteins and host membrane receptors play important roles in the process of virus entry into host cells. Current studies have shown that the main tropism for EBV are B cells and epithelial cells and that EBV is also found in the tumor cells derived from NK/T cells and leiomyosarcoma. However, the process of EBV infecting B cells and epithelial cells significantly differs, relying on heterogenous glycoprotein-receptor interactions. This review focuses on the tropism and molecular mechanism of EBV infection. We systematically summarize the key molecular events that mediate EBV cell tropism and its entry into target cells and provide a comprehensive overview.

EBV-associated NK and T-cell lymphoid neoplasms

PURPOSE OF REVIEW

Epstein-Barr virus (EBV)-associated neoplasms derived from natural killer (NK) or T cells comprise a group of clinically and biologically heterogenous disorders affecting children and adults, which are overall rare but more prevalent in Asia and South America. This review focuses on neoplasms presenting in the adulthood, addressing recent genomic discoveries as well as therapeutic developments in these highly aggressive disorders.

RECENT FINDINGS

Distinct molecular subtypes of extranodal NK/T-cell lymphomas (ENKTCLs) have been described, with differences in cell of origin, EBV pattern, genomic alterations, clinical characteristics, response to asparaginase-based therapies and to more recent approaches targeting molecular aberrations of the lymphoma. For the last two decades, progress in the clinical management of ENKTCL was based on L-asapraginase containing combinations and the incoroperation of radiotherapy. A subset of cases with PDL1-2 structural alterations may be more responsive to treatment with immune checkpoint inhibitors. Primary nodal EBV+ lymphomas derived from T or NK cells have distinctive features separating them from both peripheral T-cell lymphoma not otherwise specified and ENKTCL. Treatment algorithms correspond to those for advanced ENKTCL.

SUMMARY

With better understanding of lymphomagenesis, genomic landscape and immunologic aspects of the diseases, future treatment options will include targeted therapies including immune checkpoint inhibitors and novel antibodies.

Comprehensive Analyses of Intraviral Epstein-Barr Virus Protein-Protein Interactions Hint Central Role of BLRF2 in the Tegument Network

Protein-protein interactions (PPIs) are crucial for various biological processes. Epstein-Barr virus (EBV) proteins typically form complexes, regulating the replication and persistence of the viral genome in human cells. However, the role of EBV protein complexes under physiological conditions remains unclear. In this study, we performed comprehensive analyses of EBV PPIs in living cells using the NanoBiT system. We identified 195 PPIs, many of which have not previously been reported. Computational analyses of these PPIs revealed that BLRF2, which is only found in gammaherpesviruses, is a central protein in the structural network of EBV tegument proteins. To characterize the role of BLRF2, we generated two BLRF2 knockout EBV clones using CRISPR/Cas9. BLRF2 knockout significantly decreased the production of infectious virus particles, which was partially restored by exogenous BLRF2 expression. In addition, self-association of BLRF2 protein was found, and mutation of the residues crucial for the self-association affected stability of the protein. Our data imply that BLRF2 is a tegument network hub that plays important roles in progeny virion maturation. IMPORTANCE EBV remains a significant public health challenge, causing infectious mononucleosis and several cancer types. Therefore, the better understanding of the molecular mechanisms underlying EBV replication is of high clinical importance. As protein-protein interactions (PPIs) are major regulators of virus-associated pathogenesis, comprehensive analyses of PPIs are essential. Previous studies on PPIs in EBV or other herpesviruses have predominantly employed the yeast two-hybrid (Y2H) system, immunoprecipitation, and pulldown assays. Herein, using a novel luminescence-based method, we identified 195 PPIs, most of which have not previously been reported. Computational and functional analyses using knockout viruses revealed that BLRF2 plays a central role in the EBV life cycle, which makes it a valuable target for drug development.

Sequence analysis of Epstein–Barr virus BALF2 gene in associated tumors and healthy individuals from southern and northern China

Aim: The purpose of this study is to investigate the polymorphism and distribution characteristics of BALF2 gene in Epstein–Barr virus (EBV)-associated tumors (gastric cancer, nasopharyngeal carcinoma and lymphoma). Materials & methods: DNA sequences of 349 EBV-related samples were analyzed by nested PCR combined with DNA sequencing. Results: According to the phylogenetic tree, BALF2 was divided into six genotypes ( BALF2-A–F). Statistically, the incidence of BALF2-E in nasopharyngeal carcinoma was higher than that in healthy people, and the incidence of BALF2-E in nasopharyngeal carcinoma in South China was higher than that in North China (p = 0.001). Conclusion: BALF2 variants in EBV-associated samples are not only tumor-specific, but also differ between northern and southern regions.

The implications of cell-free DNAs derived from tumor viruses as biomarkers of associated cancers

Cancer is still ranked as a leading cause of death according to estimates from the World Health Organization (WHO) and the strong link between tumor viruses and human cancers have been proved for almost six decades. Cell-free DNA (cfDNA) has drawn enormous attention for its dynamic, instant, and noninvasive advantages as one popular type of cancer biomarker. cfDNAs are mainly released from apoptotic cells and exosomes released from cancer cells, including those infected with viruses. Although cfDNAs are present at low concentrations in peripheral blood, they can reflect tumor load with high sensitivity. Considering the relevance of the tumor viruses to the associated cancers, cfDNAs derived from viruses may serve as good biomarkers for the early screening, diagnosis, and treatment monitoring. In this review, we summarize the methods and newly developed analytic techniques for the detection of cfDNAs from different body fluids, and discuss the implications of cfDNAs derived from different tumor viruses in the detection and treatment monitoring of virus-associated cancers. A better understanding of cfDNAs derived from tumor viruses may help formulate novel anti-tumoral strategies to decrease the burden of cancers that attributed to viruses. This article is protected by copyright. All rights reserved.

Replication Compartments-The Great Survival Strategy for Epstein-Barr Virus Lytic Replication

During Epstein–Barr virus (EBV) lytic replication, viral DNA synthesis is carried out in viral replication factories called replication compartments (RCs), which are located at discrete sites in the nucleus. Viral proteins constituting the viral replication machinery are accumulated in the RCs to amplify viral genomes. Newly synthesized viral DNA is stored in a subdomain of the RC termed the BMRF1-core, matured by host factors, and finally packed into assembled viral capsids. Late (L) genes are transcribed from DNA stored in the BMRF1-core through a process that is mainly dependent on the viral pre-initiation complex (vPIC). RC formation is a well-regulated system and strongly advantageous for EBV survival because of the following aspects: (1) RCs enable the spatial separation of newly synthesized viral DNA from the cellular chromosome for protection and maturation of viral DNA; (2) EBV-coded proteins and their interaction partners are recruited to RCs, which enhances the interactions among viral proteins, cellular proteins, and viral DNA; (3) the formation of RCs benefits continuous replication, leading to L gene transcription; and (4) DNA storage and maturation leads to efficient progeny viral production. Here, we review the state of knowledge of this important viral structure and discuss its roles in EBV survival.

EBV associated T- and NK-cell lymphoproliferative diseases: A comprehensive overview of clinical manifestations and novel therapeutic insights

EBV is a ubiquitous virus that infects nearly all people around the world. Most infected people are asymptomatic and do not show serious sequelae, while others may develop Epstein-Barr virus (EBV)-positive T and NK-cell lymphoproliferations characterised by EBV-infected T or NK cells. These disorders are more common in Asian and Latin American people, suggesting genetic predisposition as a contributing factor. The revised WHO classification classifies the lymphoproliferative diseases as: extranodal NK/T-cell lymphoma nasal type (ENKTL), aggressive NK-cell leukemia (ANKL), primary EBV-positive nodal T or NK cell lymphoma (NNKTL), systemic EBV-positive T-cell lymphoproliferative disease of childhood (STCLC), systemic chronic active EBV infection (sys CAEBV), hydroa-vacciniforme (HV) and severe mosquito bite allergy (SMBA). Recent advances in the molecular pathogenesis of these diseases have led to the development of new therapeutic strategies. Due to the infrequency of the diseases and broad clinicopathological overlap, the diagnosis and classification are challenging for both clinicians and pathologists. In this article, we aim to review the recent pathological findings which can be helpful for designing new drugs, clinical presentations and differential diagnoses, and suggested therapeutic interventions to provide a better understanding of these rare disorders.

Characterization of the humoral immune response to the EBV proteome in extranodal NK/T-cell lymphoma

Extranodal natural killer/T-cell lymphoma (NKTCL) is an aggressive malignancy that has been etiologically linked to Epstein-Barr virus (EBV) infection, with EBV gene transcripts identified in almost all cases. However, the humoral immune response to EBV in NKTCL patients has not been well characterized. We examined the antibody response to EBV in plasma samples from 51 NKTCL cases and 154 controls from Hong Kong and Taiwan who were part of the multi-center, hospital-based AsiaLymph case–control study. The EBV-directed serological response was characterized using a protein microarray that measured IgG and IgA antibodies against 202 protein sequences representing the entire EBV proteome. We analyzed 157 IgG antibodies and 127 IgA antibodies that fulfilled quality control requirements. Associations between EBV serology and NKTCL status were disproportionately observed for IgG rather than IgA antibodies. Nine anti-EBV IgG responses were significantly elevated in NKTCL cases compared with controls and had ORs_{highest vs. lowest tertile} > 6.0 (Bonferroni-corrected P-values < 0.05). Among these nine elevated IgG responses in NKTCL patients, three IgG antibodies (all targeting EBNA3A) are novel and have not been observed for other EBV-associated tumors of B-cell or epithelial origin. IgG antibodies against EBNA1, which have consistently been elevated in other EBV-associated tumors, were not elevated in NKTCL cases. We characterize the antibody response against EBV for patients with NKTCL and identify IgG antibody responses against six distinct EBV proteins. Our findings suggest distinct serologic patterns of this NK/T-cell lymphoma compared with other EBV-associated tumors of B-cell or epithelial origin.

Review on natural killer /T-cell lymphoma

Extranodal natural killer (NK)/T-cell lymphoma (ENKTL) is strongly associated with Epstein-Barr virus (EBV) and has a high prevalence in Asian and in Central and South America. About 85% of ENKTLs derive from NK cells and 15% from T-cells. Various factors have been implicated in the development of ENKTL. Molecular pathogenesis of NK/T-cell lymphomas include mutations of genes, involving in the Janus Kinase (JAK)/ signal transducer and activator of transcription (STAT) pathway, RNA helicase family, epigenetic regulation, and tumor suppression. The relationship between ENKTL and human leukocyte antigen (HLA) has been demonstrated. Radiotherapy (RT) plays a key role in the first-line treatment of early-stage. In stage III/IV diseases, non-anthracycline-regimens-containing L-asparaginase are recommended. Although clinical remission after L-asparaginase-based combination therapy has been achieved in the majority of patients with advanced-stage or relapsed/refractory(r/r) ENKL, the long-term overall survival is still poor. Recently, immunotherapy and new therapeutic targets have gained much attention. In this article, we discuss the pathogenesis, diagnosis, prognostic models and management options of ENKTL. This article is protected by copyright. All rights reserved.

Clinical Features and Prognostic Factors of Children with Chronic Active Epstein-Barr Virus Infection: A Retrospective Analysis of a Single Center

OBJECTIVE

To analyze the clinical characteristics, prognosis factors and risk factors of chronic active Epstein-Barr virus infection in children.

STUDY DESIGN

Observational analysis of baseline data and follow-up evaluation data of children with chronic active Epstein-Barr virus infection in our center between January 1, 2016 and December 31, 2019; they were followed through June 30, 2020.

RESULTS

There were 96 children with chronic active Epstein-Barr virus infection (50 male and 46 female children), with the median age of 6.7 years (range from 0.6 to 17.6 years) at diagnosis. The median follow-up time was 16.5 months. The 3 most common clinical manifestations were fever, lymph node enlargement, and hepatomegaly or splenomegaly. Thirty-three patients (36.3%) also had a diagnosis of hemophagocytic lymphohistiocytosis (HLH). Epstein-Barr virus infected only T lymphocytes, natural killer cells, or both T- and natural killer-cell types in 15 (33.3%), 17 (37.8%), and 13 (28.9%), respectively. At the end of follow-up, 26 children had died, 60 survived, and 10 were lost to follow-up. Generally, progression-free survival was 69.8% ± 2.4%. The level of interleukin (IL)-6 and IL-10 and the combination of younger age and lower pathologic grade at diagnosis were independent prognostic factors by Cox regression analysis (P = .009 and .018, respectively).

CONCLUSIONS

Children with lower levels of IL-6 and IL-10, or with younger age and lower pathologic grades, generally had favorable outcomes at the terminal point of follow-up, indicating better prognostic signs.

Uncovering early events in primary Epstein-Barr virus infection using a rabbit model

Epstein-Barr virus (EBV) is an oncogenic herpesvirus implicated in the pathogenesis of several malignant and non-malignant conditions. However, a number of fundamental aspects about the biology of EBV and the mechanism(s) by which this virus induces pathology remain unknown. One major obstacle has been the lack of a suitable animal model for EBV infection. In this study, using our recently established rabbit model of EBV infection, we examined the early events following primary EBV infection. We show that, both immunocompetent and immunosuppressed animals were readily susceptible to EBV infection. However, immunosuppressed animals showed marked splenomegaly and widespread infection. Following EBV infection, the virus primarily targeted naïve IgM+, CD20+, CD21+ and CD79a+ B cells. Infected cells expressed varying sets of viral latent/lytic gene products. Notably, co-expression of latent and lytic proteins in the same cell was not observed. Infected cells in type 0/1 latency (EBERs+), were small and proliferating (Ki67+). By contrast, cells in type 2/3 latency (LMP1+), were large, non-proliferating (Ki-67-) and p53+. Although infected B-cells were widely present in splenic follicles, they did not express germinal center marker, BCL-6. Taken together, this study shows for the first time, some of the early events following primary EBV infection.

Pathological and genomic phenotype of second neuroendocrine carcinoma during long-term follow-up after radical radiotherapy for nasopharyngeal carcinoma

Background

Second head and neck neuroendocrine carcinoma (NEC) after radical radiotherapy for nasopharyngeal carcinoma (NPC) treatment is rarely reported. The prognosis of second cancer is poor, and our research focuses on finding a breakthrough in the treatment. In this study, we aimed to investigate clinicopathological characteristics and to identify the genomic landscape of second head and neck NECs.

Methods

We collected five second head and neck NEC cases in the recent three years from our patient database. Clinicopathological data and images were obtained. Genomic analysis was performed using high-throughput second generation sequencing. KEGG pathway enrichment analyses between high-frequency mutations were performed using the STRING database.

Results

All patients had been diagnosed with second NEC, according to the pathological observations. The interval between diagnosis of NPC and NEC ranged from 10 to 18 years. Two patients had brain or liver metastasis at three and nine months, respectively, after the diagnosis of NEC. Three patients died of the disease with the overall survival time ranging from three to nine months. Commonly altered genes (50%) in second head and neck NECs included TP53, RB1, NOTCH2, PTEN, POLG, KMT2C, U2AF1, EPPK1, ELAC2, DAXX, COL22A1, and ABL1. Those genetic lesions might affect p53 signaling, MAPK signaling, PI3K-Akt signaling, sphingolipid signaling, and neurotrophin signaling pathways.

Conclusions

Second head and neck NECs had poor prognosis. We revealed, for the first time, the mutational landscape, high-frequency somatic mutations, and potential signaling pathways of second head and neck NECs. Its optimal treatment model needs to be further studied in future clinical trials.

Molecular Properties and Therapeutic Targeting of the EBV-Encoded Receptor BILF1

The γ-herpesvirus Epstein-Barr Virus (EBV) establishes lifelong infections in approximately 90% of adults worldwide. Up to 1,000,000 people yearly are estimated to suffer from health conditions attributed to the infection with this virus, such as nasopharyngeal and gastric carcinomas as well as several forms of B, T and NK cell lymphoma. To date, no EBV-specific therapeutic option has reached the market, greatly reducing the survival prognoses of affected patients. Similar to other herpesviruses, EBV encodes for a G protein-coupled receptor (GPCR), BILF1, affecting a multitude of cellular signaling pathways. BILF1 has been identified to promote immune evasion and tumorigenesis, effectively ensuring a life-long persistence of EBV in, and driving detrimental health conditions to its host. This review summarizes the epidemiology of EBV-associated malignancies, their current standard-of-care, EBV-specific therapeutics in development, GPCRs and their druggability, and most importantly consolidates the findings of over 15 years of research on BILF1 in the context of EBV-specific drug development. Taken together, BILF1 constitutes a promising target for the development of novel EBV-specific therapeutics.

Deletion of Viral microRNAs in the Oncogenesis of Epstein-Barr Virus-Associated Lymphoma

Epstein–Barr virus (EBV), which encodes >80 genes and nearly 50 non-coding RNAs, is a double-stranded DNA virus. EBV is associated with various types of lymphomas and lymphoproliferative disorders not only of B-cell but also T/NK-cell origin. However, the oncogenic mechanism remains poorly understood, including the EBV receptors expressed on T/NK cells, relationship of EBV with host genes, and epigenetic regulation of EBV and host genes. The roles of host and viral non-coding RNAs during tumorigenesis have been elucidated. EBV encodes at least 49 mature microRNAs (miRNAs), of which 44 are located in BamHI-A rightward transcripts (BARTs) region, and the remaining five are located in BamHI-H rightward fragment 1. BART miRNAs modulate cell differentiation, proliferation, apoptosis, and the cell cycle, and they are considered positive regulators of oncogenesis. We and others have recently reported that EBV-positive lymphomas frequently possess large deletions in BART miRNA clusters, suggesting that some viral miRNAs have suppressive effects on oncogenesis, and that deletion of these miRNAs may aid lymphoma formation.

Extranodal NK/T-Cell Lymphoma, Nasal Type: Genetic, Biologic, and Clinical Aspects with a Central Focus on Epstein-Barr Virus Relation

Extranodal NK/T-Cell Lymphoma, nasal type (ENKTL-NT) has some salient aspects. The lymphoma is commonly seen in Eastern Asia, has progressive necrotic lesions in the nasal cavity, makes midfacial destructive lesions, and shows poor prognosis. The lymphoma cell is originated from either NK- or γδ T-cells, which express CD56. Since the authors first demonstrated the existence of Epstein–Barr virus (EBV) DNA and EBV oncogenic proteins in lymphoma cells, ENKTL-NT has been recognized as an EBV-associated malignancy. Because the angiocentric and polymorphous lymphoma cells are mixed with inflammatory cells on a necrotic background, the diagnosis of ENKTL-NT requires CD56 immunostaining and EBER in situ hybridization. In addition, serum the EBV DNA level is useful for the diagnosis and monitoring of ENKTL-NT. Although ENKTL-NT is refractory lymphoma, the prognosis is improved by the development of therapies such as concomitant chemoradiotherapy. The basic research reveals that a wide variety of intracellular/cell surface molecules, cytokines, chemokines, and micro RNAs are involved in lymphomagenesis, and some of them are related to EBV. Understanding lymphoma behavior introduces new therapeutic strategies, such as the usage of immune checkpoint inhibitors, peptide vaccines, and molecular targeting therapy. This review addresses recent advances in basic and clinical aspects of ENKTL-NT, especially its relation to EBV features.

MiR-3614-5p Is a Potential Novel Biomarker for Colorectal Cancer

MiR-3614-5p has been found in a variety of cancers including colorectal cancer. However, the association of miR-3614-5p with colorectal cancer is still unclear. Based on the Cancer Genome Atlas (TCGA) database, the relationship between miR-3614-5p and colorectal cancer can be proved. Wilcoxon rank-sum test was used to compare the miR-3614-5p expression in colorectal cancer tissues and under normal conditions, respectively. The logistic regression method was further employed to analyze the relationship between miR-3614-5p and clinicopathological characteristics. Also, the correlation between miR-3614-5p and survival rate was evaluated by Kaplan-Meier and Cox regression analysis. Besides, gene set enrichment analysis (GSEA) was used to investigate the biological functions of miR-3614-5p. The decrease of miR-3614-5p expression of colorectal cancer was significantly correlated with N stage (OR) = 0.7 for N1&N2 vs. N0), M stage (OR = 0.5 for M1 vs. M0), pathologic stage (OR = 0.7 for Stage III & Stage IV vs. Stage I & Stage II), neoplasm type (OR = 0.5 for rectum adenocarcinoma vs. colon adenocarcinoma), and lymphatic invasion (OR = 0.6 for YES vs. NO) (all p-values < 0.05). Kaplan-Meier survival analysis showed that colorectal cancer with low miR-3614-5p has a poorer prognosis than that of high miR-3614-5p (p = 0.005). According to univariate analysis, low miR-3614-5p was associated with poor overall survival (OS) [hazard ratio (HR) = 0.599; 95% confidence interval (CI): 0.418-0.857; p = 0.005]. In multivariate analysis, miR-3614-5p was closely related to OS (HR = 0.630; 95% CI: 0.405-0.978, p = 0.021). GSEA showed that the high expression phenotype of miR-3614-5p differentially enriches the P53 pathway. Meanwhile, the high expression phenotype of miR-3614-5p enhanced NK T cell activation, negative T cell selection, response to interleukin 2, and response to tumor cells. MiR-3614-5p is a possible prognostic marker of low survival rate for patients with colorectal cancer. Moreover, the P53 pathway and P38MAPK pathway may be the key pathways regulated by miR-3614-5p in colorectal cancer.

Extranodal NK/T cell lymphoma, nasal type: An updated overview

Extranodal NK/T-cell lymphoma, nasal type (ENKTCL-NT) is an aggressive malignancy associated with Epstein-Barr virus infection, with a geographic and racial predilection for some Asian and Latin American countries. ENKTCL-NT manifests as a necrotic process affecting nasal or upper aerodigestive structures and, rarely, extranasal sites such as skin, and the gastrointestinal tract. ENKTCL-NT was characterized by its poor prognosis irrespective of clinical stage and therapy. However, during the last two decades, advances in its clinicopathologic, genetic and molecular characterization have been achieved, as have changes in the chemotherapy regimens that, in combination with radiotherapy, are significantly improving the survival of these patients, especially in initial stages. For these reasons, we present an overview of the historical background of ENKTCL-NT along with an updated review of its potential etiological factors, clinicopathologic and molecular features, as well as its prognostic models, current treatment protocols, and future directions on potential promising therapeutic approaches.

Reappraisal of the prognostic value of Epstein-Barr virus status in monomorphic post-transplantation lymphoproliferative disorders-diffuse large B-cell lymphoma

The role of the Epstein-Barr virus (EBV) status in the blood for predicting survival in post-transplantation lymphoproliferative disorders-diffuse large B-cell lymphoma (PTLD-DLBCL) is unknown. We evaluated the prognostic values of pre-treatment EBV-encoded small RNA (EBER) detected with in situ hybridization in tissues and EBV DNA in the whole blood (WB) and plasma in 58 patients with monomorphic PTLD-DLBCL after solid organ transplantation. There were no significant differences in the rates of overall response, complete response, and survival according to EBER EBV and WB EBV status. In contrast, patients with positive plasma EBV DNA had significantly lower rates of overall response (60.0% vs. 94.4%, P = 0.043) and complete response (40.0% vs. 88.9%, P = 0.019) as well as worse progression-free survival (PFS) (P = 0.035) and overall survival (OS) (P = 0.039) compared with patients with negative plasma EBV DNA. In multivariate analysis, plasma EBV DNA positivity was a significantly unfavorable prognostic factor for PFS [hazard ratio (HR) 4.92, 95% confidence interval (CI) 1.22-19.86, P = 0.025] and OS (HR 4.48, 95% CI 1.14-17.63, P = 0.032). Despite small number of 6 patients with plasma EBV positivity, plasma EBV DNA positivity might be more prognostic for survival than EBER or WB EBV DNA positivity in patients with monomorphic PTLD-DLBCL.

CD8dimCD3+ lymphocytes in fever patients might be biomarkers of active EBV infection and exclusion indicator of T-LGLL

Background: Massive monoclonal or oligoclonal expansion of CD8⁺ T cells is a notable feature of primary infections of the Epstein-Barr virus (EBV). However, the clinical significance of this expansion is not clear. Results: An increase in the CD8^dimCD3⁺ lymphocyte subset in patients with active EBV infection was due to caspase-8-dependent apoptosis was found using flow cytometry in this study. The number of these cells was associated with the illness severity. Pan-T-cell antigen and receptor analyses were also compared in patients with active EBV infections and T-cell large granular lymphocytic leukemia to provide additional diagnostic information. Conclusion: The increase in CD8^dimCD3⁺ cells could be a biomarker of active EBV infection and an exclusion indicator of T-cell large granular lymphocytic leukemia with flow cytometric analysis.

Chronic Active Epstein-Barr Virus Infection: Is It Immunodeficiency, Malignancy, or Both?

Simple Summary

Chronic active Epstein–Barr virus (EBV) infection (CAEBV) is a rare syndrome of unknown etiology characterized by prolonged infectious mononucleosis-like symptoms and proliferation of EBV-infected T and/or natural killer cells. CAEBV has been primarily reported in East Asia and Latin America, suggesting a genetic predisposition in its pathogenesis. The clinical course of CAEBV is heterogeneous ranging from an indolent and occasionally self-limiting disease to an aggressive and fatal condition, but its prognosis is generally poor. This heterogeneous clinical picture does not suggest a simple etiology for the syndrome. Clinicopathological investigations of CAEBV suggest that it has aspects of both malignant neoplasm and immunodeficiency. This article summarizes the latest findings on CAEBV and discusses critical unsolved questions regarding its pathogenesis and disease concept.

Abstract

Chronic active Epstein–Barr virus (EBV) infection (CAEBV) is a rare syndrome characterized by prolonged infectious mononucleosis-like symptoms and elevated peripheral blood EBV DNA load in apparently immunocompetent persons. CAEBV has been primarily reported in East Asia and Latin America, suggesting a genetic predisposition in its pathogenesis. In most cases of CAEBV, EBV induces proliferation of its unusual host cells, T or natural killer (NK) cells. The clinical course of CAEBV is heterogeneous; some patients show an indolent course, remaining in a stable condition for years, whereas others show an aggressive course with a fatal outcome due to hemophagocytic lymphohistiocytosis, multiple organ failure, or progression to leukemia/lymphoma. The pathogenesis of CAEBV is unclear and clinicopathological investigations suggest that it has aspects of both malignant neoplasm and immunodeficiency. Recent genetic analyses of both viral and host genomes in CAEBV patients have led to discoveries that are improving our understanding of the nature of this syndrome. This article summarizes the latest findings on CAEBV and discusses critical unsolved questions regarding its pathogenesis and disease concept.

Signaling pathways involved in the T-cell-mediated immunity against Epstein-Barr virus: Lessons from genetic diseases

Primary immunodeficiencies (PIDs) provide researchers with unique models to understand in vivo immune responses in general and immunity to infections in particular. In humans, impaired immune control of Epstein-Barr virus (EBV) infection is associated with the occurrence of several different immunopathologic conditions; these include non-malignant and malignant B-cell lymphoproliferative disorders, hemophagocytic lymphohistiocytosis (HLH), a severe inflammatory condition, and a chronic acute EBV infection of T cells. Studies of PIDs associated with a predisposition to develop severe, chronic EBV infections have led to the identification of key components of immunity to EBV - notably the central role of T-cell expansion and its regulation in the pathophysiology of EBV-associated diseases. On one hand, the defective expansion of EBV-specific CD8 T cells results from mutations in genes involved in T-cell activation (such as RASGRP1, MAGT1, and ITK), DNA metabolism (CTPS1) or co-stimulatory pathways (CD70, CD27, and TNFSFR9 (also known as CD137/4-1BB)) leads to impaired elimination of proliferating EBV-infected B cells and the occurrence of lymphoma. On the other hand, protracted T-cell expansion and activation after the defective killing of EBV-infected B cells is caused by genetic defects in the components of the lytic granule exocytosis pathway or in the small adapter protein SH2D1A (also known as SAP), a key activator of T- and NK cell-cytotoxicity. In this setting, the persistence of EBV-infected cells results in HLH, a condition characterized by unleashed T-cell and macrophage activation. Moreover, genetic defects causing selective vulnerability to EBV infection have highlighted the role of co-receptor molecules (CD27, CD137, and SLAM-R) selectively involved in immune responses against infected B cells via specific T-B cell interactions.

Extranodal NK/T-Cell Lymphomas: The Role of Natural Killer Cells and EBV in Lymphomagenesis

Keywords: NK cells, extranodal NK/T-cell lymphoma, EBV.

Epstein-Barr virus NK and T cell lymphoproliferative disease: report of a 2018 international meeting

Epstein-Barr virus (EBV) normally infects B cells, but in some persons the virus infects T or NK cells. Infection of B cells can result in infectious mononucleosis, and the virus is associated with several B cell malignancies including Hodgkin lymphoma, Burkitt lymphoma, and diffuse large B cell lymphoma. Infection of T or NK cells with EBV is associated with extranodal NK/T cell lymphoma, aggressive NK-cell leukemia, systemic EBV-associated T-cell lymphoma, and chronic active EBV disease, which in some cases can include hydroa vacciniforme-like lymphoproliferative disease and severe mosquito bite allergy. While NK and T cell lymphoproliferative disease is more common in Asia and Latin America, increasing numbers of cases are being reported from the United States and Europe. This review focuses on classification, clinical findings, pathogenesis, and recent genetic advances in NK and T cell lymphoproliferative diseases associated with EBV.

Extranodal NK/T-cell lymphoma in Tunisia: clinicopathological features, immunophenotype and EBV infection

BACKGROUND

Extranodal NK/T-cell lymphomas (ENKTL) are rare non-Hodgkin's lymphomas with aggressive clinical behavior. ENKTL are frequently associated with the Epstein-Barr virus (EBV). Data on ENKTL in Africa and Arab world are extremely limited. The study investigated the clinicopathological characteristics, EBV infection, and immunophenotype of ENKTL in Tunisia. We conducted a retrospective study of ENKTL. Main clinicopathological features were reported. The expression of CD3, CD4, CD5, CD8, CD20, CD56, CD57, and Granzyme B were analyzed by immunohistochemistry. EBV infection was detected by IHC (LMP-1) and Epstein-Barr encoding region (EBER1/2) in situ hybridization.

RESULTS

A total of nine ENKTL were identified (mean age of 48 years and male-to-female ratio of 8:1). There were five nasal ENKTL, and the remaining four cases had extranasal involvement (palate, sub-mandibular gland, skin, and soft tissues of the ankle). The histopathology showed a lymphoid and pleomorphic proliferation characterized by images of angiocentrism. Strong and diffuse CD3 expression was observed in all cases. Tumor cells exhibited an expression of CD5 (two cases), CD8 (three cases), CD56 (six cases), CD57 (three cases), and Granzyme B (eight cases). All ENKTL cases were EBV-associated. Overall 5-year survival rate was 57%. Although six ENKTL were diagnosed at early clinical stages, the prognosis was unfavorable and associated with patient death in three cases.

CONCLUSIONS

ENKTL are exceptional in Tunisia with unfavorable outcome. Histopathological diagnosis remains challenging in clinical practice. However, a careful histopathological examination combined with a correct interpretation of immunohistochemistry and in situ hybridization results refines the ENKTL diagnosis.

Nasal NK/T cell lymphoma mimicking mucosa-associated lymphoid tissue lymphoma in morphology: A case report

The objective of the present study was to describe the clinicopathological features of a patient with nasal NK/T cell lymphoma that was similar in morphology to mucosa-associated lymphoid tissue lymphoma (MALToma). The clinicopathological data of a patient diagnosed with nasal NK/T cell lymphoma mimicking MALToma was collected, and the clinicopathological characteristics were discussed. The female patient was 43 years old and had suffered from persistent congestion for ten days. The mucosa in the left nasal cavity was inflamed, resulting in congestion and it was also purulent on the surface, as observed by nasal endoscopy. The disease was considered to be inflammatory based on CT scan. A biopsy after operation showed that the tumor consisted of small lymphoid cells that resembled MALToma in morphology. On the basis of the immunohistochemistry and in situ hybridization laboratory tests, a diagnosis of left nasal NK/T cell lymphoma was made. The patient received chemotherapy and radiotherapy, and remission was achieved six months after diagnosis. The patient was in a good condition at 16 months follow-up. In conclusion, NK/T cell lymphoma composed of small cells may be a type of indolent lymphoma with special characteristics of clinical presentation, image, pathology and prognosis. This case highlights that more attention is required by radiologists, pathologists and hematologists to diagnose this type of lymphoma.

High-Throughput Sequence Analysis of Peripheral T-Cell Lymphomas Indicates Subtype-Specific Viral Gene Expression Patterns and Immune Cell Microenvironments

Certain peripheral T-cell lymphomas (PTCLs) have been associated with viral infection, particularly infection with Epstein-Barr virus (EBV). However, a comprehensive virome analysis across PTCLs has not previously been reported. Here we utilized published whole-transcriptome RNA sequencing (RNA-seq) data sets from seven different PTCL studies and new RNA-seq data from our laboratory to screen for virus association, to analyze viral gene expression, and to assess B- and T-cell receptor diversity paradigms across PTCL subtypes. In addition to identifying EBV in angioimmunoblastic T-cell lymphoma (AITL) and extranodal NK/T-cell lymphoma (ENKTL), two PTCL subtypes with well-established EBV associations, we also detected EBV in several cases of anaplastic large-cell lymphoma (ALCL), and we found evidence of infection by the oncogenic viruses Kaposi's sarcoma-associated herpesvirus and human T-cell leukemia virus type 1 in isolated PTCL cases. In AITLs, EBV gene expression analysis showed expression of immediate early, early, and late lytic genes, suggesting either low-level lytic gene expression or productive infection in a subset of EBV-infected B-lymphocyte stromal cells. Deconvolution of immune cell subpopulations demonstrated a greater B-cell signal in AITLs than in other PTCL subtypes, consistent with a larger role for B-cell support in the pathogenesis of AITL. Reconstructed T-cell receptor (TCR) and B-cell receptor (BCR) repertoires demonstrated increased BCR diversity in AITLs, consistent with a possible EBV-driven polyclonal response. These findings indicate potential alternative roles for EBV in PTCLs, in addition to the canonical oncogenic mechanisms associated with EBV latent infection. Our findings also suggest the involvement of other viruses in PTCL pathogenesis and demonstrate immunological alterations associated with these cancers.IMPORTANCE In this study, we utilized next-generation sequencing data from 7 different studies of peripheral T-cell lymphoma (PTCL) patient samples to globally assess viral associations, provide insights into the contributions of EBV gene expression to the tumor phenotype, and assess the unique roles of EBV in modulating the immune cell tumor microenvironment. These studies revealed potential roles for EBV replication genes in some PTCL subtypes, the possible role of additional human tumor viruses in rare cases of PTCLs, and a role for EBV in providing a unique immune microenvironmental niche in one subtype of PTCLs. Together, these studies provide new insights into the understudied role of tumor viruses in PTCLs.

Clinical efficacy of cisplatin, dexamethasone, gemcitabine and pegaspargase (DDGP) in the initial treatment of advanced stage (stage III-IV) extranodal NK/T-cell lymphoma, and its correlation with Epstein-Barr virus

Objective: To evaluate the clinical efficacy and safety of the DDGP regimen in treating extranodal NK/T-cell lymphoma and investigate the correlation between Epstein-Barr virus (EBV)-DNA variation after treatment and the clinical efficacy of NK/T-cell lymphoma.

Methods: Sixty-four patients with extranodal NK/T-cell lymphoma received DDGP regimen-based chemotherapy. Short-term and long-term clinical efficacy and adverse reactions were observed. The relationship between EBV-DNA changes before and after therapy and clinical efficacy was investigated.

Results: After the DDGP regimen was used as the initial treatment, the short-term clinical efficacy included 39 complete remission (CR) (60.94%), 12 partial remission (PR) (18.75%), 2 stable disease (SD) (3.13%) and 11 progressive disease (PD) (17.18%). Objective response rate (ORR) was 79.69% and 82.82% for disease control rate (DCR). 3-year progression-free survival (PFS) was 62.00% and 3-year overall survive (OS) was 74.90%. Hemocytopenia was the predominant adverse effect. Between EBV-DNA positive group and its negative counterpart, a significant difference was noted in OS (P=0.046), but no difference in ORR, DCR or PFS was observed. In the EBV-DNA positive group, ORR, DCR, PFS and OS were higher for patients whose EBV-DNA copy number decreased within a normal range than patients remained positive (93.33% versus 61.53%, P=0.041 for ORR; 93.33% versus 61.53%, P=0.041 for DCR, P=0.003 for PFS, P=0.017 for OS). The main adverse reactions included bone marrow suppression, gastrointestinal reaction and coagulation dysfunction, which were mitigated and treated after expectant or dose-decrement treatment.

Conclusion: DDGP regimen can significantly improve the clinical prognosis of NK/T-cell lymphoma patients with tolerable adverse reactions. The variation in EBV-DNA is correlated with clinical efficacy and prognosis, which provides a theoretical basis for NK/T-cell lymphoma therapy.

Clinical trial: In November 2011, this clinical trial was registered on the website: www.ClinicalTrials.gov (No. NCT01501149).

Epstein-Barr virus strain variation and cancer

Epstein-Barr virus (EBV) is a human tumor virus and is etiologically linked to various malignancies. Certain EBV-associated diseases, such as Burkitt lymphomas and nasopharyngeal carcinomas, are endemic and exhibit biased geographic distribution worldwide. Recent advances in deep sequencing technology enabled high-throughput sequencing of the EBV genome from clinical samples. Rapid cloning and sequencing of cancer-derived EBV genomes, followed by reconstitution of infectious virus, have also become possible. These developments have revealed that various EBV strains are differentially distributed throughout the world, and that the behavior of cancer-derived EBV strains is different from that of the prototype EBV strain of non-cancerous origin. In this review, we summarize recent progress and future perspectives regarding the association between EBV strain variation and cancer.

Revisiting the Tissue Microenvironment of Infectious Mononucleosis: Identification of EBV Infection in T Cells and Deep Characterization of Immune Profiles

To aid understanding of primary EBV infection, we have performed an in depth analysis of EBV-infected cells and of local immune cells in tonsils from infectious mononucleosis (IM) patients. We show that EBV is present in approximately 50% of B-cells showing heterogeneous patterns of latent viral gene expression probably reflecting different stages of infection. While the vast majority of EBV+ cells are B-cells, around 9% express T-cell antigens, with a predominance of CD8+ over CD4+ cells. PD-L1 was expressed by a median of 14% of EBV+ cells. The numbers of EBER+PD-L1+ cells were directly correlated with the numbers of EBER+CD3+ and EBER+CD8+ cells suggesting a possible role for PD-L1 in EBV infection of T-cells. The microenvironment of IM tonsils was characterized by a predominance of M1-polarized macrophages over M2-polarized cells. However, at the T-cell level, a heterogeneous picture emerged with numerous Th1/cytotoxic cells accompanied and sometimes outnumbered by Th2/regulatory T-cells. Further, we observed a direct correlation between the numbers of Th2-like cells and EBV- B-cells. Also, a prevalence of cytotoxic T-cells over Th2-like cells was associated with an increased viral load. These observations point to contribution of B- and Th2-like cells to the control of primary EBV infection. 35% of CD8+ cells were differentiated CD8+TBET+ cells, frequently detected in post-capillary venules. An inverse correlation was observed between the numbers of CD8+TBET+ cells and viral load suggesting a pivotal role for these cells in the control of primary EBV infection. Our results provide the basis for a better understanding of immune reactions in EBV-associated tumors.

EBV Viral Loads in Diagnosis, Monitoring, and Response Assessment

The quantification of circulating Epstein Barr virus (EBV) DNA loads has played an important role in the diagnosis and management of EBV-associated lymphoid malignancies. Viral load measurement is particularly useful for monitoring EBV-DNA in hematopoietic stem cell transplant patients, and for assessing the prognosis or response to therapy of EBV-associated intractable lymphomas like extranodal NK/T-cell lymphoma, nasal type. Cell-free EBV-DNA in plasma can be used as a biomarker for estimating the severity or prognosis of these lymphomas. In addition to plasma, whole blood has been used for the management of transplant patients. Although measuring EBV-DNA has been useful, there is a lack of standardization and the optimal specimens for measuring viral loads are unknown. This can be attributed to the different forms of EBV-DNA that exist in peripheral blood and the different pathologies that result from diverse EBV disease states. As a result, guidelines for EBV diagnosis or the initiation of treatment are unclear. However, the newly established World Health Organization standard for EBV quantification will encourage collaborative studies across institutions and countries to establish proper guidelines for EBV diagnosis and the initiation of treatment.

Epstein–Barr Virus and Cancer

Epstein–Barr virus (EBV) contributes to about 1.5% of all cases of human cancer worldwide, and viral genes are expressed in the malignant cells. EBV also very efficiently causes the proliferation of infected human B lymphocytes. The functions of the viral proteins and small RNAs that may contribute to EBV-associated cancers are becoming increasingly clear, and a broader understanding of the sequence variation of the virus genome has helped to interpret their roles. The improved understanding of the mechanisms of these cancers means that there are great opportunities for the early diagnosis of treatable stages of EBV-associated cancers and the use of immunotherapy to target EBV-infected cells or overcome immune evasion. There is also scope for preventing disease by immunization and for developing therapeutic agents that target the EBV gene products expressed in the cancers.

[EBV and Lymphomagenesis]

Epstein-Barr virus (EBV) is a double stranded DNA virus of the family Herpesviridae. EBV is associated with a variety of lymphomas, and the mechanisms by which it promotes lymphomagenesis have been elucidated; this includes, for example, by translocation/activation of Myc in Burkitt lymphoma. However, the mechanisms by which it induces lymphoid tumors other than Burkitt lymphoma are unclear. Recently, we reported that the genome of EBV present in EBV-associated lymphomas harbors frequent intragenic deletions and that the deletion of a gene essential for virus replication promotes lymphomagenesis in a mouse model. Although intragenic deletions have been detected in other tumor viruses, little is known about the effects and importance of those of EBV, a large DNA virus whose genome encodes more than 70 genes. In this review, we summarize the role of EBV in lymphomagenesis with a focus on the impact of intragenic deletions.