Innate immune modulation in EBV infection

The Role of Natural Killer Cells in the Tumor Immune Microenvironment of EBV-Associated Nasopharyngeal Carcinoma

Endemic nasopharyngeal carcinoma (NPC) is closely associated with the Epstein-Barr virus (EBV), which contributes to tumor development and influences the tumor immune microenvironment (TIME) in NPC. Natural killer (NK) cells, as part of the innate immune system, play a crucial role in responding to viral infections and malignant cell transformations. Notably, NK cells possess a unique ability to target tumor cells independent of major histocompatibility complex class I (MHC I) expression. This means that MHC I-deficient tumor cells, which can escape from effective T cell attack, are susceptible to NK-cell-mediated killing. The activation of NK cells is determined by the signals generated through inhibitory and activating receptors expressed on their surface. Understanding the role of NK cells in the complex TIME of EBV+ NPC is of utmost importance. In this review, we provide a comprehensive summary of the current understanding of NK cells in NPC, focusing on their subpopulations, interactions, and cytotoxicity within the TIME. Moreover, we discuss the potential translational therapeutic applications of NK cells in NPC. This review aims to enhance our knowledge of the role of NK cells in NPC and provide valuable insights for future investigations.

Sex-dependent different clinicopathological characterization of Epstein-Barr virus-associated gastric carcinoma: a large-scale study

BACKGROUND

Epstein-Barr virus (EBV)-associated gastric cancer (EBVaGC) has been reported to account for approximately 5-16% of all GCs with good prognosis compared to EBV-negative GC. We evaluated the clinicopathological characteristics of EBVaGC including survival rate in South Korea.

METHODS

A total of 4,587 patients with GC who underwent EBV in situ hybridization (EBV-ISH) were prospectively enrolled at the Seoul National University Bundang Hospital from 2003 to 2021. Age, sex, smoking status, cancer type and stage, tumor size and location, histological type, molecular features and survival information were analyzed.

RESULTS

A total of 456 patients with GC (9.9%) were positive for EBV. The EBVaGC group displayed a higher proportion of males (P < 0.001), a predominant presence in the proximal stomach (P < 0.001), a higher proportion of undifferentiated cancer (P < 0.001), and a lower cancer stage (P = 0.004) than the EBV-negative group. Cox multivariate analyses revealed age (hazard ratio [HR] = 1.025, P < 0.001), tumor size (HR = 1.109, P < 0.001), and cancer stage (stage2 HR = 4.761, P < 0.001; stage3 HR = 13.286, P < 0.001; stage4 HR = 42.528, P < 0.001) as significant risk factors for GC-specific mortality, whereas EBV positivity was inversely correlated (HR = 0.620, P = 0.022). Furthermore, the EBVaGC group displayed statistically significant survival advantages over the EBV-negative cancer group in terms of both overall (P = 0.021) and GC-specific survival (P = 0.007) on the Kaplan-Meier survival curve. However, this effect was evident only in males.

CONCLUSIONS

EBVaGC patients showed better prognoses despite their association with proximal location and poorly differentiated histology in male, probably due to the difference in immunity between males and females.

[Infectious Gastric Diseases Other than Helicobacter]

In addition to Helicobacter pylori, the acute bacterial causes of infectious gastritis, include phlegmonous gastritis, gastric tuberculosis, and gastric syphilis. Bacterial gastritis often improves with appropriate broad-spectrum antibiotics, emphasizing the need for prompt diagnosis and treatment based on the clinical and endoscopic findings. Among viral gastritis, cytomegalovirus gastritis, primarily occurring in immunocompromised patients, necessitates antiviral intervention, while immunocompetent individuals typically achieve amelioration by administering proton pump inhibitors. In contrast, most gastric infections caused by the Epstein-Barr virus (EBV) are asymptomatic, but an EBV infection is a cause of stomach cancer. EBV-associated gastric cancer exhibits distinct clinical, pathological, genetic, and post-genetic mutation features, making it clinically significant. The colonization of Candida albicans in the stomach is uncommon, and typical antifungal treatment is unnecessary. Candida infections in gastric ulcers can be treated with anti-ulcer treatment alone. Lastly, anisakidosis in the stomach, which occurs when consuming raw seafood, can manifest in various clinical presentations and is typically treated through endoscopic removal of the nematode. This article aims to contribute to the rapid diagnosis and treatment of rare stomach infections beyond Helicobacter pylori in real clinical situations.

Pathogenesis and therapeutic implications of EBV-associated epithelial cancers

Epstein-Barr virus (EBV), one of the most common human viruses, has been associated with both lymphoid and epithelial cancers. Undifferentiated nasopharyngeal carcinoma (NPC), EBV associated gastric cancer (EBVaGC) and lymphoepithelioma-like carcinoma (LELC) are amongst the few common epithelial cancers that EBV has been associated with. The pathogenesis of EBV-associated NPC has been well described, however, the same cannot be said for primary pulmonary LELC (PPLELC) owing to the rarity of the cancer. In this review, we outline the pathogenesis of EBV-associated NPC and EBVaGCs and their recent advances. By drawing on similarities between NPC and PPLELC, we then also postulated the pathogenesis of PPLELC. A deeper understanding about the pathogenesis of EBV enables us to postulate the pathogenesis of other EBV associated cancers such as PPLELC.

Potential role of EBV and Toll-like receptor 9 ligand in patients with systemic lupus erythematosus

SLE is a multisystem autoimmune disease characterized by multiple immunological abnormalities including production of autoantibodies. While the etiology of SLE is largely unknown, it is generally accepted that both genetic and environmental factors contribute to disease risk and immune dysregulation. Production of IFN-α is important for protecting the host against infections; however, over stimulation of innate immune pathways can induce autoimmune disease. Environmental factors, particularly Epstein-Barr virus (EBV), have been proposed to play an important role in SLE disease. Improper engagement of Toll-like receptor (TLR) pathways by endogenous or exogenous ligands may lead to the initiation of autoimmune responses and tissue injury. EBV is shown to be a potent stimulant of IFN-α by TLR signaling cascades. Given the highlighted role of IFN-α in SLE pathogenesis and potential role of EBV infection in this disease, the present study is aimed at exploring the in vitro effects of EBV infection and CPG (either alone or in combination) on IFN-α. We also examined the expression level of CD20 and BDCA-4 and CD123 in PBMCs in 32 SLE patients and 32 healthy controls. Our results showed PBMCs treated with CPG-induced higher levels of IFN-α and TLR-9 gene expression fold change compared to cells treated with either EBV or EBV-CPG. Moreover, PBMCs treated with CPG produced significantly higher IFN-α concentration in supernatant compared to cells treated with EBV but not EBV-CPG. Our results further highlight the potential role of EBV infection and TLRs in SLE patients although more studies are warranted to ascertain the global imprint that EBV infection can have on immune signature in patients with SLE.

The Impact of Co-Infections for Human Gammaherpesvirus Infection and Associated Pathologies

The two oncogenic human gammaherpesviruses Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) cause significant disease burden, particularly in immunosuppressed individuals. Both viruses display latent and lytic phases of their life cycle with different outcomes for their associated pathologies. The high prevalence of infectious diseases in Sub-Saharan Africa (SSA), particularly HIV/AIDS, tuberculosis, malaria, and more recently, COVID-19, as well as their associated inflammatory responses, could potentially impact either virus' infectious course. However, acute or lytically active EBV and/or KSHV infections often present with symptoms mimicking these predominant diseases leading to misdiagnosis or underdiagnosis of oncogenic herpesvirus-associated pathologies. EBV and/or KSHV infections are generally acquired early in life and remain latent until lytic reactivation is triggered by various stimuli. This review summarizes known associations between infectious agents prevalent in SSA and underlying EBV and/or KSHV infection. While presenting an overview of both viruses' biphasic life cycles, this review aims to highlight the importance of co-infections in the correct identification of risk factors for and diagnoses of EBV- and/or KSHV-associated pathologies, particularly in SSA, where both oncogenic herpesviruses as well as other infectious agents are highly pervasive and can lead to substantial morbidity and mortality.

Epstein-Barr Virus Envelope Glycoprotein gp110 Inhibits IKKi-Mediated Activation of NF-κB and Promotes the Degradation of β-Catenin

Epstein-Barr virus (EBV) infects host cells and establishes a latent infection that requires evasion of host innate immunity. A variety of EBV-encoded proteins that manipulate the innate immune system have been reported, but whether other EBV proteins participate in this process is unclear. EBV-encoded envelope glycoprotein gp110 is a late protein involved in virus entry into target cells and enhancement of infectivity. Here, we reported that gp110 inhibits RIG-I-like receptor pathway-mediated promoter activity of interferon-β (IFN-β) as well as the transcription of downstream antiviral genes to promote viral proliferation. Mechanistically, gp110 interacts with the inhibitor of NF-κB kinase (IKKi) and restrains its K63-linked polyubiquitination, leading to attenuation of IKKi-mediated activation of NF-κB and repression of the phosphorylation and nuclear translocation of p65. Additionally, gp110 interacts with an important regulator of the Wnt signaling pathway, β-catenin, and induces its K48-linked polyubiquitination degradation via the proteasome system, resulting in the suppression of β-catenin-mediated IFN-β production. Taken together, these results suggest that gp110 is a negative regulator of antiviral immunity, revealing a novel mechanism of EBV immune evasion during lytic infection. IMPORTANCE Epstein-Barr virus (EBV) is a ubiquitous pathogen that infects almost all human beings, and the persistence of EBV in the host is largely due to immune escape mediated by its encoded products. Thus, elucidation of EBV's immune escape mechanisms will provide a new direction for the design of novel antiviral strategies and vaccine development. Here, we report that EBV-encoded gp110 serves as a novel viral immune evasion factor, which inhibits RIG-I-like receptor pathway-mediated interferon-β (IFN-β) production. Furthermore, we found that gp110 targeted two key proteins, inhibitor of NF-κB kinase (IKKi) and β-catenin, which mediate antiviral activity and the production of IFN-β. gp110 inhibited K63-linked polyubiquitination of IKKi and induced β-catenin degradation via the proteasome, resulting in decreased IFN-β production. In summary, our data provide new insights into the EBV-mediated immune evasion surveillance strategy.

Map of thrombogenesis in viral infections and viral-driven tumours

Viruses are pathogenic agents responsible for approximately 10% of all human cancers and significantly contribute to the global cancer burden. Until now, eight viruses have been associated with the development of a broad range of malignancies, including solid and haematological tumours. Besides triggering and promoting oncogenesis, viral infections often go hand-in-hand with haemostatic changes, representing a potential risk factor for venous thromboembolism (VTE). Conversely, VTE is a cardiovascular condition that is particularly common among oncological patients, with a detrimental impact on patient prognosis. Despite an association between viral infections and coagulopathies, it is unclear whether viral-driven tumours have a different incidence and prognosis pattern of thromboembolism compared to non-viral-induced tumours. Thus, this review aims to analyse the existing evidence concerning the association of viruses and viral tumours with the occurrence of VTE. Except for hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infection, which are associated with a high risk of VTE, little evidence exists concerning the thrombogenic potential associated with oncoviruses. As for tumours that can be induced by oncoviruses, four levels of VTE risk are observed, with hepatocellular carcinoma (HCC) and gastric carcinoma (GC) associated with the highest risk and nasopharyngeal carcinoma (NPC) associated with the lowest risk. Unfortunately, the incidence of cancer-related VTE according to tumour aetiology is unknown. Given the negative impact of VTE in oncological patients, research is required to better understand the mechanisms underlying blood hypercoagulability in viral-driven tumours to improve VTE management and prognosis assessment in patients diagnosed with these tumours.

EBV Infection and Its Regulated Metabolic Reprogramming in Nasopharyngeal Tumorigenesis

Viral oncogenes may drive cellular metabolic reprogramming to modulate the normal epithelia cell malignant transformation. Understanding the viral oncogene-mediated signaling transduction dysregulation that involves in metabolic reprogramming may provide new therapeutic targets for virus-associated cancer treatment. Latent EBV infection and expression of viral oncogenes, including latent membrane proteins 1 and 2 (LMP1/2), and EBV-encoded BamH I-A rightward transcripts (BART) microRNAs (miR-BARTs), have been demonstrated to play fundamental roles in altering host cell metabolism to support nasopharyngeal carcinoma (NPC) pathogenesis. Yet, how do EBV infection and its encoded oncogenes facilitated the metabolic shifting and their roles in NPC carcinogenesis remains unclear. In this review, we will focus on delineating how EBV infection and its encoded oncoproteins altered the metabolic reprograming of infected cells to support their malignances. Furthermore, based on the understanding of the host's metabolic signaling alterations induced by EBV, we will provide a new perspective on the interplay between EBV infection and these metabolic pathways and offering a potential therapeutic intervention strategy in the treatment of EBV-associated malignant diseases.

Evaluation of the Presence of Bacterial and Viral Agents in the Semen of Infertile Men: A Systematic and Meta-Analysis Review Study

Objectives

Infections in the male genitourinary system with bacterial and viral agents may play a significant role in male infertility. These agents usually infect the urethra, seminal vesicles, prostate, epididymis, vas deferens, and testes retrograde through the reproductive system. A meta-analysis review study was performed to evaluate the presence of bacterial and viral agents in the semen of infertile men and its correlation with infertility.

Methods

Relevant cross-sectional and/or case-control studies were found by an online review of national and international databases (Web of Science, PubMed, Scopus, Science Direct, and Google scholar), and suitable studies were selected. A checklist determined the qualities of all studies. Heterogeneity assay among the primary studies was evaluated by Cochran’s Q test and I² index (significance level 50%). A statistical analysis was conducted using the Comprehensive Stata ver. 14 package (StataCorp, College Station, TX, United States).

Results

Seventy-two studies were included in this meta-analysis. Publication bias was compared with Egger’s test, and the impact of each research on overall estimate was evaluated by sensitivity analysis. In 56 studies, the rate of bacterial infections in the semen of infertile men was 12% [95% confidence interval (CI): 10–13]. Also, in 26 case-control studies, the association of infertility in men with bacterial infections was evaluated. The results show that the odds ratio of infertility in men exposed to bacterial infections is 3.31 times higher than that in non-infected men (95% CI: 2.60–4.23). Besides, in 9 studies that examined the prevalence of human papillomavirus (HPV), herpes simplex virus 1 (HSV1), herpes simplex virus 2 (HSV2), and herpes simplex virus 1-2 (HSV1-2) in infertile men, the frequency of these viruses was 15% (95% CI: 9–21). In 6 case-control studies, the association between human cytomegalovirus (HCMV), Cytomegalovirus (CMV), and HPV and male infertility was evaluated. The chance of male infertility due to exposure to these viruses was 2.24 times higher than those without exposure to these viruses (CI 95%: 1.9–4.52). The results show that the chance of infertility in men exposed to bacteria was significantly higher than that in the uninfected population.

Conclusion

This meta-analysis showed that viral and bacterial infections are a risk factor and could impair male fertility potential. Moreover, our study supports the hypothesis that bacterial and viral infections of the genital tract correlate positively with impairment of sperm quality in the male population.

Epstein-Barr Virus in Myasthenia Gravis: Key Contributing Factor Linking Innate Immunity with B-Cell-Mediated Autoimmunity

Epstein-Barr virus (EBV), a common human herpes virus latently infecting most of the world’s population with periodic reactivations, is the main environmental factor suspected to trigger and/or sustain autoimmunity by its ability to disrupt B-cell tolerance checkpoints. Myasthenia gravis (MG) is a prototypic autoimmune disorder, mostly caused by autoantibodies to acetylcholine receptor (AChR) of the neuromuscular junction, which cause muscle weakness and fatigability. Most patients display hyperplastic thymus, characterized by ectopic germinal center formation, chronic inflammation, exacerbated Toll-like receptor activation, and abnormal B-cell activation. After an overview on MG clinical features and intra-thymic pathogenesis, in the present chapter, we describe our main findings on EBV presence in MG thymuses, including hyperplastic and thymoma thymuses, in relationship with innate immunity activation and data from other autoimmune conditions. Our overall data strongly indicate a critical contribution of EBV to innate immune dysregulation and sustained B-cell-mediated autoimmune response in the pathological thymus of MG patients.

New Look of EBV LMP1 Signaling Landscape

Simple Summary

Epstein-Barr Virus (EBV) infection is associated with various lymphomas and carcinomas as well as other diseases in humans. The transmembrane protein LMP1 plays versatile roles in EBV life cycle and pathogenesis, by perturbing, reprograming, and regulating a large range of host cellular mechanisms and functions, which have been increasingly disclosed but not fully understood so far. We summarize recent research progress on LMP1 signaling, including the novel components LIMD1, p62, and LUBAC in LMP1 signalosome and LMP1 novel functions, such as its induction of p62-mediated selective autophagy, regulation of metabolism, induction of extracellular vehicles, and activation of NRF2-mediated antioxidative defense. A comprehensive understanding of LMP1 signal transduction and functions may allow us to leverage these LMP1-regulated cellular mechanisms for clinical purposes.

Abstract

The Epstein–Barr Virus (EBV) principal oncoprotein Latent Membrane Protein 1 (LMP1) is a member of the Tumor Necrosis Factor Receptor (TNFR) superfamily with constitutive activity. LMP1 shares many features with Pathogen Recognition Receptors (PRRs), including the use of TRAFs, adaptors, and kinase cascades, for signal transduction leading to the activation of NFκB, AP1, and Akt, as well as a subset of IRFs and likely the master antioxidative transcription factor NRF2, which we have gradually added to the list. In recent years, we have discovered the Linear UBiquitin Assembly Complex (LUBAC), the adaptor protein LIMD1, and the ubiquitin sensor and signaling hub p62, as novel components of LMP1 signalosome. Functionally, LMP1 is a pleiotropic factor that reprograms, balances, and perturbs a large spectrum of cellular mechanisms, including the ubiquitin machinery, metabolism, epigenetics, DNA damage response, extracellular vehicles, immune defenses, and telomere elongation, to promote oncogenic transformation, cell proliferation and survival, anchorage-independent cell growth, angiogenesis, and metastasis and invasion, as well as the development of the tumor microenvironment. We have recently shown that LMP1 induces p62-mediated selective autophagy in EBV latency, at least by contributing to the induction of p62 expression, and Reactive Oxygen Species (ROS) production. We have also been collecting evidence supporting the hypothesis that LMP1 activates the Keap1-NRF2 pathway, which serves as the key antioxidative defense mechanism. Last but not least, our preliminary data shows that LMP1 is associated with the deregulation of cGAS-STING DNA sensing pathway in EBV latency. A comprehensive understanding of the LMP1 signaling landscape is essential for identifying potential targets for the development of novel strategies towards targeted therapeutic applications.

Copy number loss in granzyme genes confers resistance to immune checkpoint inhibitor in nasopharyngeal carcinoma

Background

Anti-programmed death (PD)-1 therapy has recently been used in recurrent or metastatic (R/M) nasopharyngeal carcinoma (NPC). The long-term survival and its biomarkers responding to anti-PD-1 treatment in patients with R/M NPC remain unclear.

Methods

Patients with R/M NPC were enrolled between March 2016 and January 2018 from two phase I clinical trials. The median follow-up period was 24.7 months. Eligible patients progressed on standard chemotherapy had measurable disease by Response Evaluation Criteria in Solid Tumor V.1.1. Non-obligatory contemporaneous tumor samples were collected for whole-exome sequencing. The primary outcome was objective response rate (ORR). Duration of response (DOR), progression-free survival (PFS), and overall survival (OS) were secondary outcomes assessed in all patients.

Results

Among 124 evaluable patients, anti-PD-1 therapy achieved an ORR of 29.8% and a durable clinical benefit rate of 60.5%. The median OS (mOS) was 17.1 months (95% CI 14.2 to 24.7), median PFS (mPFS) was 3.8 months (95% CI 3.4 to 6.0), and median DOR was 9.5 months. Significant OS benefit from treatment was observed in patients without liver metastasis (23.8 vs 13.3 months, p=0.006). Copy number deletion in genes encoding granzyme B or granzyme H (GZMB/H) was associated with poor treatment outcome (mPFS altered vs wildtype: 1.7 vs 3.6 months, p=0.03; mOS altered vs wildtype: 10.1 vs 18 months, p=0.012).

Conclusions

Anti-PD-1 treatment provided promising clinical benefit in pretreated patients with R/M NPC. Copy number loss in either GZMB or GZMH genes was associated with reduced survival.

Epstein-Barr Virus-associated Gastric Carcinoma

Epstein-Barr virus-associated gastric carcinoma (EBVaGC) comprises approximately 10% of all gastric cancers and is now defined as one of the four subtypes of gastric cancer according to the molecular classification proposed by the Cancer Genome Atlas project. EBVaGC has characteristic genetic profiles that harbor a DNA methylation phenotype, frequent mutations in PIK3CA and ARID1A, and amplification of JAK2 and programmed death-ligand (PD-L)1/PD-L2. Therefore, EBVaGC shows several distinct clinicopathological features, including a male predominance, proximal stomach location, gastric carcinoma with lymphoid stroma histology, low risk of lymph node metastasis, and favorable prognosis. In clinical practice, patients with early EBVaGC might be good candidates for endoscopic resection or minimally invasive surgery since the rate of lymph node metastasis is very low, even with deep submucosal invasion. Furthermore, in the case of advanced EBVaGC, the applicability of immunotherapy has been investigated based on its increased expression of PD-L1 and high immunogenicity. In conclusion, EBV can serve as a biomarker in gastric cancer, and further identification of other molecular characteristics of EBVaGC is essential for new potential therapeutic targets.

Post-procedural Bacillus cereus septic arthritis in a patient with systemic lupus erythematosus

INTRODUCTION

Bacillus species are often considered as contaminants when cultured from clinical samples. Bacillus cereus may be a pathogen in certain circumstances and is known to cause musculoskeletal infections. This report aims to educate clinicians and clinical microbiology laboratories on B. cereus musculoskeletal infections and to heighten awareness that Bacillus species should not always be dismissed as contaminants.

CASE PRESENTATION

We report the case of a patient who presented to a tertiary hospital in Pretoria, South Africa, in November 2018 with B. cereus septic arthritis and underlying systemic lupus erythematosus (SLE). The isolate would otherwise have been dismissed as a contaminant had it not been for the crucial interaction between the laboratory and the treating clinicians. To our knowledge, this is the first case report of septic arthritis caused by B. cereus in an SLE patient where the organism was cultured from the joint specimen. Identification of the organism was performed using matrix-assisted laser desorption/ionisation mass spectrometry.

MANAGEMENT AND OUTCOME

Definitive treatment was with intravenous vancomycin, continued for four weeks, in addition to arthroscopy and management of the underlying SLE. The patient had a good clinical outcome and regained full mobility.

CONCLUSION

Musculoskeletal infections, specifically septic arthritis caused by B. cereus, are exceedingly rare infections. Immune suppression, trauma, prosthetic implants and invasive procedures are important risk factors for B. cereus musculoskeletal infections. Close collaboration with a multi-disciplinary team approach will effect the best outcome for complicated patients with B. cereus infections.

The Binary Classification Of Chronic Diseases

Acute diseases start with an insult and end when insult disappears. If the trauma induces an immune reaction (which happens in most cases), this reaction must be terminated with some type of resolution mechanism, when the cause of the trauma ceases. Chronicity develops if insult is permanent or if the resolution mechanism is defective. Another way to reach disease chronicity is a positive feedback loop, whereby the immune reaction activates an internal, insult-like reaction. A distinction between chronic states characterized by a persistent, low suppressive effect and those characterized by a persistent, high suppressive effect of regulatory T cells (Treg), is proposed. This two-class division represents two ways to reach chronicity: (a) by maintaining inflammatory reaction long after insult disappears ("low Treg"), or (b) by suppressing inflammatory reaction prior to the disappearance of insult ("high Treg"). This two-class division may explain the strong association between certain pathogens and cancer, on one hand, and between several other pathogens and autoimmunity, on the other hand. The weak association between autoimmune diseases and HIV infection and the relatively weak association between autoimmune diseases and cancer may be elucidated as well. In addition, the model rationalizes why immune-modulating drugs, which are effective in cancer, are also effective in "high Treg" viral infections, while corticosteroids, which are generally effective in autoimmune diseases, are also effective in other "low Treg" diseases (such as asthma, atopic dermatitis, and "low Treg" infections) but are not effective in solid malignancies and "high Treg" infections. Moreover, the model expounds why certain bacteria inhibit tumor growth and why these very bacteria induce autoimmune diseases.

What the HLA-I!-Classical and Non-classical HLA Class I and Their Potential Roles in Type 1 Diabetes

PURPOSE OF REVIEW

Hyperexpression of classical HLA class I (HLA-I) molecules in insulin-containing islets has become a widely accepted hallmark of type 1 diabetes pathology. In comparison, relatively little is known about the expression, function and role of non-classical subtypes of HLA-I. This review focuses on the current understanding of the non-classical HLA-I subtypes: HLA-E, HLA-F and HLA-G, within and outside the field of type 1 diabetes, and considers the possible impacts of these molecules on disease etiology.

RECENT FINDINGS

Evidence is growing to suggest that non-classical HLA-I proteins are upregulated, both at the RNA and protein levels in the pancreas of individuals with recent-onset type 1 diabetes. Moreover, associations between non-classical HLA-I genotypes and age at onset of type 1 diabetes have been reported in some studies. As with classical HLA-I, it is likely that hyperexpression of non-classical HLA-I is driven by the release of diffusible interferons by stressed β cells (potentially driven by viral infection) and exacerbated by release of cytokines from infiltrating immune cells. Non-classical HLA-I proteins predominantly (but not exclusively) transduce negative signals to immune cells infiltrating at the site of injury/inflammation. We propose a model in which the islet endocrine cells, through expression of non-classical HLA-I are fighting back against the infiltrating immune cells. By inhibiting the activity and function on NK, B and select T cells, the non-classical HLA-I, proteins will reduce the non-specific bystander effects of inflammation, while at the same time still allowing the targeted destruction of β cells by specific islet-reactive CD8+ T cells.

Early herpes and TTV DNAemia in septic shock patients: a pilot study

BACKGROUND

Septic shock patients exhibit an increased incidence of viral reactivation. Precise timing of such reactivation-as an early marker of immune suppression, or as a consequence of the later-is not known precisely. Here, using a fully designed nucleic acid extraction automated procedure together with tailored commercial PCR kits, we focused on the description of early reactivation within the first week of ICU admission of several herpes viruses and Torque Teno virus (TTV) in 98 septic shock patients.

RESULTS

Most of septic shock patients had at least one viremia event during the first week (88%). TTV and herpesviruses were detected in 56% and 53% of septic shock patient, respectively. The two most frequent herpesviruses detected within the first week were EBV (35%) and HSV1 (26%). Different kinetic were observed among herpesviruses, faster for EBV and HSV1 than for CMV and HHV6. Although no association was found between herpes viremia and secondary infections, patients with herpesviridae-related viremia were more severe, e.g., higher SOFA scores and plasma lactate levels. While reactivating only 1 virus was not associated with mortality, patients with multiple viremia events had higher ICU mortality. Surprisingly, EBV + TTV early reactivation seemed associated with a lower D28 mortality. No clear association was observed between viremia and immune biomarkers.

CONCLUSION

Applying a semi-automated process of viral DNAemia determination to this cohort of 98 patients with septic shock, we observed that the number of patients with positive viremia increased during the first week in the ICU. Of note, there was no improvement in predicting the outcome when using viremia status. Nevertheless, this pilot study, introducing standardized procedures from extraction to detection, provides the basis for future standardized diagnostic criteria. A prospective longitudinal clinical study using these procedures will enable determination of whether such viremia is due to a lack of a latent virus control by the immune system or a true clinical viral infection.

Manipulation of Type I Interferon Signaling by HIV and AIDS-Associated Viruses

Type I Interferons were first described for their profound antiviral abilities in cell culture and animal models, and later, they were translated into potent antiviral therapeutics. However, as additional studies into the function of Type I Interferons progressed, it was also seen that pathogenic viruses have coevolved to encode potent mechanisms allowing them to evade or suppress the impact of Type I Interferons on their replication. For chronic viral infections, such as HIV and many of the AIDS-associated viruses, including HTLV, HCV, KSHV, and EBV, the clinical efficacy of Type I Interferons is limited by these mechanisms. Here, we review some of the ways that HIV and AIDS-associated viruses thrive in Type I Interferon-rich environments via mechanisms that block the function of this important antiviral cytokine. Overall, a better understanding of these mechanisms creates avenues to better understand the innate immune response to these viruses as well as plan the development of antivirals that would allow the natural antiviral effect of Type I Interferons to manifest during these infections.

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen's Encephalitis

Rasmussen's encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.

Macaca arctoides gammaherpesvirus 1 (strain herpesvirus Macaca arctoides): virus sequence, phylogeny and characterisation of virus-transformed macaque and rabbit cell lines

Herpesvirus Macaca arctoides (HVMA) has the propensity to transform macaque lymphocytes to lymphoblastoid cells (MAL-1). Inoculation of rabbits with cell-free virus-containing supernatant resulted in the development of malignant lymphomas and allowed isolation of immortalised HVMA-transformed rabbit lymphocytes (HTRL). In this study, the HVMA genome sequence (approx. 167 kbp), its organisation, and novel aspects of virus latency are presented. Ninety-one open reading frames were identified, of which 86 were non-repetitive. HVMA was identified as a Lymphocryptovirus closely related to Epstein-Barr virus, suggesting the designation as 'Macaca arctoides gammaherpesvirus 1' (MarcGHV-1). In situ lysis gel and Southern blot hybridisation experiments revealed that the MAL-1 cell line contains episomal and linear DNA, whereas episomal DNA is predominantly present in HTRL. Integration of viral DNA into macaque and rabbit host cell genomes was demonstrated by fluorescence in situ hybridisation on chromosomal preparations. Analysis of next-generation sequencing data confirmed this finding. Approximately 400 read pairs represent the overlap between macaque and MarcGHV-1 DNA. Both, MAL-1 cells and HTRL show characteristics of a polyclonal tumour with B- and T-lymphocyte markers. Based on analysis of viral gene expression and immunohistochemistry, the persistence of MarcGHV-1 in MAL-1 cells resemble the latency type III, whereas the expression pattern observed in HTRL was more comparable with latency type II. There was no evidence of the presence of STLV-1 proviral DNA in MAL-1 and HTRL. Due to the similarity to EBV-mediated cell transformation, MarcGHV-1 expands the available in vitro models by simian and rabbit cell lines.

Pathobiologic Roles of Epstein-Barr Virus-Encoded MicroRNAs in Human Lymphomas

Epstein-Barr virus (EBV) is a human γ-herpesvirus implicated in several human malignancies, including a wide range of lymphomas. Several molecules encoded by EBV in its latent state are believed to be related to EBV-induced lymphomagenesis, among which microRNAs-small RNAs with a posttranscriptional regulating role-are of great importance. The genome of EBV encodes 44 mature microRNAs belonging to two different classes, including BamHI-A rightward transcript (BART) and Bam HI fragment H rightward open reading frame 1 (BHRF1), with different expression levels in different EBV latency types. These microRNAs might contribute to the pathogenetic effects exerted by EBV through targeting self mRNAs and host mRNAs and interfering with several important cellular mechanisms such as immunosurveillance, cell proliferation, and apoptosis. In addition, EBV microRNAs can regulate the surrounding microenvironment of the infected cells through exosomal transportation. Moreover, these small molecules could be potentially used as molecular markers. In this review, we try to present an updated and extensive view of the role of EBV-encoded miRNAs in human lymphomas.

Outlooks on Epstein-Barr virus associated gastric cancer

Epstein-Barr virus associated gastric cancer (EBVaGC) comprises approximately 10% of gastric carcinomas. Multiple factors contribute to tumorigenesis, including EBV driven hypermethylation of tumor suppressor genes, inflammatory changes in gastric mucosa, host immune evasion by EBV and changes in cell cycle pathways. The unique molecular characteristics of EBVaGC, such as programmed death ligand 1 (PD-L1) overexpression, highlight the potential for using EBV as a biomarker for response to immunotherapy. Few studies have reported benefit from immunotherapy in EBV positive cancers, and clinical trials investigating the impact of checkpoint inhibitors in EBVaGC are currently underway. This review provides the most recent updates on molecular pathophysiology, epidemiology, clinical features and treatment advances pertaining to EBVaGC.

Toll-like receptors 7 and 9 in myasthenia gravis thymus: amplifiers of autoimmunity?

Pathogen infections and dysregulated Toll-like receptor (TLR)-mediated innate immune responses are suspected to play key roles in autoimmunity. Among TLRs, TLR7 and TLR9 have been implicated in several autoimmune conditions, mainly because of their ability to promote abnormal B cell activation and survival. Recently, we provided evidence of Epstein-Barr virus (EBV) persistence and reactivation in the thymus of myasthenia gravis (MG) patients, suggesting an involvement of EBV in the intrathymic pathogenesis of the disease. Considerable data highlight the existence of pathogenic crosstalk among EBV, TLR7, and TLR9: EBV elicits TLR7/9 signaling, which in turn can enhance B cell dysfunction and autoimmunity. In this article, after a brief summary of data demonstrating TLR activation in MG thymus, we provide an overview on the contribution of TLR7 and TLR9 to autoimmune diseases and discuss our recent findings indicating a pivotal role for these two receptors, along with EBV, in driving, perpetuating, and/or amplifying intrathymic B cell dysregulation and autoimmune responses in MG. Development of therapeutic approaches targeting TLR7 and TLR9 signaling could be a novel strategy for treating the chronic inflammatory autoimmune process in myasthenia gravis.

The Immune Response to Epstein Barr Virus and Implications for Posttransplant Lymphoproliferative Disorder

Posttransplant lymphoproliferative disorder (PTLD) is a serious complication in organ transplant recipients and is most often associated with the Epstein Barr virus (EBV). EBV is a common gammaherpes virus with tropism for B lymphocytes and infection in immunocompetent individuals is typically asymptomatic and benign. However, infection in immunocompromised or immunosuppressed individuals can result in malignant B cell lymphoproliferations, such as PTLD. EBV+ PTLD can arise after primary EBV infection, or because of reactivation of a prior infection, and represents a leading malignancy in the transplant population. The incidence of EBV+ PTLD is variable depending on the organ transplanted and whether the recipient has preexisting immunity to EBV but can be as high as 20%. It is generally accepted that impaired immune function due to immunosuppression is a primary cause of EBV+ PTLD. In this overview, we review the EBV life cycle and discuss our current understanding of the immune response to EBV in healthy, immunocompetent individuals, in transplant recipients, and in PTLD patients. We review the strategies that EBV uses to subvert and evade host immunity and discuss the implications for the development of EBV+ PTLD.

Review on Toll-Like Receptor Activation in Myasthenia Gravis: Application to the Development of New Experimental Models

Abnormal toll-like receptor (TLR) activation and uncontrolled resolution of inflammation are suspected to play a key role in the development of autoimmune diseases. Acquired myasthenia gravis (MG) is an invalidating neuromuscular disease leading to muscle weaknesses. MG is mainly mediated by anti-acetylcholine receptor (AChR) autoantibodies, and thymic hyperplasia characterized by ectopic germinal centers is a common feature in MG. An abnormal expression of certain TLRs is observed in the thymus of MG patients associated with the overexpression of interferon (IFN)-β, the orchestrator of thymic changes in MG. Experimental models have been developed for numerous autoimmune diseases. These models are induced by animal immunization with a purified antigen solubilized in complete Freund's adjuvant (CFA) containing heat-inactivated mycobacterium tuberculosis (MTB). Sensitization against the antigen is mainly due to the activation of TLR signaling pathways by the pathogen motifs displayed by MTB, and attempts have been made to substitute the use of CFA by TLR agonists. AChR emulsified in CFA is used to induce the classical experimental autoimmune MG model (EAMG). However, the TLR4 activator lipopolysaccharide (LPS) has proved to be efficient to replace MTB and induce a sensitization against purified AChR. Poly(I:C), the well-known TLR3 agonist, is also able by itself to induce MG symptoms in mice associated with early thymic changes as observed in human MG. In this review, we discuss the abnormal expression of TLRs in MG patients and we describe the use of TLR agonists to induce EAMG in comparison with other autoimmune experimental models.

The Folate Cycle As a Cause of Natural Killer Cell Dysfunction and Viral Etiology in Type 1 Diabetes

The folate pathway is critical to proper cellular function and metabolism. It is responsible for multiple functions, including energy (ATP) production, methylation reactions for DNA and protein synthesis and the production of immunomodulatory molecules, inosine and adenosine. These play an important role in immune signaling and cytotoxicity. Herein, we hypothesize that defects in the folate pathway in genetically susceptible individuals could lead to immune dysfunction, permissive environments for chronic cyclical latent/lytic viral infection, and, ultimately, the development of unchecked autoimmune responses to infected tissue, in this case islet beta cells. In the context of type 1 diabetes (T1D), there has been a recent increase in newly diagnosed cases of T1D in the past 20 years that has exceeded previous epidemiological predictions with yet unidentified factor(s). This speaks to a potential environmental trigger that adversely affects immune responses. Most research into the immune dysfunction of T1D has focused on downstream adaptive responses of T and B cells neglecting the role of the upstream innate players such as natural killer (NK) cells. Constantly, surveilling the blood and tissues for pathogens, NK cells remove threats through direct cytotoxic responses and recruitment of adaptive responses using cytokines, such as IL-1β and IFN-γ. One long-standing hypothesis suggests viral infection as a potential trigger for the autoimmune response in T1D. Recent data suggest multiple viruses as potential causal agents. Intertwined with this is an observed reduced NK cell enumeration, cytotoxicity, and cytokine signaling in T1D patients. Many of the viruses implicated in T1D are chronic latent/lysogenic infections with demonstrated capacity to reduce NK cell response and number through mechanisms that resemble those of pregnancy tolerance. Defects in the folate pathway in T1D patients could result in decreased immune response to viral infection or viral reactivation. Dampened NK responses to infections result in improper signaling, improper antigen presentation, and amplified CD8⁺ lymphocyte proliferation and cytotoxicity, a hallmark of beta cell infiltrates in patients with T1D onset. This would suggest a critical role for NK cells in T1D development linked to viral infection and the importance of the folate pathway in maintaining proper NK response.

The Expanding Role of Natural Killer Cells in Type 1 Diabetes and Immunotherapy

Treatments for autoimmune diseases including type 1 diabetes (T1D) are aimed at resetting the immune system, especially its adaptive arm. The innate immune system is often ignored in the design of novel immune-based therapies. There is increasing evidence for multiple natural killer (NK) subpopulations, but their role is poorly understood in autoimmunity and likely is contributing to the controversial role reported for NKs. In this review, we will summarize NK subsets and their roles in tolerance, autoimmune diabetes, and immunotherapy.

Fresh Insights into Disease Etiology and the Role of Microbial Pathogens

Pathogens have been implicated in the initiation and/or promotion of systemic sclerosis (scleroderma, SSc); however, no evidence was found to substantiate the direct contribution to this disease in past years. Recently, significant advances have been made in understanding the role of the innate immune system in SSc pathogenesis, supporting the idea that pathogens might interact with host innate immune-regulatory responses in SSc. In light of these findings, we review the studies that identified the presence of pathogens in SSc, along with studies on pathogens implicated in driving the innate immune dysregulation in SSc. The goal of this review is to illustrate how these pathogens, specifically viruses, may play important role both as triggers of the innate immune system, and critical players in the development of SSc disease.

Stable intronic sequence RNAs (sisRNAs): a new layer of gene regulation

Upon splicing, introns are rapidly degraded. Hence, RNAs derived from introns are commonly deemed as junk sequences. However, the discoveries of intronic-derived small nucleolar RNAs (snoRNAs), small Cajal body associated RNAs (scaRNAs) and microRNAs (miRNAs) suggested otherwise. These non-coding RNAs are shown to play various roles in gene regulation. In this review, we highlight another class of intron-derived RNAs known as stable intronic sequence RNAs (sisRNAs). sisRNAs have been observed since the 1980 s; however, we are only beginning to understand their biological significance. Recent studies have shown or suggested that sisRNAs regulate their own host's gene expression, function as molecular sinks or sponges, and regulate protein translation. We propose that sisRNAs function as an additional layer of gene regulation in the cells.

The other side of the coin: Leveraging Epstein-Barr virus in research and therapy

Epstein-Barr virus is (EBV) a ubiquitous virus prevalent in 90% of the human population. Transmitted through infected saliva, EBV is the causative agent of infectious mononucleosis (IM) and is further implicated in malignancies of lymphoid and epithelial origins. In the past few decades, research efforts primarily focused on dissecting the mechanism of EBV-induced oncogenesis. Here, we present an alternate facet of the oncovirus EBV, on its applications in research and therapy. Finally, discussions on the prospective utilization of EBV in nasopharyngeal carcinoma (NPC) diagnosis and therapy will also be presented.

Increased expression of Toll-like receptors 7 and 9 in myasthenia gravis thymus characterized by active Epstein-Barr virus infection

Considerable data implicate the thymus as the main site of autosensitization to the acetylcholine receptor in myasthenia gravis (MG), a B-cell-mediated autoimmune disease affecting the neuromuscular junction. We recently demonstrated an active Epstein-Barr virus (EBV) infection in the thymus of MG patients, suggesting that EBV might contribute to the onset or maintenance of the autoimmune response within MG thymus, because of its ability to activate and immortalize autoreactive B cells. EBV has been reported to elicit and modulate Toll-like receptor (TLR) 7- and TLR9-mediated innate immune responses, which are known to favor B-cell dysfunction and autoimmunity. Aim of this study was to investigate whether EBV infection is associated with altered expression of TLR7 and TLR9 in MG thymus. By real-time PCR, we found that TLR7 and TLR9 mRNA levels were significantly higher in EBV-positive MG compared to EBV-negative normal thymuses. By confocal microscopy, high expression levels of TLR7 and TLR9 proteins were observed in B cells and plasma cells of MG thymic germinal centers (GCs) and lymphoid infiltrates, where the two receptors co-localized with EBV antigens. An increased frequency of Ki67-positive proliferating B cells was found in MG thymuses, where we also detected proliferating cells expressing TLR7, TLR9 and EBV antigens, thus supporting the idea that EBV-associated TLR7/9 signaling may promote abnormal B-cell activation and proliferation. Along with B cells and plasma cells, thymic epithelium, plasmacytoid dendritic cells and macrophages exhibited enhanced TLR7 and TLR9 expression in MG thymus; TLR7 was also increased in thymic myeloid dendritic cells and its transcriptional levels positively correlated with those of interferon (IFN)-β. We suggested that TLR7/9 signaling may be involved in antiviral type I IFN production and long-term inflammation in EBV-infected MG thymuses. Our overall findings indicate that EBV-driven TLR7- and TLR9-mediated innate immune responses may participate in the intra-thymic pathogenesis of MG.

The Incubation Period of Primary Epstein-Barr Virus Infection: Viral Dynamics and Immunologic Events

Epstein-Barr virus (EBV) is a human herpesvirus that causes acute infectious mononucleosis and is associated with cancer and autoimmune disease. While many studies have been performed examining acute disease in adults following primary infection, little is known about the virological and immunological events during EBV’s lengthy 6 week incubation period owing to the challenge of collecting samples from this stage of infection. We conducted a prospective study in college students with special emphasis on frequent screening to capture blood and oral wash samples during the incubation period. Here we describe the viral dissemination and immune response in the 6 weeks prior to onset of acute infectious mononucleosis symptoms. While virus is presumed to be present in the oral cavity from time of transmission, we did not detect viral genomes in the oral wash until one week before symptom onset, at which time viral genomes were present in high copy numbers, suggesting loss of initial viral replication control. In contrast, using a sensitive nested PCR method, we detected viral genomes at low levels in blood about 3 weeks before symptoms. However, high levels of EBV in the blood were only observed close to symptom onset–coincident with or just after increased viral detection in the oral cavity. These data imply that B cells are the major reservoir of virus in the oral cavity prior to infectious mononucleosis. The early presence of viral genomes in the blood, even at low levels, correlated with a striking decrease in the number of circulating plasmacytoid dendritic cells well before symptom onset, which remained depressed throughout convalescence. On the other hand, natural killer cells expanded only after symptom onset. Likewise, CD4+ Foxp3+ regulatory T cells decreased two fold, but only after symptom onset. We observed no substantial virus specific CD8 T cell expansion during the incubation period, although polyclonal CD8 activation was detected in concert with viral genomes increasing in the blood and oral cavity, possibly due to a systemic type I interferon response. This study provides the first description of events during the incubation period of natural EBV infection in humans and definitive data upon which to formulate theories of viral control and disease pathogenesis.

Chronic viral infections are ubiquitous in the human population. Many of these viruses persist in spite of the host immune response. Epstein-Barr virus (EBV) is a human herpesvirus and the primary causative agent of acute infectious mononucleosis. The virus is primarily transmitted through salivary exchange yet the kinetics of dissemination and initial immune response remain poorly understood, especially during EBV’s lengthy six-week incubation period. By doing prospective analysis of natural infection in human subjects, we were able to examine responses during the incubation period. We found that virus disseminates into the blood from the oral cavity much earlier than previously predicted and often before large-scale viral replication in oral cells. This correlated with a systemic innate immune response in the form of type I interferon signaling. A subsequent decrease in circulating plasmacytoid dendritic cells was observed simultaneously with polyclonal CD8 T cell activation. These data suggest that EBV replication is self-limiting in the oral cavity and that infection is established for several weeks before virally infected cells traffic to peripheral blood and initiate innate and adaptive immune response.

Understanding the interplay between host immunity and Epstein-Barr virus in NPC patients

Epstein-Barr virus (EBV) has been used as a paradigm for studying host-virus interactions, not only because of its importance as a human oncogenic virus associated with several malignancies including nasopharyngeal carcinoma (NPC) but also owing to its sophisticated strategies to subvert the host antiviral responses. An understanding of the interplay between EBV and NPC is critical for the development of EBV-targeted immunotherapy. Here, we summarize the current knowledge regarding the host immune responses and EBV immune evasion mechanisms in the context of NPC.

The interplay between Epstein-Barr virus and B lymphocytes: implications for infection, immunity, and disease

Human B cells are the primary targets of Epstein-Barr virus (EBV) infection. In most cases, EBV infection is asymptomatic because of a highly effective host immune response, but some individuals develop self-limiting infectious mononucleosis, while others develop EBV-associated lymphoid or epithelial malignancies. The viral and immune factors that determine the outcome of infection are not understood. The EBV life cycle includes a lytic phase, culminating in the production of new viral particles, and a latent phase, during which the virus remains largely silent for the lifetime of the host in memory B cells. Thus, in healthy individuals, there is a tightly orchestrated interplay between EBV and the host that allows the virus to persist. To promote viral persistence, EBV has evolved a variety of strategies to modulate the host immune response including inhibition of immune cell function, blunting of apoptotic pathways, and interfering with antigen processing and presentation pathways. In this article, we focus on mechanisms by which dysregulation of the host B cell and immune modulation by the virus can contribute to development of EBV+ B cell lymphomas.

Recognition of human oncogenic viruses by host pattern-recognition receptors

Human oncogenic viruses include Epstein-Barr virus, hepatitis B virus, hepatitis C virus, human papilloma virus, human T-cell lymphotropic virus, Kaposi's associated sarcoma virus, and Merkel cell polyomavirus. It would be expected that during virus-host interaction, the immune system would recognize these pathogens and eliminate them. However, through evolution, these viruses have developed a number of strategies to avoid such an outcome and successfully establish chronic infections. The persistent nature of the infection caused by these viruses is associated with their oncogenic potential. In this article, we will review the latest information on the interaction between oncogenic viruses and the innate immune system of the host. In particular, we will summarize the available knowledge on the recognition by host pattern-recognition receptors of pathogen-associated molecular patterns present in the incoming viral particle or generated during the virus' life cycle. We will also review the data on the recognition of cell-derived danger associated molecular patterns generated during the virus infection that may impact the outcome of the host-pathogen interaction and the development cancer.

Multiple functions are mediated by the miRNAs of Epstein-Barr virus

Epstein-Barr virus is a gammaherpes virus that is causally associated with several malignancies and expresses multiple miRNAs in both normal and tumor cells. Since the identification of virally encoded miRNAs, various mRNAs have been identified as targets for regulation by EBV's miRNAs in host cells. We shall summarize these targets, the robustness of their identification, and examine how the regulation of these targets by EBV contributes to the successful infection of its host.

Viral Diseases of the Liver

Viruses other than the classic hepatotropic viruses, hepatitis A through E, may cause hepatic injury [1]. Among these are Epstein–Barr virus (EBV), cytomegalovirus (CMV), herpes simplex virus (HSV), varicella zoster virus (VZV), human herpes viruses (HHV) 6, 7, and 8, human parvovirus B19, and adenoviruses (Table 11.1). The clinical presentation of infections with these viruses may be indistinguishable from that associated with infection with classic hepatotropic viruses. The presentation ranges from mild and transient elevation of aminotransferases to acute hepatitis and can also lead to acute liver failure [1]. These viruses should be considered as possible etiologic agents in patients who have acute liver injury and whose serologic markers for the classic hepatotropic viruses are not indicative of an active infection [1]. In the present chapter, we review the clinical manifestations and the potential for immune-mediated liver injury associated with several of these viruses (see summary Table 11.2).

Epstein-Barr virus nuclear antigen 3C interact with p73: Interplay between a viral oncoprotein and cellular tumor suppressor

The p73 protein has structural and functional homology with the tumor suppressor p53, which plays an important role in cell cycle regulation, apoptosis, and DNA repair. The p73 locus encodes both a tumor suppressor (TAp73) and a putative oncogene (ΔNp73). p73 May play a significant role in p53-deficient lymphomas infected with Epstein-Barr virus (EBV). EBV produces an asymptomatic infection in the majority of the global population, but it is associated with several human B-cell malignancies. The EBV-encoded Epstein-Barr virus nuclear antigen 3C (EBNA3C) is thought to disrupt the cell cycle checkpoint by interacting directly with p53 family proteins. Doxorubicin, a commonly used chemotherapeutic agent, induces apoptosis through p53 and p73 signaling such that the lowΔNp73 level promotes the p73-mediated intrinsic pathway of apoptosis. In this report, we investigated the mechanism by which EBV infection counters p73α-induced apoptosis through EBNA3C.

Genome-wide analyses of Epstein-Barr virus reveal conserved RNA structures and a novel stable intronic sequence RNA

BACKGROUND

Epstein-Barr virus (EBV) is a human herpesvirus implicated in cancer and autoimmune disorders. Little is known concerning the roles of RNA structure in this important human pathogen. This study provides the first comprehensive genome-wide survey of RNA and RNA structure in EBV.

RESULTS

Novel EBV RNAs and RNA structures were identified by computational modeling and RNA-Seq analyses of EBV. Scans of the genomic sequences of four EBV strains (EBV-1, EBV-2, GD1, and GD2) and of the closely related Macacine herpesvirus 4 using the RNAz program discovered 265 regions with high probability of forming conserved RNA structures. Secondary structure models are proposed for these regions based on a combination of free energy minimization and comparative sequence analysis. The analysis of RNA-Seq data uncovered the first observation of a stable intronic sequence RNA (sisRNA) in EBV. The abundance of this sisRNA rivals that of the well-known and highly expressed EBV-encoded non-coding RNAs (EBERs).

CONCLUSION

This work identifies regions of the EBV genome likely to generate functional RNAs and RNA structures, provides structural models for these regions, and discusses potential functions suggested by the modeled structures. Enhanced understanding of the EBV transcriptome will guide future experimental analyses of the discovered RNAs and RNA structures.

Professional antigen presenting cells in human herpesvirus 8 infection

Professional antigen presenting cells (APC), i.e., dendritic cells (DC), monocytes/macrophages, and B lymphocytes, are critically important in the recognition of an invading pathogen and presentation of antigens to the T cell-mediated arm of immunity. Human herpesvirus 8 (HHV-8) is one of the few human viruses that primarily targets these APC for infection, altering their cytokine profiles, manipulating their surface expression of MHC molecules, and altering their ability to activate HHV-8-specific T cells. This could be why T cell responses to HHV-8 antigens are not very robust. Of these APC, only B cells support complete, lytic HHV-8 infection. However, both complete and abortive virus replication cycles in APC could directly affect viral pathogenesis and progression to Kaposi's sarcoma (KS) and HHV-8-associated B cell cancers. In this review, we discuss the effects of HHV-8 infection on professional APC and their relationship to the development of KS and B cell lymphomas.

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.