Epstein-Barr virus replication in tongue epithelial cells

Epstein-Barr virus lytic replication and cancer

Epidemiological studies have provided strong evidence that Epstein-Barr virus (EBV) lytic replication is linked to cancer development. Evidence of abortive lytic replication in some tumors and infections with recombinant viruses incapable of lytic replication in animal models have reinforced this view. Furthermore, multiple lytic proteins have been shown to induce genetic instability, a well-characterized precancerous state. In particular, lytic proteins dysregulated the DNA damage response, interfered with cell cycle progression, and induced the development of structural genetic abnormalities. However, there is so far no direct evidence from in vivo or in vitro studies that lytic replication alone can induce cancer. Here, we critically review the currently available evidence that EBV lytic replication contributes to cancer development and suggest future research directions.

Immunological Aspects of EBV and Oral Mucosa Interactions in Oral Lichen Planus

Oral lichen planus (OLP) is considered a T cell-mediated chronic inflammatory process activated by an unknown antigen, making basal keratinocytes vulnerable to a cytotoxic cell mediated immune response. The aim of this review is to summarize information on the role and pathways of Epstein–Barr virus (EBV) and immune cells in inducing OLP as an autoimmune lesion. The pathogenesis of OLP is analyzed from immunological aspects of interactions between EBV and oral mucosa. The results of the available studies allow us to assume that EBV can act both as an exogenous and an endogenous antigen in the pathogenesis of OLP. We emphasized the role of antigen-presenting cells (APC), such as dendritic cells (Langerhans cells, LC), in detecting and capturing antigens and modulating the adaptive immune response. Although EBV shows tropism for B cells and epithelial cells, under certain conditions it can infect monocytes, LCs, NK, and T lymphocytes. It means that under some circumstances of the chronic inflammatory process, EBV particles can react as endogenous agents. During the development of the autoimmune process, a decisive role is played by the loss of immune tolerance. Factors like the activity of cytokines, chemokines, and autoantibodies secreted by EBV-positive plasma cells, autoantigens formed due to virus protein mimicry of human proteins, new self-peptides released from damaged tissues, self-reactive B and T cells, dysregulation of LC function, the anti-apoptotic effect of EBV early lytic antigens, and an imbalance between inflammatory and anti-inflammatory immune cells facilitate the development of an autoimmune process.

The Epstein-Barr Virus Glycoprotein BDLF2 Is Essential for Efficient Viral Spread in Stratified Epithelium

Epstein-Barr virus (EBV) is a ubiquitous human pathogen that infects the majority of the adult population regardless of socioeconomic status or geographical location. EBV primarily infects B and epithelial cells and is associated with different cancers of these cell types, such as Burkitt lymphoma and nasopharyngeal carcinoma. While the life cycle of EBV in B cells is well understood, EBV infection within epithelium is not, largely due to the inability to model productive replication in epithelium in vitro. Organotypic cultures generated from primary human keratinocytes can model many aspects of EBV infection, including productive replication in the suprabasal layers. The EBV glycoprotein BDLF2 is a positional homologue of the murine gammaherpesvirus-68 protein gp48, which plays a role in intercellular spread of viral infection, though sequence homology is limited. To determine the role that BDLF2 plays in EBV infection, we generated a recombinant EBV in which the BDLF2 gene has been replaced with a puromycin resistance gene. The ΔBDLF2 recombinant virus infected both B cell and HEK293 cell lines and was able to immortalize primary B cells. However, the loss of BDLF2 resulted in substantially fewer infected cells in organotypic cultures compared to wild-type virus. While numerous clusters of infected cells representing a focus of infection are observed in wild-type-infected organotypic cultures, the majority of cells observed in the absence of BDLF2 were isolated cells, suggesting that the EBV glycoprotein BDLF2 plays a major role in intercellular viral spread in stratified epithelium. IMPORTANCE The ubiquitous herpesvirus Epstein-Barr virus (EBV) is associated with cancers of B lymphocytes and epithelial cells and is primarily transmitted in saliva. While several models exist for analyzing the life cycle of EBV in B lymphocytes, models of EBV infection in the epithelium have more recently been established. Using an organotypic culture model of epithelium that we previously determined accurately reflects EBV infection in situ, we have ascertained that the loss of the viral envelope protein BDLF2 had little effect on the EBV life cycle in B cells but severely restricted the number of infected cells in organotypic cultures. Loss of BDLF2 has a substantial impact on the size of infected areas, suggesting that BDLF2 plays a specific role in the spread of infection in stratified epithelium.

High-Risk Human Papillomavirus and Epstein-Barr Virus Coinfection: A Potential Role in Head and Neck Carcinogenesis

Simple Summary

A subset of carcinomas that arise in the head and neck region show a viral etiology. In fact, a subgroup of oropharyngeal cancers are caused by some types of human papillomavirus (HPV), so-called high-risk (HR)-HPVs, whereas undifferentiated nasopharyngeal carcinomas are etiologically related to Epstein–Barr virus (EBV). However, studies have reported the presence of both HR-HPV and EBV in some types of head and neck cancers. In this review, we discuss the potential contribution and role of HR-HPV/EBV coinfection in head and neck carcinogenesis, as well as the mechanisms that are potentially involved. In addition, HR-HPV/EBV interaction models are proposed.

Abstract

High-risk human papillomaviruses (HR-HPVs) and Epstein–Barr virus (EBV) are recognized oncogenic viruses involved in the development of a subset of head and neck cancers (HNCs). HR-HPVs are etiologically associated with a subset of oropharyngeal carcinomas (OPCs), whereas EBV is a recognized etiological agent of undifferentiated nasopharyngeal carcinomas (NPCs). In this review, we address epidemiological and mechanistic evidence regarding a potential cooperation between HR-HPV and EBV for HNC development. Considering that: (1) both HR-HPV and EBV infections require cofactors for carcinogenesis; and (2) both oropharyngeal and oral epithelium can be directly exposed to carcinogens, such as alcohol or tobacco smoke, we hypothesize possible interaction mechanisms. The epidemiological and experimental evidence suggests that HR-HPV/EBV cooperation for developing a subset of HNCs is plausible and warrants further investigation.

Oral hairy leukoplakia in a child using a corticosteroid nasal spray

We report a case of atypical oral hairy leukoplakia (OHL) in a 9-year-old immunocompetent girl treated with fluticasone propionate nasal spray for allergic rhinitis. The OHL in childhood is uncommon and should be included in a differential diagnosis of white lesions in the oral mucosa.

Epstein-Barr virus (EBV) reactivation and therapeutic inhibitors

Epstein-Barr virus (EBV) is a ubiquitous human virus which infects almost all humans during their lifetime and following the acute phase, persists for the remainder of the life of the individual. EBV infects B lymphocytes leading to their immortalisation, with persistence of the EBV genome as an episome. In the latent phase, EBV is prevented from reactivating through efficient cytotoxic cellular immunity. EBV reactivates (lytic phase) under conditions of psychological stress with consequent weakening of cellular immunity, and EBV reactivation has been shown to occur in a subset of individuals with each of a variety of cancers, autoimmune diseases, the autoimmune-like disease, chronic fatigue syndrome/myalgic encephalitis and under other circumstances such as being an inpatient in an intensive care unit. Chronic EBV reactivation is an important mechanism in the pathogenesis of many such diseases, yet is rarely tested for in immunocompetent individuals. This review summarises the pathogenesis of EBV infection, EBV reactivation and its role in disease, and methods which may be used to detect it. Known inhibitors of EBV reactivation and replication are discussed, including drugs licensed for treatment of other herpesviruses, licensed or experimental drugs for various other indications, compounds at an early stage of drug development and nutritional constituents such as vitamins and dietary supplements.

Hairy leukoplakia; lessons learned: 30-plus years

Well into the fourth decade of the HIV/AIDS pandemic, we can look back on the early years, the initial discoveries, and the broad sweep of the progress of our understanding of the nature, causes, and significance of the oral lesions seen in those infected with the virus. Prominent among these is oral hairy leukoplakia (HL), a previously unknown lesion of the mouth associated with Epstein-Barr virus (EBV) and initially seen only in people with AIDS, in the then-recognized risk groups, or those shown to be HIV positive. Subsequently, it became clear that the distribution of HL extends well beyond the HIV spectrum. In this brief review, we consider the clinical and histological features of HL, discuss how it was discovered, explore its cause, diagnosis, relationship with AIDS, pathogenesis, significance in EBV biology, options for management, and how it changes with HIV/AIDS therapy.

Serological profiling of the EBV immune response in Chronic Fatigue Syndrome using a peptide microarray

BACKGROUND

Epstein-Barr-Virus (EBV) plays an important role as trigger or cofactor for various autoimmune diseases. In a subset of patients with Chronic Fatigue Syndrome (CFS) disease starts with infectious mononucleosis as late primary EBV-infection, whereby altered levels of EBV-specific antibodies can be observed in another subset of patients.

METHODS

We performed a comprehensive mapping of the IgG response against EBV comparing 50 healthy controls with 92 CFS patients using a microarray platform. Patients with multiple sclerosis (MS), systemic lupus erythematosus (SLE) and cancer-related fatigue served as controls. 3054 overlapping peptides were synthesised as 15-mers from 14 different EBV proteins. Array data was validated by ELISA for selected peptides. Prevalence of EBV serotypes was determined by qPCR from throat washing samples.

RESULTS

EBV type 1 infections were found in patients and controls. EBV seroarray profiles between healthy controls and CFS were less divergent than that observed for MS or SLE. We found significantly enhanced IgG responses to several EBNA-6 peptides containing a repeat sequence in CFS patients compared to controls. EBNA-6 peptide IgG responses correlated well with EBNA-6 protein responses. The EBNA-6 repeat region showed sequence homologies to various human proteins.

CONCLUSION

Patients with CFS had a quite similar EBV IgG antibody response pattern as healthy controls. Enhanced IgG reactivity against an EBNA-6 repeat sequence and against EBNA-6 protein is found in CFS patients. Homologous sequences of various human proteins with this EBNA-6 repeat sequence might be potential targets for antigenic mimicry.

Human immunity against EBV-lessons from the clinic

The mammalian immune system has evolved over many millennia to be best equipped to protect the host from pathogen infection. In many cases, host and pathogen have coevolved, each acquiring sophisticated ways of inducing or protecting from disease. Epstein-Barr virus (EBV) is a human herpes virus that infects >90% of individuals. Despite its ubiquity, infection by EBV is often subclinical; this invariably reflects the necessity of the virus to preserve its host, balanced with sophisticated host immune mechanisms that maintain viral latency. However, EBV infection can result in various, and often fatal, clinical sequelae, including fulminant infectious mononucleosis, hemophagocytic lymphohistiocytosis, lymphoproliferative disease, organomegaly, and/or malignancy. Such clinical outcomes are typically observed in immunosuppressed individuals, with the most extreme cases being Mendelian primary immunodeficiencies (PIDs). Although these conditions are rare, they have provided critical insight into the cellular, biochemical, and molecular requirements for robust and long-lasting immunity against EBV infection. Here, we review the virology of EBV, mechanisms underlying disease pathogenesis in PIDs, and developments in immune cell–mediated therapy to treat disorders associated with or induced by EBV infection.

Epstein-Barr Virus: Diseases Linked to Infection and Transformation

Epstein–Barr virus (EBV) was first discovered in 1964, and was the first known human tumor virus now shown to be associated with a vast number of human diseases. Numerous studies have been conducted to understand infection, propagation, and transformation in various cell types linked to human diseases. However, a comprehensive lens through which virus infection, reactivation and transformation of infected host cells can be visualized is yet to be formally established and will need much further investigation. Several human cell types infected by EBV have been linked to associated diseases. However, whether these are a direct result of EBV infection or indirectly due to contributions by additional infectious agents will need to be fully investigated. Therefore, a thorough examination of infection, reactivation, and cell transformation induced by EBV will provide a more detailed view of its contributions that drive pathogenesis. This undoubtedly expand our knowledge of the biology of EBV infection and the signaling activities of targeted cellular factors dysregulated on infection. Furthermore, these insights may lead to identification of therapeutic targets and agents for clinical interventions. Here, we review the spectrum of EBV-associated diseases, the role of the encoded latent antigens, and the switch to latency or lytic replication which occurs in EBV infected cells. Furthermore, we describe the cellular processes and critical factors which contribute to cell transformation. We also describe the fate of B-cells and epithelial cells after EBV infection and the expected consequences which contribute to establishment of viral-associated pathologies.

Epstein-Barr virus mRNA profiles and viral DNA methylation status in nasopharyngeal brushings from nasopharyngeal carcinoma patients reflect tumor origin

Undifferentiated nasopharyngeal carcinoma (NPC) is 100% associated with Epstein-Barr virus (EBV) as oncogenic driver. NPC is often diagnosed late due to initial vague complaints and obscured location. Prior studies suggest that measurement of EBV DNA load and RNA transcripts in nasopharyngeal (NP) brushings is useful for minimally invasive NPC diagnosis. However, whether these EBV markers relate to local virus replication or reflect tumor origin remains to be demonstrated. To resolve this, we analysed EBV-DNA characteristics and quantified latent and lytic viral RNA transcripts in NP brushings and matching frozen NP-biopsy specimens from patients suspected of having NPC. We observed non-fragmented and Cp-promotor methylated EBV-DNA in both NP brushings and biopsies suggestive of tumor origin. Using quantitative RT-PCR we determined expression levels of 7 critical latent (EBER1, Qp-EBNA1, EBNA2, BART, LMP1, LMP2, BARF1) and 5 lytic (Zta, Rta, TK, PK and VCA-p18) RNA transcripts. Although latent and early lytic RNA transcripts were frequently detected in conjunction with high EBV viral load, in both brushings and biopsies the latent transcripts prevailed and reflected a typical NPC-associated latency-II transcription profile without EBNA2. Late lytic RNA transcripts were rare and detected at low levels mainly in NP brushings, suggestive of abortive viral reactivation rather than complete virus replication. EBV-IgA serology (EBNA1, VCA, Zta) did not correlate to the level of viral reactivation in situ. Overall, viral RNA profiling, DNA fragmentation and methylation analysis in NP brushings and parallel biopsies indicate that NP brush sampling provides a true and robust indicator of NPC tumor presence.

Epstein-Barr Virus and Its Association with Oral Hairy Leukoplakia: A Short Review

In immunocompromised subjects, Epstein-Barr virus (EBV) infection of terminally differentiated oral keratinocytes may result in subclinical productive infection of the virus in the stratum spinosum and in the stratum granulosum with shedding of infectious virions into the oral fluid in the desquamating cells. In a minority of cases this productive infection with dysregulation of the cell cycle of terminally differentiated epithelial cells may manifest as oral hairy leukoplakia. This is a white, hyperkeratotic, benign lesion of low morbidity, affecting primarily the lateral border of the tongue. Factors that determine whether productive EBV replication within the oral epithelium will cause oral hairy leukoplakia include the fitness of local immune responses, the profile of EBV gene expression, and local environmental factors.

Viral O-GalNAc peptide epitopes: a novel potential target in viral envelope glycoproteins

Viral envelope glycoproteins are major targets for antibodies that bind to and inactivate viral particles. The capacity of a viral vaccine to induce virus-neutralizing antibodies is often used as a marker for vaccine efficacy. Yet the number of known neutralization target epitopes is restricted owing to various viral escape mechanisms. We expand the range of possible viral glycoprotein targets, by presenting a previously unknown type of viral glycoprotein epitope based on a short peptide stretch modified with small O-linked glycans. Besides being immunologically active, these epitopes have a high potential for antigenic variation. Thus, sera from patients infected with EBV develop individual IgG responses addressing the different possible glycopeptide glycoforms of one short peptide backbone that reflect individual variations in the course of virus infection. In contrast, in HSV type 2 meningitis patients, CSF antibodies are focussed to only one single glycoform peptide of a major viral glycoprotein. Thus, dependent on the viral disease, the serological response may be variable or constant with respect to the number of targeted peptide glycoforms. Mapping of these epitopes relies on a novel three-step procedure that identifies any reactive viral O-glycosyl peptide epitope with respect to (i) relevant peptide sequence, (ii) the reactive glycoform out of several possible glycopeptide isomers of that peptide sequence, and (iii) possibly tolerated carbohydrate or peptide structural variations at glycosylation sites. In conclusion, the viral O-glycosyl peptide epitopes may be of relevance for development of subunit vaccines and for improved serodiagnosis of viral diseases. Copyright © 2015 John Wiley & Sons, Ltd.

Telomerase activity impacts on Epstein-Barr virus infection of AGS cells

The Epstein-Barr virus (EBV) is transmitted from host-to-host via saliva and is associated with epithelial malignancies including nasopharyngeal carcinoma (NPC) and some forms of gastric carcinoma (GC). Nevertheless, EBV does not transform epithelial cells in vitro where it is rapidly lost from infected primary epithelial cells or epithelial tumor cells. Long-term infection by EBV, however, can be established in hTERT-immortalized nasopharyngeal epithelial cells. Here, we hypothesized that increased telomerase activity in epithelial cells enhances their susceptibility to infection by EBV. Using HONE-1, AGS and HEK293 cells we generated epithelial model cell lines with increased or suppressed telomerase activity by stable ectopic expression of hTERT or of a catalytically inactive, dominant negative hTERT mutant. Infection experiments with recombinant prototypic EBV (rB95.8), recombinant NPC EBV (rM81) with increased epithelial cell tropism compared to B95.8, or recombinant B95.8 EBV with BZLF1-knockout that is not able to undergo lytic replication, revealed that infection frequencies positively correlate with telomerase activity in AGS cells but also partly depend on the cellular background. AGS cells with increased telomerase activity showed increased expression mainly of latent EBV genes, suggesting that increased telomerase activity directly acts on the EBV infection of epithelial cells by facilitating latent EBV gene expression early upon virus inoculation. Thus, our results indicate that infection of epithelial cells by EBV is a very selective process involving, among others, telomerase activity and cellular background to allow for optimized host-to-host transmission via saliva.

Twenty-first-century oral hairy leukoplakia--a non-HIV-associated entity

OBJECTIVE

This study presents the clinicopathologic features of a series (N = 35) of patients with non-human immunodeficiency virus (HIV)-associated oral hairy leukoplakia (OHL).

METHODS

Patients with non-HIV-associated OHL were identified from three centers. Epstein-Barr virus infection was demonstrated by using EBV early ribonucleic acid in situ hybridization. The presence of Candida co-infection was evaluated by diastase periodic acid-Schiff staining. The clinical features were determined by review of the medical records.

RESULTS

Twenty-eight patients had intercurrent respiratory problems requiring long-term steroid inhaler use, four suffered from autoimmune diseases requiring immunosuppressant therapy, and four had diabetes. The majority of lesions were located on the tongue, and 24 showed evidence of Candida co-infection.

CONCLUSIONS

In the twenty-first century, the presence of OHL should not be regarded as pathognomic for HIV infection or significant systemic immunosuppression. Local and systemic immunosuppression, in the form of steroid inhaler use, is a risk factor for the development of OHL.

Epstein-Barr virus infection and persistence in nasopharyngeal epithelial cells

Epstein-Barr virus (EBV) infection is closely associated with undifferentiated nasopharyngeal carcinoma (NPC), strongly implicating a role for EBV in NPC pathogenesis; conversely, EBV infection is rarely detected in normal nasopharyngeal epithelial tissues. In general, EBV does not show a strong tropism for infecting human epithelial cells, and EBV infection in oropharyngeal epithelial cells is believed to be lytic in nature. To establish life-long infection in humans, EBV has evolved efficient strategies to infect B cells and hijack their cellular machinery for latent infection. Lytic EBV infection in oropharyngeal epithelial cells, though an infrequent event, is believed to be a major source of infectious EBV particles for salivary transmission. The biological events associated with nasopharyngeal epithelial cells are only beginning to be understood with the advancement of EBV infection methods and the availability of nasopharyngeal epithelial cell models for EBV infection studies. EBV infection in human epithelial cells is a highly inefficient process compared to that in B cells, which express the complement receptor type 2 (CR2) to mediate EBV infection. Although receptor(s) on the epithelial cell surface for EBV infection remain(s) to be identified, EBV infection in epithelial cells could be achieved via the interaction of glycoproteins on the viral envelope with surface integrins on epithelial cells, which might trigger membrane fusion to internalize EBV in cells. Normal nasopharyngeal epithelial cells are not permissive for latent EBV infection, and EBV infection in normal nasopharyngeal epithelial cells usually results in growth arrest. However, genetic alterations in premalignant nasopharyngeal epithelial cells, including p16 deletion and cyclin D1 overexpression, could override the growth inhibitory effect of EBV infection to support stable and latent EBV infection in nasopharyngeal epithelial cells. The EBV episome in NPC is clonal in nature, suggesting that NPC develops from a single EBV-infected nasopharyngeal epithelial cell, and the establishment of persistent and latent EBV infection in premalignant nasopharyngeal epithelium may represent an early and critical event for NPC development.

Significant role of macrophages in human cancers associated with Epstein-Barr virus (Review)

Epstein-Barr virus (EBV) is a ubiquitous pathogen that was first identified as a human cancer virus. Many human cancers are associated with EBV, and we demonstrated that EBV infects macrophages. Macrophages infected with EBV show a close correlation with many human cancers, and thus more attention must be given to the role of macrophages infiltrating into cancer tissues associated with EBV. In this review, I discuss the role of macrophages in the process of EBV-associated oncogenesis with regard to interleukin-10.

Epstein-Barr virus in oral mucosa from human immunodeficiency virus positive patients

Objective: the detection rate of Epstein-Barr virus (EBV) is higher in people living with human immunodeficiency virus (HIV). In an attempt to contribute to our epidemiological understanding of this coinfection and to investigate the activity of EBV in normal oral mucosa, we performed a cross-sectional study with HIV-positive patients. Methods: oral smears from 145 HIV-positive patients were collected between March 2010 and March 2011. Nested polymerase chain reaction (PCR) and reverse transcriptase-PCR (RT-PCR) were used to genotype EBV and to detect EBNA-2 expression, respectively. Results: EBV DNA was detected in 48.3% of the study participants, of whom 32.85% were EBV-1 and 45.71% were EBV-2 carriers. Additionally, 14.28% were coinfected with both types. EBNA-2 mRNA was expressed in 45.7% of the EBV -positive samples, including 20.0% with EBV-1 only, 20.0% with EBV-2 only and 1.4% with both genotypes. Immune status affected the overall EBV infection, and EBV-2 positivity was significantly correlated with sexual lifestyle of the participants. EBV co-infection with both viral types was dependent upon HIV viral load and the activity of the EBNA-2 gene. Conclusion: we report a high prevalence of active EBV in the oral mucosa of asymptomatic HIV-seropositive individuals. This study addresses the need for monitoring and treatment of HIV-infected patients with EBV reactivation.

Cyclin D1 overexpression supports stable EBV infection in nasopharyngeal epithelial cells

Undifferentiated nasopharyngeal carcinomas (NPCs) are commonly present with latent EBV infection. However, events regulating EBV infection at early stages of the disease and the role of EBV in disease pathogenesis are largely undefined. Genetic alterations leading to activation of cyclin D1 signaling in premalignant nasopharyngeal epithelial (NPE) cells have been postulated to predispose cells to EBV infection. We previously reported that loss of p16, a negative regulator of cyclin D1 signaling, is a frequent feature of NPC tumors. Here, we report that early premalignant lesions of nasopharyngeal epithelium overexpress cyclin D1. Furthermore, overexpression of cyclin D1 is closely associated with EBV infection. Therefore we investigated the potential role of cyclin D1 overexpression in dysplastic NPE cells in vitro. In human telomerase reverse transcriptase-immortalized NPE cells, overexpression of cyclin D1 or a p16-resistant form of CDK4 (CDK4(R24C)) suppressed differentiation. This suppression may have implications for the close association of EBV infection with undifferentiated NPC. In these in vitro models, we found that cellular growth arrest and senescence occurred in EBV-infected cell populations immediately after infection. Nevertheless, overexpression of cyclin D1 or a p16-resistant form of CDK4 or knockdown of p16 in the human telomerase reverse transcriptase-immortalized NPE cell lines could counteract the EBV-induced growth arrest and senescence. We conclude that dysregulated expression of cyclin D1 in NPE cells may contribute to NPC pathogenesis by enabling persistent infection of EBV.

Lytic Epstein-Barr virus infection in epithelial cells but not in B-lymphocytes is dependent on Blimp1

Epstein-Barr virus (EBV) replicates in superficial differentiated cells of oral hairy leukoplakia (OHL). Differentiation of squamous epithelial cells depends on B-lymphocyte-induced maturation protein 1 (Blimp1). Here we show that expression of the EBV immediate-early protein BZLF1 is restricted to Blimp1-positive epithelial cells in OHL. Luciferase assays revealed Blimp1-dependent induction of the BZLF1 promoter Zp in epithelial cell lines. Expression of ZEB1, a negative regulator of Zp, and of Xbp-1, which mediates the Blimp1 effect on Zp in B-cells, was not affected by enforced Blimp1 expression. Moreover, Xbp-1 protein expression was not detected in differentiated epithelial cells of OHL. Thus, Blimp1 induces BZLF1 expression in epithelial cells independently of ZEB1 and Xbp-1. In contrast to epithelial cells of OHL, BZLF1 expression was also observed in Blimp1-negative lymphoid cells in infectious mononucleosis tonsils, suggesting that EBV replication in B-cells may be induced independently of terminal differentiation.

Epstein-Barr virus in the multiple sclerosis brain: a controversial issue--report on a focused workshop held in the Centre for Brain Research of the Medical University of Vienna, Austria

Recent epidemiological and immunological studies provide evidence for an association between Epstein-Barr virus infection and multiple sclerosis, suggesting a role of Epstein-Barr virus infection in disease induction and pathogenesis. A key question in this context is whether Epstein-Barr virus-infected B lymphocytes are present within the central nervous system and the lesions of patients with multiple sclerosis. Previous studies on this topic provided highly controversial results, showing Epstein-Barr virus reactivity in B cells in the vast majority of multiple sclerosis cases and lesions, or only exceptional Epstein-Barr virus-positive B cells in rare cases. In an attempt to explain the reasons for these divergent results, a workshop was organized under the umbrella of the European Union FP6 NeuroproMiSe project, the outcome of which is presented here. This report summarizes the current knowledge of Epstein-Barr virus biology and shows that Epstein-Barr virus infection is highly complex. There are still major controversies, how to unequivocally identify Epstein-Barr virus infection in pathological tissues, particularly in situations other than Epstein-Barr virus-driven lymphomas or acute Epstein-Barr virus infections. It further highlights that unequivocal proof of Epstein-Barr virus infection in multiple sclerosis lesions is still lacking, due to issues related to the sensitivity and specificity of the detection methods.

Epithelial raft cultures for investigations of virus growth, pathogenesis and efficacy of antiviral agents

The organotypic epithelial raft cultures, originally developed to study keratinocytes differentiation, represent a novel approach to the study of viruses able to infect epithelial cells. Organotypic epithelial raft cultures accurately reproduce the process of epithelial differentiation in vitro and can be prepared from normal keratinocytes, explanted epithelial tissue, or established cell lines. This culture system permits cells to proliferate and fully differentiate at the air-liquid interface on a dermal-equivalent support. Normal primary human keratinocytes (PHKs) stratify and fully differentiate in a manner similar to the normal squamous epithelial tissues, while transformed cell lines exhibit dysplastic morphologies similar to the (pre)neoplastic lesions seen in vivo. This three-dimensional (3D) culture system provides an essential tool for investigations of virus growth, virus-host cell interactions, for the genetic analysis of viral proteins and regulatory sequences, and for the evaluation of antiviral agents. The 3D epithelial cultures have proven a breakthrough in the research on papillomaviruses, since their life cycle is strictly linked to the differentiation of the host epithelium. In the last years, several reports have shown the usefulness of the 3D epithelial cultures for the study of other viruses that target at least during a part of their life cycles epithelial cells. The 3D epithelial cultures allow the analysis of virus-host cell interactions in stratified epithelia that more closely resemble the in vivo situation. In this review we describe the advances on research on 3D epithelial cultures for the study of virus growth and pathogenesis of different families of viruses, including papilloma-, herpes-, pox-, adeno-, and parvoviruses.

Oral Hairy Leukoplakia in HIV-Negative Patients: Report of 10 Cases

Ten cases of oral hairy leukoplakia (OHL) in HIV- negative patients are presented. Eight of the 10 patients were on steroid treatment for chronic obstructive pulmonary disease, 1 patient was on prednisone as part of a therapeutic regimen for gastrointestinal stromal tumor, and 1 patient did not have any history of immunosuppression. There were 5 men and 5 women, ages 32-79, with mean age being 61.8 years. Nine out of 10 lesions were located unilaterally on the tongue, whereas 1 lesion was located at the junction of the hard and soft palate. All lesions were described as painless, corrugated, nonremovable white plaques (leukoplakias). Histologic features were consistent with Epstein—Barr virus—associated hyperkeratosis suggestive of OHL, and confirmatory in situ hybridization was performed in all cases. Candida hyphae and spores were present in 8 cases. Pathologists should be aware of OHL presenting not only in HIV-positive and HIV-negative organ transplant recipients but also in patients receiving steroid treatment, and more important, certain histologic features should raise suspicion for such diagnosis without prior knowledge of immunosuppression.

Epstein-Barr virus infection and risk of lymphoma: immunoblot analysis of antibody responses against EBV-related proteins in a large series of lymphoma subjects and matched controls

Epstein-Barr Virus (EBV) is consistently associated with distinct lymphoproliferative malignancies and aberrant EBV antibody patterns are found in most EBV cancer patients. We evaluate the detection of an abnormal reactive serological pattern to EBV (ab_EBV) infection and the risk of lymphoma in a multicentric case-control study. Serum samples were collected at study entry from 1,085 incident lymphoma cases from Spain, France, Germany, Czech Republic, Italy and 1,153 age, sex and country matched controls. EBV immunoglobulin G (IgG) serostatus was evaluated through a peptide-based ELISA combining immunodominant epitopes of EBNA1 (BKRF1) and VCA-p18 (BFRF3). Further, immunoblot analysis was performed to evaluate distinct antibody diversity patterns to EBV early antigens (EA), besides EBNA1, VCA-p18, VCA-p40 (BdRF1) and Zebra (BZLF1). Patients with chronic active EBV infection and aberrant EBV activity were characterized as having an abnormal reactive pattern (ab_EBV). Ab_EBV was observed in 20.9% of 2,238 included subjects with an increased proportion of cases presenting ab_EBV as compared to the control population (23.9% vs. 18.0% p = 0.001). Ab_EBV positivity was a risk factor for all lymphomas combined (odds ratio [OR] = 1.42, 95% confidence interval [CI]=1.15-1.74), and specifically for chronic lymphocytic leukaemia (OR = 2.96, 95%CI = 2.22-3.95). Lower levels of ab_EBV were observed for follicular lymphoma (OR = 0.38, 95%CI = 0.15-0.98). EBV may be involved in a larger subset of lymphomas among clinically immunocompetent subjects than previously thought, probably explained by an underlying loss of immune control of EBV latent infection. Ab_EBV is a useful tool to explore EBV imbalances preceding or paralleling possible EBV associated oncogenic events.

Aberrant Epstein-Barr virus persistence in HIV carriers is characterized by anti-Epstein-Barr virus IgA and high cellular viral loads with restricted transcription

OBJECTIVE

Epstein-Barr virus (EBV)-positive lymphomas in HIV carriers are paralleled by elevated EBV-DNA loads in the circulation. Approximately 20% of asymptomatic HIV carriers also show elevated circulating EBV-DNA loads. We aimed to characterize the nature of this EBV DNA and to determine the transcriptional phenotype of EBV in blood, in relation to serological parameters.

DESIGN

A total of 197 random asymptomatic HIV carriers, representing 2% of the Dutch HIV-positive population, were sampled for blood, peripheral blood mononuclear cells and plasma. In addition, 39 EBV-DNA carriers were sampled twice, with a 5-year interval.

METHODS

EBV-DNA loads were determined by LightCycler-based real-time polymerase chain reaction (PCR). EBV transcription was studied by nucleic acid sequence-based amplification and reverse transcriptase PCR. IgA and IgG antibodies to EBV antigens EBNA1 and VCA-p18 were quantified by synthetic peptide-based enzyme-linked immunosorbent assay.

RESULTS

: Elevated EBV-DNA loads were found in whole blood of 19.3% of the tested HIV population, which were persistent in 82%. Plasma samples were EBV-DNA negative and circulating EBV DNA could be attributed to the B-cell compartment. Transcription of only LMP2 and (non-translated) transcripts from the BamHI-A region of the EBV genome was found, whereas EBNA1, LMP1 and lytic EBV transcripts were absent despite high cellular EBV-DNA loads. IgA-reactivity to VCA-p18 was seen in 69%. IgG to VCA-p18 was significantly higher in high EBV-DNA load carriers.

CONCLUSION

Asymptomatic HIV carriers show aberrant EBV persistence in the circulation, characterized by elevated, B-cell-associated EBV-DNA loads. EBV transcription is restricted, arguing for EBV gene shutdown in circulating EBV-carrying B cells. Increased IgA and IgG reactive to VCA-p18 is indicative of increased lytic EBV replication, possibly occurring at mucosal lymphoid sites but not in the circulation.

Epstein-Barr virus infection of Langerhans cell precursors as a mechanism of oral epithelial entry, persistence, and reactivation

Epstein-Barr virus (EBV) is a ubiquitous human herpesvirus associated with many malignant and nonmalignant human diseases. Life-long latent EBV persistence occurs in blood-borne B lymphocytes, while EBV intermittently productively replicates in mucosal epithelia. Although several models have previously been proposed, the mechanism of EBV transition between these two reservoirs of infection has not been determined. In this study, we present the first evidence demonstrating that EBV latently infects a unique subset of blood-borne mononuclear cells that are direct precursors to Langerhans cells and that EBV both latently and productively infects oral epithelium-resident cells that are likely Langerhans cells. These data form the basis of a proposed new model of EBV transition from blood to oral epithelium in which EBV-infected Langerhans cell precursors serve to transport EBV to the oral epithelium as they migrate and differentiate into oral Langerhans cells. This new model contributes fresh insight into the natural history of EBV infection and the pathogenesis of EBV-associated epithelial disease.

Epstein-Barr virus in oral diseases

Epstein-Barr virus (EBV), a B-lymphotropic gamma-herpesvirus, causes infectious mononucleosis and oral hairy leukoplakia, and is associated with various types of lymphoid and epithelial malignancies. Saliva is the main vehicle for EBV transmission from individual to individual. Recent studies have also implicated EBV in the pathogenesis of advanced types of periodontal disease. EBV DNA is detected in 60-80% of aggressive periodontitis lesions and in 15-20% of gingivitis lesions or normal periodontal sites. The periodontal presence of EBV is associated with an elevated occurrence of periodontopathic anaerobic bacteria. Moreover, EBV active infection occurs in approximately 70% of symptomatic and large-size periapical lesions. EBV and cytomegalovirus often co-exist in marginal and apical periodontitis. Periodontal therapy can markedly suppress the EBV load in periodontal pockets as well as in saliva, which has the potential to reduce the risk of viral transmission between close individuals. EBV proteins up-regulate cytokines and growth factors, which seem to play a central role in the proliferative response of tongue epithelial cells in oral hairy leukoplakia and in the cell-transformation process of EBV-associated malignancies. Further research is needed to identify the full range of EBV-related diseases in the human oral cavity.

Contribution of C/EBP proteins to Epstein-Barr virus lytic gene expression and replication in epithelial cells

The contribution of C/EBP proteins to Epstein-Barr virus (EBV) lytic gene expression and replication in epithelial cells was examined. Nasopharyngeal carcinoma cell lines constitutively expressed C/EBPbeta and had limited C/EBPalpha expression, while the AGS gastric cancer cell line expressed significant levels of both C/EBPalpha and C/EBPbeta. Induction of the lytic cycle in EBV-positive AGS/BX1 cells with phorbol ester and sodium butyrate treatment led to a transient stimulation of C/EBPbeta expression and a prolonged increase in C/EBPalpha expression. In AGS/BX1 cells, endogenous C/EBPalpha and C/EBPbeta proteins were detected associated with the ZTA and oriLyt promoters but not the RTA promoter. Electrophoretic mobility shift assays confirmed binding of C/EBP proteins to multiple sites in the ZTA and oriLyt promoters. The response of these promoters in reporter assays to transfected C/EBPalpha and C/EBPbeta proteins was consistent with the promoter binding assays and emphasized the relative importance of C/EBPs for activation of the ZTA promoter. Mutation of the oriLyt promoter proximal C/EBP site had little effect on ZTA activation of the promoter in a reporter assay. However, this mutation impaired oriLyt DNA replication, suggesting a separate replication-specific contribution for C/EBP proteins. Finally, the overall importance of C/EBP proteins for lytic gene expression was demonstrated using CHOP10 to antagonize C/EBP DNA binding activity. Introduction of CHOP10 significantly impaired induction of the ZTA, RTA, and BMRF1 proteins in chemically treated AGS/BX1 cells. Thus, C/EBPbeta and C/EBPalpha expression are associated with lytic induction in AGS cells, and expression of C/EBP proteins in epithelial cells may contribute to the tendency of these cells to exhibit constitutive low-level ZTA promoter activity.

Activation of Kaposi's sarcoma-associated herpesvirus lytic gene expression during epithelial differentiation

The oral cavity has been identified as the major site for the shedding of infectious Kaposi's sarcoma-associated herpesvirus (KSHV). While KSHV DNA is frequently detected in the saliva of KSHV seropositive persons, it does not appear to replicate in salivary glands. Some viruses employ the process of epithelial differentiation for productive viral replication. To test if KSHV utilizes the differentiation of oral epithelium as a mechanism for the activation of lytic replication and virus production, we developed an organotypic raft culture model of epithelium using keratinocytes from human tonsils. This system produced a nonkeratinized stratified squamous oral epithelium in vitro, as demonstrated by the presence of nucleated cells at the apical surface; the expression of involucrin and keratins 6, 13, 14, and 19; and the absence of keratin 1. The activation of KSHV lytic-gene expression was examined in this system using rKSHV.219, a recombinant virus that expresses the green fluorescent protein during latency from the cellular EF-1alpha promoter and the red fluorescent protein (RFP) during lytic replication from the viral early PAN promoter. Infection of keratinocytes with rKSHV.219 resulted in latent infection; however, when these keratinocytes differentiated into a multilayered epithelium, lytic cycle activation of rKSHV.219 occurred, as evidenced by RFP expression, the expression of the late virion protein open reading frame K8.1, and the production of infectious rKSHV.219 at the epithelial surface. These findings demonstrate that KSHV lytic activation occurs as keratinocytes differentiate into a mature epithelium, and it may be responsible for the presence of infectious KSHV in saliva.

Detection of Epstein-Barr virus (EBV) in the oral mucosa of renal transplant patients

The purpose of this study was to determine the prevalence of Epstein-Barr virus (EBV)-DNA in the oral mucosa of renal transplant patients and observe the efficacy of mouth rinses with phosphate-buffered saline (PBS) to eliminate EBV present in the saliva. Lingual, gingival, and buccal cytobrushings were obtained from normal oral mucosa of 10 renal transplant patients and 10 normal subjects, and were examined through polymerase chain reaction (PCR), before and after rinses with PBS. EBV-DNA was detected in 86.6% of renal transplant recipients and in 46.6% of healthy subjects. No significant difference was observed between oral scrapes obtained before and after rinses with PBS with regard to detection of EBV-DNA. Our results suggest that the use of PCR to detect the presence of EBV-DNA in oral mucosa in the absence of specific lesions gives rise to the problem of identifying the viral replication sites. In addition, PBS was not effective at minimizing contamination by saliva.

Capacity of Epstein-Barr virus to infect monocytes and inhibit their development into dendritic cells is affected by the cell type supporting virus replication

Epstein-Barr virus (EBV) is a ubiquitous human herpesvirus that is involved in the pathogenesis of a wide spectrum of malignant and non-malignant diseases. Strong evidence implicates T lymphocytes in the control of EBV replication and tumorigenesis, but cellular components of the innate immune system are poorly characterized in terms of their function in the development of EBV-specific immunity or interaction with the virus. This study demonstrates that EBV virions produced in epithelial cells surpass their B cell-derived counterparts in the capacity to enter monocytes and inhibit their development into dendritic cells (DCs). Different ratios of the gp42 and gH glycoproteins in the envelope of virions that were derived from major histocompatibility complex class II-positive or -negative cells accounted primarily for the differences in EBV tropism. EBV is shown to enter both monocytes and DCs, although the cells are susceptible to virus-induced apoptosis only if infected at early stages of DC differentiation. The purified gH/gL heterodimer binds efficiently to monocytes and DCs, but not to B cells, suggesting that high expression levels of a putative binding partner for gH contribute to virus entry. This entry takes place despite very low or undetectable expression of CD21, the canonical EBV receptor. These results indicate that the site of virus replication, either in B cells or epithelial cells, alters EBV tropism for monocytes and DCs. This results in a change in the virus's immunomodulating capacity and may have important implications for the regulation of virus-host interactions during primary and chronic EBV infection.