Epstein-Barr virus infection in carcinoma of the salivary gland

Candida Infection Associated with Salivary Gland-A Narrative Review

Candida species are common global opportunistic pathogens that could repeatedly and chronically cause oral mucosa infection and create an inflammatory environment, leading to organ dysfunction. Oral Candida infections may cause temporary or permanent damage to salivary glands, resulting in the destruction of acinar cells and the formation of scar tissue. Restricted function of the salivary glands leads to discomfort and diseases of the oral mucosa, such as dry mouth and associated infection. This narrative review attempts to summarize the anatomy and function of salivary glands, the associations between Candida and saliva, the effects of Candida infection on salivary glands, and the treatment strategies. Overall, clinicians should proactively manage Candida infections by educating patients on oral hygiene management for vulnerable populations, conducting frequent checks for a timely diagnosis, and providing an effective treatment plan.

Terminal Repeat Analysis of EBV Genomes

Epstein-Barr virus (EBV) was the first human virus associated directly with human malignancies. During EBV infection of various host cells the double-stranded linear EBV DNA carried by the virions undergoes circularization. Since there are variable numbers of terminal repetitions (TRs) at the ends of the linear EBV genome, the resulting circular episomes enclose a variable number of TRs. Thus, in cells carrying viral episomes, the sizes of the terminal restriction enzyme fragments of EBV is affected by the number of TRs (Raab-Traub and Flynn Cell 47:883-889, 1986). Southern blot analysis revealed that in monoclonal proliferations, arising from a single cell, there was only a single band representing the joined EBV termini, whereas multiple terminal restriction enzyme fragments that differ in size were characteristic for oligoclonal or polyclonal proliferations. Using suitable probes, one can distinguish the episomal form from the linear EBV genomes that are formed during lytic EBV replication or during integration into the host genome. TR analysis is a useful tool for the determination of EBV clonality in different clinical samples and in cell lines carrying EBV genomes. A single terminal restriction enzyme fragment may indicate EBV infection at an early phase of clonal cell proliferation, whereas polyclonal EBV genomes may derive from multiple infections of proliferating cells.

Epstein- Barr Virus: Clinical and Epidemiological Revisits and Genetic Basis of Oncogenesis

Epstein-Barr virus (EBV) is classified as a member in the order herpesvirales, family herpesviridae, subfamily gammaherpesvirinae and the genus lymphocytovirus. The virus is an exclusively human pathogen and thus also termed as human herpesvirus 4 (HHV4). It was the first oncogenic virus recognized and has been incriminated in the causation of tumors of both lymphatic and epithelial nature. It was reported in some previous studies that 95% of the population worldwide are serologically positive to the virus. Clinically, EBV primary infection is almost silent, persisting as a life-long asymptomatic latent infection in B cells although it may be responsible for a transient clinical syndrome called infectious mononucleosis. Following reactivation of the virus from latency due to immunocompromised status, EBV was found to be associated with several tumors. EBV linked to oncogenesis as detected in lymphoid tumors such as Burkitt's lymphoma (BL), Hodgkin's disease (HD), post-transplant lymphoproliferative disorders (PTLD) and T-cell lymphomas (e.g. Peripheral T-cell lymphomas; PTCL and Anaplastic large cell lymphomas; ALCL). It is also linked to epithelial tumors such as nasopharyngeal carcinoma (NPC), gastric carcinomas and oral hairy leukoplakia (OHL). In vitro, EBV many studies have demonstrated its ability to transform B cells into lymphoblastoid cell lines (LCLs). Despite these malignancies showing different clinical and epidemiological patterns when studied, genetic studies have suggested that these EBV- associated transformations were characterized generally by low level of virus gene expression with only the latent virus proteins (LVPs) upregulated in both tumors and LCLs. In this review, we summarize some clinical and epidemiological features of EBV- associated tumors. We also discuss how EBV latent genes may lead to oncogenesis in the different clinical malignancies

Nasopharyngeal Carcinoma: An Evolving Role for the Epstein-Barr Virus

The Epstein-Barr herpesvirus (EBV) is an important human pathogen that is closely linked to several major malignancies including the major epithelial tumor, undifferentiated nasopharyngeal carcinoma (NPC). This important tumor occurs with elevated incidence in specific areas, particularly in southern China but also in Mediterranean Africa and some regions of the Middle East. Regardless of tumor prevalence, undifferentiated NPC is consistently associated with EBV. The consistent detection of EBV in all cases of NPC, the maintenance of the viral genome in every cell, and the continued expression of viral gene products suggest that EBV is a necessary factor for the malignant growth in vivo. However, the molecular characterization of the infection and identification of critical events have been hampered by the difficulty in developing in vitro models of NPC. Epithelial cell infection is difficult in vitro and in contrast to B-cell infection does not result in immortalization and transformation. Cell lines established from NPC usually do not retain the genome, and the successful establishment of tumor xenografts is difficult. However, critical genetic changes that contribute to the onset and progression of NPC and key molecular properties of the viral genes expressed in NPC have been identified. In some cases, viral expression becomes increasingly restricted during tumor progression and tumor cells may express only the viral nuclear antigen EBNA1 and viral noncoding RNAs. As NPC develops in the immunocompetent, the continued progression of deregulated growth likely reflects the combination of expression of viral oncogenes in some cells and viral noncoding RNAs that likely function synergistically with changes in cellular RNA and miRNA expression.

EBV Persistence--Introducing the Virus

Persistent infection by EBV is explained by the germinal center model (GCM) which provides a satisfying and currently the only explanation for EBVs disparate biology. Since the GCM touches on every aspect of the virus, this chapter will serve as an introduction to the subsequent chapters. EBV is B lymphotropic, and its biology closely follows that of normal mature B lymphocytes. The virus persists quiescently in resting memory B cells for the lifetime of the host in a non-pathogenic state that is also invisible to the immune response. To access this compartment, the virus infects naïve B cells in the lymphoepithelium of the tonsils and activates these cells using the growth transcription program. These cells migrate to the GC where they switch to a more limited transcription program, the default program, which helps rescue them into the memory compartment where the virus persists. For egress, the infected memory cells return to the lymphoepithelium where they occasionally differentiate into plasma cells activating viral replication. The released virus can either infect more naïve B cells or be amplified in the epithelium for shedding. This cycle of infection and the quiescent state in memory B cells allow for lifetime persistence at a very low level that is remarkably stable over time. Mathematically, this is a stable fixed point where the mechanisms regulating persistence drive the state back to equilibrium when perturbed. This is the GCM of EBV persistence. Other possible sites and mechanisms of persistence will also be discussed.

Epstein-Barr virus and nasopharyngeal carcinoma

Since its discovery 50 years ago, Epstein-Barr virus (EBV) has been linked to the development of cancers originating from both lymphoid and epithelial cells. Approximately 95% of the world's population sustains an asymptomatic, life-long infection with EBV. The virus persists in the memory B-cell pool of normal healthy individuals, and any disruption of this interaction results in virus-associated B-cell tumors. The association of EBV with epithelial cell tumors, specifically nasopharyngeal carcinoma (NPC) and EBV-positive gastric carcinoma (EBV-GC), is less clear and is currently thought to be caused by the aberrant establishment of virus latency in epithelial cells that display premalignant genetic changes. Although the precise role of EBV in the carcinogenic process is currently poorly understood, the presence of the virus in all tumor cells provides opportunities for developing novel therapeutic and diagnostic approaches. The study of EBV and its role in carcinomas continues to provide insight into the carcinogenic process that is relevant to a broader understanding of tumor pathogenesis and to the development of targeted cancer therapies.

Epstein-Barr virus BART gene expression

Introns from the Epstein-Barr virus (EBV) BART RNAs produce up to 20 micro RNAs (miRNAs) but the spliced exons of the BART RNAs have also been investigated as possible mRNAs, with the potential to express the RPMS1 and A73 proteins. Recombinant RPMS1 and A73 proteins were expressed in Escherichia coli and used to make new monoclonal antibodies that reacted specifically with artificially expressed RPMS1 and A73. These antibodies did not detect endogenous expression of A73 and RPMS1 proteins in a panel of EBV-infected cell lines representing the different known types of EBV infection. BART RNA could not be detected on Northern blots of cytoplasmic poly(A)(+) RNA from the C666.1 NPC cell line and BART RNA was found to be mainly in the nucleus of C666.1 cells, arguing against an mRNA role for BART RNAs. In contrast, some early lytic cycle EBV mRNAs were found to be expressed in C666.1 cells. Artificially expressed A73 protein was known to be able to bind to the cellular RACK1 protein and has now also been shown to be able to regulate calcium flux, presumably via RACK1. Overall, the results support the conclusion that the miRNAs are functionally important products of BART transcription in the cell lines studied because the A73 and RPMS1 proteins could not be detected in natural EBV infections. However, the possibility remains that A73 and RPMS1 might be expressed in some situations because of the clear potential relevance of their biochemical functions.

Cancer patterns in Inuit populations

Inuit people inhabit the circumpolar region, with most living in Alaska, northwest Canada, and Greenland. Although malignant diseases were believed to be almost non-existent in Inuit populations during the beginning of the 20th century, the increasing life expectancy within these populations showed a distinct pattern, characterised by a high risk of Epstein-Barr virus-associated carcinomas of the nasopharynx and salivary glands, and a low risk of tumours common in white populations, including cancer of the prostate, testis, and haemopoietic system. Both genetic and environmental factors seem to be responsible for this pattern. During the second half of the 20th century, Inuit societies underwent major changes in lifestyle and living conditions, and the risk of lifestyle-associated tumours, especially cancers of the lung, colon, and breast, increased considerably after changes in smoking, diet, and reproductive factors. This Review will briefly summarise the current knowledge on cancer epidemiology in Inuit populations, with emphasis on the characteristic Inuit types of cancer.

Sporadic EBV-associated lymphoepithelial salivary gland carcinoma with EBV-positive low-grade myoepithelial component

Salivary gland lymphoepithelial carcinomas (LECs) are associated with Epstein-Barr virus (EBV) in endemic areas, whereas sporadic cases are usually EBV negative. We have studied two EBV-associated LECs from Caucasian patients for their EBV gene expression profile and their immunophenotype. Tumour cells of case 1 showed expression of EBNA1 only, corresponding to an EBV latency type I. Tumour cells of this case expressed various basal and glandular cytokeratins. In case 2, the LEC was accompanied by a low-grade spindle cell lesion with an immunophenotype of myoepithelial cells, whereas the high-grade tumour expressed cytokeratin (Ck) 8 only. In case 2, the high-grade tumour showed an EBV lantency II pattern with expression of EBNA1, LMP1 and LMP2A (latency II). The spindle cell lesion of this case was also EBV-infected and showed low levels of EBNA1 and LMP1 expression, while LMP2A was not detectable. The detection of EBV in both components of case 2 together with immunophenotypic evidence of transition between both components supports the notion that at least some LECs arise through a low-grade myoepithelial intermediate. Expression of LMP2A may be of therapeutic interest because it may make such cases amenable to immunotherapy with EBV-specific cytotoxic T cells.

Cancer susceptibility in nasopharyngeal carcinoma families--a population-based cohort study

Undifferentiated nasopharyngeal carcinoma is a result of environmental factors, in particular EBV infection, affecting genetically susceptible individuals. The familial risk of nasopharyngeal carcinoma is among the highest of any malignancy. Whether this susceptibility is restricted to nasopharyngeal carcinoma is unknown as information on the risk of other cancers in relatives is limited. We did a population-based study of the cancer incidence in nasopharyngeal carcinoma families in Greenland, a nasopharyngeal carcinoma-endemic area. Using population-based registers, a cohort of all persons born in Greenland was followed from 1973 to 2002. In this cohort, 134 individuals developed nasopharyngeal carcinoma and their relatives were identified through registers and interviews. Subsequently, the occurrence of cancer was determined by linkage to the population-based cancer register and the risk of cancer in nasopharyngeal carcinoma relatives and nonrelatives compared by relative risks. Among 766 first-degree relatives, the relative risk of nasopharyngeal carcinoma following the family index case was 8.0 [95% confidence interval (95% CI), 4.1-14.0]. Sex and age of the relative or the index case had no modifying effect on the familial risk of nasopharyngeal carcinoma. The relative risks of carcinoma of the salivary glands, 8.4 (95% CI, 2.7-19.5), and uterine cervix, 2.2 (95% CI, 1.1-3.9), were also significantly increased. In families with multiple cases of nasopharyngeal carcinoma, the risk of other cancers than nasopharyngeal carcinoma was further increased. These results indicate that the increased risk of cancer in nasopharyngeal carcinoma families is not restricted to nasopharyngeal carcinoma, but extends to the virally associated cancers of the salivary glands and cervical uteri.

Diagnostic application of Epstein-Barr virus-encoded RNA in situ hybridisation

AIMS

Epstein-Barr virus (EBV) has been implicated in the pathogenesis of nasopharyngeal carcinoma and a range of proliferative lymphoid conditions. In situ hybridisation (ISH) looking for virus-encoded RNA (EBER) transcripts is performed simply using a commercially available probe. We aimed to examine the application of this test in a routine diagnostic setting.

METHODS

In total, 26 cases in which EBV ISH was requested for diagnostic purposes were examined. We looked at the indication for testing, the result and its implication for the final diagnosis.

RESULTS

Cases were classified into three categories: possible nasopharyngeal carcinoma; possible EBV-related lymphoma; and possible immunodeficiency-associated lymphoproliferative disorder. Six of nine cases of possible nasopharyngeal carcinoma were EBV ISH positive (3/3 primary and 3/6 secondary), confirming the diagnosis. Three of 14 possible lymphoma cases were EBV ISH positive which, along with appropriate ancillary tests, assisted in making the diagnoses of Burkitt's lymphoma, lymphomatoid granulomatosis and extranodal NK/T-cell lymphoma of nasal type. All of three immunodeficiency-associated cases were EBV ISH positive. Two of these were post-transplant lymphoproliferative disorders, monomorphic type. The third case was classified as HIV-related polymorphic lymphoproliferative disorder.

CONCLUSIONS

In our experience, EBV ISH is a straightforward and rapid procedure to perform, giving unequivocal results. Used in the appropriate clinicopathological setting it can be a highly useful ancillary diagnostic aid.

Epstein-Barr virus in head and neck cancer assessed by quantitative polymerase chain reaction

OBJECTIVES/HYPOTHESIS

Epstein-Barr virus (EBV) has classically been associated with nasopharyngeal carcinoma and Burkitt's lymphoma. Recently, multiple studies have been published linking EBV with oral squamous cell carcinoma and, to a lesser extent, hypopharyngeal and laryngeal tumors. Using a sensitive method of detection, the authors sought to analyze the presence and quantity of EBV DNA in a large cohort of head and neck cancers.

STUDY DESIGN

: Retrospective cohort study.

METHODS

Three hundred head and neck cancer samples exclusive of nasopharyngeal carcinoma were examined for the presence of EBV using quantitative polymerase chain reaction. Eighty-four tumor samples from the larynx, 30 from the hypopharynx, 73 from the oropharynx, and 113 from the oral cavity were analyzed for EBV quantity, which was expressed as the number of viral copies per cell genome. Representative samples, which contained the highest EBV DNA levels, were examined using in situ hybridization. Results were correlated with tumor grade and site and tobacco and alcohol exposure.

RESULTS

Three of 300 (1%) tumor samples were overtly positive for EBV DNA (defined as >0.1 copies of viral DNA/cell genome). Five of 300 (2%) tumor samples showed low levels (defined as >0.01 and <0.1 copies of viral DNA/cell genome), and 68 of 300 tumor samples (23%) showed trace levels (defined as < 0.01 copies of viral DNA/cell genome) of EBV DNA. No correlation was found between EBV positivity and tobacco exposure, alcohol exposure, or tumor grade.

CONCLUSION

In the overwhelming majority of head and neck cancers in this North American cohort, EBV did not appear to contribute to growth of a dominant clonal population with integrated EBV genome and was unlikely to be a genetic etiological agent in tumor development. The low quantities of EBV detected in a minority of head and neck cancers may be related to the presence of EBV genome in rare lymphoid or epithelial cells adjacent to the primary head and neck cancer.

Occupational Exposures and Salivary Gland Cancer Mortality Among African American and White Workers in the United States

We conducted a large death certificate-based case-control study to assess occupational risks for salivary gland cancer. African American (168 cases, 672 controls) and white (2237 cases, 8748 controls) cases from 24 states (1984-1989) were matched to controls by age, sex, race, and region. Race- and sex-stratified multiple logistic regression models calculated adjusted odds ratios. The proportion of young cases (<50 years) was greatest among African Americans (20.8% vs. 8.8%). Higher socioeconomic status, ionizing radiation, formaldehyde, solvents, outdoor work, and animal contact were associated with elevated risk among white men. Physical activity reduced mortality risks among men, although significantly only among whites. Odds ratios for formaldehyde, solvents, benzene, and animal contact were 2.0 or greater among African American women, although not statistically significant. These findings suggest occupational and demographic factors needing further investigation.

[Undifferentiated salivary gland carcinomas]

Undifferentiated salivary gland carcinomas may be divided into small cell and large cell types. Among large cell undifferentiated carcinomas, lymphoepithelial carcinomas have to be distinguished, the latter of which are endemic in the Arctic regions and southern China where virtually all cases of these tumors are associated with the Epstein-Barr virus (EBV). Association with EBV may also be observed in sporadic cases, and detection of EBV gene products may aid their diagnosis. Immunohistology may be employed to resolve the differential diagnosis of undifferentiated salivary gland carcinomas, comprising malignant lymphomas, amelanotic melanomas, Merkel cell carcinomas, and adenoid cystic carcinomas, in particular in small biopsy materials. Because of the rarity of undifferentiated salivary gland carcinomas, the differential diagnosis should always include metastases of undifferentiated carcinomas arising at other primary sites, particularly when expressing the thyroid transcription factor-1 (TTF-1).

Host cell-dependent expression of latent Epstein-Barr virus genomes: regulation by DNA methylation

Epstein-Barr virus (EBV) is a ubiquitous human gammaherpesvirus associated with a wide spectrum of malignant neoplasms. Expression of latent (growth transformation-associated) EBV genes is host cell specific. Transcripts for EBV-encoded nuclear antigens (EBNAs) are initiated at one of the alternative promoters: Wp, Cp (for EBNA1-6), or Qp (for EBNA1 only). Wp is active shortly after EBV infection of human B cells in vitro but is progressively methylated and silenced in established lymphoblastoid cell lines (LCLs). In parallel Cp, an unmethylated, lymphoid-specific promoter is switched on. In contrast, Cp is methylated and silent in Burkitt's lymphoma (BL) cell lines, which keep the phenotype of BL biopsy cells (group I BL lines). These cells use Qp for the initiation of EBNA1 messages. Qp is unmethylated both in group I BLs (Qp on) and in LCLs (Qp off). Thus, DNA methylation does not play a role in silencing Qp. In LCLs and nasopharyngeal carcinoma (NPC) cells, transcripts for latent membrane protein 1 (LMP1) are initiated from LMP1p, a promoter regulated by CpG methylation. LMPlp is silent in group I BL lines but can be activated by demethylating agents. Promoter silencing by CpG methylation involves both direct interference with transcription factor binding (Wp, Cp) and indirect mechanisms involving the recruitment of histone deacetylases (LMPlp). A dyad symmetry sequence(DS) within oriP (the latent origin of EBV replication) and intragenic RNA polymerase III control regions of EBER 1 and 2 transcription units are invariably unmethylated in EBV-carrying cells.

Epstein-Barr virus and oncogenesis: from latent genes to tumours

Epstein-Barr virus (EBV) is a ubiquitous human herpesvirus associated with the development of both lymphoid and epithelial tumours. As a common virus infection, EBV appears to have evolved to exploit the process of B cell development to persist as a life-long asymptomatic infection. However, the virus can contribute to oncogenesis as evidenced by its frequent detection in certain tumours, namely Burkitt's lymphoma (BL), post-transplant B cell lymphomas, Hodgkin's disease (HD) and nasopharyngeal carcinoma (NPC), and by its unique ability to efficiently transform resting B cells in vitro into permanently growing lymphoblastoid cell lines (LCLs). These transforming effects are associated with the restricted expression of EBV genes such that only a subset of so-called latent virus proteins are expressed in virus infected tumours and in LCLs. Distinct forms of EBV latency are manifest in the different tumours and these appear to be a vestige of the pattern of latent gene expression used by the virus during the establishment of persistent infection within the B cell pool. This review summarises our current knowledge of EBV latent gene function and how this relates to the role of the virus in the aetiology of different tumours.

Updated Epstein-Barr virus (EBV) DNA sequence and analysis of a promoter for the BART (CST, BARF0) RNAs of EBV

Two sequences required for activity of the Epstein-Barr virus BART RNA promoter in transfection assays have been identified by site-directed mutagenesis. One contains a consensus AP-1 site; the other has some similarity to Ets and Stat consensus binding sites. Candidate sequences were suggested by mapping a region of unmethylated DNA in EBV around the BART promoter followed by in vivo footprinting the promoter in the C666-1 nasopharyngeal carcinoma cell line, which expresses BART RNAs. The data are presented in the context of a revised EBV DNA sequence, known as EBV wt, that is proposed as a future standard sequence for EBV.

Epstein-Barr virus-recent advances

Epstein-Barr virus is a tumorigenic herpes virus that is ubiquitous in the adult population. The virus is generally spread to and between young children through salivary contact, and only causes clinical illness where primary infection is delayed until adolescence or beyond, when an intense immunopathological reaction leads to the symptoms of infectious mononucleosis in roughly 50% of cases. More than 90% of the world's population carry Epstein-Barr virus as a life-long, latent infection of B lymphocytes. Recent data show that by mimicking B-cell antigen-activation pathways the virus enters the long-lived memory B lymphocyte pool where it evades immune elimination by severely restricting its own gene expression. By influencing B-cell survival mechanisms Epstein-Barr virus may induce tumours such as B lymphoproliferative disease and Hodgkin's disease. Vaccines are being developed to prevent and/or treat these conditions, but an animal model is required to study pathogenesis before a rational vaccine strategy can be formulated.

Pathogenic roles for Epstein-Barr virus (EBV) gene products in EBV-associated proliferative disorders

Epstein-Barr virus (EBV) is associated with a still growing spectrum of clinical disorders, ranging from acute and chronic inflammatory diseases to lymphoid and epithelial malignancies. Based on a combination of in vitro and in vivo findings, EBV is thought to contribute in the pathogenesis of these diseases. The different EBV gene expression patterns in the various disorders, suggest different EBV-mediated pathogenic mechanisms. In the following pages, an overview of the biology of EBV-infection is given and functional aspects of EBV-proteins are discussed and their putative role in the various EBV-associated disorders is described. EBV gene expression patterns and possible pathogenic mechanisms are discussed. In addition, expression of the cellular genes upregulated by EBV in vitro is discussed, and a comparison with the in vivo situation is made.

Epstein-Barr virus latent membrane protein-1 (LMP-1) expression in oral squamous cell carcinoma

OBJECTIVES

Epstein-Barr virus (EBV) is frequently associated with malignant cell transformation through the action of the oncoprotein latent membrane protein-1 (LMP-1). The present study aimed to determine the presence of EBV in oral squamous cell carcinomas (OSCCs) and the expression of LMP-1 in neoplastic cells of EBV-positive OSCCs.

STUDY DESIGN/METHODS

In a retrospective study of 78 OSCCs, we investigated the presence of the DNA of EBV by polymerase chain reaction, the expression of the oncoprotein LMP-1 by immunohistochemistry, and the presence of EBV-encoded RNA (EBER) by in situ hybridization.

RESULTS

EBV DNA was detected in 19.2% of the cases. Expression of LMP-1 in neoplastic cells was found in 85.7% of the EBV-positive OSCCs. EBV presence was significantly more frequent (P <.05) in OSCCs localized on the lateral tongue. EBV-positive OSCCs more frequently presented (P <.05) greater nuclear atypia.

CONCLUSION

EBV can appear in latent form in OSCC and express its main oncoprotein, LMP-1.

Epstein-Barr virus complementary strand transcripts (CSTs/BARTs) and cancer

Epstein-Barr virus (EBV) encodes a family of related transcripts, the complementary strand transcripts (CSTs) or BARTs (Bam A rightward transcripts). These are present in all types of EBV infection but are expressed to particularly high levels in nasopharyngeal carcinomas. Although convincing demonstration of protein expression from these transcripts is still subject to some debate, potential proteins encoded by them have been shown to modify Notch signalling pathways.

The LMP2A ITAM is essential for providing B cells with development and survival signals in vivo

In Epstein-Barr virus-transformed B cells, known as lymphoblastoid cell lines (LCLs), LMP2A binds the tyrosine kinases Syk and Lyn, blocking B-cell receptor (BCR) signaling and viral lytic replication. SH2 domains in Syk mediate binding to a phosphorylated immunoreceptor tyrosine-based activation motif (ITAM) in LMP2A. Mutation of the LMP2A ITAM in LCLs eliminates Syk binding and allows for full BCR signaling, thereby delineating the significance of the LMP2A-Syk interaction. In transgenic mice, LMP2A causes a developmental alteration characterized by a block in surface immunoglobulin rearrangement resulting in BCR-negative B cells. Normally B cells lacking cognate BCR are rapidly apoptosed; however, LMP2A transgenic B cells develop and survive without a BCR. When bred into the recombinase activating gene 1 null (RAG(-/-)) background, all LMP2A transgenic lines produce BCR-negative B cells that develop and survive in the periphery. These data indicate that LMP2A imparts developmental and survival signals to B cells in vivo. In this study, LMP2A ITAM mutant transgenic mice were generated to investigate whether the LMP2A ITAM is essential for the survival phenotype in vivo. LMP2A ITAM mutant B cells develop normally, although transgene expression is comparable to that in previously described nonmutated LMP2A transgenic B cells. Additionally, LMP2A ITAM mutant mice are unable to promote B-cell development or survival when bred into the RAG(-/-) background or when grown in methylcellulose containing interleukin-7. These data demonstrate that the LMP2A ITAM is required for LMP2A-mediated developmental and survival signals in vivo.

Human herpesvirus type 8 in salivary gland tumors

BACKGROUND

The new human herpesvirus type 8 (HHV-8) has been detected in all types of Kaposi's sarcomas, as well as in body-cavity lymphomas and Castleman's disease, furthermore molecular biologic studies have identified a number of potential viral oncogenes. There is evidence for sexual transmission of HHV-8 in HIV-seropositive patients, but the route of infection among the HIV-seronegative population is uncertain. Findings of HHV-8 DNA in saliva in some cases are suggestive of nonsexual transmission associated with latent infection of the salivary gland (as it is known for EBV, CMV, HHV-6 and HHV-7).

OBJECTIVE

As little is known about the etiological factors of salivary gland tumors and to give more insights into HHV-8 cell tropism normal salivary gland tissue (n=12) and different salivary glands neoplasm (n=58) were tested for HHV-8 sequences and antigens in HIV-seronegative patients.

STUDY DESIGN

Biopsies of both normal salivary gland and tumors were investigated for HHV-8 sequences. A nested-PCR method was used for amplification of HHV-8 DNA fragments and the nature of the amplification products was confirmed by Southern blot hybridization. In addition, we used an in situ hybridization technique and immunohistochemical staining for detection of HHV-8 infected cells. The sera of the respective patients were tested for anti-HHV-8 antibodies using commercial IFA and an ELISA-assay.

RESULTS

HHV-8 DNA sequences could be detected in one bilateral MALT-lymphoma of the parotid gland of a HHV-8 seropositive female patient suffering from Sjögren's syndrome (SS). The remaining parotid samples did neither show HHV-8 sequences nor HHV-8 antigens. Using above assays only one additional patient was seropositive for HHV-8.

CONCLUSION

Our data suggest that HHV-8 does not usually infect the salivary gland in HIV-seronegative patients and does not seem to play a pathogenic role in vascular and epithelial salivary gland neoplasm. Pathogenic role of HHV-8 in Sjögren's syndrome associated MALT-lymphoma remains unclear and should be subject of further studies.

Structure and coding content of CST (BART) family RNAs of Epstein-Barr virus

CST (BART BARF0) family viral RNAs are expressed in several types of Epstein-Barr virus (EBV) infection, including EBV-associated cancers. Many different spliced forms of these RNAs have been described; here we have clarified the structures of some of the more abundant splicing patterns. We report the first cDNAs representing a full-length CST mRNA from a clone library and further characterize the transcription start. The relative abundance of splicing patterns and genomic analysis of the open reading frames (ORFs) suggest that, in addition to the much studied BARF0 ORF, there may be important products made from some of the upstream ORFs in the CST RNAs. Potential biological functions are identified for two of these. The product of the RPMS1 ORF is shown to be a nuclear protein that can bind to the CBF1 component of Notch signal transduction. RPMS1 can inhibit the transcription activation induced through CBF1 by NotchIC or EBNA-2. The protein product of another CST ORF, A73, is shown to be a cytoplasmic protein which can interact with the cell RACK1 protein. Since RACK1 modulates signaling from protein kinase C and Src tyrosine kinases, the results suggest a possible role for CST products in growth control, perhaps consistent with the abundant transcription of CST RNAs in cancers such as nasopharyngeal carcinoma.

The Epstein-Barr virus and its association with human cancers

The Epstein-Barr virus (EBV) has been linked to the development of a variety of human malignancies, including Burkitt's lymphoma, Hodgkin's disease, nasopharyngeal carcinoma, some T cell lymphomas, post-transplant lymphoproliferative disease, and more recently, certain cancers of the stomach and smooth muscle. This review summarizes these associations and in particular the role of the viral latent genes in the transformation process.

In vivo models for Epstein-Barr virus (EBV)-associated B cell lymphoproliferative disease (BLPD)

EBV infects B lymphocytes in vivo and establishes a life-long persistent infection in the host. The latent infection is controlled by EBV-specific MHC class 1-restricted CTL. Immunosuppression reduces CTL activity, and this facilitates outgrowth of EBV+ve B cell lymphoproliferative disease (BLPD). BLPD are aggressive lesions with high mortality. This review presents some key facets in the development of EBV-associated BLPD and in vivo studies on its pathogenesis. The animal models used to date include the common marmoset (Callithrix jacchus), the cottontop tamarin (Saguinus oedipus oedipus), rhesus monkey, murine herpesvirus 68 (MHV68), and the severe combined immunodeficient (scid) mouse, each of which has been used to address particular aspects of EBV biology and BLPD development. Scid mice inoculated i.p. with PBMC from EBV-seropositive individuals develop EBV+ve BLPD-like tumours. Thus this small animal model (hu-PBMC-scid) is currently used by many laboratories to investigate EBV-associated diseases. We and others have studied BLPD pathogenesis in the hu-PBMC-scid model and shown that EBV+ve B cells on their own do not give rise to tumours in this model without inclusion of autologous T cell subsets in the inoculum. Based on the findings that (1) established tumours do not contain T cells and (2) tumour cells express a variety of B cell growth factors, a stepwise model of lymphomagenesis in the scid mouse model can be defined. Additionally, the hu-PBMC-scid model can be used to assess novel therapeutic regimes against BLPD before introduction into a clinical setting.

Detection of Epstein-Barr virus in invasive breast cancers

BACKGROUND

Epstein-Barr virus (EBV) may be a cofactor in the development of different malignancies, including several types of carcinomas. In this study, we investigated the presence of EBV in human breast cancers.

METHODS

We used tissues from 100 consecutive primary invasive breast carcinomas, as well as 30 healthy tissues adjacent to a subset of the tumors. DNA was amplified by use of the polymerase chain reaction (PCR), with the primers covering three different regions of the EBV genome. Southern blot analysis was performed by use of a labeled EBV BamHI W restriction fragment as the probe. Infected cells were identified by means of immunohistochemical staining, using monoclonal antibodies directed against the EBV nuclear protein EBNA-1.

RESULTS

We were able to detect the EBV genome by PCR in 51% of the tumors, whereas, in 90% of the cases studied, the virus was not detected in healthy tissue adjacent to the tumor (P<.001). The presence of the EBV genome in breast tumors was confirmed by Southern blot analysis. The observed EBNA-1 expression was restricted to a fraction (5%-30%) of tumor epithelial cells. Moreover, no immunohistochemical staining was observed in tumors that were negative for EBV by PCR. EBV was detected more frequently in breast tumors that were hormone-receptor negative (P =.01) and those of high histologic grade (P =.03). EBV detection in primary tumors varied by nodal status (P =.01), largely because of the difference between subjects with more than three lymph nodes versus less than or equal to three lymph nodes involved (72% versus 44%).

CONCLUSIONS

Our results demonstrated the presence of the EBV genome in a large subset of breast cancers. The virus was restricted to tumor cells and was more frequently associated with the most aggressive tumors. EBV may be a cofactor in the development of some breast cancers.

Herpesvirus infection of inflammatory cells in human periodontitis

Human cytomegalovirus (HCMV) and Epstein-Barr virus type 1 (EBV-1) are frequently detected in human periodontitis lesions. However, no information is available on the types of gingival cells infected by herpesviruses. The present study determined the presence of herpesviruses in polymorphonuclear neutrophils, monocytes, macrophages and T and B lymphocytes in biopsies of periodontitis lesions from 20 adults. A nested polymerase chain reaction method was employed to detect HCMV, EBV-1, EBV-2, human herpes virus-6 and herpes simplex virus (HSV) in periodontal tissue biopsy and in gingival cell fractions separated by immunomagnetic cell sorting. Tissue specimens from 18 (90%) and cell fractions from 14 (70%) patients demonstrated herpesviruses. Periodontitis-derived monocytes and macrophages revealed HCMV in cell fractions from 11 (55%) patients and HSV in cells from 1 (5%) patient. T lymphocytes harbored HCMV in cell fractions from 4 (20%) patients and HSV in cell fractions from 4 (20%) patients. B lymphocytes showed EBV-1 in cell fractions from 9 (45%) patients. Periodontal polymorphonuclear neutrophils demonstrated no herpesviruses. This study suggests that HCMV mainly infects periodontal monocytes, macrophages and less frequently T lymphocytes and that EBV-1 infects periodontal B lymphocytes. The possible etio-pathologic significance of periodontal herpesvirus infection is discussed.

Characterization of Epstein-Barr virus (EBV)-infected natural killer (NK) cell proliferation in patients with severe mosquito allergy; establishment of an IL-2-dependent NK-like cell line

The clinical evidence of a relationship between severe hypersensitivity to mosquito bite (HMB) and clonal expansion of EBV-infected NK cells has been accumulated. In order to clarify the mechanism of EBV-induced NK cell proliferation and its relationship with high incidence of leukaemias or lymphomas in HMB patients, we studied clonally expanded NK cells from three HMB patients and succeeded in establishing an EBV-infected NK-like cell line designated KAI3. Immunoblotting and reverse transcriptase-polymerase chain reaction (RT-PCR) analyses revealed that KAI3 cells as well as infected NK cells exhibited an EBV latent infection type II, where EBV gene expression was limited to EBNA 1 and LMP1. As KAI3 was established by culture with IL-2, IL-2 responsiveness of peripheral blood NK cells from patients was examined. The results represented markedly augmented IL-2-induced IL-2R alpha expression in NK cells. This characteristic property may contribute to the persistent expansion of infected NK cells. However, KAI3 cells as well as the NK cells from patients were not protected from apoptosis induced by either an anti-Fas antibody or NK-sensitive K562 cells. Preserved sensitivity to apoptosis might explain the relatively regulated NK cell numbers in the peripheral blood of the patients. To our knowledge, KAI3 is the first reported NK-like cell line established from patients of severe chronic active EBV infection (SCAEBV) before the onset of leukaemias or lymphomas. KAI3 cells will contribute to the study of EBV persistency in the NK cell environment and its relationship with high incidence of leukaemias or lymphomas in HMB patients.

Cancer risk in a cohort of Danes working in Greenland

Greenland is a high-incidence area for certain virus-associated cancers. The long term cancer risk in a cohort of 7,761 Danish employees who had been working for some time (median 19.7 months) in Greenland during the period 1955-1978 was studied. During a total of 162,300 person-years (average 20.9 years) of follow-up ending on December 31, 1992, the number of cancers observed was 732 vs. 669 expected (relative risk (RR) = 1.09, 95% confidence interval (CI) 1.02-1.18). Whereas the men did not experience any unusual cancer incidence at any cancer site, the women were at elevated risk of developing breast cancer (RR = 1.5, 95% CI 1.2-1.8 (n = 96)); malignant melanoma (RR = 1.8, 95% CI 1.0-2.9 (n = 16)); and lymphatic and hematopoietic malignancies (RR = 1.7, 95% CI 1.0-2.8 (n = 16)). Exposure during adulthood to a high-incidence area for cervical cancer, nasopharyngeal carcinoma and tumors of the major salivary glands did not confer any measurable increase in the risk for these virus-associated cancers. Postponement of childbearing might explain part of the elevated breast cancer risk. Intensive exposure to ultraviolet light, that is likely to explain the increased risk of malignant melanoma among the women, might also be involved in the excess incidence of lymphatic and hematopoietic malignancies observed in these women. However, why the men did not experience similar alterations in the risk of melanoma and cancers of the immune system is enigmatic.

Epstein-Barr virus infection in the neoplastic and nonneoplastic cells of lymphoid malignancies

BACKGROUND

The Epstein-Barr virus (EBV) has been frequently detected in lymphoid malignancies. However, EBV infection in the nonneoplastic cells of lymphoid malignancies has not been extensively studied.

METHODS

Four hundred nine cases of lymphoid malignancies including 377 non-Hodgkin's lymphoma (NHL) and 32 Hodgkin's disease (HD) were examined for EBV infection by EBER-1 in situ hybridization (EBER-ISH), immunostaining against LMP-1, Epstein-Barr nuclear antigen 2 (EBNA2) and ZEBRA, and Southern hybridization using a BamHIW fragment as a probe. Double staining with EBER-ISH and immunostaining against CD20, CD45RO, and LMP-1 was performed in selected cases.

RESULTS

Although EBER-1-positive cells (EPCs) were detected in 49 of 276 B-cell lymphomas, 31 of 100 T-cell lymphomas, 1 of 1 natural killer-cell lymphoma, and 17 of 32 HDs, almost all of the tumor cells were exclusively EBER-1-positive in the 10 NHL cases. Some EPCs were of different cell lineages than the tumor cells in 15 of the 26 NHLs examined by double staining. LMP-1, EBNA2, and ZEBRA were detected in 22, 4, and 3 cases, respectively. In 4 LMP-1-positive HDs, double staining revealed that some EBER-1-positive Reed-Sternberg cells were negative for LMP-1, EBV genomic DNA was detected in 8 of the 39 examined cases.

CONCLUSIONS

T-cell lymphomas contained EPCs more frequently than B-cell lymphomas. Nonneoplastic lymphocytes were infected with EBV more frequently than lymphoma cells. Rowe's latency II may be unstable in lymphoid malignancies. Some NHLs, especially T-cell lymphoma, may provide favorable conditions for EBV infection of nonneoplastic lymphocytes.

The ecology and pathology of Epstein-Barr virus

Epstein-Barr virus achieves its ubiquitous and uniform epidemiological distribution by a dual strategy of latency to guarantee lifelong persistence and intermittent replication to guarantee transmission. These two functions appear to dictate residence in different cell types: latency in B lymphocytes and replication in epithelial cells. Both of these cell compartments are potential sites for EBV-associated malignancies.

Lymphoepithelial carcinoma of the salivary gland: in situ detection of Epstein-Barr virus

AIM

To examine the role of Epstein-Barr virus (EBV) in lymphoepithelial carcinoma of the salivary gland in Hong Kong Chinese.

METHODS

Ten cases of lymphoepithelial carcinoma of the salivary gland (eight parotid and two submandibular) were examined. In situ hybridisation was used to localise EBER RNA, immunohistochemical methods to detect expression of latent membrane protein 1 (LMP-1) in EBV positive tumours, and Southern blot analysis to examine the clonality of EBV in the two cases where frozen tissue was available.

RESULTS

None of the cases had a history of Sjögren's syndrome or histological evidence of a benign lymphoepithelial lesion. The IgA antibody titre against EBV viral capsid antigen was elevated in four cases. All cases were EBV positive by in situ hybridisation, with a strong uniform positive signal in the epithelial cells, and all cases expressed LMP-1. Southern blot analysis revealed that the clonal episomal form of the virus was present. Two of the three female patients in this series also developed carcinoma of cervix. One of these carcinomas had histological features of a lymphoepithelioma-like carcinoma but was EBV negative.

CONCLUSIONS

A consistent association between EBV and lymphoepithelial carcinoma of the salivary gland was found. The presence of the virus in a clonal episomal form, and the expression of LMP-1 viral oncoprotein is further evidence of the role of EBV in the oncogenesis of this tumour.

Immune regulation in Epstein-Barr virus-associated diseases

Epstein-Barr virus (EBV) is a member of the human herpesvirus family and, like many other herpesviruses, maintains a lifelong latent association with B lymphocytes and a permissive association with stratified epithelium in the oropharynx. Clinical manifestations of primary EBV infection range from acute infectious mononucleosis to an asymptomatic persistent infection. EBV is also associated with a number of malignancies in humans. This review discusses features of the biology of the virus, both in cell culture systems and in the natural host, before turning to the role of the immune system in controlling EBV infection in healthy individuals and in individuals with EBV-associated diseases. Cytotoxic T cells that recognize virally determined epitopes on infected cells make up the major effector arm and control the persistent infection. In contrast, the options for immune control of EBV-associated malignancies are more restricted. Not only is antigen expression restricted to a single nuclear antigen, EBNA1, but also these tumor cells are unable to process EBV latent antigens, presumably because of a transcriptional defect in antigen-processing genes (such as TAP1 and TAP2). The likelihood of producing a vaccine capable of controlling the acute viral infection and EBV-associated malignancies is also discussed.

Detection of Epstein-Barr Virus Genome in Sinonasal Undifferentiated Carcinoma by Use of in Situ Hybridization

Associations between Epstein-Barr virus and undifferentiated carcinomas of nasopharynx, parotid gland, and thymus have recently been reported. Epstein-Barr virus has also been associated with malignant lymphoma of the nose and paranasal sinuses. These findings raise the possibility that Epstein-Barr virus may additionally be linked to undifferentiated carcinoma of the nose and paranasal sinuses (SNUC), an uncommon but distinctive and highly aggressive neoplasm. Histologically, SNUC consists of small and medium cells, the precise characterization of which often requires immunocytochemical analysis. This study investigates the presence of DNA sequences of Epstein-Barr virus in biopsy specimens of 13 cases of SNUC that were defined immunocytochemically by use of previously reported criteria. In situ hybridization was used to detect Epstein-Barr virus genome in different cell types in routinely processed, paraffin-embedded tissues. Epstein-Barr virus-specific DNA sequences were detected in tumor cells of SNUC specimens from 5 of the 13 cases examined. No correlation was found between positive hybridization and primary tumor site, morphologic subtype, or disease course. Epstein-Barr virus DNA was detected in 38% (5 of 13) of the SNUC samples analyzed. This finding suggests that this virus may play a role in the pathogenesis of this rare neoplasm.

Epstein-Barr virus (EBV) infection and undifferentiated carcinoma of the parotid gland in Caucasian patients

The Epstein-Barr virus (EBV) has been detected in certain types of lymphoma and some epithelial neoplasms such as nasopharyngeal lymphoepithelioma and occasional undifferentiated carcinomas in several organs including the salivary glands. However, clonal EBV genomes have been detected in undifferentiated carcinomas of the parotid gland exclusively in Alaskan natives and Eskimos, both groups being at the highest risk for nasopharyngeal carcinoma. The authors investigated the possibility that EBV may be present in undifferentiated parotid carcinomas in Caucasian subjects. To test this hypothesis, in situ hybridization (ISH) technique with biotinylated EBV-DNA probes was utilized on routinely processed, paraffin-embedded tissues from 7 cases of undifferentiated carcinomas of the parotid gland. EBV genomes were demonstrated in the cytoplasm of tumor cells from 3 out of 7 specimens tested. Surprisingly, EBV genomes were found in 3 out of 5 (60%) undifferentiated carcinomas that had developed in patients with a history of a long-persisting asymptomatic parotid mass, which had suddenly increased in size. Conversely, none of the undifferentiated carcinomas with continuous and rapid growth studied was found to be positive for EBV-DNA by ISH technique. Taken together, these data might suggest a possible role of EBV in the transformation of benign parotid gland lesions into malignant and aggressive undifferentiated carcinoma of the parotid gland, the so-called carcinoma expleomorphic adenoma.

Detection and characterization of Epstein-Barr virus in clinical specimens

Epstein-Barr virus (EBV) is associated with a wide spectrum of benign and malignant diseases. Recent additions to the list include oral hairy leukoplakia; a subset of Hodgkin's lymphomas, particularly those with mixed cellularity histology or those occurring in underdeveloped countries; a subset of diffuse large cell/immunoblastic lymphoma in the immunocompromised, particularly primary central nervous system lymphoma; a subset of peripheral T cell lymphomas; and a subset of gastric carcinomas, particularly undifferentiated carcinomas. There are several distinctive aspects of the biology of the virus that are important in investigations of virus in clinical specimens. The presence of repeated elements in the genome facilitates detection of viral nucleic acids by a variety of hybridization techniques as well as the characterization of the clonality of virus-infected tissues. Latent viral infection is associated with several different patterns of viral gene expression in infected cells. Latent gene products are important because of their growth-regulating and -transforming properties as well as the potent cytotoxic T cell response they elicit. The abundant expression of the EBER RNA transcripts makes possible the sensitive detection of latent infection in EBV-associated tumors. Lytic infection can be inhibited by antiviral nucleoside analogues. Two lytic gene products are of special interest because of their homology to the cellular proteins BCL-2 and interleukin-10. Two viral biotypes or strains with different properties in terms of lymphocyte immortalization and transformation have recently been characterized. Current evidence suggests a differential biotype association with particular malignancies. Characterization of the association of EBV with various disease processes promises to be important for diagnosis and treatment as well as for a better understanding of the epidemiology and pathogenesis of these diabetes.