Molecular Epidemiology of Epstein–Barr Virus Infection

A brief overview of the Epstein Barr virus and its association with Burkitt's lymphoma

Epstein Barr virus (EBV) is known as an oncovirus and associates with several human malignancies such as Burkitt's lymphoma, other non-Hodgkin lymphomas, nasopharyngeal carcinoma, Hodgkin's disease, gastric adenocarcinoma, etc. in Burkitt's lymphoma, and the key event is the translocation of MYC gene, that increase of cell survival and aberrant expression of MYC gene. The biology of EBV and its function in the development of Burkitt's lymphoma are discussed in this review

[Epstein-Barr virus (Herpesviridae: Gammaherpesvirinae: Lymphocryptovirus: Human gammaherpesvirus 4) in Kalmyks and Slavs living in Russia: virus types, LMP1 oncogene variants, and malignancies]

INTRODUCTION

The discovery of the Epstein-Barr virus types (Herpesviridae: Gammaherpesvirinae: Lymphocryptovirus: Human gammaherpesvirus 4) (EBV) - EBV-1 and EBV-2, which have different transforming abilities in vitro, stimulated the study of their prevalence in populations in order to elucidate the relationship with malignant neoplasms.The aims of the work are to study the prevalence of EBV-1 and EBV-2 among representatives of 2 ethnic groups of Russia, Kalmyks and Slavs, sequencing analysis of the LMP1 oncogene in virus isolates, and analysis of the correlation between virus types and the incidence of certain forms of tumors.

MATERIALS AND METHODS

DNA samples were isolated from the biological material of oral swabs obtained from ethnic Kalmyks of the Republic of Kalmykia (RK) (n = 50) and Slavs, residents of the Moscow Region (MR) (n = 40). DNA samples were used to amplify EBV DNA, followed by determination of its concentration per 1 cell of washout, amplification of the LMP1 oncogene in viral samples, their sequencing, and determination of LMP1 protein variants.

RESULTS

It has been established that with the same burden of EBV among representatives of both ethnic groups in the Kalmyk group, the ratio of persons infected with transforming and non-transforming types of the virus was almost the same (EBV-1 - 51%; and EBV-2 - 49%). Meanwhile, in the group of Slavs the transforming EBV-1 type virus dominated (80.6%). The predominance of EBV-1 type in representatives of the Slavs correlated with increased incidence of certain forms of tumors in the population of the MR when compared with similar values in the population of the RK, where both types of the virus were prevalent. Differences between the compared rates of cancer incidence were not statistically significant. Analysis of viral isolates showed a similar set of LMP1 variants in both ethnic groups.

CONCLUSION

In order to establish the influence of EBV types on the incidence of malignant tumors, additional studies involving representatives of various ethnic groups from different geographical regions are needed.

The viral capsid as novel nanomaterials for drug delivery

The purpose of this review is to highlight recent scientific developments and provide an overview of virus self-assembly and viral particle dynamics. Viruses are organized supramolecular structures with distinct yet related features and functions. Plant viruses are extensively used in biotechnology, and virus-like particulate matter is generated by genetic modification. Both provide a material-based means for selective distribution and delivery of drug molecules. Through surface engineering of their capsids, virus-derived nanomaterials facilitate various potential applications for selective drug delivery. Viruses have significant implications in chemotherapy, gene transfer, vaccine production, immunotherapy and molecular imaging.

Role of Bacterial and Viral Pathogens in Gastric Carcinogenesis

Simple Summary

Stomach cancer is one of the most common cancers in the world, with over one million new cases diagnosed in 2020. Despite recent advances in cancer treatments, gastric cancer remains a serious clinical problem. This disease is tightly linked to gastric infections with Helicobacter pylori bacterium, Epstein–Barr virus, and some other less known pathogens. Here, we discuss how gastric pathogens induce tumorigenic changes in the stomach.

Abstract

Gastric cancer (GC) is one of the deadliest malignancies worldwide. In contrast to many other tumor types, gastric carcinogenesis is tightly linked to infectious events. Infections with Helicobacter pylori (H. pylori) bacterium and Epstein–Barr virus (EBV) are the two most investigated risk factors for GC. These pathogens infect more than half of the world’s population. Fortunately, only a small fraction of infected individuals develops GC, suggesting high complexity of tumorigenic processes in the human stomach. Recent studies suggest that the multifaceted interplay between microbial, environmental, and host genetic factors underlies gastric tumorigenesis. Many aspects of these interactions still remain unclear. In this review, we update on recent discoveries, focusing on the roles of various gastric pathogens and gastric microbiome in tumorigenesis.

Sequence Variations of Epstein-Barr Virus-Encoded Small Noncoding RNA and Latent Membrane Protein 1 in Hematologic Tumors in Northern China

OBJECTIVE

To investigate the relationship between hematologic tumors and Epstein-Barr virus (EBV)-encoded small noncoding RNA (EBER) variations as well as latent membrane protein 1 (LMP1) variations.

METHODS

Patients with leukemia and myelodysplastic syndrome (MDS) were selected as subjects. Genotypes 1/2 and genotypes F/f were analyzed using the nested PCR technology, while EBER and LMP1 subtypes were analyzed by the nested PCR and DNA sequencing.

RESULTS

Type 1 was more dominant than type 2, found in 59 out of 82 (72%) leukemia and in 31 out of 35 (88.6%) MDS, while type F was more prevalent than type f in leukemia (83/85, 97.6%) and MDS (29/31, 93.5%) samples. The distribution of EBV genotypes 1/2 was not significantly different among leukemia, MDS, and healthy donor groups, neither was that of EBV genotypes F/f. EB-6m prototype was the dominant subtype of EBER in leukemia and MDS (73.2% [30/41] and 83.3% [10/12], respectively). The frequency of EB-6m was lower than that of healthy people (96.7%, 89/92), and the difference was significant (p < 0.05). China 1 subtype was the dominant subtype of LMP1 in leukemia and MDS (70% [28/40] and 90% [9/10], respectively), and there was no significant difference in the distribution of LMP1 subtypes among the 3 groups (p > 0.05).

CONCLUSION

The distribution of EBV 1/2, F/f, EBER, and LMP1 subtypes in leukemia and MDS was similar to that in the background population in Northern China, which means that these subtypes may be rather region-restricted but not associated with leukemia and MDS pathogenesis.

Differences in the Epstein-Barr Virus gp350 IgA Antibody Response Are Associated With Increased Risk for Coinfection With a Second Strain of Epstein-Barr Virus

BACKGROUND

The Epstein-Barr virus (EBV) viral glycoprotein gp350 has been proposed as a candidate antigen for an EBV vaccine. However, the proposed formulations of these vaccines have not taken into account the presence of 2 unique EBV strains (EBV-1 and EBV-2) present in areas of high incidence of the EBV-associated cancer, Burkitt lymphoma.

METHODS

In this study, we analyze the kinetics of EBV-1 and EBV-2 infection in an asymptomatic infant cohort from Kisumu, Kenya. We also analyzed the kinetics of the antibody response against 5 EBV antigens, gp350 (IgG and IgA), VCA (IgG), EBNA-1 (IgG), EAd (IgG), and Zta (IgG).

RESULTS

We observed a high frequency of coinfection with both EBV types over time, with the only observable defect in the antibody response in infants coinfected being a significantly lower level of anti-gp350 IgA at peak response. Gp350 IgA levels were also significantly lower in coinfected infants 2.5 months postinfection and at the time of coinfection.

CONCLUSIONS

These results suggest that anti-gp350 IgA antibodies may be important for sterilizing immunity against secondary infection. These findings have implications for the development of an efficacious EBV vaccine to prevent both EBV-1 and EBV-2 infection in a population at high risk for Burkitt lymphoma.

Characterization of Epstein-Barr virus-encoded small RNA gene variations in virus associated lymphomas in Northern China

Epstein-Barr virus (EBV)-encoded small RNAs (EBER1 and EBER2) are highly expressed in all forms of EBV latency in EBV-associated malignancies. EBER gene variations and their association with EBV-associated disease still remain poorly characterized. To investigate the patterns of EBER gene variations and their roles in tumorigenesis, EBER gene sequences were analyzed by nested-PCR and DNA sequencing in 101 lymphomas from Northern China, a non-nasopharyngeal carcinoma (NPC) endemic area. In addition, EBV type 1 and type 2 classifications were made by using nested-PCR assays across type-specific regions in the EBNA2 gene. EB-6m was the dominant subtype (95.0%, 96/101) in lymphoma. The distribution of the EBER subtypes in the four lymphoma groups was not significantly different (p > 0.05), neither was that of the EBNA2 type (p > 0.05). Compared with previous data in the same area, the distribution of EBER subtypes in lymphoma was similar to that in EBV-associated gastric carcinoma (EBVaGC) and throat washing (TW) from healthy donors (p > 0.05), but was significantly different from that of NPC. The EBNA2 type distribution between lymphoma and the other three groups was significantly different (p < 0.05). The proportion of type 1 and type 2 dual infections was higher in lymphoma than that in GC, NPC and TW. The mutation 7123nt A → T was identified in 11 of 101 (10.9%, 11/101) lymphomas, significantly more than that in EBV-associated gastric carcinomas (EBVaGC) (0%, 0/50) and throat washings (TWs) from healthy donors (3.3%, 3/92) (p < 0.05). These findings indicate that EBER subtypes may not be associated with pathogenesis of lymphoma, but that a point mutation at position 7123nt (A → T) provides a new area for further exploration. Furthermore it is necessary to investigate the role of EBNA2-subtype mixed infections in the establishment of lymphoma.

Intracellular Nucleic Acid Detection in Autoimmunity

Protective immune responses to viral infection are initiated by innate immune sensors that survey extracellular and intracellular space for foreign nucleic acids. The existence of these sensors raises fundamental questions about self/nonself discrimination because of the abundance of self-DNA and self-RNA that occupy these same compartments. Recent advances have revealed that enzymes that metabolize or modify endogenous nucleic acids are essential for preventing inappropriate activation of the innate antiviral response. In this review, we discuss rare human diseases caused by dysregulated nucleic acid sensing, focusing primarily on intracellular sensors of nucleic acids. We summarize lessons learned from these disorders, we rationalize the existence of these diseases in the context of evolution, and we propose that this framework may also apply to a number of more common autoimmune diseases for which the underlying genetics and mechanisms are not yet fully understood.

Primary immunodeficiencies associated with EBV-Induced lymphoproliferative disorders

Primary immunodeficiency diseases (PIDs) are a subgroup of inherited immunological disorders that increase susceptibility to viral infections. Among the range of viral pathogens involved, EBV remains a major threat because of its high prevalence of infection among the adult population and its tendency to progress to life-threatening lymphoproliferative disorders (LPDs) and/or malignancy. The high mortality in immunodeficient patients with EBV-driven LPDs, despite institution of diverse and often intensive treatments, prompts the need to better study these PIDs to identify and understand the affected molecular pathways that increase susceptibility to EBV infection and progression. In this article, we have provided a detailed literature review of the reported cases of EBV-driven LPDs in patients with PID. We discuss the PIDs associated with development of EBV-LPDs. Then, we review the nature and the therapeutic outcome of common EBV- driven LPDs in the PID patients and review the mechanisms common to the major PIDs. Deep study of these common pathways and gaining a better insight into the disease nature and outcomes, may lead to earlier diagnosis of the disease, choosing the best treatment modalities available and development of novel therapeutic strategies to decrease morbidity and mortality brought about by EBV infection.

Sequence Variation Analysis of Epstein-Barr Virus Nuclear Antigen 1 Gene in the Virus Associated Lymphomas of Northern China

Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1) is the only viral protein expressed in all EBV-positive tumors as it is essential for the maintenance, replication and transcription of the virus genome. According to the polymorphism of residue 487 in EBNA1 gene, EBV isolates can be classified into five subtypes: P-ala, P-thr, V-val, V-leu and V-pro. Whether these EBNA1 subtypes contribute to different tissue tropism of EBV and are consequently associated with certain malignancies remain to be determined. To elucidate the relationship, one hundred and ten EBV-positive lymphoma tissues of different types from Northern China, a non-NPC endemic area, were tested for the five subtypes by nested-PCR and DNA sequencing. In addition, EBV type 1 and type 2 classification was typed by using standard PCR assays across type-specific regions of the EBNA3C genes. Four EBNA1 subtypes were identified: V-val (68.2%, 75/110), P-thrV (15.5%, 17/110), V-leuV (3.6%, 4/110) and P-ala (10.9%, 12/110). The distribution of the EBNA1 subtypes in the four lymphoma groups was not significantly different (p = 0.075), neither was that of the EBV type 1/type 2 (p = 0.089). Compared with the previous data of gastric carcinoma (GC), nasopharyngeal carcinoma (NPC) and throat washing (TW) from healthy donors, the distribution of EBNA1 subtypes in lymphoma differed significantly (p = 0.016), with a little higher frequency of P-ala subtype. The EBV type distribution between lymphoma and the other three groups was significantly different (p = 0.000, p = 0.000, p = 0.001, respectively). The proportion of type 1 and type 2 mixed infections was higher in lymphoma than that in GC, NPC and TW. In lymphomas, the distribution of EBNA1 subtypes in the three EBV types was not significantly different (p = 0.546). These data suggested that the variation patterns of EBNA1 gene may be geographic-associated rather than tumor-specific and the role of EBNA1 gene variations in tumorigenesis needs more extensive and deep explorations.

Epstein-Barr Virus: From the Detection of Sequence Polymorphisms to the Recognition of Viral Types

The Epstein-Barr virus is etiologically linked with the development of benign and malignant diseases, characterized by their diversity and a heterogeneous geographic distribution across the world. The virus possesses a 170-kb-large genome that encodes for multiple proteins and non-coding RNAs. Early on there have been numerous attempts to link particular diseases with particular EBV strains, or at least with viral genetic polymorphisms. This has given rise to a wealth of information whose value has been difficult to evaluate for at least four reasons. First, most studies have looked only at one particular gene and missed the global picture. Second, they usually have not studied sufficient numbers of diseased and control cases to reach robust statistical significance. Third, the functional significance of most polymorphisms has remained unclear, although there are exceptions such as the 30-bp deletion in LMP1. Fourth, different biological properties of the virus do not necessarily equate with a different pathogenicity. This was best illustrated by the type 1 and type 2 viruses that markedly differ in terms of their transformation abilities, yet do not seem to cause different diseases. Reciprocally, environmental and genetic factors in the host are likely to influence the outcome of infections with the same virus type. However, with recent developments in recombinant virus technology and in the availability of high throughput sequencing, the tide is now turning. The availability of 23 complete or nearly complete genomes has led to the recognition of viral subtypes, some of which possess nearly identical genotypes. Furthermore, there is growing evidence that some genetic polymorphisms among EBV strains markedly influence the biological and clinical behavior of the virus. Some virus strains are endowed with biological properties that explain crucial clinical features of patients with EBV-associated diseases. Although we now have a better overview of the genetic diversity within EBV genomes, it has also become clear that defining phenotypic traits evinced by cells infected by different viruses usually result from the combination of multiple polymorphisms that will be difficult to identify in their entirety. However, the steadily increasing number of sequenced EBV genomes and cloned EBV BACS from diseased and healthy patients will facilitate the identification of the key polymorphisms that condition the biological and clinical behavior of the viruses. This will allow the development of preventative and therapeutic approaches against highly pathogenic viral strains.

Herpesvirus infections of the central nervous system in immunocompromised patients

Human herpesviruses may cause infections of the central nervous system during primary infection or following reactivation from a latent state. Especially in immunosuppressed patients the infection can take a life-threatening course, and therefore early diagnosis of herpesvirus-associated neurological diseases should have high priority. Clinical presentation in these patients is usually without typical features, making diagnosis even more challenging. Therefore general broad testing for different herpesviruses in cerebrospinal fluid samples is highly recommended. In addition, determination of the virus DNA level in the cerebrospinal fluid by quantitative assays seems to be of high importance to determine prognosis. Moreover, it might help to differentiate between specific virus-associated disease and unspecific presence of virus in the cerebrospinal fluid, especially in immunocompromised patients. Polymerase chain reaction analysis of cerebrospinal fluid has revolutionized the diagnosis of nervous system viral infections, particularly those caused by human herpesviruses. This review summarizes the role human herpesviruses play in central nervous system infections in immunocompromised patients, with a focus on the clinical manifestation of encephalitis.

EBNA1 and LMP1 variants in multiple sclerosis cases and controls

BACKGROUND

Prior infection with Epstein-Barr virus (EBV) is an established risk factor for multiple sclerosis (MS). Some findings from observational studies, including possible epidemics and differences in prevalence, may be explained if different strains of EBV conferred different MS risk.

METHODS

DNA was extracted from peripheral lymphocytes obtained from 66 MS cases and 66 age- and cohort-matched controls. Nested polymerase chain reaction (PCR) was performed to amplify the N- and C-terminus regions of EBNA1 and the hyper-variable region of the LMP1 gene. For EBNA1, we compared the presence of the prototype B95.8 vs variant sequence and the presence of multiple strains in MS cases and controls. For LMP1, we considered differences in the proportions of mutations between cases and controls.

RESULTS

Comparing the proportion of mutant sequence between MS cases and controls in the EBNA1 N-terminal (0/28 vs 1/27) and C-terminal regions (3/40 vs 8/36) revealed no significant differences (P > 0.05). No individual variants in LMP1 were associated with risk of MS (all P > 0.05). Neither EBNA1 nor LMP1 variation was associated with anti-EBNA1 IgG antibody titers.

CONCLUSIONS

These findings do not support a strong role for variation in EBNA1 N-terminus, EBNA1 C-terminus or LMP1 contributing to MS risk.

New variations of Epstein-Barr virus-encoded small RNA genes in nasopharyngeal carcinomas, gastric carcinomas, and healthy donors in northern China

It has been generally believed that the Epstein-Barr virus (EBV)-encoded small RNA 1 and 2 (EBER1 and EBER2) genes are conserved as two families that correlated with type 1 (B95-8) and type 2 (AG876 or P3HR-1) EBV strains. EBER polymorphism and its association with EBV-associated disease have not received much attention. To explore the variations of EBER genes in different malignancies and healthy donors, the sequences of EBER genes were analyzed in 154 EBV-positive samples, including 47 nasopharyngeal carcinoma (NPC), 50 EBV-associated gastric carcinoma (EBVaGC) biopsies and 57 throat washing (TW) samples from healthy donors in northern China, where NPC is non-endemic. Three main distinct variants of EBER genes, designated as EB-6m, EB-8m, and EB-10m, were identified. EB-6m had a previously identified EBER sequence identical to P3HR-1 and was found in 33/47 (70.2%) NPC, 48/50 (96.0%) EBVaGC, and 54/57 (94.7%) TW isolates. EB-8m and EB-10m were new EBER variants with more mutations in EBER2 genes. They were found in 13/47 (27.7%) NPC cases, whereas in only 1/50 (2.0%) EBVaGC cases and not found in TW cases. The distributions were significantly different (P < 0.05). Other five isolates (one NPC, one EBVaGC and three TW cases) showed different sequences and could not be assigned to any of the three groups. Type 1 EBV strains showed heterogeneous in terms of EBER variants. These results suggest that EBER locus can be useful to identify different EBV isolates, and it would be interesting to evaluate the association of EBER polymorphisms with EBV-associated tumors.

99th Dahlem conference on infection, inflammation and chronic inflammatory disorders: Epstein-Barr virus and multiple sclerosis: epidemiological evidence

While the causes of multiple sclerosis (MS) are unknown, there is strong evidence that infection with Epstein-Barr virus (EBV) is an important factor. In this review, we discuss the epidemiological evidence and argue for a causal role of EBV in MS aetiology. One of the most striking and consistent observations is that MS is extremely rare among EBV-negative individuals. Further, the timing of EBV infection appears to be critical, with individuals who are infected during adolescence and young adulthood, when the infection is more likely to manifest as mononucleosis, having a two- to threefold greater risk of MS compared to individuals infected in early life. These observations challenge the hygiene hypothesis which states that being in a high hygiene environment in early life increases future risk of MS - if this general formulation were true, EBV-negative individuals would be expected to have an increased risk of MS. Additional support for the causal role of EBV comes from longitudinal, prospective studies which show remarkable consistency, in that antibodies against EBV are elevated prior to MS onset. However, while infection with EBV is consistent with many observations of MS epidemiology, there are some that remain unexplained, suggesting that other factors are also involved in determining risk.

Epstein-barr virus infection and multiple sclerosis: a review

Epstein-Barr virus (EBV) infection results in a life-long persistence of the virus in the host's B-lymphocytes and has been associated with numerous cancers including Burkitt's lymphoma, Hodgkin lymphoma, and nasopharyngeal carcinoma. There is considerable evidence that EBV infection is a strong risk factor for the development of multiple sclerosis. Early age at primary EBV infection is typically asymptomatic, but primary infection during adolescence or adulthood often manifests as infectious mononucleosis, which has been associated with a two- to threefold increased risk of MS. Most importantly, MS risk is extremely low in individuals who are EBV negative, but it increases several folds following EBV infection. Additional evidence supporting a role for EBV in MS pathogenesis includes the observations of elevated antibodies to EBV antigens (especially EBV nuclear antigen-1) prior to the onset of MS, and an increased risk of MS among EBV-positive children. The biological mechanism by which EBV may cause MS is not known, but several possibilities are discussed.

Variations of Epstein-Barr virus nuclear antigen 1 gene in gastric carcinomas and nasopharyngeal carcinomas from Northern China

The Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1), the only viral protein consistently expressed in all EBV-associated tumors, is classified into five distinct subtypes: P-ala, P-thr, V-leu, V-val and V-pro based on the signature changes at amino acid residue 487. By now, whether the EBNA1 subtypes preferentially associate with particular malignancies or represent geographical polymorphism remains controversial. In China, most studies of the EBNA1 variations focused on nasopharyngeal carcinoma (NPC) in endemic area, among which some suggested the V-val subtype is preferentially associated with NPC. To characterize the variations of EBNA1 in NPC non-endemic area in China and to explore the association of EBNA1 variations with EBV-associated gastric carcinoma (EBVaGC) and NPC, the C-terminal sequences of EBNA1 were analyzed for 41 EBVaGC, 41 NPC biopsies and 55 throat washing (TW) samples from healthy donors in Northern China. Three major patterns of the EBNA1 variations, V-val, P-thrV and V-leuV, were observed, and V-val was the most common subtype in all the three groups, followed by P-thrV and V-leuV. The distribution of the EBNA1 subtypes among EBVaGC, NPC and healthy donors was not significantly different (P>0.05). In addition, preferential linkages between EBNA1 subtypes and EBNA3C variants were found to exist. There was no evidence that particular EBNA1 subtypes are preferentially associated with EBVaGC or NPC in Northern China, suggesting that EBNA1 gene variations are geographically restricted rather than tumor-specific polymorphisms.

The extent of genetic diversity of Epstein-Barr virus and its geographic and disease patterns: a need for reappraisal

Epstein-Barr virus (EBV) is a ubiquitous, gamma-1 lymphotrophic virus etiologically linked to nasopharyngeal carcinoma (NPC), endemic to Southern China, and Burkitt lymphoma (BL), endemic to equatorial Africa, both of which are rare elsewhere in the world. Why EBV is associated with different malignancies in different geographic regions remains puzzling and may be related to EBV genotypic variability through specific disease and geographic associations. We review the literature on sequence variation in EBV genes, focusing on LMP-1, EBNA-1, and BZLF-1 and their distribution by geography and disease. Given the limitations of current studies, definitive conclusions regarding the link between EBV genotypes, disease and geography are not possible. We suggest that the true extent of EBV diversity is likely to be greater than is currently recognized. Additional studies conducted in carefully selected populations, that are sufficiently powered to provide robust estimates, and that utilize testing approaches that permit full characterization of viral diversity are needed to further our understanding of patterns of EBV genetic variation and their association with malignancies in different regions.

Polymerase chain reaction genotyping of Epstein-Barr virus in scraping samples of the tongue lateral border in HIV-1 seropositive patients

The Epstein-Barr virus (EBV) is the etiological agent of oral hairy leukoplakia (OHL), an oral lesion with important diagnostic and prognostic value in acquired immunodeficiency disease syndrome. The two EBV genotypes, EBV-1 and EBV-2, can be distinguished by divergent gene sequences encoding the EBNA-2, 3A, 3B, and 3C proteins. The purpose of this study was to identify the EBV genotype prevalent in 53 samples of scrapings from the lateral border of the tongue of HIV-1 seropositive patients, with and without OHL, and to correlate the genotypes with presence of clinical or subclinical OHL with the clinic data collected. EBV-1 and EBV-2 were identified through PCR and Nested-PCR based on sequence differences of the EBNA-2 gene. EBV-1 was identified in the 31 samples (15 without OHL, 7 with clinical OHL and 9 with subclinical OHL), EBV-2 in 12 samples (10 without OHL, 1 with clinical and 1 subclinical OHL), and a mixed infection in 10 samples (2 without OHL, 3 with clinical and 5 with subclinical OHL). The presence of EBV-1 was higher in women, but a significant statistical result relating one the EBV genotypes to the development of OHL was not found. We conclude that the oral epithelium in HIV-1 seropositive patients can be infected by EBV-1, EBV-2 or by a mixed viral population.

Environmental risk factors in multiple sclerosis

OBJECTIVES

Multiple sclerosis (MS) likely results from an interaction between genetic and exogenous factors. While genetics shapes the overall population MS susceptibility, observed epidemiological patterns strongly suggest a role for the environment in disease initiation and modulation.

RESULTS

Findings from studies on seasonality in MS patients' birth, disease onset and exacerbations, as well as apparent temporal trends in incidence and gender ratio support an influential effect of viruses, metabolic and lifestyle factors on MS risk. Epstein-Barr virus, vitamin D status, and smoking are factors that may explain such epidemiological patterns.

CONCLUSIONS

Further epidemiological investigations are encouraged and opportunities to use data from existing cohort studies as well as the design of new studies should be pursued. In particular, the development of new large multicentre population-based case-control studies which incorporate the study of the role of environment and genetics, including epigenetic mechanisms, in determining MS risk is proposed.

Environmental risk factors for multiple sclerosis. Part II: Noninfectious factors

As discussed in Part I of this review, the geographic distribution of multiple sclerosis (MS) and the change in risk among migrants provide compelling evidence for the existence of strong environmental determinants of MS, where "environmental" is broadly defined to include differences in diet and other behaviors. As we did for infections, we focus here primarily on those factors that may contribute to explain the geographic variations in MS prevalence and the change in risk among migrants. Among these, sunlight exposure emerges as being the most likely candidate. Because the effects of sun exposure may be mediated by vitamin D, we also examine the evidence linking vitamin D intake or status to MS risk. Furthermore, we review the evidence on cigarette smoking, which cannot explain the geographic variations in MS risk, but may contribute to the recently reported increases in the female/male ratio in MS incidence. Other proposed risk factors for MS are mentioned only briefly; although we recognize that some of these might be genuine, evidence is usually sparse and unpersuasive.

Detection of polyomaviruses and herpesviruses in human adrenal tumors

The presence of polyomaviruses and herpesviruses in adrenal tumors and their role in adrenal tumorigenesis has never been investigated, even though the adrenal gland seems to be a preferential site of infection by these viruses and adrenal steroid hormones have been shown to activate their replication. We examined in a large series of normal adrenal gland tissues (n=20) and adrenal tumors (n=107) the presence of herpesviruses and polyomaviruses sequences and gene expression, which were detected in a high proportion of both normal and neoplastic adrenal samples (overall, viruses were found in 15% normal adrenals, 27.8% benign adrenal tumors and 35.3% malignant tumors). The polyomaviruses SV40 and BK virus were more frequently found in malignant adrenal tumors, whereas herpesviruses, especially Epstein-Barr virus and human cytomegalovirus, were more frequently detected in functioning benign adrenocortical tumors, often as coinfection. Moreover, tumors from patients with severe hypercortisolism frequently showed herpesvirus coinfections at high viral genome copy number. Our study suggests that the adrenal gland could be a reservoir of infection for these viruses and that hormone overproduction by the adrenal gland could represent a trigger for virus reactivation. On the other hand, these viruses could also contribute to adrenal cell proliferation and tumorigenesis.

Recent advances in the diagnosis and therapy of richter’s syndrome

Richter's syndrome (RS) denotes the development of aggressive lymphoma that arises in patients with chronic lymphocytic leukemia (CLL). Presenting features typically include a rapid clinical deterioration with fever in the absence of infection, progressive lymph node enlargement, and an elevation in serum LDH. Diagnostic biopsy of affected sites usually reveals large cell lymphomas; however, Hodgkin variant cases have been described. Richter's transformation occurs in approx 5% of CLL patients and may be associated with infection with Epstein-Barr virus (EBV). Chromosome 11 and 14 abnormalities have also been described as well as tumor suppressor gene defects involving p53, p21, and p27. Treatment options for these patients are limited and include combination chemotherapy with or without the addition of monoclonal antibodies and stem cell transplantation. Response to therapy is variable and generally short-lived. Median survival is usually in the order of 5-8 mo. More effective management for RS is needed as well as prognostic models that will identify CLL patients at risk of transformation. This review will address the current status of RS and deal with the pathophysiology, diagnostic approach, and treatment of this challenging disease.

Epstein Barr virus genotypes and LMP-1 variants in HIV-infected patients

Two Epstein Barr virus (EBV) genotypes: EBV-1 and EBV-2 have been described. A 30-bp deletion in latent membrane protein-1 gene (del-LMP-1) has been identified in various pathologies. The aim of this study was to determine EBV genotypes and 30-bp deletion frequency in HIV-infected patients from Argentina. The study was performed on 258 individuals:

CASES

144 HIV-infected patients that included: (a) 7 AIDS patients with primary central nervous system lymphoma (PCNSL), (b) 62 AIDS patients, and (c) 75 asymptomatic HIV-infected patients.

CONTROLS

114 HIV-negative individuals. EBV genotypes and variants in LMP-1 gene were detected by polymerase chain reaction (PCR)-Southern blot on DNA extracted from peripheral blood mononuclear cells and brain biopsies. In PCNSL, the presence of EBV was confirmed by EBER RNA in situ hybridization, and DNA sequencing of 3' end LMP-l gene of PCR products was performed. In HIV-infected patients, EBV-1 was detected in 48.6%, EBV-2 in 18.8%, and co-infection with both genotypes in 32.6%. In control group, EBV-1 was present in 74.3%, EBV-2 in 12.4%, and co-infection in 13.3%. Del-LMP-1 was found in 44.4% of HIV-infected patients samples (20.7% alone and 23.7% co-infection with non-deleted form) while it was found in 25.3% (6.3% alone and 19% with co-infection) in HIV-negative individuals. In HIV-infected patients EBV-2, co-infection and 30-bp deletion are more prevalent than in control group. In all, PCNSL brain biopsies samples, del-LMP-1 always was detected with EBV-2, but more cases would have to be included to draw definitive conclusions.

A Cohort Study among University Students: Identification of Risk Factors for Epstein‐Barr Virus Seroconversion and Infectious Mononucleosis

BACKGROUND

A vaccine against Epstein-Barr virus (EBV) infection is in clinical trials. Up-to-date information on risk factors for EBV infection and infectious mononucleosis (IM) among young adults is required to inform a vaccination strategy.

METHODS

We carried out a prospective study on a cohort of university students. All EBV-seronegative students were asked to report symptoms of IM and were followed up 3 years later to undergo repeat EBV testing and to complete a lifestyle questionnaire. EBV typing was performed for these subjects, as well as for students who were EBV seropositive at enrollment and for additional students with IM.

RESULTS

A total of 510 students (25%) who took part in the study were EBV seronegative when they entered the university; of the 241 who donated a second blood sample 3 years later, 110 (46%) had seroconverted to EBV, 27 (25%) of whom developed IM [corrected] Penetrative sexual intercourse was a risk factor for EBV seroconversion (P = .004), but neither condom use nor oral sex significantly altered the rate of seroconversion. EBV type 1 was significantly overrepresented in IM, compared with silent seroconversion (P = .001).

CONCLUSIONS

Our findings suggest that acquisition of EBV is enhanced by penetrative sexual intercourse, although transmission could occur through related sexual behaviors, such as "deep kissing." We also found that EBV type 1 infection is significantly more likely to result in IM. Overall, the results suggest that a large EBV type 1 load acquired during sexual intercourse can rapidly colonize the B cell population and induce the exaggerated T cell response that causes IM. Thus, IM could, perhaps, be prevented with a vaccine that reduces the viral load without necessarily inducing sterile immunity.

Richter syndrome: biology, incidence, and therapeutic strategies

Richter's transformation denotes the development of high-grade non-Hodgkin lymphoma, prolymphocytic leukemia, Hodgkin disease, or acute leukemia in patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma. A search of published articles in Medline (PubMed) and abstracts from professional meetings was performed. An electronic database search of patients with CLL at The University of Texas M. D. Anderson Cancer Center (Houston, TX) determined the incidence of Richter syndrome (RS) in patients with CLL between 1992 and 2002. RS occurs in approximately 5% of patients with CLL. The large cells of RS may arise through transformation of the original CLL clone or represent a new neoplasm. RS may be triggered by viral infections, such as Epstein-Barr virus. Trisomy 12 and chromosome 11 abnormalities are more frequent in patients with RS than in the overall population of patients with CLL. Multiple genetic defects, such as mutations of the p53 tumor suppressor gene, p16INK4A, and p21, loss of p27 expression, deletion of retinoblastoma, increased copy number of C-MYC, and decreased expression of the A-MYB gene, have been described. These abnormalities may cause CLL cells to proliferate and-by facilitating the acquisition of new genetic abnormalities-to transform into RS cells. Therapeutic strategies include intensive chemotherapy, monoclonal antibodies, and stem cell transplantation. The response rates range from 5% to 43% (complete response, 5-38%), and the median survival duration ranges from 5 months to 8 months. In conclusion, RS may be triggered by viral infections or by genetic defects. Current treatments are aggressive, but prognosis is poor. Novel curative treatment strategies are needed.

Epstein-barr virus (EBV) in healthy carriers: Distribution of genotypes and 30 bp deletion in latent membrane protein-1 (LMP-1) oncogene

There are two types of Epstein Barr virus (EBV): EBV-1 and EBV-2, distinguished by genomic polymorphism in the genes encoding the nuclear antigens (EBNA-2, -3A, -3B, -3C). Latent membrane protein 1 (LMP-1) is an EBV protein with known oncogenic properties. Different variants had been described; among them, a 30 base pair (bp) deletion (del-LMP-1) had been reported in benign and malignant pathologies, but there is little information about its frequency in healthy populations. The aim of this study was to determine the distribution of the EBV genotypes and the 30 bp deletion frequency, in EBV healthy carriers from Argentina. Analysis of EBNA-3C and LMP-1 genes were done by polymerase chain reaction (PCR) followed by Southern blot hybridization on DNA of peripheral blood mononuclear cells (PBMCs) from blood bank donors. EBV-1 was present in 75.9% of samples, EBV-2 in 14.6%, and co-infections with both types in 6.5%. The deleted LMP-1 variant was found in 7.4% of analyzed samples, corresponding 3.2% to deleted variant alone and 4.2% to co-infections with non-deleted form. The non-deleted variant was found in 64.6% whereas in the remaining 28%, no PCR product was detected. These results showed that EBV-1 was the more prevalent type in healthy carriers of Argentina, similar to reports from others countries. A predominance of the non-deleted LMP-1 variant was observed. The presence of co-infections with both types and variants demonstrated that healthy individuals may also harbor multiple EBV infections.

Comparative analysis of NK/T-cell lymphoma and peripheral T-cell lymphoma in Korea: Clinicopathological correlations and analysis of EBV strain type and 30-bp deletion variant LMP1

Natural killer/T-cell lymphoma (NKTL) and peripheral T-cell lymphomas (PTCL) are prevalent in the Asian population and exhibit a high association with the Epstein-Barr virus (EBV). Moreover, differentiation of these two groups is often difficult and problematic. We investigated 35 cases of NKTL (22 nasal cases and 13 extranasal cases) and 30 cases of PTCL in terms of their clinical features, immunohistology, EBV positivity, EBV strain-type polymorphism and latent membrane protein 1 (LMP1) deletion variant distribution. Eighteen cases (82%) of nasal NKTL and seven (54%) of extranasal NKTL showed EBV positivity by EBV in situ hybridization. Fifteen cases (50%) of PTCL revealed EBV positivity. EBV strain type A was predominant in NKTL (18:5), and EBV strain types A and B were distributed evenly in PTCL (6:6). EBV-positive patients had significantly shorter survival than EBV-negative patients (P < 0.05), and EBV positivity correlated with advanced clinical stage (P < 0.05). Patients harboring type A EBV showed slightly poorer prognoses than those having type B, though it was not obviously statistically different (P = 0.07). The LMP1 deletion variant was prevalent in both NKTL (three wild-type LMP1, 15 deletion variants) and PTCL (three wild-type LMP1, eight deletion variants, two coexistent forms) patients, but did not have prognostic impact. Our results indicate that EBV acts as a negative prognostic factor in NKTL and PTCL, and that the intrinsic properties of a specific viral strain might influence the clinical behavior of these diseases.

Sequence analysis of EBV DNA isolated from mouth washings and PBMCs of healthy individuals and blood of EBV-LPD patients

BACKGROUND

Lymphoproliferative disorder (LPD) caused by Epstein-Barr virus (EBV) is a severe complication of bone marrow transplantation. The EBV strain causing LPD is of either donor or recipient origin, however, available data are limited to only a small number of cases. To obtain solid evidence, comparison of the EBV strain that caused the EBV-LPD with pre-stem cell transplantation (SCT) EBV strains of donor and recipient is imperative. Available techniques rely on the production of EBV transformed lymphoblastoid cell lines and lack sensitivity.

OBJECTIVE

The aim of this study was to develop a simple method for EBV sequence analysis on mouth washings (MWs) and peripheral blood mononuclear cells (PBMCs).

STUDY DESIGN

EBV DNA was extracted from MWs and PBMCs that were collected from 20 healthy individuals. DNA was used for sequence analysis, using a polymerase chain reaction for the C-terminus of the LMP-1 gene.

RESULTS

In seropositive individuals EBV DNA could be detected in 11/14 (79%) MWs and in 13/14 (93%) PBMC samples. Sequence analysis showed that in 11 out of 14 (79%) healthy individuals sequence patterns could be established. In these 11 healthy individuals 13 sequence patterns could be detected. Eleven of these 13 patterns (84.6%) were unique. These results encouraged us to explore the feasibility of this method on EBV DNA isolated from plasma from 9 EBV-LPD patients at time of EBV reactivation. In 7 EBV-LPD patients 8 sequence patterns were detected. Six out of 8 sequence patterns (75%) were unique.

CONCLUSION

Our method is suitable for strain identification and we intend to use this technique to evaluate EBV origin in EBV-LPD patients.

Reduced expression and promoter methylation of p16 gene in Epstein-Barr virus-associated gastric carcinoma

Epstein-Barr virus (EBV)-associated gastric carcinoma (EBVaGC) is a unique type of gastric carcinoma (GC), which is considered to develop in a different pathway from EBV-negative GC. To evaluate a possible role of p16, an inhibitor of G1/S transition of the cell cycle, in the carcinogenesis of EBVaGC, p16-immunohistochemistry and methylation-specific PCR analysis (MSP) were applied to surgically resected gastric carcinomas. When the percentage of p16-positive cells in more than 1000 carcinoma cells was expressed as p16 labeling index (p16-LI), it ranged from 2.5 to 88.1 (mean 42.9+/-24.4) in 70 gastric carcinomas. EBVaGC showed significantly lower values (n=15, 26.1+/ -22.1) than EBV-negative GC (n=55, 47.5+/-23.2) (P=0.0036). Fresh frozen tissues of 55 gastric carcinomas (16 EBVaGC and 39 EBV-negative GC) were further subjected to MSP, to evaluate abnormal methylation of the promoter region of the p16 gene. The frequency of methylation was significantly higher in EBVaGC (14/16) than in EBV-negative GC (9/39) (<0.0001). The methylation-positive carcinomas showed significantly lower p16-LI (35.9+/-21.6) than the unmethylated ones (55.2+/-22.7) (P=0.0014). Thus, a marked decrease of p16 expression, caused by the aberrant methylation of the p16 gene promoter, is closely associated with the development of EBVaGC.

Characterization of Epstein-Barr virus genotype in AIDS-related non-Hodgkin's lymphoma

In the present study sequence variations at the C terminus of the Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA-1), EBV-encoded latent membrane protein 1 (LMP-1), and EBNA-2 and EBNA-3C genes were investigated in 64 cases of EBV-positive AIDS-related diffuse large cell lymphoma (AIDS-DLCL), both systemic (12) and localized primarily to the central nervous system (52), and in 12 cases of EBV-positive AIDS-related Burkitt's lymphoma (AIDS-BL). Sequence analysis of the EBNA-1 C-terminal region led to the distinction of two major unrelated EBV strains, termed strain P (prototype) and strain V (variant), and their related subtypes, namely P-ala, P-thr, V-leu, V-val, and V-pro. Analysis of the LMP-1 gene was performed to assess the frequency of the C-terminus deletion variant, whereas analysis of EBNA-2 and EBNA-3C genes led to the identification of the distribution of the EBV type 1 and type 2 strains. The frequency of EBNA-1 subtypes was assessed in 49 cases of AIDS-NHL, including 37 cases of AIDS-DLCL and 12 cases of AIDS-BL. The P strain was detected in 45 of 49 cases (91.8%) whereas the V strain was found in 4 of 49 samples (8.1%). A significant difference in the distribution of the P and V strains was found between AIDS-DLCL and AIDS-BL (p < 0.01), because of the exclusive infection by the P strain of the AIDS-DLCL samples analyzed. The frequency of LMP-1 deletion variants and of EBV type 1 and type 2 strains in AIDS-DLCL overlapped with that of the general population, and no correlation was found with the evaluated clinicoepidemiological data of patients, that is, disease site, tumor histology, CD4(+) cell counts, and HIV transmission route. In conclusion, we found that the distribution of the EBV genotype in all of the AIDS-NHL samples analyzed is similar to the viral representation found in control individuals of both immunocompetent and immunocompromised populations.

Pathogenetic and histogenetic features of HIV-associated Hodgkin's disease

Compared with the cases in the general population, Hodgkin's disease (HD) arising in the HIV setting shows distinctive features in terms of epidemiology, aetiopathogenesis, histopathology and clinical behaviour. Although HD does not represent an AIDS-defining condition, recent evidence consistently indicates that HIV-infected individuals have a significantly increased risk of developing HD. HIV-related HD is characterised by the preponderance of aggressive histological subtypes, advanced stage at presentation, and highly malignant clinical course. Moreover, unlike HD in the general population, the large majority of HIV-related HD cases are pathogenetically linked to Epstein-Barr virus (EBV), with rates of EBV positivity ranging from 80 to 100%. Hodgkin and Reed-Sternberg cells of these cases invariably show a strong expression of the EBV-encoded latent membrane protein-1 (LMP-1), which functions as a constitutively activated tumour necrosis factor (TNF) receptor-like molecule. Usurpation of physiologically relevant pathways by LMP-1 may lead to the simultaneous or sequential activation of signalling pathways involved in the promotion of cell activation, growth, and survival, contributing thus to most of the features of HIV-related HD.

Detection of Epstein-Barr Virus, but not Human Herpesvirus 8, DNA in Cervical Secretions From Swedish Women by Real-Time Polymerase Chain Reaction

BACKGROUND

Epstein-Barr virus (EBV) and human herpesvirus 8 (HHV-8) are two related herpesviruses that may be sexually transmitted.

GOAL

To examine the presence of HHV-8 and EBV DNA in the female genital tract.

STUDY DESIGN

Real-time polymerase chain reaction systems for quantification of DNA from HHV-8, EBV, and herpes simplex virus type 2 were developed and used for examination of cervical secretions from 112 Swedish women. HHV-8, EBV, and herpes simplex virus type 2 serology was also performed on samples from all subjects.

RESULTS

EBV DNA was found in 10 cervical secretion samples, sometimes in high amounts. No cervical secretion or leukocyte sample contained detectable HHV-8 DNA. Antibodies to HHV-8-latent and -lytic antigens were found in 2.7 % and 24% of serum samples, respectively.

CONCLUSION

This study supports a possible sexual route of transmission for EBV but not for HHV-8. The new real-time polymerase chain reaction systems could be valuable in future studies of relations between virus load and disease.

Deletions within the epstein-barr virus latent membrane protein-1 oncogene in adult ordinary, HIV-associated and paediatric Hodgkin's disease

The aims of this study were the following: a) to perform Epstein-Barr virus (EBV) strain type assignment in three groups of Hodgkin's disease(HD): adult ordinary (39 cases), paediatric (24 cases), and HIV-associated (30 cases) and to compare the prevalence of type 1 and type 2 in each of the groups with that existing in two reference populations made up of 50 adults and 39 children; b) to assess the frequency of latent membrane protein-1 (LMP-1) 30-base pair (bp) deletions in the HD groups and in the healthy controls; and c) to relate the presence of LMP-1 deletions with EBV type. Type 2 EBV was observed in 12.8% of ordinary HD, in 26.7% of HIV-associated HD, in 25% of paediatric HD, in 4% of adult controls, and in none of the healthy children. The existence of double infections by type 1 and 2 EBV was also observed in 5.1% of ordinary HD, in 6.7% of HIV-associated HD, and in 10% of adult controls. The 30-bp deletion was identified overall in 33.3% of ordinary HD, in 83.3% of HIV-positive HD, 79.2% of paediatric HD, 34.7% of adult controls, and 36.4% of healthy children. Statistical analysis showed a significant association of the deleted strains with HD occurring in HIV-positive patients (P= 0.00003) and childhood HD (P= 0.006). On the other hand, the prevalence of the 30-bp deletion in the adult ordinary HD group reflects the prevalence of the deletion in the general population. Co-infections by deleted and non-deleted EBV strains were detected in 12.8% of ordinary HD, in 33.3% of HIV-associated HD, in 50% of paediatric HD, in 26.5% of adult controls, and in 27.3% of healthy children. Concerning the relationship between the deletion and the EBV typing, 26% of type 1 specimens carried the 30-bp deletion in an isolated manner compared with 64.7% of type 2. The statistical analysis showed that the deletion was associated with type 2 strains when coinfections were excluded and only the cases in which the deletion appeared alone were considered (P=0.003).

Biologically relevant phenotypic changes and enhanced growth properties induced in B lymphocytes by an EBV strain derived from a histologically aggressive Hodgkin's disease

Epstein-Barr virus (EBV) isolates show a wide genomic heterogeneity, and a key issue is whether distinct strain variations may contribute to the development and/or malignancy of EBV-related disorders. Herein, we report on the virologic and biologic characterization of an EBV strain derived from a cyto-histologically aggressive EBV-related Hodgkin's disease (HD) (case HD-3) showing a high number of "anaplastic" Reed-Sternberg cells expressing markedly high levels of CD30, CD40 and LMP-1. The HD-3-derived EBV showed strong in vitro immortalizing properties, as suggested by the unusually high number of spontaneous lymphoblastoid cell lines (LCLs) obtained from the patient. Immunofluorescence and immuno-cytochemical analyses showed that HD-3 LCLs expressed significantly higher levels of CD23, CD30, CD38, CD39, CD40 and CD71 antigens and CD54 and CD58 adhesion molecules than B95.8 LCLs. In contrast, the expression of CD11a, CD24, CD95, bcl-2, LMP-1 and EBNA-2 was similar in both groups of LCLs. These phenotypic changes are consistent with the induction of a pronounced activation status and are not dependent on the cellular background, having been closely reproduced by the same virus in LCLs from an unrelated donor (DEN-HD-3 LCLs). HD-3 LCLs were able to grow in vitro at low serum concentrations (up to 0.1%) and were significantly more clonogenic in soft agarose than B95.8 LCLs. Moreover, although no evidence of tumor formation was observed in nude mice injected with B95.8 LCLs, all 5 spontaneous LCLs of patient HD-3 and the 2 DEN-HD-3 LCLs grew in transplanted animals as lymphoproliferations composed of EBER+, LMP-1+ cells. Our findings indicate that the biologic properties of the HD-3 EBV strain are significantly different from those of the B95.8 virus and may have contributed to the cytologic and histo-pathologic malignancy of this HD case. Moreover, molecular characterization of the HD-3 EBV genome identified a 63-bp deletion within the 3' end of the LMP-1 gene as a likely significant change that may be responsible, at least in part, for the biologically relevant phenotypic modifications and enhanced in vitro and in vivo growth potential induced in B lymphocytes by this virus strain.

Animal virus receptors

The term 'receptor' is generally accepted as the cell-surface component that participates in virus binding and facilitates subsequent viral infection. Recent advances in technology have permitted the identification of several virus receptors, increasing our understanding of the significance of this initial virus-cell and virus-host interaction. Virus binding was previously considered to involve simple recognition and attachment to a single cell surface molecule by virus attachment proteins. The classical concept of these as single entities that participate in a lock-and-key-type process has been superseded by new data indicating that binding can be a multistep process, often involving different virus-attachment proteins and more than one host-cell receptor.

Tissue distribution of Epstein-Barr virus genotypes in hosts coinfected by HIV

BACKGROUND

In healthy people, oral and pharyngeal epithelium preferentially carries Epstein-Barr virus (EBV) belonging to a genotype that possesses three copies of a 29 base-pair repeat in the first intron of the BZLF-1 gene, while peripheral blood mostly carries a genotype that bears two copies. Whether EBV shows differential tropism in HIV-1-coinfected hosts, who are prone to develop oral hairy leukoplakia, has not been studied.

METHODS

Tongue scrapings and CD45+-enriched peripheral blood cells of 20 HIV1-infected patients and 40 healthy controls were examined. EBV-specific DNA was amplified from segments in the first intron of the BZLF-1 gene, in exon C of the LMP-1 gene, and the type A/B-specifying domain of the EBNA-3C gene. Size polymorphisms of these amplicons were assessed by agarose gel electrophoresis, and DNA sequence differences among BZLF-1 gene amplicons by single-strand conformation polymorphism analysis.

RESULTS

The predominant EBV genotype in peripheral blood as well as tongue carried two copies of the BZLF-1 repeat. In controls, although the BZLF-1 genotype with two copies was exclusively detected in the blood, the genotype with three copies predominated in the tongue. The findings could not be correlated with EBV genotyped according size polymorphisms in the EBNA-3C or LMP-1 genes. DNA sequences of a proportion or all of the clones derived from the BZLF-1 amplicons in the tongues of HIV-1-infected patients were identical to those in the blood.

CONCLUSIONS

These findings are consistent with EBV haematogenous superinfection of the tongue of HIV-positive individuals. Such superinfection may precede or lead to the development of oral hairy leukoplakia.

Epstein-Barr virus in the pathogenesis of Hodgkin's disease

Epidemiologic and clinico-pathologic features of Hodgkin's disease suggest that an infectious agent may be involved in the pathogenesis of this puzzling disorder. Recently accumulated data provide direct evidence supporting a causal role of Epstein-Barr virus in a significant proportion of cases. In addition to allowing a better understanding of the complex pathogenesis of Hodgkin's disease, these virological advances, briefly reviewed herein, also constitute an important basis for the development of new therapeutic strategies.

Polymorphism of the IL-1 gene complex in Epstein-Barr virus seronegative and seropositive adult blood donors

Epstein-Barr virus (EBV) seronegativity is rare in adults. To examine whether genetic differences would explain this, we studied the genetic polymorphisms of the genes of the interleukin-1 (IL-1) complex in seronegative adults. These cytokines (i.e. IL-1alpha, IL-1beta and IL-1 receptor antagonist, IL-1RA) regulate, in several ways, the inflammatory reactions of the body. In each of these genes there are polymorphic sites and the various alleles differ in their frequency in several diseases of inflammatory nature. In 400 healthy blood donors (from 18 to 60 years of age) there were 20 (5%) seronegative persons. The frequency of allele 2 of the IL-1beta gene (base exchange polymorphism at position -511 from the transcriptional start site) was decreased in the seronegative patients (0.20 versus 0.42 in the seropositive patients, P < 0.05, chi2-test). Moreover, the frequency of allele 2 of the IL-1RA (polymorphism defined by variable numbers of 86-bp repeats in intron 2) was slightly, but not significantly, decreased in the seronegative patients. Alleles of these two loci are known to be associated, but in the seronegative patients this association was abnormal: 11 out of 20 (55%) were of the IL-1RA-2 negative/IL-1beta-2 negative type, while of the seropositive patients, 25% were of this type (P < 0.01, chi2-test). These data suggest that immunological differences, depending on cytokine gene polymorphisms, regulate the resistance to EBV infection.

Epidemiology of infection with Epstein-Barr virus types 1 and 2: lessons from the study of a T-cell-immunocompromised hemophilic cohort

In apparent contrast to earlier work on Epstein-Barr virus (EBV) carriage in the general Caucasian population, in vitro virus isolations from human immunodeficiency virus (HIV)-positive male homosexual cohorts have shown frequent examples of multiple EBV infection and an overall prevalence of type 2 EBV strains exceeding 30%. Here we ask to what extent these findings might hold true in another T-cell-immunocompromised cohort, HIV-positive hemophilic patients. Resident EBV strains were rescued within lymphoblastoid cell lines derived from the blood and throat washings of 39 such individuals, using the same in vitro protocols of virus isolation as for the homosexual cohort. A mean of 19 independent cell lines was made per patient, and in each case the resident virus was characterized by PCR-based viral genomic analysis and by immunoblotting to reveal the viral "EBNAprint." By these criteria a significant proportion (14 of 39) of the hemophilic cohort carried more than one EBV strain, suggesting that T-cell impairment does indeed sensitize virus carriers to reinfection with new strains of exogenously transmitted virus. However, the overall incidence of type 2 EBV infection was 10%, which is close to that observed in the earlier work with healthy carriers and substantially lower than that seen in HIV-positive homosexuals. We infer that type 2 EBV is relatively rare in the general Caucasian population but has become endemic in the homosexual community.

Deletion of Epstein-Barr virus latent membrane protein 1 gene in United States and Brazilian Hodgkin's disease and reactive lymphoid tissue: high frequency of a 30-bp deletion

A 30-basepair (bp) deletion in the Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) gene has been reported in nasopharyngeal carcinoma and EBV-associated malignant lymphomas. Prior studies have found the deletion in about 10% to 28% of cases of Hodgkin's disease (HD), particularly in cases with aggressive histology. We studied the prevalence of 30-bp LMP1 gene deletion in EBV-positive HD in the United States (US) (12 cases) and Brazil (26 cases) with comparison to reactive lymphoid tissues (21 cases) and HD without EBV-positive Reed-Sternberg cells (15 cases). We studied the status of the LMP1 gene by Southern blot hybridization of polymerase chain reaction (PCR) products obtained after amplification with primers spanning the site of the deletion. We also performed EBV typing, EBER1 in situ hybridization, and LMP1 protein immunohistochemistry. EBV was detected in 12/26 (46%) cases of HD from the US and 26/27 (96%) cases of Brazilian HD. The 30-bp LMP1 gene deletion was observed in 4/12 (33%) cases of EBV-positive HD from US, and 12/26 (46%) cases of Brazilian EBV-positive HD, including 3 cases of type B EBV, as compared with 12/21 (57%) reactive lymphoid tissues and 9/15 (60%) cases of EBV-negative HD. US and Brazilian HD showed a higher prevalence of the 30-bp LMP1 gene deletion, compared with studies of others. The unexpected finding of high incidence of 30-bp deletion in LMP1 gene in reactive lymphoid tissue and HD without EBV-positive Reed-Sternberg cells suggests that this deletion may not be relevant to HD pathogenesis in most cases.

Direct identification by PCR of EBV types and variants in clinical samples

Both Epstein-Barr virus (EBV) type A and type B, and variants of type A, were identified simultaneously by polymerase chain reaction (PCR) amplification of a DNA region coding for a 13 amino acid repeat in the Epstein-Barr virus nuclear antigen (EBNA) 6. Whereas this region varies extensively in type A isolates, no variation was seen in type B isolates. When a repetitive region in the LMP1-coding region was amplified by PCR, it was possible to distinguish individual variants of type B isolates from each other. Forty-two saliva samples from HIV-1-carrying individuals were examined for the presence of type A and type B virus. Both types and multiple variants of each type were found with a much higher frequency than in the saliva samples from healthy individuals. Type A EBV alone was detected in mouthwash samples from 6 infectious mononucleosis (IM) patients. Both type A and B were detected in the peripheral blood B-lymphocytes (PBL) from 1 healthy individual. The same type A variant was demonstrated both in PBL and in the mouthwash sample from another healthy individual. In this study it was shown that a combination of the EBNA 6- and LMP 1-specific PCRs followed by Southern hybridisation can be used to identify both type A and type B virus, as well as to distinguish between multiple variants of the same strain, in saliva and B-cells from both healthy and immunosuppressed individuals.