Epstein-Barr virus genotypes associated with nasopharyngeal carcinoma in southern China

The Phylogeographic Diversity of EBV and Admixed Ancestry in the Americas⁻Another Model of Disrupted Human-Pathogen Co-Evolution

Epstein-Barr virus (EBV) is an etiological agent for gastric cancer with significant worldwide variations. Molecular characterizations of EBV have shown phylogeographical variations among healthy populations and in EBV-associated diseases, particularly the cosegregated BamHI-I fragment and XhoI restriction site of exon 1 of the LMP-1 gene. In the Americas, both cosegregated variants are present in EBV carriers, which aligns with the history of Asian and European human migration to this continent. Furthermore, novel recombinant variants have been found, reflecting the genetic makeup of this continent. However, in the case of EBV-associated gastric cancer (EBV-associated GC), the cosegregated European BamHI-“i” fragment and XhoI restriction site strain prevails. Thus, we propose that a disrupted coevolution between viral phylogeographical strains and mixed human ancestry in the Americas might explain the high prevalence of this particular gastric cancer subtype. This cosegregated region contains two relevant transcripts for EBV-associated GC, the BARF-1 and miR-BARTs. Thus, genome-wide association studies (GWAS) or targeted sequencing of both transcripts may be required to clarify their role as a potential source of this disrupted coevolution.

Determination and genome-wide analysis of Epstein-Barr virus (EBV) sequences in EBV-associated gastric carcinoma from Guangdong, an endemic area of nasopharyngeal carcinoma

About 10 % of gastric carcinoma worldwide is associated with EBV, which is defined as EBV-associated gastric carcinoma (EBVaGC). To date, EBV sequence data from EBVaGC in Guangdong, China, an endemic area of nasopharyngeal carcinoma (NPC), are not available. In the present study, two EBV genomes from EBVaGC specimens from Guangdong (designated as GDGC1 and GDGC2) were determined by next-generation sequencing, de novo assembly and joining of contigs by Sanger sequencing. In addition, we sequenced EBV from two Korean EBVaGC cell lines, YCCEL1 and SNU-719. Genomic diversity, including single nucleotide polymorphisms (SNPs) and insertions and deletions (indels), phylogenetic analysis and rates of protein evolution, was performed using bioinformatics software. The four gastric carcinoma-derived EBV (GC-EBV) were all type I. Compared with the reference EBV genome, a total of 1815 SNPs (146 indels), 1519 SNPs (106 indels), 1812 SNPs (126 indels) and 1484 SNPs (106 indels) were found in GDGC1, GDGC2, YCCEL1 and SNU-719, respectively. These variations were distributed across the entire genome, especially in latent genes. In contrast, the sequences of promoters and non-coding RNAs were strictly conserved. Phylogenetic analyses suggested the presence of at least two parental lineages of EBV among the GC-EBV genomes. Rates of protein evolution analyses showed that lytic genes were under purifying selection; in contrast, latency genes were under positive selection. In conclusion, this study determined the EBV genomes in EBVaGC from Guangdong and performed a detailed genome-wide analysis of GC-EBV, which would be helpful for further understanding of the relationship between EBV genomic variation and EBVaGC carcinogenesis.

Sequence variations of Epstein-Barr virus-encoded BARF1 gene in nasopharyngeal carcinomas and healthy donors from southern and northern China

The BamHI A rightward frame 1 (BARF1) gene of the Epstein-Barr virus (EBV) is involved in carcinogenesis and immunomodulation of EBV-associated malignancies. The geographical distributions and the disease associations of BARF1 variants remain unclear. In the current study, the BARF1 variants in nasopharyngeal carcinoma (NPC) cases and healthy donors from southern and northern China, the NPC endemic and non-endemic areas, as well as in 153 sequenced EBV genomes from diseased and normal people from around the world, were determined and compared among areas and populations. Only 1 consistent coding change, V29A, and several consistent silent mutations were identified. Two BARF1 types (B95-8 and V29A) and 2 B95-8 subtypes (B95-8^t165545c and B95-8^P ) were classified. For Chinese isolates, the B95-8 type was dominant in both southern and northern China, but the isolates from southern China showed a higher frequency of the B95-8^t165545c subtype than the isolates from northern China (76.0%, 38/50 NPC cases and 50.7%, 37/73 healthy donors vs 26.4%, 24/91 NPC cases and 7.6%, 6/79 healthy donors, P < .0001). Furthermore, the B95-8^t165545c subtype was more frequent in NPC cases than healthy donors in both southern China (P = .005) and northern China (P = .001). For EBV genomes, the B95-8^P subtype was dominant in northern China, Europe, America, and Australia, while V29A was dominant in Africa. The B95-8^t165545c subtype was only identified in Asia and demonstrated high frequency (81.2%, 26/32) in genomes from NPC cases in southern China. These results further reveal conservation and possibly geographically spread variations of BARF1 and may also indicate the preference of EBV strains with the B95-8^t165545c subtype in NPC cases, without biological or pathogenic implications.

New Insights from Elucidating the Role of LMP1 in Nasopharyngeal Carcinoma

Latent membrane protein 1 (LMP1) is an Epstein-Barr virus (EBV) oncogenic protein that has no intrinsic enzymatic activity or sequence homology to cellular or viral proteins. The oncogenic potential of LMP1 has been ascribed to pleiotropic signaling properties initiated through protein-protein interactions in cytosolic membrane compartments, but the effects of LMP1 extend to nuclear and extracellular processes. Although LMP1 is one of the latent genes required for EBV-immortalization of B cells, the biology of LMP1 in the pathogenesis of the epithelial cancer nasopharyngeal carcinoma (NPC) is more complex. NPC is prevalent in specific regions of the world with high incidence in southeast China. The epidemiology and time interval from seroconversion to NPC onset in adults would suggest the involvement of multiple risk factors that complement the establishment of a latent and persistent EBV infection. The contribution of LMP1 to EBV pathogenesis in polarized epithelia has only recently begun to be elucidated. Furthermore, the LMP1 gene has emerged as one of the most divergent sequences in the EBV genome. This review will discuss the significance of recent advances in NPC research from elucidating LMP1 function in epithelial cells and lessons that could be learned from mining LMP1 sequence diversity.

The conundrum of the Epstein-Barr virus-associated gastric carcinoma in the Americas

Epstein-Barr virus-associated gastric carcinoma shows a higher prevalence in the Americas than Asia. We summarize all studies of Epstein Barr virus-associated gastric carcinoma in the Americas, focusing on host characteristics, environmental associations and phylogeographic diversity of Epstein-Barr virus strains. In the Americas, the prevalence of Epstein Barr virus-associated gastric carcinoma is 11.4%, more frequent in males and portray predominantly diffuse-type histology. EBERs, EBNAs, BARTs and LMP are the highest expressed genes; their variations in healthy individuals may explain the phylogeographic diversity of Epstein-Barr virus across the region. Gastric cancer cases harbor exclusively the western genotype (subtype D and kept Xho I site), suggesting a disrupted co-evolution between the pathogen and its host. Epstein-Barr virus-associated gastric carcinoma molecular subtype cases from The Cancer Genome Atlas display PIK3CA gene mutations, amplification of JAK2, PD-L1 and PD-L2 and CpG island methylator phenotype, leading to more extensive methylation of host and viral genomes than any other subtypes from the study. Environmental conditions include negative- and positive- associations with being firstborn child and smoking, respectively. A marginal association with H. pylori has also been reported. Lymphoepithelioma-like carcinoma is associated with Epstein Barr virus in 80%-86% of cases, most of which have been included as part of Epstein Barr virus-associated gastric carcinoma series (prevalence 1.1%-7.6%). Whether these cases represent a variant of Epstein-Barr virus-associated gastric carcinoma is discussed. We propose novel research strategies to solve the conundrum of the high prevalence of Epstein-Barr virus-associated gastric carcinoma in the Americas.

Associations of Epstein-Barr Virus DNA in PBMCs and the Subtypes with Breast Cancer Risk

Objective: Epstein-Barr virus (EBV) has been found to be implicated in the development of breast cancer. The purpose of the present study was to identify the associations of EBV DNA and the subtypes in peripheral blood mononuclear cells (PBMCs) with the risk of breast cancer. Material and Methods: A case-control study with 671 breast cancer cases and 859 age-matched controls was conducted in Guangzhou, China. Face-to-face interviews were performed and blood samples were collected immediately after admission to the hospital for patients or after the interview for controls. EBV DNA in PBMCs and the subtypes were detected using Polymerase Chain Reaction (PCR) and restricted fragment length polymorphisms (RFLP). IgA antibodies against EBV VCA-p18 and EBNA-1 were examined using commercial enzyme-linked immunosorbent assay kits. Unconditional logistic regression analysis was applied to evaluate the associations of the DNA positivity and subtypes of EBV with the risk of breast cancer. Results: Among the 1530 subjects, 164 cases (24.4 %) and 206 controls (24.0 %) were positive for EBV DNA in PBMCs and no significant difference occurred between cases and controls. The presence of EBV DNA was related to the positivity of EBV IgA antibodies. Of the DNA positive samples, 71 cases and 109 controls for F/f subtype and 58 cases and 112 controls for C/D subtype were successfully obtained. The D subtype was associated with an increased breast cancer risk compared with the C subtype [OR (95% CI): 2.86 (1.25~6.53)]. We did not find an association of the F/f polymorphism with breast cancer risk. Conclusions: The present study suggested that the presence of EBV DNA in PBMCs may not be an appropriate biomarker for breast cancer risk. The subtype D of EBV was likely to be related to breast tumorigenesis.

Epstein-Barr Virus Infection in Gastric Remnant Carcinoma and Recurrent Gastric Carcinoma in Qingdao of Northern China

BACKGROUND

Epstein-Barr virus (EBV) is associated with a subset of gastric carcinoma which was defined as EBV associated gastric carcinoma (EBVaGC). The proportion of EBVaGC in gastric remnant carcinoma (GRC) which occurs in the intact stomach five or more years after gastric surgery for benign disease is significantly higher than that in conventional gastric carcinoma (CGC). The infection of EBV in recurrent gastric carcinoma (RGC) with local anastomotic recurrence is poorly understood.

METHODS

53 cases of GRC and 58 cases of RGC were analyzed for the presence of EBV, and the variants of EBV Encoded RNAs (EBER), EBV Nuclear Antigen 1 (EBNA1) and Latent Membrane Protein 1 (LMP1) gene in both groups were investigated.

RESULTS

Thirteen (24.5%) out of 53 GRC cases and 3 (5.2%) out of 58 RGC cases were identified as EBVaGCs. In 17 paired RGC cases, only one case was classified as EBVaGC in both times specimen. Another one case was identified as EBVaGC in the primary gastroectomy specimen while the recurrent gastric cancer was not. The third EBVaGC in RGC was identified while the primary gastric cancer was not EBVaGC. In GRC and RGC cases, type 1, type F, EB-6m, V-val subtype, del-LMP1 were predominant type or variants, accounting for 10(76.9%) and 2(66.7%), 13(100%) and 3(100%), 13(100%) and 3(100%), 9(69.2%) and 3(100%), 12(92.3%) and 3(100%), respectively. However, Type C was the predominant type in GRC accounting for 9(69.2%) cases while type D was the predominant one accounting for 2(66.7%) cases in RGC.

CONCLUSIONS

The prevalence of EBVaGc in GRC and RGC was significantly different. The distributions of these variants were similar to each other in the two groups which indicated that there were no more aggressive EBV variants in EBVaGC in GRC compared with that in RGC.

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

Is gastric lymphoepithelioma-like carcinoma a special subtype of EBV-associated gastric carcinoma? New insight based on clinicopathological features and EBV genome polymorphisms

BACKGROUND

Gastric lymphoepithelioma-like carcinoma (LELC) is a rare entity that is closely associated with Epstein-Barr virus (EBV). However, the EBV latency pattern and genome polymorphisms in gastric LELC have not been systematically explored.

METHODS

The clinicopathological features, EBV latency pattern and genome polymorphisms of EBV-positive gastric LELC in Guangzhou, southern China were investigated and compared with those of ordinary EBV-associated gastric carcinoma (EBVaGC) in the same area.

RESULTS

Ten (1.42%) of 702 gastric carcinoma cases were identified as gastric LELC, in which eight (80%) cases were EBV-positive. The clinicopathological characteristics and EBV latency pattern of EBV-positive gastric LELC were similar to those of ordinary EBVaGC. In EBV genotype analysis, type A strain, type F, I, mut-W1/I, XhoI- and del-LMP1 variants were predominant among EBV-positive gastric LELCs, accounting for eight (100%), six (75%), eight (100%), seven (87.5%), five (62.5%) and six (75%) cases, respectively, which are similar to those in ordinary EBVaGC. For EBNA1 polymorphisms, the V-leu and P-ala subtypes were predominant in EBV-positive gastric LELC, which is different from the predominant V-val subtype in ordinary EBVaGC. EBV-positive gastric LELC has a favorable prognosis when compared to ordinary EBVaGC (median survival time 43.0 vs. 18.0 months).

CONCLUSIONS

Gastric LELC is strongly associated with EBV and EBV-positive gastric LELC should be regarded as a special subtype of EBVaGC. This, to our best knowledge, is the first time in the world that the EBV latency pattern and genome polymorphisms of EBV-positive gastric LELC are systematically revealed.

High prevalence of the EBER variant EB-8m in endemic nasopharyngeal carcinomas

Epstein-Barr virus (EBV)-encoded small RNAs (EBERs) are the most highly expressed transcripts in all EBV-associated tumors and are involved in both lymphoid and epithelioid carcinogenesis. Our previous study on Chinese isolates from non-endemic area of nasopharyngeal carcinoma (NPC) identified new EBER variants (EB-8m and EB-10m) which were less common but relatively more frequent in NPC cases than healthy donors. In the present study, we determined the EBER variants in NPC cases and healthy donors from endemic and non-endemic areas of NPC within China and compared the EBER variants, in relation to the genotypes at BamHI F region (prototype F and f variant), between population groups and between two areas. According to the phylogenetic tree, four EBER variants (EB-6m, EB-8m, EB-10m and B95-8) were identified. EB-6m was dominant in all population groups except for endemic NPC group, in which EB-8m was dominant. EB-8m was more common in endemic NPC cases (82.0%, 41/50) than non-endemic NPC cases (33.7%, 32/95) (p<0.0001), and it was also more frequent in healthy donors from endemic area (32.4%, 24/74) than healthy donors from non-endemic area (1.1%, 1/92) (p<0.0001). More importantly, the EB-8m was more prevalent in NPC cases than healthy donors in both areas (p<0.0001). The f variant, which has been suggested to associate with endemic NPC, demonstrated preferential linkage with EB-8m in endemic isolates, however, the EB-8m variant seemed to be more specific to NPC isolates than f variant. These results reveal high prevalence of EBER EB-8m variant in endemic NPC cases, suggesting an association between NPC development and EBV isolates carrying EB-8m variant. Our finding identified a small healthy population group that shares the same viral strain which predominates in NPC cases. It could be interesting to carry extensive cohort studies following these individuals to evaluate the risk to develop NPC.

Variations of Epstein-Barr virus nuclear antigen 1 in Epstein-Barr virus-associated gastric carcinomas from Guangzhou, southern China

Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1) is the only viral protein consistently expressed in all EBV-associated malignancies, and play a critical role in the onset, progression, and/or maintenance of these tumors. Based on the signature changes at amino acid residue 487, EBNA1 is classified into five distinct subtypes: P-ala, P-thr, V-leu, V-val and V-pro. In the present study, the sequence variations of EBNA1 in EBV-associated gastric carcinoma (EBVaGC) and throat washing (TW) samples of healthy EBV carriers in Guangzhou, southern China, where nasopharyngeal carcinoma (NPC) is endemic, were analyzed by PCR and DNA sequencing. V-val subtype was the most predominant (53.6%, 15/28) in EBVaGC, followed by P-ala (42.9%, 12/28) and V-leu (32.1%, 9/28) subtypes. In TWs of healthy EBV carriers, V-val subtype was also predominant (85.7%, 18/21). The sequence variations of EBNA1 in EBVaGC were similar to those in TW of healthy EBV carriers (p>0.05), suggesting that the EBV strains in EBVaGC might originate from the viral strains prevalent within the background population. The predominance of V-val subtype in EBVaGC in Guangzhou was similar to that in EBVaGC in northern China and Japan, but was different from that in EBVaGC in America, suggesting that the variations of EBNA1 in EBVaGC represent geographic-associated polymorphisms rather than tumor-specific mutations. In addition, the EBNA1 variations in EBVaGC in gastric remnant carcinoma were also determined. V-leu subtype was detected in all 4 (100%) cases, although 2 cases occurred as mixed infection with P-ala subtype. This is different from the predominant V-val subtype in EBVaGC in conventional gastric carcinoma, suggesting that V-leu might be a subtype that adapts particularly well to the microenvironment within the gastric stump and enters the remnant gastric mucosa epithelia easily. This, to our best knowledge, is the first investigation of EBNA1 polymorphisms in EBVaGC from endemic area of NPC.

Epstein-Barr virus-associated gastric carcinoma: a newly defined entity

Epstein-Barr virus (EBV)-associated gastric carcinoma (EBVaGC) is a recently recognized entity, which is defined by the presence of EBV in the gastric carcinoma cells. EBVaGC represents about 10% of gastric carcinoma worldwide, and >80,000 patients are estimated to develop EBVaGC annually. EBVaGC shows some distinct clinicopathologic characteristics, such as male predominance, predisposition to the proximal stomach, and a high proportion in diffuse-type gastric carcinomas. Besides, EBVaGC also shows characteristic molecular abnormality, that is, global and nonrandom CpG-island methylation of the promoter region of many cancer-related genes, which causes downregulation of their expression. Moreover, EBVaGC has a relative favorable prognosis. The uniform presence of EBV-encoded small RNA in tumor cells but not in the surrounding normal epithelial cells, and the detection of monoclonal EBV episomes in EBVaGC, strongly suggests that EBV play an etiological role in gastric carcinogenesis. Therefore, EBVaGC should be regarded as a distinct entity of gastric carcinoma, although it only accounts for a relatively small fraction of total gastric carcinomas. In this review, the epidemiological and clinicopathologic features of EBVaGC and the genetic abnormalities of EBVaGC cell including chromosomal and epigenetic abnormalities are described. The roles of EBV in gastric carcinogenesis are discussed. We make an emphasis on the EBV latency pattern and genome polymorphisms as well as local immunity in EBVaGC. In addition, the treatment of EBVaGC is also briefly discussed. Taken together, this review aims to give the reader a full understanding of a newly defined entity of gastric carcinoma, EBVaGC.

Sequence variations of latent membrane protein 2A in Epstein-Barr virus-associated gastric carcinomas from Guangzhou, southern China

Latent membrane protein 2A (LMP2A), expressed in most Epstein-Barr virus (EBV)-associated malignancies, has been demonstrated to be responsible for the maintenance of latent infection and epithelial cell transformation. Besides, it could also act as the target for a CTL-based therapy for EBV-associated malignancies. In the present study, sequence variations of LMP2A in EBV-associated gastric carcinoma (EBVaGC) and healthy EBV carriers from Guangzhou, southern China, where nasopharyngeal carcinoma (NPC) is endemic, were investigated. Widespread sequence variations in the LMP2A gene were found, with no sequence identical to the B95.8 prototype. No consistent mutation was detected in all isolates. The immunoreceptor tyrosine-based activation motif (ITAM) and PY motifs in the amino terminus of LMP2A were strictly conserved, suggesting their important roles in virus infection; while 8 of the 17 identified CTL epitopes in the transmembrane region of LMP2A were affected by at least one point mutation, which may implicate that the effect of LMP2A polymorphisms should be considered when LMP2A-targeted immunotherapy is conducted. The polymorphisms of LMP2A in EBVaGC in gastric remnant carcinoma (GRC) were for the first time investigated in the world. The LMP2A sequence variations in EBVaGC in GRC were somewhat different from those in EBVaGC in conventional gastric carcinoma. The sequence variations of LMP2A in EBVaGC were similar to those in throat washing of healthy EBV carriers, indicating that these variations are due to geographic-associated polymorphisms rather than EBVaGC-associated mutations. This, to our best knowledge, is the first detailed investigation of LMP2A polymorphisms in EBVaGC in Guangzhou, southern China, where NPC is endemic.

Unique variations of Epstein-Barr virus-encoded BARF1 gene in nasopharyngeal carcinoma biopsies

The Epstein-Barr virus (EBV) BamHI-A rightward frame 1 (BARF1) gene is frequently expressed in EBV-associated epithelial malignancies and involves in oncogenicity and immunomodulation. To characterize the variations of BARF1 gene in different populations, the sequences of BARF1 gene in Northern Chinese nasopharyngeal carcinoma (NPC), EBV-associated gastric carcinoma (EBVaGC) and healthy donors were analyzed. The correlation of BARF1 variation with polymorphisms of BamHI F fragment (type F and f variants) and EBV-coded viral interleukin-10 (vIL-10) gene (B95-8 and SPM patterns) was also explored. Two major subtypes of BARF1 gene, designated as B95-8 and V29A, were identified. B95-8 subtype had identical amino acid sequence to B95-8 and was the dominant subtype among the EBV isolates from Northern China. V29A subtype, with one consistent amino acid change at residue 29 (V→A) and several nucleotide changes, showed higher frequency in NPC cases (25.3%, 20/79) than in EBVaGC cases (0/45) or healthy donors (4.3%, 2/46) (NPC vs. EBVaGC: P=0.0001; NPC vs. healthy donor: P=0.004). A preferential linkage between BamHI F and BARF1/vIL-10 polymorphisms was found. Type f isolates was specially correlated with the V29A/SPM genotype in NPC isolates and type f/V29A/SPM was preferentially found in NPC. BARF1/c-fms homology domain, transforming domain and cytotoxic T lymphocyte (CTL) epitopes of BARF1 were highly conserved in most isolates, suggesting the important role of BARF1 in virus infection and the potential usefulness in EBV-targeting immunotherapy of EBV-associated tumors. The relatively higher prevalence of type f/V29A/SPM strains in NPC may also suggest the association between these variations in multiple viral genes and NPC.

Characterization of Epstein-Barr virus gp350/220 gene variants in virus isolates from gastric carcinoma and nasopharyngeal carcinoma

To characterize the sequence variation of the gp350/220 and explore its potential association with EBV-associated tumors, the gp350/220 gene was sequenced from 41 EBV-associated gastric carcinoma (EBVaGC) and 81 nasopharyngeal carcinoma (NPC) biopsies as well as 35 throat washing (TW) samples from healthy donors. Preferential linkages between variants of the N-terminus of gp350/220 and EBNA3C variants were detected, and type A/BLLF1-a was the dominant variant in this study. The dominant variant in the C-terminal region of gp350/220 was 9P. The similar distribution of gp350/220 variants in NPC, EBVaGC and healthy donors suggest that gp350/220 variations are geographically restricted rather than tumor-specific polymorphisms.

Epstein-Barr virus genome polymorphisms of Epstein-Barr virus-associated gastric carcinoma in gastric remnant carcinoma in Guangzhou, southern China, an endemic area of nasopharyngeal carcinoma

Epstein-Barr virus (EBV) is associated with a subset of gastric carcinoma which was defined as EBV-associated gastric carcinoma (EBVaGC). The proportion of EBVaGC in gastric remnant carcinoma (GRC) was apparently higher than that in conventional gastric carcinoma (CGC) which occurs in the intact stomach. To clarify the possible mechanisms, 26 GRC cases from Guangzhou were investigated for the presence of EBV, and the EBV genome polymorphisms of EBVaGC in GRC were analyzed. Besides, the clinicopathologic characteristics, EBV latency pattern of EBVaGC in GRC were also investigated. Eight (30.8%) out of 26 cases were identified as EBVaGCs. Type A strain, prototype F, type I, mut-W1/I1, XhoI- and del-LMP1 variants were predominant among EBVaGC patients, accounting for 7 (87.5%), 7 (87.5%), 8 (100%), 6 (75%), 5 (62.5%) and 8 (100%) cases, respectively. All EBVaGC cases were male and with the histology of diffuse-type carcinoma. The tumor cells expressed EBNA1 (87.5%) and LMP2A (62.5%) but not LMP1, EBNA2 and ZEBRA. Thus, the EBV latency pattern was latency I. These were similar to those in CGC, except for the significantly higher proportion of EBVaGC in GRC than in CGC, suggesting that there is no more aggressive EBV variant in EBVaGC in GRC, and the injuries of gastric mucosa and/or changes of the microenvironment within the remnant stomach may be involved in the development of EBVaGC in GRC. This, to our knowledge, is the first study concerning about the EBV genome polymorphisms of EBVaGC in GRC in the world.

The association of genomic variation of Epstein-Barr virus BamHI F fragment with the proliferation of nasopharyngeal carcinoma

To investigate the f variant of Epstein-Barr virus (EBV) in nasopharyngeal carcinogenesis, we detected the f variant in primary nasopharyngeal carcinoma (NPC), metastatic carcinoma of the lymph node (LN), and chronic inflammation of the nasopharynx from the Guangdong region. Meanwhile, we analyzed the relationship between the f variant of EBV and LMP1, Fascin, pStat3, p53, Bcl-2, and Ki-67 expression in NPC. The results showed that the f variant of EBV was found in 11 cases of primary NPCs with LN metastasis, 12 LN metastases, and 18 primary NPCs without LN metastasis. However, only one demonstrated the F/f variant in 50 cases of chronic inflammation of the nasopharynx. The expression rate of LMP1, Fascin, pStat3, p53, Bcl-2, and Ki-67 in NPC with the f or F/f variant was higher than that with the F prototype. Furthermore, there was a significantly positive correlation between the f variant of EBV and Ki-67 expression (p < 0.05). Our study suggests that the f variant of EBV may be closely related to nasopharyngeal carcinogenesis.

Widespread sequence variation in the Epstein-Barr virus latent membrane protein 2A gene among northern Chinese isolates

Latent membrane protein 2A (LMP2A) is expressed in most Epstein-Barr virus (EBV)-associated malignancies. Besides its roles in the maintenance of latent infection and epithelial-cell transformation, LMP2A could also act as the target for a CTL-based therapy for EBV-associated malignancies. In the present study, sequence polymorphisms in LMP2A from northern Chinese EBV-associated gastric carcinoma patients, nasopharyngeal carcinoma patients and healthy donors were identified and compared with the prototype B95-8 strain. Four consistent mutations were detected in all isolates. Frequent mutations in the analysed sequences distinguished two and seven types of sequence variation in exon 1 and exons 2-8, respectively, with no consistent association shown between the genotyping of the two gene fragments. The immunoreceptor tyrosine-based activation motif and PY motif in the amino terminus were strictly conserved. Nine of the 16 identified CTL epitopes were affected by at least one point mutation, which may confer complexity to proposed immunotherapeutic approaches for EBV-associated malignancies. Most changed epitopes showed higher mutation rates in tumour isolates than in throat-washing samples from healthy donors, in accordance with the idea that virus strains can evade immune surveillance by altering amino acids within LMP epitopes. This first detailed investigation of sequence variations in the LMP2A gene reveals classifiable sequence polymorphisms in exon 1 and exons 2-8, and encourages further work on the impact of viral gene variations on tumour persistence and CTL-based immunotherapy.

Association of distinctive Epstein-Barr virus variants with gastric carcinoma in Guangzhou, southern China

To investigate the clinicopathologic features, Epstein-Barr virus (EBV) latency pattern and genome polymorphism of EBV-associated gastric carcinoma (EBVaGC) in Guangzhou, an endemic area of nasopharyngeal carcinoma (NPC), an in situ hybridization assay of EBV-encoded small RNA-1 (EBER-1) was used to identify the presence of EBV in 676 consecutive gastric carcinoma cases. EBV-encoded proteins EBNA1, EBNA2, LMP1, and ZEBRA were detected by immunohistochemistry. EBV genome polymorphism was also analyzed by PCR and DNA sequencing. Of the 676 cases, 45 EBV-positive cases (6.7%) were identified, including 37 (8.5%) male and 8 (3.3%) female cases. EBNA1 was detected in 42 cases (93.3%), while EBNA2, LMP1, and ZEBRA were all negative. In the EBV genome polymorphism analysis, type A strain, prototype F, type I, XhoI-, and del-LMP1 variants were predominant among EBVaGC patients, accounting for 44 (97.8%), 37 (82.2%), 45 (100%), 34 (75.6%), and 42 (93.3%) cases, respectively. Moreover, a new hotspot mutation in the BamHI-W1/I1 boundary region (148,972 T --> C) was found in 39 (86.7%) of the 45 cases. The predominant EBV variants in EBVaGC in Guangzhou are prototype F, type I, and XhoI-, which are different from those in NPC in this area (predominant variant-type "f") and in EBVaGC in Latin American countries (predominant type "i" and XhoI+), suggesting that the EBV variants are not only geographically distributed but also disease restricted, and the pathogenic role of EBV in different EBV associated epithelial malignancies in different areas may be distinct.

Prevalence and characteristics of Epstein-Barr virus-associated gastric carcinomas in Tunisia

OBJECTIVE

Epstein-Barr virus (EBV) has been linked to gastric carcinoma (GC) with worldwide geographical variations of prevalence ranging from 1 to 18% of cases. Investigations carried out in north Africa have shown that some EBV-associated types of cancers are common in this area. This study was taken to determine the prevalence of EBV-associated GC in Tunisia.

METHODS

Ninety-six nonselected GC cases (male/female ratio 1.7/1, mean age 60.9 years, range: 20-88 years) were evaluated for the presence of EBV by polymerase chain reaction as well as by in-situ hybridization for EBV-encoded small RNAs (EBERs) and immunohistochemistry for LMP-1 and EBNA-2 expression.

RESULTS

EBV was detected by polymerase chain reaction in 36% of cases, whereas EBERs were detected in the tumor cells in only four cases (4.1%). Immunohistochemistry for LMP-1 and EBNA-2 was negative in all cases. The mean age for patients harboring EBERs-positive GC was 55.7 years (range: 52-59 years). All EBERs-positive GC cases were males of advanced clinical stage (pT3-pT4). According to Lauren's classification, two cases were of diffuse histological type and two cases were of intestinal type. In three cases, the tumors have a proximal location and in the remaining case the tumor arises in the antrum. All EBV strains detected from EBV-associated GC were exclusively of type A and D, prototype F, and XhoI-maintained variant.

CONCLUSION

We conclude that the prevalence of EBV-associated GC in Tunisia is low (4.1%), suggesting that this virus is not an important etiological factor in GC arising in north African populations. The clinicopathological profile of EBV-associated GC in Tunisia did not differ markedly from that found elsewhere.

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.

Epstein-Barr virus associated gastric carcinoma: a report from Iran in the last four decades

BACKGROUND

Epstein-Barr virus has been proved to be associated with many of the human malignancy including gastric carcinoma, one of the most important human malignancies in the world. There has been no study about the presence of EBV in gastric adenocarcinoma in Iran.

METHODS

We examined the presence of EBV in 273 formalin fixed paraffin-embedded cases of gastric carcinoma from Cancer institute of Tehran University, from 1969 to 2004. In situ hybridization of EBV-encoded small RNA-1 (EBER-1) was conducted. The strain of positive cases was examined by means of polymerase chain reaction and/or restriction fragment length polymorphism analysis.

RESULTS

We found 9 (3%; 95% CI = 1-5%) EBV positive cases. The gender difference was not statisticaly significant. The proportion of EBV-GC cases in diffuse type was higher than intestinal type (OR = 0.08; 95% CI = 0.002-0.64). EBV-GC cases had no relation with age, location and invasion. Six out of 9 EBV-GC cases were born during the period between 1928 and 1930. All 9 cases were Type A. Prototype F was seen in 6 out of 8 cases. Type "i" was found in 8 cases and type I in 1 case. XhoI+ and XhoI- polymorphism accounted 6 and 3 of the cases, respectively.

CONCLUSION

Our study is the first to describe the frequency of EBV-GC in Iran and the Middle East, highlighting a very low prevalence with specific clinicopathologic features. The predominance of EBV-GC birth year in a fixed period, suggests that EBV infection or other events at early childhood may be related to the development of EBV-GC later in the life. The predominance of the type "i" and XhoI+ cases are contradictory to other studies in Asia and is similar to what is reported from Latin American countries.

Polymorphism analysis of Epstein-Barr virus isolates of nasopharyngeal carcinoma biopsies from Tunisian patients

Many studies suggest that the focal distribution of nasopharyngeal carcinoma (NPC) may be influenced not only by host genetics, diet and environments but also by interplay with Epstein-Barr virus (EBV) genetics. Specific EBV gene variants (the A and C types, the BamHI f configuration, a C terminal 30 bp deletion and a N terminal loss of an XhoI site in the BNLF1 gene) have been explored in high incidence areas in southern Asian NPC patients. In contrast, in Tunisia where NPC represents the most frequent type of Head and Neck cancer the distribution of these polymorphisms remains poorly investigated. In order to characterize the epidemiology of EBV variants in Tunisian NPC patients, we have investigated the A or B type of the EBV nuclear antigen (EBNA)2 gene, the C or D type of the BamHI W1/I1 region, the F/f variants of the BamHI F region and the presence or the absence of the XhoI site, 30 bp deletion and Taq1 site in the BNLF1 gene in 47 NPC biopsies, 12 being younger than 30 and 35 older than 30. Our results show a unique genetic profile of the tumor EBV strains regarding the A and D types, the prototype F and retention of the XhoI restriction site in the N terminal region of BNLF1 gene. With regard to the C terminal region of this gene, four genetic profiles were detected: (1) the occurrence of the 30 bp deletion in association with the Taq1 site in 39 cases (83%), (2) the presence of the Taq1 site by itself in 5 cases, (3) the occurrence of the 30 bp deletion by itself in 2 cases and (4) the occurrence of a new deletion of 81 bp covering the 30 bp deletion in association with the Taq1 site in one case. With the exception of the 81 bp deletion, which has not been previously described in the literature, the summarized results have shown the same genetic profile in Tunisian NPC tumor isolates as tumor isolates from other North African and Mediterranean countries. Hence, the observed EBV polymorphisms are not fully specific of to the Tunisian NPCs. Nevertheless, the notion of a divergence between North African and Asian tumor EBV isolates is reinforced by this study.

Distribution of Epstein-Barr virus genotypes in throat washings, sera, peripheral blood lymphocytes and in EBV positive tumor biopsies from Slovenian patients with nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a malignancy closely associated with Epstein-Barr virus (EBV). It is prevalent among the Chinese of Southern China, whereas outside China, the position seems to be different. The aim of this study was to determine the distribution of EBV genotypes in the patients with NPC in Slovenia, which is a nonendemic area. Detection of EBV was undertaken by testing the throat washes, sera, peripheral blood lymphocytes (PBLs), and biopsies of primary tumors of 48 patients with NPC in Slovenia. The sera of 20 patients with serologically confirmed primary EBV infection served as a control clinical material. The analysis of genotypes was carried out on three regions of EBV genome; BamHI WYH, BamHI I, and BamHI F, using the polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). The results show that, in Slovenia, the predominant combination of EBV genotypes based on the differences in the three genomic regions is ADF. This combination was found in 56 out of 103 different EBV positive clinical samples (throat washes, sera, PBLs, and tumor biopsies) of patients with NPC and in 15 out of 17 sera of patients with primary EBV infection. Very low number of genotypes C and f were detected, in spite of the fact that these two genotypes were considered to be associated with the development and/or maintenance of NPC in Southern China. Genotype f was found in only two tumor biopsies; in all other clinical samples (throat washes, sera and PBLs), genotype F was detected. Genotype C was proven in 31/103 clinical samples, with the highest percentage in tumor biopsies (37.5%). As in the NPC patients from other countries (Alaska is an exception), genotype A was predominant and was detected in 86/103 clinical samples. Genotype B was found in 15 clinical samples of patients with NPC and in 3 the two genotypes A and B were found. In comparison to China, these results show different EBV genotypes distribution. It seems that the genetic disposition of human population is an important factor that may contribute to different susceptibility for specific EBV genotypes.

Nasal natural killer/T-cell lymphoma and its association with type "i"/XhoI loss strain Epstein-Barr virus in Chile

BACKGROUND

Nasal T/natural killer (NK)-cell lymphoma is an aggressive type of non-Hodking's lymphoma associated with Epstein-Barr virus (EBV) and striking geographical variations worldwide.

AIM

To characterise nasal NK/T-cell lymphoma associated with genotypes of EBV in Chile, a Latin American country, where multiple strains of EBV, including two new recombinant strains, in healthy individuals were recently found.

METHODS

Cases with diagnosis of primary nasal lymphoma were selected for histological and immunohistochemical analysis (CD3, CD3e, CD4, CD8, CD79a, CD56, CD57 and TIA-1) and in-situ hybridisation, serology and genotyping analysis for EBV.

RESULTS

Out of 22 cases, 9 (41%) cases fulfilled the World Health Organization criteria for nasal NK/T-cell lymphoma; of these 7 (78%) cases were positive for EBV. Genotyping analysis revealed 6 cases of type 1 EBV and wildtype F at the BamHI-F region, 4 cases type "i" EBV at the BamHI-W1/I1 region; XhoI wild type was found in 2 and XhoI loss in 4 cases, respectively. Cosegregation analysis of the BamHI-W1/I1 region and XhoI restriction site showed the new recombinant strain type "i"/XhoI loss in 3 cases and type "i"/XhoI wild-type strain in 1 case. Most patients were treated with combined anthracycline-containing regimens. Half of the cases attained complete remission.

CONCLUSION

Although nasal NK/T-cell lymphomas from Chile share similar clinicopathological features, high association with EBV and unfavourable prognosis with those described elsewhere, genotype analysis shows that the new recombinant type "i"/XhoI loss strain might contribute to explain the intermediate incidence of nasal NK/T-cell lymphomas in Latin America.

Association of a distinctive strain of Epstein-Barr virus with gastric cancer

Epstein-Barr virus (EBV) has been linked to gastric carcinoma (GC) with worldwide geographical variations attributable to types and variants of EBV. Here, we compare EBV strains between EBVaGC and healthy donors in Latin America, a high frequency area for EBVaGC. Tumor samples from 73 EBVaGC cases and throat washings from 329 healthy adults were examined for types 1 and 2 EBV and polymorphism at BamHI-F and BamHI-W1/I1 boundary regions and XhoI restriction site in LMP1 gene. Type 1 and prototype F of BamHI- F polymorphism accounted 59 (81%) and 69 (95%) of EBVaGC cases and 257 (78%) and 267 (81%) of healthy donors, respectively. Types I and "i" of BamHI W1/I1 polymorphism accounted 2 (3%) and 62 (85%) of EBVaGC and 85 (26%) and 170 (52%) of healthy donors, respectively (p<0.001). XhoI+ and - polymorphism accounted 60 (82%) and 4 (5%) of EBVaGC and 142 (43%) and 92 (28%) of healthy donors, respectively (p<0.001). Cosegregation analysis demonstrated that most of the 62 type "i" EBVaGC cases harbor XhoI+ strain (81%). However, among 143 type "i" healthy adults, both XhoI polymorphism were present in relatively similar frequencies (XhoI+ 58% and XhoI- 42%) (OR 9.0; 95% CI 1.2-69). Our findings are against to the proposed hypothesis that EBV strains are geographically but not disease-restricted. We conclude that most of the EBVaGC cases harbor a distinctive EBV strain (type "i"/XhoI +), but in healthy donors, this strain was as common as other strains. This finding is contrary to the proposed hypothesis that EBV strains are geographically but not disease-restricted and identified a healthy population group that share the same strain that predominate in EBVaGC cases.

BAMHI DNA fragment H-polymorphism of Epstein-Barr virus is associated with the mutations present in an 89 BP sequence localized in EBNA2 gene

To characterize the genotypes of Epstein-Barr virus (EBV) isolate present in North Africa, viruses were isolated from B-lymphoblastoid cell lines established from the saliva of both Algerian Nasopharyngeal Carcinoma (NPC) patients and EBV-positive normal individuals, Algerian Burkitt's lymphoma cell lines, and NPC biopsies. By nucleotide sequence analysis, we showed that there were two specific missense mutations in an 89 bp region of EBNA2 gene at position 49390-49479 of the EBV genome: a mutation at 49449 (C-->A) and another mutation at 49444 (T-->C), changing their amino acid sequence. The first mutation was found in all B cell lines established from the saliva and 50% of BL cell lines, as well as the W91 cell line, while the second mutation was found in EBV isolates from NPC biopsies, BL cell lines and the M-ABA isolate. A PCR-RFLP analysis on the BamHI DNA fragment H showed that the Hl-H2-polymorphism was specifically associated with M-ABA-like mutation, while H-polymorphism was linked with W91-like mutation. The latter was not identified in NPC biopsies, but was found rather in saliva from NPC patients, normal individuals and BL cell lines. The M-ABA-like mutation, on the other hand, was found in 100% of NPC biopsies and some BL cell lines. This suggests that EBV with H1-H2-polymorphism is tightly implicated in NPC development in North Africa rather than EBV with H-polymorphism.

Amino acid changes in functional domains of latent membrane protein 1 of Epstein-Barr virus in nasopharyngeal carcinoma of southern China and Taiwan: prevalence of an HLA A2-restricted 'epitope-loss variant'

Full-length sequences of the Epstein-Barr virus (EBV) gene for latent membrane protein (LMP)-1 from 22 nasopharyngeal carcinoma (NPC) biopsy specimens and 18 non-neoplastic counterparts (NPI) were determined. Relative to the B95-8 strain, the amino acid sequences of the toxic-signal and transformation domains were changed variably in NPC and NPI specimens; in contrast, no change was observed in the NF-kappaB (nuclear factor kappaB) activation domain. HLA typing revealed that 47 % of NPC and 31 % of NPI specimens were HLA A2-positive. A major A2-restricted epitope within LMP-1 (residues 125-133) was analysed. At residue 126, a change of L-->F was detected in 91 % (20/22) of NPC and 67 % (12/18) of NPI specimens. In addition, a deletion at residue 126 was detected in one NPC sample from Taiwan. At residue 129, a change of M-->I was observed in all samples, regardless of whether they were NPC or NPI. The changes in this peptide between NPC and NPI specimens, including mutation and deletion, are statistically significant (P<0.05). A recent report indicated that this variant sequence is recognized poorly by epitope-specific T cells. Genotyping results indicated that 96 % of NPC and 67 % of NPI samples carried a type A virus. By scanning the entire sequence of LMP-1, eight distinct patterns were identified. Detailed examination of these patterns revealed that type A strains are more prevalent in NPC than in NPI specimens and are marked by the loss of an XhoI site, the presence of a 30 bp deletion and the presence of a mutated, A2-restricted, T cell target epitope sequence. These results suggest that an EBV strain carrying an HLA A2-restricted 'epitope-loss variant' of LMP-1 is prevalent in NPC in southern China and Taiwan.

Epstein-Barr virus (EBV)-related oral squamous cell carcinoma in Okinawa, a subtropical island, in southern Japan--simultaneously infected with human papillomavirus (HPV)

Up to now, many authors have reported on the EBV infection and its carcinogenic importance in undifferentiated nasopharyngeal carcinoma (WHO classification, type III), but the infection of the virus in well differentiated oral squamous cell carcinoma has not been well described. We introduce the EBV-related well differentiated oral squamous cell carcinomas in Okinawa, a subtropical island in the southernmost part of Japan. This study aimed to clarify the pathogenesis of this malignancy in this area by carrying out analysis of the histology and the Epstein-Barr (EBV) and human papillomavirus (HPV) infection. In the Department of Oral Surgery, Ryukyu University Hospital Okinawa, 188 cases of oral malignant tumours were encountered from 1996 to 2000. The histopathological examination and the sequence analysis of LMP-1 carboxy terminal region and EBNA2 region of EBV were carried out, as were the analysis of virus subtypes, A and B, BamHI-F and f, and C and D. Additionally, HPV infection in the squamous cell carcinomas were demonstrated using E6 and E7 region primer sets by PCR method. In Okinawa, 94% (177/188) of the cases were squamous cell carcinomas. A surprisingly large number of EBV (72%) and HPV (78%) infections in the oral squamous cell carcinomas were demonstrated. EBV type B virus infection was found in 36% of EBV-related oral squamous cell carcinoma in Okinawa, but in only 2-5% of the mainland cases. In both regions the incidence of the BamHI- f variant infection was very low. The infected virus in 79 out of 80 (39 Okinawan and 41 mainland) cases was BamHI- F type. In Okinawa, the numbers of C and D variants were almost equal, whereas in the mainland the D variant was rare. Further, a 30 bp deletion in LMP-1 gene was frequently demonstrated in Okinawan and mainland cases of type A virus, but not in type B virus. Lastly, single nucleotide mutations in EBNA2 region of type A virus when compared with B95-8 strain were demonstrated in Okinawan cases. The prognosis for (mostly EBV/HPV infected) squamous cell carcinomas in Okinawa was better than that in the mainland where most cases were negative for EBV and/or HPV.

Analyses of Epstein-Barr virus latent membrane protein-1 in Malaysian nasopharyngeal carcinoma: high prevalence of 30-bp deletion, Xho1 polymorphism and evidence of dual infections

Nasopharyngeal carcinoma, a malignancy associated closely with Epstein-Barr virus (EBV), is prevalent among Chinese of Southern China origin. Epidemiological studies indicate a high prevalence of EBV in Asia with viral isolates having typical characteristics of the putative viral oncogene, latent membrane protein 1 (LMP-1), such as the loss of the Xho1 restriction site in Exon 1 and the 30-bp deletion in Exon 3. The EBV LMP-1 gene from throat washings of 120 nasopharyngeal carcinoma patients and 14 healthy individuals were analyzed. Similar analyses were also carried out on 30 and 12 postnasal space biopsies from nasopharyngeal carcinoma patients and healthy individuals, respectively. The 30-bp deletion was detected in 20% of nasopharyngeal carcinoma throat washes and in 100% of nasopharyngeal carcinoma postnasal space biopsies. Interestingly, 16% of the nasopharyngeal carcinoma biopsies possessed both the deleted and the undeleted variants, suggestive of dual infections. The notion of dual infections in nasopharyngeal carcinoma was further supported by the coexistence of both "F" and "f" (BamH1F region) EBV variants in 11% of the nasopharyngeal carcinoma biopsies. All of the throat washes and biopsies from the healthy controls showed the undeleted variant. The loss of the Xho1 restriction site was found with higher frequency both in throat washes and biopsies from patients with nasopharyngeal carcinoma. The discrepancy in the frequency of the 30-bp deletion between throat washes (20%) and postnasal space biopsies (100%) was an indication that this deletion is specific for viral isolates from primary tumour sites.

Epstein-Barr virus in the pathogenesis of NPC

Epstein-Barr virus (EBV) is consistently detected in nasopharyngeal carcinoma (NPC) from regions of high and low incidence. EBV DNA within the tumor is homogeneous with regard to the number of terminal repeats. The detection of a single form of viral DNA suggests that the tumors are clonal proliferations of a single cell that was initially infected with EBV. Specific EBV genes are consistently expressed within the NPC tumors and in early, dysplastic lesions. The viral proteins, latent membrane protein 1 and 2, have profound effects on cellular gene expression and cellular growth, resulting in the highly invasive, malignant growth of NPC tumors. In addition to potential genetic changes, the establishment of a latent, transforming infection in epithelial cells is likely to be a major contributing factor to the development of this tumor.

Identification of Epstein-Barr virus strain variants in hairy leukoplakia and peripheral blood by use of a heteroduplex tracking assay

Epstein-Barr virus (EBV) strains can be distinguished by specific sequence variations in the LMP1 gene. In this study, a heteroduplex tracking assay (HTA) specific for LMP1 was developed to precisely identify the prototypic undeleted strain B958, other undeleted strains (Ch2, AL, NC, and Med-), and strains with the 30-bp deletion (Med+ and Ch1). This technique also provides an estimate of the relative abundance of strains in patient samples. In this study, EBV strains were identified in 25 hairy leukoplakia (HLP) biopsies and six matched peripheral blood samples and throat washes with the LMP1-HTA. To investigate the relationship of the virus found in the peripheral blood to that in the HLP lesion, the strain variants in the peripheral blood B lymphocytes and those present within the epithelial cells in the HLP lesion and in throat washes were identified. In many of the subjects, compartmental differences in the EBV strain profiles in the oral cavity and peripheral blood were readily apparent. The throat wash specimens usually had a strain profile similar to that within the corresponding HLP sample, which was distinct from the strain profile detected in the peripheral blood. These analyses reveal that the nature of EBV infection can be very dynamic, with changes in relative strain abundance over time as well as the appearance of new strains. The patterns of abundance in the blood and oral cavity provide evidence for compartmentalization and for the transmission of strains between the blood and oropharynx.

Characteristics of Epstein-Barr virus isolated from the malignant lymphomas in Korea

Epstein-Barr virus (EBV) is a common herpes virus linked to a variety of human neoplasms. In this study, the EBV detection was identified with the paraffin-embedded tissues from 62 non-Hodgkin's lymphomas, 20 Hodgkin's lymphomas, and 48 non-neoplastic tonsils, using PCR for EBNA-1 and EBER-1 mRNA in situ hybridization for EBER-1 mRNA. The isolates were analyzed for type 1/2, variants C/D and F/f, and LMP-1 30 bp deletion. EBV was isolated in 31 of 48 (66%) non-neoplastic tonsils, 24 of 42 (57%) B cell lymphomas, in 15 of 20 (75%) T cell lymphomas, and 17 of 20 (85%) Hodgkin's lymphomas. These viruses were classified as type 1 for 81% of non-neoplastic tonsils, 95% of B cell lymphomas, 93% of T cell lymphomas, and 73% of Hodgkin's diseases. Both type 1 and 2 viruses were isolated in one non-neoplastic tonsil and 3 Hodgkin's diseases. Type C virus was predominant in non-neoplastic tonsils (77%) and B cell lymphomas (75%), while type D virus was common in T cell lymphomas (71%) and Hodgkin's diseases (73%) (P < 0.05). Majority of the viruses detected in non-neoplastic tonsils (93%) and malignant lymphomas (91%) were "F" prototype. LMP-1 30 bp deletion was found in high frequency in both non-neoplastic tonsils (92%) and malignant lymphomas (86%). In conclusion, most of EBV found in Korea was type 1, and "DF" genotype was more frequent in T cell lymphomas and Hodgkin's diseases than in non-neoplastic tonsils and B cell lymphomas. LMP-1 30 bp deletion did not seem to be associated with malignant lymphomas.

Epstein--Barr virus gene polymorphisms in Chinese Hodgkin's disease cases and healthy donors: identification of three distinct virus variants

Epstein--Barr virus (EBV) is associated with several malignancies. Specific EBV gene variants, e.g. the BamHI f configuration, a C-terminal region 30 bp deletion in the latent membrane protein-1 (LMP1) gene (del-LMP) and the loss of an XhoI site in LMP1 (XhoI-loss), are found in Chinese cases of nasopharyngeal carcinoma (NPC), suggesting that EBV sequence variation may be involved in oncogenesis. In order to understand better the epidemiology of these EBV variants, they were studied in virus isolates from EBV-positive Chinese cases of Hodgkin's disease (HD; n=71) and donor throat washings from healthy CHINESE: Sequencing was performed of 15 representative EBV isolates, including the first analysis of the LMP1 promoter in Asian wild-type EBV isolates. The following observations were made. (i) Three EBV LMP1 variants were identified, designated Chinese groups (CG) 1--3. In both EBV-associated HD and in healthy Chinese, CG1-like viruses showing del-LMP1 and XhoI-loss were predominant. (ii) CG1viruses were distinct from European and African variants, suggesting that this profile is useful for epidemiological studies. (iii) Specific patterns of mutations were present in the LMP1 promoter in both CG1 and CG2. (iv) The BamHI f variant was not found in Chinese HD, in contrast to Chinese NPC and European HD. This study confirms that EBV isolates in Chinese HD and other tumours differ from those reported in Western cases. However, this reflects the predominant virus strain present in the healthy Chinese population, suggesting that these are geographically restricted polymorphisms rather than tumour-specific strains.

In nasopharyngeal carcinoma-bearing patients, tumors and lymphocytes are infected by different Epstein-Barr virus strains

Despite the fact that most adult humans worldwide are latently infected by the Epstein-Barr virus (EBV), only a very small percentage of them will develop an EBV-associated malignancy. We do not know whether this situation reflects the existence of more sensitive individuals or of particularly tumorigenic EBV strains. We postulated that if highly tumorigenic EBV strains did exist, they would be preferentially found in consistently EBV-associated tumors, such as nasopharyngeal carcinoma (NPC), and differ significantly from the strains present in other, non-pathological sites of the same patients. To test this hypothesis, we compared the BNLF1 gene of the EBV strains present in tumors and in "reservoir lymphocytes" of 6 NPC-bearing patients from Tunisia. Our results show that all of these patients were infected by more than 1 (and up to 7) EBV strains. Moreover, lymphocytes and tumor cells from the same individual were systematically infected by different viral strains. The origin and biological significance of these multistrain infections are discussed.

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.

Epstein-Barr virus expression within keratinizing nasopharyngeal carcinoma

Three stages of maturation can be seen in keratinizing nasopharyngeal carcinomas. These stages are similar morphologically to basal cells, intermediate and superficial squamous cells seen in normal squamous epithelium. Taking advantage of such a diverse tumour cell population, 10 keratinizing nasopharyngeal carcinoma (NPC) were examined by in situ hybridization for the presence of latent Epstein-Barr Virus (EBV) using EBV encoded RNAs (EBERs) and by immunohistology for the presence of EBV early antigen-diffuse (EA-D) and the 350/220 kd membrane glycoprotein of the EBV. The basal cell-like tumour cells are mainly infected latently with the virus; viral replication was found in isolated intermediate squamous cells, whilst superficial squamous cells are largely depleted of all the viral markers. We used a control series of nonkeratinizing nasopharyngeal carcinomas composed of undifferentiated and poorly differentiated tumour cells and EBV latency was present in these tumours. Viral replication was detected by RT-PCR, in the undifferentiated tumours but viral replication was not seen by immunohistology. The possible relationship between EBV life cycle in these tumours and tumour cell differentiation is discussed in the light of these findings.

Epstein-Barr virus strain characterization

The Epstein-Barr virus (EBV), a ubiquitous human herpesvirus originally described in cultured lymphoblasts from African Burkitt's lymphoma, is the causative agent of infectious mononucleosis, but appears to be involved in the pathogenesis of a variety of diseases. EBV has the ability to establish lifelong persistent infection, where only a restricted pattern of the viral proteins is expressed. Periodic reactivation of EBV occurs, where mature EBV particles are produced. Strain variation is potentially important in the biology and epidemiology of EBV, and in attempts to relate EBV to associated diseases. Analysis of the EBV genomes isolated from patients with EBV-associated diseases and from various parts of the world has so far failed to identify conclusive disease-specific viral subtypes. This review focuses on the different strategies which have been used for strain characterization or subtyping of EBV.

Molecular epidemiology of Epstein-Barr virus (EBV) in EBV-related malignancies

The prevalent strain of Epstein-Barr virus (EBV) in EBV-related malignancies and in healthy adults in Southern Japan was examined by means of polymerase chain reaction (PCR) and/or restriction fragment length polymorphism (RFLP) analysis. In EBV-related gastric cancers, 51/73 cases were subtype A, 4 were subtype B and the EBNA-2 region was not amplified in 18 cases. Sixty-three were wild-type F, and only one was variant "f". Sixty-one cases had type C and 2 type D. EBNA-2 subtype A was found in 10/12 EBV-related T/NK-cell lymphomas, and 11 samples harbored the wild-type F. Neither subtype B nor the "f" variant was detected. Type C EBV was found in 8 cases and type D in 3 specimens. Two Japanese nasopharyngeal carcinomas (NPC) harbored subtype A with wild-type F and type C. Throat washings from healthy adults harbored wild-type F virus in 60/153 cases, and 25 of these samples were EBNA-2 subtype A. Type C viruses were detected in 92% of cases and type D in 7.4%. Therefore, the prevalent strain in EBV-related malignancies in Southern Japan was the same as in the healthy population in this geographical region.

Identification of type B-specific and cross-reactive cytotoxic T-lymphocyte responses to Epstein-Barr virus

Persistent Epstein-Barr virus (EBV) infection is primarily controlled by HLA class I-restricted memory cytotoxic T-cell (CTL) responses which can be reactivated in vitro by stimulation of peripheral blood lymphocytes with autologous lymphoblastoid cell lines. During an investigation of a donor infected by both type A and type B EBV, CTL specific for type B EBV were isolated. The CTL were found to recognize an epitope encoded by the EBNA-6B gene. The minimal epitope sequence was identified as QNGALAINTF, corresponding to residues 213 to 222 in the EBNA-6B protein, and presentation of this epitope was shown to be via HLA B62 (B15). This is the first report of the characterization of an epitope that is EBV type B specific. CTL recognizing sequences common to type A and type B EBV were identified as well. A cross-reactive epitope recognized by these CTL was encoded within the EBNA-6 gene of both type A and type B. This minimal sequence for this epitope was LLDFVRFMGV (residues 284 to 293 in both types), and the epitope was restricted through HLA A*0201. This second epitope sequence overlaps with a published EBV B44-restricted epitope (EENLLDFVRF). The implications of these findings are discussed with respect to the design and efficacy of epitope-based vaccines.

Genomic analysis of Epstein-Barr virus in nasal and peripheral T-cell lymphoma: a comparison with nasopharyngeal carcinoma in an endemic area

The Epstein-Barr virus (EBV) is prevalent in nasal and peripheral T-cell lymphoma (NPTL) in Taiwan, where nasopharyngeal carcinoma (NPC) is endemic. In order to understand the pathogenesis of these two malignancies in this endemic area, genomic analysis of EBV in NPTL with comparison to NPC is important. We investigated the EBV subtype (types A and B), BamH-I "f" variant, and the Xho-I site mutant of the latent membrane protein-1 (LMP-1) gene in 19 cases of EBV-associated NPTL and in 30 cases of NPC. EBV DNA from three patients with infectious mononucleosis (IM) was simultaneously studied as representative of normal healthy carriers. Similar to NPC and IM, the EBV in NPTL was found to belong to the type A strain in the majority (18 of 19) of cases by analyzing the 3' divergence of EBNA-2 genes. The extra restriction enzyme site in the BamHI-F region ("f" variant) of EBV DNA was frequently (15 of 30) demonstrated in NPC, but only rarely (1 of 19) was it detected in NPTL and IM (0 of 3). The Xho-I site mutant of the LMP-1 gene previously characterized in Chinese NPC also prevailed in NPTL and IM with an identical nucleotide sequence. No correlation exists between the EBV subtype and its variants. In conclusion, type A EBV is prevalent in Taiwanese NPTL, a finding much distinct from the dominance of type B virus in nonendemic European patients. The EBV genomes in NPTL are closely similar to those in IM or normal healthy carriers, but are distinct from NPC for the infrequency of the "f" variant. The prevalence of the LMP-1 mutant in this endemic region suggests that this EBV strain may confer a growth advantage role in the pathogenesis of these EBV-associated diseases. The rarity of the "f" variant in NPTL and its high frequency in NPC may explain the differential tumorigenesis of different EBV strains.

Tissue distribution of Epstein-Barr virus genotypes

The genome of naturally occurring Epstein-Barr virus contains either two or three copies of a 29-bp tandem repeat sequence in the first intron of the BZLF gene. These genotypes differ markedly in their distribution between blood and epithelial tissues, presumably because they have adapted to separate life cycles in these sites. The genotype prevalent in the blood also appears to be better able to transform B lymphocytes.

Clonal Epstein-Barr virus associated cholangiocarcinoma with lymphoepithelioma-like component

Epstein-Barr virus (EBV) has been linked to several undifferentiated carcinomas of the aerodigestive tract, especially the nasopharynx, but has not been reported in the biliary tract. We here presented a case of an unusual cholangiocarcinoma harboring EBV genome in a 47-year-old Chinese woman. Physical examination in 1988 in Taiwan, including abdominal sonography of the liver, was essentially negative. She experienced three episodes of malaria in 1990 when she worked in Ghana, Africa, and felt a tumor mass in the epigastrium in October 1992. She received an extended left lobectomy for a huge hepatic tumor of 12 x 10 x 5.5 cm in February 1993. Light microscopy revealed a cholangiocarcinoma composed of both well-differentiated adenocarcinoma and lymphoepitheliomatous undifferentiated carcinoma components. Abundant EBV EBER1 was shown in both tumor components, but not in the nontumor liver. Southern blot analysis and polymerase chain reaction showed a monoclonal episomal form of EBV, with a genotype characteristic for Chinese EBV strain type 1. This finding suggests that the EBV infection preceded monoclonal EBV-harboring tumor cell expansion in this case.

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.

In situ detection of Epstein-Barr virus in non-small cell lung carcinomas

Epstein-Barr virus (EBV) is strongly associated with nasopharyngeal carcinoma and lymphoepithelioma-like carcinomas (LELC) of foregut-derived organs. Recently this group of EBV-associated carcinomas has been expanded by the identification of the virus in conventional adenocarcinomas of the stomach. In situ hybridization (ISH) using a sensitive digoxigenin-labelled EBER RNA probe was performed on 167 consecutive unselected primary non-small cell lung carcinomas, to determine the frequency of EBV association in these tumours. Nine cases (5.4 per cent) showed strong EBER signals in the tumour cell nuclei. By immunohistochemistry, four of the EBER-positive tumours showed patchy expression of the viral latent membrane protein (LMP-1) and none showed any expression of the EBV nuclear antigen 2 (EBNA2). Morphologically, all the positive tumours were LELC, whereas no conventional type of non-small cell lung carcinoma showed EBV association. The LELC presented a morphological spectrum from undifferentiated to squamoid or glandular differentiation. The patients showed a male to female ratio of 8:1. The mean age at presentation was 48 years. Smoking was not a risk factor. All patients were alive at follow-up periods of 23-52 months. Southern blot analysis performed on eight of the nine positive tumours showed a clonal episomal form of EBV, suggesting the clonal expansion of an infected tumour cell early in oncogenesis. These characteristics of the EBV-associated lung tumours justify their consideration as a distinct clinicopathological entity.