Epstein-Barr virus in B-cell non-Hodgkin's lymphomas: Unexpected infection patterns and different infection incidence in low- and high-grade types

Two hundred and eight cases of B-cell non-Hodgkin's lymphoma (B-NHL) occurring in Europeans without any signs of HIV infection were investigated for their association with an Epstein-Barr virus (EBV) infection. The polymerase chain reaction (PCR) was applied for EBV-DNA detection, in situ hybridization (ISH) for the cellular localization of EBV-encoded small nuclear RNAs (EBER) and immediate-early RNAs (BHLF), and immunohistology (IH) for the detection of EBV-encoded latent membrane protein (LMP) and EBV nuclear antigen 2 (EBNA2) expression. PCR and EBER-ISH produced congruent results in those cases with amplifiable DNA. EBV was present overall in 26 per cent (54/208) of the B-NHL cases. Through EBER-ISH, the virus could be localized merely in rare non-neoplastic bystander lymphocytes in 27 and additionally in tumour cells of 27 cases. Unexpectedly, the proportion of EBV-infected tumour cells present in the different cases varied between 1 and 100 per cent. All but three of the cases with infected tumour cells were of high-grade malignancy. Correlation with the morphological and immunological tumour phenotype revealed that all cases with more than 80 per cent EBER-positive tumour cells were either B-anaplastic large cell lymphomas (B-ALCL), sporadic Burkitt's lymphomas, or B-NHLs with partial or full plasmacellular differentiation. LMP was consistently absent from Burkitt's lymphomas and constantly expressed in B-ALCLs with EBER-positive tumour cells, while in all other instances it varied greatly and was rarer than EBER expression. The above findings suggest that in cases where EBV is present in 80–100 per cent of tumour cells, EBV infection takes place before malignant transformation and thus may have contributed to the malignant phenotype, whereas in the other cases with only a smaller number of infected tumour and single bystander cells, EBV infection may have occurred following malignant transformation. In these cases, infection would appear to be of little or no significance in tumourigenesis.     

Functional tyrosine kinase inhibitor profiling: a generally applicable method points to a novel role of platelet-derived growth factor receptor-beta in tuberous sclerosis

A ubiquitous herpesvirus that establishes life-long infection, the Epstein-Barr virus (EBV) has yielded little insight into how a single agent in general accord with its host can produce diverse pathologies ranging from oral hairy leukoplakia to nasopharyngeal carcinoma, from infectious mononucleosis to Hodgkin's disease (HD) and Burkitt's lymphoma. Its pathogenesis is further confounded by the less than total association of virus with histologically similar tumors. In other viral systems, defective (interfering) viral genomes are known to modulate outcome of infection, with either ameliorating or intensifying effects on disease processes initiated by prototype strains. To ascertain whether defective EBV genomes are present in HD, we examined paraffin-embedded tissue from 56 HD cases whose EBV status was first determined by cytohybridization for nonpolyadenylated EBV RNAs (EBERs). Using both standard polymerase chain reaction (PCR) and PCR in situ hybridization, we successfully amplified sequences that span abnormally juxtaposed BamHI W and Z fragments characteristic of defective heterogeneous (het) EBV DNA from 10 of 32 (31%) EBER-positive tumors. Of 24 EBER-negative HD, 8 yielded PCR products indicating presence of het EBV DNA. Two of these contained defective EBV in the apparent absence of the prototype virus. Of the 42 tumors analyzed for defective EBV by both PCR techniques, there was concordance of results in 38 (90%). Detection of defective EBV genomes with the potential to disrupt viral gene regulation suggests one mechanism for pathogenic diversity that may also account for loss of prototypic EBV from individual tumor cells.     

Solitary plasmacytoma associated with Epstein-Barr virus: a clinicopathologic,cytogenetic study and literature review

Solitary plasmacytoma (SP) is an uncommon, indolent tumor of plasma cell neoplasms that presents as a mass lesion in extramedullary sites. Evidence of Epstein-Barr virus (EBV) infection is frequently associated with various lymphatic and hematopoietic malignancies but is relatively rare in SP. Moreover, it is essential to distinguish EBV-positive plasmacytoma from plasmablastic lymphoma. In this study, we found 4 EBV-encoded RNA (EBER)–positive patients among 46 consecutive immunocompetent patients of SP and compared the clinicopathologic features of these patients with those of the EBER-negative cohort. In the 4 EBER-positive patients, the common presenting feature was a local mass lesion without symptoms of chronic active EBV infection. Upon histologic examination, neoplastic cells demonstrated well-differentiated morphology in the absence of plasmablastic lymphoma components. Fluorescence in situ hybridization analysis showed that all cases were negative for del13q14, t(11;14)(q13;32) and MYC rearrangement but that 1 case had cytogenetic aberrations involving del17p13. Follow-up data revealed that EBER-positive patients had benign prognoses without aggressive clinical course and that there was no significant difference in the overall survival time between the 2 groups, but EBER-positive patients were more likely to have disease progression (relapse/progression to multiple myeloma) compared with EBER-negative patients. More case studies are needed to better understand the impact of EBV on disease pathogenesis and development in immunocompetent patients of SP.     

Detection of EBV in nasopharyngeal carcinoma by quantum dot fluorescent in situ hybridization

Aims

Nasopharyngeal carcinoma (NPC) is a common cancer in Southeast Asia and is frequently associated with Epstein–Barr virus (EBV) infection. The primary aim of this study was to improve the method of EBV detection by exploring quantum dots in FISH detection, and compare QD-based FISH with conventional ISH.

Materials and methods

Biopsy specimens were retrospectively retrieved from 35 NPC patients as paraffin-embedded tissue blocks. QD-FISH was developed to detect the presence of EBV encoded small RNA (EBER) using biotin-labeled EBER oligonucleotide probe indirectly labeled with streptavidin-conjugated quantum dots. Conventional ISH was also performed using a commercial kit to assess concordance between the two methods.

Results

All the 35 NPC cases were nonkeratinizing carcinoma (7 differentiated and 28 undifferentiated subtypes). EBER-positive signals were detected in 91.43% (32/35) and 80% (28/35) cases by QD-FISH and ISH, respectively. There was no significant difference in the number of EBER-positive cases by the two methods. A moderate concordance was found between QD-FISH and ISH for EBER status (κ = 0.55). Four EBER-negative cases by ISH showed EBER-positive signals when detected by QD-FISH.

Conclusions

EBV is closely associated with NPC in Chinese patients. QD-FISH is a novel effective method for EBER detection, and has a moderate concordance with conventional ISH.     

Distribution of Epstein-Barr virus in systemic rheumatic disease (rheumatoid arthritis, systemic lupus erythematosus, dermatomyositis) with associated lymphadenopathy: a study of 49 cases

Among systemic rheumatic diseases (SRDs), lymphadenopathy is frequently found in patients with rheumatoid arthritis (RA) and systemic lupus erythematous (SLE). Epstein-Barr virus (EBV)-associated lymphoproliferative disorders (LPDs) may occur in patients following methotrexate therapy for RA and dermatomyositis (DM). However, little is known about the distribution of EBV in reactive LPDs in patients with SRDs who had no history of methotrexate therapy. We analyzed 49 such patients (SLE=25, RA=23, DM=1) for the presence and distribution of EBV+ cells using Epstein-Barr virus (EBV)-encoded small RNA (EBER) specific in situ hybridization. A positive signal for EBERs was identified in 9 (SLE=5, RA=4) (18%) of 49 cases, and 3 main distribution patterns of EBER+cells could be delineated: pattern A, more than 500 EBER-positive cells were located in the germinal centers as well as interfollicular area (SLE=2); pattern B, EBER + cells were located in a few germinal centers (RA=2); and pattern C, up to 100 EBER+ cells were located in the interfollicular area (SLE=3, RA=2). Recent EBV infection may be a cause of lymph node lesion in only 2 cases of patients with pattern A. However, the pathognomonic significance of pattern B and pattern C EBER + cell distribution patterns still remains unclear. Our study indicates that the underlying immune deficits of patients with SRDs may also play an important role in the development of EBV-associated LPDs in SRDs, as previously suggested by several authors.     

Different roles of p53 between Epstein-Barr virus-positive and -negative gastric carcinomas of matched histology

To clarify the role of p53 in the development of Epstein-Barr virus (EBV)-associated gastric carcinoma, we examined DNA-ploidy pattern, the immunoreactivity of p53, p21(WAF1) and Ki-67 and the incidence of mitosis and apoptosis in EBV-positive and -negative gastric carcinomas of similar histology: a lace pattern and/or gastric carcinoma with lymphoid stroma. There was no significant difference in DNA-ploidy pattern, Ki-67 index or frequencies of mitosis and apoptosis between the two groups. In deeply invasive tumours (involving the muscularis propria or deeper), p53-positive ones were rare in the EBV-encoded small RNA (EBER)-positive group and very common in the EBER-negative group, while in superficial tumours, around one-half of them were p53-positive in both groups. In p53-positive superficial tumours, p21(WAF1)-positive ones accounted for 80% in the EBER-positive group and were scarce in the EBER-negative group. It is thus possible that p53 immunoreactivity reflects the overexpression of wild-type p53 and the stabilization of mutant p53 in the EBER-positive and -negative groups, respectively. The role of p53 in tumour development seems to be smaller in EBER-positive than in -negative gastric carcinomas.     

Frequent presence of latent Epstein-Barr virus infection in lymphoepithelioid cell lymphoma (Lennert's lymphoma)

This study deals with the investigation of the biological significance of an Epstein–Barr virus (EBV) infection in lymphoepithelioid cell lymphoma. A selection of EBV-detection techniques was applied to 15 cases, including polymerase chain reaction (PCR) for the detection of EBV-DNA, in situ hybridization (ISH) for the cellular localization of EBV-encoded small nuclear (EBER 1 and EBER 2) and immediate-early (BHLF) RNAs, and immunohistology for the detection of EBV-encoded latent membrane protein (LMP) expression. PCR and EBER-ISH produced congruent results in those cases with amplifiable DNA, leading to an EBV presence in 11/15 lymphoepithelioid cell lymphoma cases (73%). EBER-ISH combined with immunohistology localized the virus predominantly in several B immunoblasts and small B lymphocytes in eight of the EBV-positive cases, five of which also contained single infected lymphocytes expressing T-cell characteristic antigens. LMP was detected using immunohistology in only a proportion of immunoblasts in four of these cases. The remaining three EBV-positive lymphoepithelioid cell lymphoma cases contained only single EBER-positive small B lymphocytes without LMP expression. No case contained BHLF-RNA expressing cells. These data imply that, although latently EBV-infected cells are frequently present in lymphoepithelioid cell lymphoma cases, the virus is probably not directly involved in the pathogenesis of this entity.     

Epstein-Barr virus infection and its gene expression in gastric lymphoma of mucosa-associated lymphoid tissue

The role of Epstein-Barr virus (EBV) in the pathogenesis of gastric lymphoma of mucosa-associated lymphoid tissue (MALT) has not been well understood. The aim of the study was to investigate EBV infection and its gene expression in this tumor in order to understand its role in the pathogenesis. EBV infection was screened by in situ hybridization for EBV-encoded nonpolyadenylated RNA (EBER ISH) in 79 cases of gastric MALT lymphoma of nonimmunocompromised patients. The expression of EBV proteins [LMP1 (latent membrane protein 1), EBNA2 (EBV nuclear antigen 2), ZEBRA (switch protein encoded by BZLF1 gene)] was studied by immunohistochemistry in EBER-positive cases. EBV was detected with EBER ISH in 15 (19%) of the 79 cases. EBV was found in virtually all tumor cells in 2 cases of high-grade MALT lymphoma (2.5%) (EBV-associated), and was found only in occasional large or small lymphoid cells in 13 cases (16.5%). False positive EBER signal was detected in the mucinous glandular epithelial cells of gastric antrum with FITC-labeled oligonucleotide probe but not with digoxigenin or ³⁵S-labeled riboprobes. Type II latency (EBER+LMP1+ EBNA2-) was detected in both EBV-associated cases. Type III latency (EBER+LMP1+EBNA2+) was also identified in one EBV-associated case besides latency II. Double labeling showed coexpression of LMP1 and EBNA2 in a small number of tumor cells, indicating the presence of type III latency in single cell level. In cases with only occasional EBER-positive large or small lymphoid cells, LMP1 and EBNA2 were not detected. ZEBRA was negative in all the cases. These findings suggest that EBV may contribute to the pathogenesis of a small proportion of high-grade MALT lymphoma, where virtually all tumor cells harbored EBV and the oncogenic viral protein LMP1 was expressed. Moreover, latency III of EBV infection may exist in nonimmunocompromised patient. J. Med. Virol. 56:342–350, 1998 . © 1998 Wiley-Liss, Inc.     

EB病毒感染及30 bp缺失潜伏膜蛋白1基因在鼻咽部癌不同组织学类型中的比较

目的 比较鼻咽部癌4种组织学类型中EB病毒的感染率以及野生型潜伏膜蛋白(LMP)1和缺失型LMPl EB病毒变异株单独或双重感染的检出频率,阐明缺失型LMPl基因在鼻咽癌变过程中的作用。方法 采用EBER原位杂交法检测117例鼻咽部癌,包括48例非角化性癌、25例角化性鳞状细胞癌、5例腺鳞癌、6例黏液表皮样癌和33例腺癌标本。采用巢式聚合酶链反应(PCR)法检测99例EBER阳性的癌组织和53个健康成人的外周血单个核细胞EB病毒LMPl基因。结果EBER原位杂交示,48例非角化性癌和25例角化性鳞状细胞癌的EB病毒感染率均为100％;而腺鳞癌和黏液表皮样癌的：EB病毒感染率为9／11,腺癌为51,5％(17／33)。阳性病例中大多数非角化性癌细胞呈EBER阳性,而在17例腺癌中仅见到少数EBER阳性肿瘤细胞。在非角化性癌中检测到单独缺失型LMPl：EB病毒变异株的百分率(85.4％,41／48)不但高于健康成人外周血单个核细胞(8．7％,4／46),而且高于角化性鳞状细胞癌(16．0％,4／25)。在角化性鳞状细胞癌中检出野生型LMPl和缺失型LMPl基因EB病毒的双重感染率(56．0％,14／25)高于非角化性癌的(12．5％,6／48)。在腺癌和健康成人单个核细胞中检出的大多数EB病毒为野生型LMPl和缺失型LMPl基因变异株同时并存。非角化性癌／角化性鳞状细胞癌、腺鳞癌／黏液表皮样癌和腺癌之间的：EB病毒感染率差异有显著性意义。非角化性癌和角化性鳞状细胞癌EB病毒的感染率相同,但非角化性癌中单独缺失型LMPl EB病毒变异株检出率远远大于角化性鳞状细胞癌,角化性鳞状细胞癌多数含有野生型LMPl和缺失型LMPl双重EB病毒变异株。结论由于分化导向不同而发生的鼻咽部癌不同组织学类型具有不同的EB病毒感染率。缺失型LMPl基因的EB病毒变异株可能在非角化性癌中呈选择性优势。     

Detection of Epstein–Barr virus small RNAs in routine paraffin sections using non-isotopic RNA/RNA in situ hybridization

The Epstein–Barr virus (EBV) is associated with an increasing range of reactive and neoplastic lesions. There is a need for a sensitive and specific method for detecting latent EBV in routine histological sections. We report the use of a highly sensitive paraffin section RNA/RNA in situ hybridization (ISH) technique using digoxigenin-labelled antisense riboprobes for demonstrating EBV encoded-small RNAs (EBERs), EBV gene products that are transcribed in abundance during latent EBV infection. We applied EBER-ISH to 846 paraffin embedded specimens, including cases of reactive lymphoid hyperplasia ( n = 28), infectious mononucleosis (16), Burkitt's lymphoma (44), immunodeficiency-associated lymphomas in transplant recipients (9) and AIDS patients (128), Hodgkin's disease (130), CD30 antigen positive lymphomas (106), peripheral T-cell lymphomas (104), sporadic B-cell non-Hodgkin's lymphomas (162), undifferentiated nasopharyngeal carcinoma (86), salivary gland lymphoepithelioma (11), and oral hairy leukoplakia (5). Strong, reproducible EBER staining was seen in EBV latently infected cells in archival surgical biopsy and autopsy specimens. EBER-ISH is specific, has a sensitivity comparable to that of the polymerase chain reaction, and is now the method of choice for the in situ detection of latent EBV infection.     

Epstein-Barr virus is present in neoplastic cytotoxic T cells in extranodal, and predominantly in B cells in nodal T non-Hodgkin lymphomas

Epstein-Barr virus (EBV)-positive T non-Hodgkin lymphomas (T-NHLs) have been described, but it is at present unknown how EBV infects T lymphocytes. It has been postulated that cytotoxic T cells (CTLs) or natural killer (NK) cells can be infected by EBV during the killing of an EBV-infected target cell. The objective of this study was therefore to determine whether the neoplastic cells in EBV-positive T-NHLs (n=221) of various locations have a cytotoxic phenotype. To identify EBV-harbouring cells, combinations were used of EBV-encoded RNA (EBER) in situ hybridization (RISH) and immunohistochemistry for T- and B-cell markers and the cytotoxic proteins TIA-1 and granzyme B. EBV was detected in the neoplastic cells of all nasal T-NHLs (n=9), 5/34 gastrointestinal (GI) T-NHLs, and 2/6 lung T-NHLs, but not in primary cutaneous T-NHLs (n=103). Moreover, EBV was found in the neoplastic cells of 2/48 nodal anaplastic large cell lymphomas (ALCLs), but not in neoplastic T cells of other nodal T-NHLs. However, 5/17 nodal peripheral T-NHLs not otherwise specified (PTCLs NOS) and 1/4 T-prolymphocytic leukaemias did contain EBV-positive non-T cells. Double staining revealed that in EBV-positive extranodal T-NHLs (n=16), the EBER-positive cells had a cytotoxic phenotype (TIA-1- and/or granzyme B-positive). In nodal non-ALCL T-NHLs, the EBER-positive cells were not positive for TIA-1 or granzyme B, nor did they express CD3, CD21 or HECA452. Instead, most of these cells expressed the B-cell marker CD20. These PTCLs NOS with EBER-positive cells showed features of AILD-like T-NHL. It is concluded that neoplastic cells of EBV-positive extranodal T-NHLs always have a cytotoxic phenotype, supporting the view that EBV can infect CTLs. In nodal non-ALCL T-NHL, EBV is only found in T-NHL with AILD-like features and is present in B cells, where it may contribute to the outgrowth of a malignant B-cell clone.     

Epstein–Barr virus-associated primary gastrointestinal lymphoma in non-immunocompromised patients in Korea

We examined 81 cases of primary gastrointestinal lymphomas in Korea, including 64 gastric lymphomas and 17 intestinal lymphomas, for EBV expression by EBER-1 in situ hybridization (ISH) and EBNA-1 PCR. In EBER-1 positive cases, we performed immunohistochemistry for latent membrane protein-1 (LMP-1) and EBV diffuse early antigen (EA(D)) to compare EBV latent gene expression and lytic process.   EBER-1 was detected in 15 of 81 cases of lymphomas. EBER-1 expression showed three different patterns on tumour cells; diffuse 4/81 (5%), localized 4/81 (5%), and a few scattered pattern 7/81 (9%). We regarded diffuse pattern and localized pattern as EBER-1 positive group (8/81: 10%). Diffuse pattern of EBER-1 was shown in all three T-cell lymphomas and one B-cell lymphoma. A localized pattern was seen all in B-cell lymphomas. The EBER-1 expression was 11% in the stomach (7/64) and 6% in the intestine (1/17). Five of the eight EBER-1 positive gastric lymphomas were histologically diffuse large B-cell lymphomas, and the other three were peripheral T-cell lymphoma, unspecified, one angiocentric lymphoma, and one intestinal T-cell lymphoma by REAL classification. Eight MALT type gastric B-cell lymphomas showed no EBV association. EBV nuclear antigen (EBNA-1) was detected in 15 of 45 resected cases (33%) by PCR. EBER-1 positive cases were all EBNA-1 positive. Twelve EBNA-positive/EBER-negative cases consisted of seven cases showing a few scattered EBER-1 positive lymphocytes. LMP-1 and diffuse early antigen (EA(D)) was detected in five and three cases, respectively. Although follow-up information in our series was incomplete, it seemed that there was no significant difference in their staging or prognosis between EBER-positive cases and EBER-negative group. It is concluded that EBV is associated with some lymphomas among Koreans without overt pre-existing immunodeficiency, especially in T-cell lymphomas.     

Detection of human herpesvirus DNA in Kikuchi-Fujimoto disease and reactive lymphoid hyperplasia

Kikuchi-Fujimoto disease (KFD), or histiocytic necrotizing lymphadenitis, is a subacute inflammatory disorder most often seen in young women with clinicopathologic features suggestive of an infectious etiology. The most commonly suspected infectious agents in KFD are the human herpesviruses EBV, HHV6, HHV7 and HHV8. In order to identify herpesviruses in KFD, we have compared the frequency of detection of herpesvirus DNA with a recently developed real time PCR method, EBER in situ hybridization, and EBV latent membrane protein (LMP) immunostaining in 30 cases of KFD and 12 cases of reactive lymphoid hyperplasia (RLH). EBV DNA was commonly detected, while HSV2, CMV, HHV6, and HHV7 DNA were seldomly detected, and HSV1, VZV, and HHV8 DNA were not detected in KFD. EBV was also commonly detected in RLH. EBER-positive cells with apoptotic features were identified in necrotizing regions of many KFD cases, and LMP-positive cell debris was detected in one case. Viable EBER-positive cells were identified in four of twelve RLH cases, and rare LMP positivity detected in three cases. These data lend support to the notion that the necrotizing lesions in KFD may in some cases be due to a vigorous immune response to EBV-infected lymphoid cells.     

Plasmacytic hyperplasia in age-related Epstein-Barr virus-associated lymphoproliferative disorders: a report of two cases

Age-related Epstein-Barr virus (EBV)+B-cell lymphoproliferative disorder (LPD) is a recently recognized entity that occurs in patients over 40 years of age without any known immunodeficiency. However, this entity is thought to be related to the immunological deterioration that is part of the aging process. Histologically, age-related EBV+B-cell LPDs are classified into the polymorphous subtype and large B-cell lymphoma subtypes. However, plasmacytic hyperplasia, which is thought to be the earliest recognizable EBV+PT-LPD, has not been reported among EBV+B-cell LPDs. We report here two cases of age-related EBV-associated LPD and demonstrate the histological evolution. Pathologically, the initial lymph node biopsy specimens from both cases showed the classical Hodgkin lymphoma-like polymorphous subtype. Hodgkin (H) and Reed-Sternberg (RS) cells were CD3-, CD20+, CD15-. CD30+, CD45RB+, and latent membrane antigen-1+. In-situ hybridization (ISH) study demonstrated that numerous H and RS cells contained EBV-encoded small RNA (EBER)+. Repeated lymph node biopsy specimens from each case contained a mixture of lymphoid cells with prominent plasma cell differentiation, including immunoblasts without atypia. A portion of B-immunoblasts were CD30+ and EBER+. As assessed by polymerase chain reaction (PCR) assay, only the initial biopsy specimen in Case 1 displayed a solitary faint immunoglobulin heavy chain (IgH) gene rearrangement, consistent with the presence of a small clonal B-cell population. However, PCR analyses for EBV-genomes demonstrated the same single clonal infection of EBV in the initial and recurrent lymph node lesions in the present two cases. These two cases demonstrated the presence of plasmacytic hyperplasia in age-related EBV+B-cell LPDs, and plasmacytic hyperplasia also appears to be the earliest lesion of age-related EBV+B-cell LPDs.     

Frequent presence of subtype A virus in Epstein-Barr virus-associated malignancies

AIMS: Epstein-Barr virus (EBV) is associated with many human malignancies. It is implicated in a pathogenetic role in some of these tumours. Two subtypes, type A and B have been identified on the basis of DNA sequence divergence in the nuclear protein genes (EBNA) 2, 3, 4 and 6. They differ in their transforming efficiency and prevalence pattern in different geographical locations. We aimed to identify the virus subtype infection pattern in our EBV-associated diseases. METHODS: Paraffin-embedded tissue from 38 lymphomas (17 Hodgkin's, 14 Burkitt's, four T cell and 3 B cell non-Hodgkin's lymphomas) and 14 nasopharyngeal carcinomas (NPC) were studied, with 12 reactive lymph nodes and tonsils as normal control. EBER in situ hybridisation was performed to confirm EBV association in the tumour cells. A nested polymerase chain reaction (PCR) protocol was employed using two pairs of consensus primers which flanked a 105-bp deletion in the type A virus. U2 region encoding for EBNA-2 was chosen as the target of amplification, with cell lines B95.8 and AG876 serving as positive controls for types A and B virus, respectively. RESULTS: All cases showed presence of type A virus, consistently detected with nested PCR protocol but not with single step PCR. There was no type B virus or mix infections detected. CONCLUSIONS: Nested PCR technique has successfully increased the sensitivity of EBV subtype detection, and type A virus is the prevalent strain associated with human diseases in Malaysia.     

Epstein-Barr virus-associated gastric carcinoma in southern India: A comparison with a large-scale Japanese series

Epidemiological and clinicopathological features of Epstein-Barr virus (EBV) associated gastric carcinoma was compared in India and Japan, two countries differing markedly in gastric cancer incidence. Using in situ hybridization assay, the presence of EBV-encoded small RNA (EBER) was examined in 215, and 2,011 gastric cancer cases in Kerala, India, and Japan, respectively. Ten cases (5%), all males, in the Indian series were EBER-positive. This frequency was similar to that in the Japanese series (6.2%). As was the case with Japanese series, the EBV-associated gastric carcinoma in the Indian series was observed most frequently in the middle part of the stomach (1 in antrum, 4 in middle part, 2 in cardia, and 3 unknown), and, histologically, the diffuse type Lauren's classification (8 cases) was more common than the intestinal type (2 cases). Virus subtyping by PCR-RFLP revealed that all of the 10 EBV strains isolated from the EBER-positive Indian cases were subtype A, and wild-type F for Bam HI F region. In Bam HI I region, 8 cases were type C and the remaining 2 cases were type D. In either series, there was no significant difference in the frequency of tumors with p53 overexpression between EBER-positive and -negative cases. However, the proportion of cells with p53 overexpression in EBER-negative tumors was significantly higher than that in EBER-positive tumors regardless of histological type in both series. In conclusion, the frequency and major clinicopathological features of EBV-associated gastric carcinoma in south India were similar to those observed in Japanese series although gastric cancer incidence in these two countries differs markedly.