The nucleotide polymorphisms within the Epstein-Barr virus C and Q promoters from nasopharyngeal carcinoma affect transcriptional activity in vitro.

Epstein-Barr virus (EBV) is a ubiquitous human gamma herpesvirus that is associated with Burkitt's lymphoma (BL), gastric carcinoma, nasopharyngeal carcinoma (NPC), and NK/T-cell lymphoma. Two viral promoters, Cp and Qp, are important for EBV latent infection. The latency Cp, which is used in primary infection, drives expression of the full spectrum of EBV nuclear antigens. Qp is active in EBV-associated tumors and drives the latency I/II expression pattern. In this study, we determined nucleotides polymorphisms in the Cp and Qp promoter regions in peripheral blood mononuclear cells (PBMCs) from Cantonese healthy carriers and in biopsies of NPC, nasal NK/T lymphoma, BL, and gastric carcinoma. The sequence changes of -12G>T and +69 C>T in Cp and -197 G>A and +1 G>C in Qp were frequently identified in NPC. Transient transfection studies using luciferase gene reporters revealed a significant reduction (57.11%) in gene expression from the Cp +69T variant and increased expression (43.5%) from the Qp +1C variant compared to the prototype, suggesting that these sequence variations affect promoter activity. Our results indicate that the nucleotides polymorphisms in Cp and Qp occur frequently in NPC and might contribute to the oncogenesis of EBV.

Heat shock factor 1 upregulates transcription of Epstein-Barr Virus nuclear antigen 1 by binding to a heat shock element within the BamHI-Q promoter.

Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1) is essential for maintenance of the episome and establishment of latency. In this study, we observed that heat treatment effectively induced EBNA1 transcription in EBV-transformed B95-8 and human LCL cell lines. Although Cp is considered as the sole promoter used for the expression of EBNA1 transcripts in the lymphoblastoid cell lines, the RT-PCR results showed that the EBNA1 transcripts induced by heat treatment arise from Qp-initiated transcripts. Using bioinformatics, a high affinity and functional heat shock factor 1 (HSF1)-binding element within the -17/+4 oligonucleotide of the Qp was found, and was determined by electrophoretic mobility shift assay and chromatin immunoprecipitation assay. Moreover, heat shock and exogenous HSF1 expression induced Qp activity in reporter assays. Further, RNA interference-mediated HSF1 gene silencing attenuated heat-induced EBNA1 expression in B95-8 cells. These results provide evidence that EBNA1 is a new target for the transcription factor HSF1.

Detection of Stage I nasopharyngeal carcinoma by serologic screening and clinical examination.

In a prospective study, 42 048 adults residing in Zhongshan City, Guangdong, China, were followed for 16 years, and 171 of them developed nasopharyngeal carcinoma (NPC). Although Epstein-Barr virus (EBV) antibody levels of the cohort fluctuated, the antibody levels of 93% of the patients with NPC were raised and maintained at high levels for up to 10 years prior to diagnosis. This suggests that the serologic window affords an opportunity to monitor tumor progression during the preclinical stage of NPC development, facilitating early NPC detection. We reviewed the clinical records of the 171 patients with NPC in the prospective study to assess the efficacy of early NPC detection by serologic screening and clinical examination. Of the 171 patients, 51 had Stage I tumor (44 were among the 73 patients detected by clinical examination and 7 were among the 98 patients presented to outpatient department). Initial serologic screening predicted 58 (95.1%) of the 61 patients detected within 2 years. The risk of the screened population (58/3093) raised 13 times relative to cohort (61/42 048) during this period. Clinical examination detected all the 58 predicted cases, and 35 (60.3%) of which were diagnosed with Stage I tumor. The serologic prediction rate fell to 33.6% (37/110) 2 to 16 years after screening. The proportion of cases detected by clinical examination fell to 40.5% (15/37). The proportion of Stage I tumors among the cases detected by clinical examination during both periods remained at about 60%. We concluded that early detection of NPC can be accomplished by repeated serologic screening to maintain high prediction rates and by promptly examining screened subjects to detect tumors before the symptoms develop.

Nasopharyngeal extranodal NK/T-cell lymphoma, nasal type: retrospective study of 18 consecutive cases in Guangzhou, China.

OBJECTIVE: The aim of this study was to investigate the frequency and clinicopathologic features of nasopharyngeal extranodal NK/T-cell lymphoma, nasal type (NKTCL), as well as DNA sequence variation of Epstein-Barr virus (EBV) in neoplastic cells harboring in NKTCLs from Guangzhou district. MATERIALS AND METHODS: The clinical data of 18 unselected consecutive nasopharyngeal NKTCLs in one institution were reviewed retrospectively. Immunohistochemical staining and EBV-encoded RNAs (EBERs) in situ hybridization were applied. DNA extraction, polymerase chain reaction (PCR), nested PCR, and sequencing for analyzing the C-terminal and N-terminal regions of LMP1 gene as well as BamHI F fragment of EBV were applied in 16 available samples. RESULTS: NKTCLs accounted for 69.2% (18/26) of nasopharyngeal T- and NK-cell lineage non-Hodgkin lymphomas. In all, 10 out of 18 patients (55.56%) had cervical lymph node(s) involvement. The serum anti-EBV antibody level was elevated (VCA-IgA titer ≥1:40) in 6 of 12 available patients. Two major immunophenotypic subtypes, namely, TIA-1+/EBERs+/CD56+ (10 cases) and TIA-1+/EBERs+/CD56- (8 cases) could be recognized. Genotyping analysis revealed that 10 out of 13 cases (76.9%) of NKTCL were harbored with del-LMP1 [del-LMP1 (Gly335) variant 7 cases, del-LMP1 (Asp335) variant 3 cases]. XhoI-loss was shown in 8/11 cases (72.73%). BamHI "f" variant of Bam F fragment was shown only in 4/14 cases (28.57%).The most common combination was del-LMP1 (Gly335)/ XhoI-loss/F (6/9, 66.7%). CONCLUSIONS: The majority of nasopharyngeal T- and NK-cell lymphomas are NKTCL in Guangzhou district. The patients often have involvement of cervical lymph node(s) and an elevated level of serum anti-EBV antibodies. The CD56 expression rate seems lower than that found in sinonasal NKTCL. The most common EBV variant harboring in nasopharyngeal NKTCL seems somewhat different from that harboring in nasopharyngeal carcinoma in Guangzhou.

Clinicopathologic features and Epstein-Barr virus infection status of Burkitt's lymphoma in Guangzhou district.

BACKGROUND AND OBJECTIVE: Sporadic Burkitt's lymphoma (sBL) is uncommon and its relation to Epstein-Barr virus (EBV) is unknown in China. This study was to investigate the clinical presentation, morphologic features, immunophenotype and EBV infection status of sBL in Guangzhou district, a prevalent area of EBV infection. METHODS: The clinical data of 21 sBL patients were reviewed. A panel of immunohistochemical staining was performed and EBV-encoded small RNAs (EBERs) in situ hybridization was applied to identify EBV infection. RESULTS: From January 2000 to October 2007, 21 cases(0.87%) of sBL were confirmed among 2416 cases of non-Hodgkin's lymphoma(NHL) in Sun Yat-sen University Cancer Center. Male to female ratio was 4.25 (17/4). The median age was 23 years. Of the 21 patients, 19 (90.48%) had lymph node(s) involvement; 16 (76.19%) had multiple sites involvement; 12 (57.14%) were at advanced stages (III/IV). The 2-year survival rate of 15 patients who received chemotherapy or resection plus chemotherapy was 56.00%. Twenty cases showed the prototypic morphology of sBL, and one was the variant of sBL with plasmacytoid differentiation. The main immunophenotype of these 21 sBLs was sIgM+/CD20+/CD10+/Bcl-6+/Bcl-2-[or Bcl-6+(>95%)/Bcl-2+(<10%)]/TdT-/Ki-67+ 100%. Of 20 detectable cases, 11 showed CD5 expression in a few (3%-20%) tumor cells. P53 was overexpressed in ten cases (47.62%). Six cases (28.57%) had EBV infection, with EBNA1 and EBERs expression, but not LMP1. There were no significant differences in morphology and immunophenotype between EBV-positive and EBV-negative cases. CONCLUSIONS: sBL is uncommon in Guangzhou district, mainly seen in boys and young men. Most patients had lymph node(s) involvement, showing similar morphology and immunophenotype as that of endemic BL. Type I EBV latent infection is associated with 28.57% of cases.

[Six anti-Epstein-Barr virus antibodies in healthy adults in a high risk area of nasopharyngeal carcinoma].

BACKGROUND AND OBJECTIVE: Nasopharyngeal carcinoma (NPC), with a remarkable geographic distribution, is consistently associated with Epstein-Barr virus (EBV) infection, and almost all NPC patients have sustained high levels of serum antibodies against EBV. This study was to compare the levels of six anti-EBV antibodies in healthy natives of Zhongshan (a high-incidence area of NPC) with those in provisional migrants from foreign provinces (low-incidence areas of NPC), and to illustrate the relationship between EBV infection and the geographic distribution of NPC. METHODS: The serum levels of EBNA1-IgA, EBNA1-IgG, VCA-p18-IgA, VCA-p18-IgG, Zta-IgA and Zta-IgG in 303 healthy Zhongshan natives and 92 provisional migrants were tested using ELISA, and presented by values of adjusted relative absorbance (ArA). The serum levels and positive rates of the six antibodies were compared between the two groups. RESULTS: The mean ArA values of both Zta-IgA and VCA-p18-IgA were significantly higher in Zhongshan natives than in provisional migrants (0.84+/-0.03 vs. 0.42+/-0.04, P <0.05; 0.96+/-0.05 vs. 0.40+/-0.05, P<0.05). In addition, the positive rates of Zta-IgA and VCA-p18-IgA in subjects aged of 30-49, or of 50 and above were significantly higher in Zhongshan natives than in provisional migrants (29.27% vs. 3.03% and 48.28% vs. 6.67% for Zta-IgA, P<0.05; 28.46% vs. 9.09% and 43.10% vs. 13.33% for VCA-p18-igA, P<0.05). CONCLUSION: Zhongshan natives are likely to have an elevation of serum IgA antibodies against EBV lytic antigens (Zta and VCA-p18), which represents reactivation of EBV latency infection and implies that Zhongshan natives may have higher risk to develop NPC than provisional migrants.

Correlation of immunophenotype of sinonasal non-Hodgkin's lymphoma to Epstein-Barr virus infection.

BACKGROUND & OBJECTIVE: There are differences in the prevalence rate and composition of immunophenotypes of sinonasal non-Hodgkin's lymphoma (NHL) depending on the geography. This study was to investigate the immunophenotypes of sinonasal NHLs and their relationship to Epstein-Barr virus (EBV) infection in Guangzhou, China. METHODS: Fifty-seven NHL samples of the sinonasal region were collected from the Department of Pathology, Cancer Center of Sun Yat-sen University from Apr. 1, 2000 to Oct. 31, 2006. HE staining and immunohistochemical staining were performed. Both Epstein-Barr virus-encoded small RNA (EBER) hybridization and PCR were applied to identify EBV infection. RESULTS: Seventy-one sinonasal NHLs were found in all 1 412 NHLs (71/1 412, 5.03%). Only 57 out of the 71 NHL biopsy tissues were suitable for this study. The median age of the patients was 50 years (ranged from 3 to 75 years). There were 38 males and 19 females. Forty-four sinonasal NHLs (44/57, 77.19%) were NK/T-cell lymphoma, nasal type, all of which were infected with EBV. Among them, 37 patients (84.09%) appeared to be NK-cell neoplasm (EBV+/CD56+), and 7 cases (15.91%) showed an EBV+/CD56-cytotoxic T-cell phenotype. Eleven cases (11/57, 19.30%) were B-cell lymphoma. There were 6 cases of diffuse large B-cell immunophenotype, 2 cases of Burkitt (Burkitt-like) lymphoma (EBV+), 1 case of extramedullary plasmacytoma (EBV+), 1 case of MALT-lymphoma (EBV-), and 1 case of small lymphocytic lymphoma (EBV-). Only 2 cases (2/57, 3.51%; EBV-) were peripheral T-cell lymphoma, unspecified. The del-LMP1 EBV strain harbored in 25 out of 37 available DNA samples of NK/T-cell lymphoma (25/37, 67.57%); and the wt-LMP1 EBV strain was found in 12 samples (12/37, 32.43%). CONCLUSION: The most common sinonasal NHL is the NK/T-cell lymphoma, nasal type, which can be further subclassified into NK-cell neoplasm (EBV+/CD56+) and EBV+/CD56-cytotoxic T-cell phenotype. The major EBV strain in NK/T-cell lymphomas is del-LMP1 strain.

Epstein-Barr virus infection in precursor lesions of nasopharyngeal carcinoma.

BACKGROUND & OBJECTIVE: The infiltrating neoplastic cells within early-stage nasopharyngeal carcinoma (NPC) are consistently infected with Epstein-Barr virus (EBV). The precursor lesions could often be found in paracancerous epithelium of early-stage NPC. This study was to investigate the role of EBV infection and the intrahost evolution of EBV genotype developed in nasopharyngeal carcinogenesis through detection of EBV harboring in precursor lesions. METHODS: EBV-encoded RNA (EBER) in 15 cases of early-stage NPC biopsy tissue was detected by nucleic acid in situ hybridization. EBV type and latent membrane protein 1 (LMP1) EBV strain in precursor lesions and carcinoma nests were detected by nested polymerase chain reaction (PCR). DNA sequencing of the representative PCR products of carboxyl-terminus of LMP1 gene was analyzed by using four-colored fluorescence terminator sequencing technique. RESULTS: Most infiltrating carcinoma cells of all 15 cases of NPC showed EBER-positive. EBER-positive abnormal epithelial cells and/or infiltrating lymphocytes were found in 14 of 15 cases of precursor lesion. Single A-type EBV was detected in 9 of 11 available DNA samples of carcinoma nest and 9 of 10 available DNA samples of precursor lesion. The carboxyl-terminus of EBV LMP1 gene was detected in all 15 DNA samples of carcinoma nest, among which 14 were single 30-bp deleted LMP1 (del-LMP1) EBV infection and 1 was coinfection of wild-type LMP1 (wt-LMP1) EBV strain and del-LMP1 EBV strain. Among the 11 available DNA samples of precursor lesion suitable for carboxyl-terminus amplification, 5 were coinfection of wt-LMP1 and del-LMP1 EBV, 4 were single del-LMP1 EBV infection, 1 was single wt-LMP1 EBV infection, and 1 showed negative reaction. The DNA sequence of the carboxyl-terminus of wt-LMP1 gene was identical with that of B95-8 cells, while that of del-LMP1 gene had a 30-bp deletion (codon: 346-355) and 4 missense point mutations (codon: 334, 335, 338, and 366). CONCLUSION: EBV infection in nasopharyngeal epithelial cells is a preinvasive event of carcinogenesis of NPC, and the intrahost evolution of EBV genotype would take place during nasopharyngeal carcinogenesis.

Epstein-Barr virus serology in early detection and screening of nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is a common cancer among Chinese, especially Southern Chinese; except for a few other ethnic groups with moderate incidence, it is otherwise a rare cancer in the world. NPC has a male dominance of about 3:1 and mainly afflicts people in mid-life. There is now compelling evidences to suggest that Epstein-Barr virus (EBV), a category I human tumor virus defined by UICC (International Agency for Research on Cancer) in 1997, is a causal agent of NPC and is most likely to be involved in the multi-step and multi-factorial development of NPC. In this article, the role of EBV in pathogenesis of NPC is reviewed briefly, and principle applications of EBV antibodies and EBV DNA as markers of NPC are outlined. Based on current knowledge of EBV antibody responses by NPC and taking available testing technologies into account, serologic screening strategy to facilitate efficient early detection of NPC is formulated.

[Study of sequence variations of Epstein-Barr virus LMP1 gene in nasopharyngeal carcinoma].

OBJECTIVE: To detect the sequence variations frequently found within the N- and C-terminal regions of Epstein-Barr virus (EBV) LMP1 gene in nasopharyngeal carcinoma (NPC) and to study the underlying mechanisms. METHODS: Fresh tumor tissues were sampled from 63 patients with untreated NPC encountered in Affiliated Tumor Hospital of Sun Yat-sen University, Guangzhou. The N-terminal region of EBV LMP1 gene was amplified with nested polymerase chain reaction (PCR), followed by XhoI enzyme digestion. Nested PCR was also employed to detect the 30 base pairs deletion within the C-terminal region. Four-colored fluorescence terminator sequencing method was applied for bi-directional solid-phase sequencing of the 8 representative PCR products in 4 cases of NPC. The DNA sequence within the N- and C-terminal regions of LMP1 gene was then analyzed. RESULTS: There were 4 patterns of sequence variations, namely, wt-XhoI/wt-LMP1 (4 cases, 6.3%), wt-XhoI and XhoI-loss/del-LMP1 (4 cases, 6.3%), wt-XhoI/del-LMP1 (5 cases, 7.9%) and XhoI-loss/del-LMP1 (50 cases, 79.5%), detected in the 63 studied cases. Sequence analysis showed that the EBV LMP1 gene had underwent non-synonymous and synonymous substitutions, as compared with the prototype of B95-8 cells. The ratio of non-synonymous to synonymous substitutions was 2.25. CONCLUSIONS: XhoI-loss/del-LMP1 is the predominant sequence variation pattern of EBV LMP1 gene in NPC from Guangzhou. The XhoI-loss variation seems to develop on top of del-LMP1. When compared with the EBV LMP1 gene in peripheral blood B-lymphocytes of virus carriers and in preinvasive epithelial lesions (reported previously), it is likely that the sequence variation patterns of LMP1 gene may represent 4 different phases of intrahost evolution of EBV during nasopharyngeal carcinogenesis.

[Value of EBNA1-IgA and EA-IgG in serological diagnosis of nasopharyngeal carcinoma].

OBJECTIVE: To evaluate the value of EBNA1-IgA and EA-IgG in serological diagnosis of nasopharyngeal carcinoma (NPC). METHODS: The serum EBNA1-IgA and EA-IgG of 56 patients with NPC and 58 healthy adults were detected by ELISA. The sensitivity, specificity, positive predictive value, accuracy rate and odds ratio of the two tests used singly or in combination were compared with each other. RESULTS: The sensitivity of EBNA1-IgA (91.07%) was higher than that of EA-IgG (87.50%), while the specificity of EA-IgG (87.93%) was higher than that of EBNA1-IgA (84.48%). The combination of EBNA1-IgA and EA-IgG could enhance the specificity (94.83%), positive predictive value (0.9375), likelihood ratio (15.5435) and odds ratio (75.0000) for serological diagnosis of NPC. Forty-five patients showed both positive EBNA1-IgA and positive EA-IgG. A positive EA-IgG was detected in 4 out of 5 patients with negative EBNA1-IgA and a positive EBNA1-IgA was founded in 6 out of 7 patients with negative EA-IgG. CONCLUSION: Although relatively high sensitivity and specificity could be obtained by either EBNA1-IgA or EA-IgG test alone, the combination of these two tests with a complementary effect is able to enhance the reliability of serological diagnosis of NPC as most patients have positive ENBA1-IgA and EA-IgG concurrently.

[Effect of macrophage migration inhibitory factor (MIF) on expression of MMP-2,MMP-9,and IL-8 in nasopharyngeal carcinoma cell strains].

BACKGROUND & OBJECTIVE: Although nasopharyngeal carcinoma (NPC) shows highly invasive and metastatic features than other head and neck carcinomas, the major relevant mechanism is still unknown. This study was designed to investigate whether the macrophage migration inhibitory factor (MIF) can affect the expression of matrix metalloproteinase 2, 9 (MMP-2, MMP-9) and interleukin 8 (IL-8) in nasopharyngeal carcinoma (NPC) cell strains. METHODS: Two nasopharyngeal carcinoma cell strains, CNE-1 and CNE-2 were adopted in this study. The variations of expression percentages of MMP-2 or MMP-9-positive cells detected by flow cytometry in NPC cell strains with or without MIF activation were compared. Western blot analysis and reverse transcriptase-polymerase chain reaction (RT-PCR) were applied to evaluate the protein and mRNA expression level of MMP-2 and MMP-9 in cell strains treated with and without MIF, respectively. The concentration of IL-8 in the supernatant of the cells with different treatments was tested using enzyme-linked immunosorbent assay (ELISA). RESULTS: (1)After treatment with MIF for 24 h, the percentage of MMP-9-positive cells was significantly increased in both CNE-1 (from 28.5+/-2.5% to 82.4+/-3.5%, P=0.001) and CNE-2 (from 32.8+/-3.5% to 86.1+/-1.6%, P=0.002). However, the percentages of MMP-2-positive cells did not significantly change between these two cell strains with or without MIF treatment (P >0.05). (2) The relative intensity of MMP-9 protein expression was also enhanced in both cell strains (CNE-1:from 83.1+/-6.0 to 242.9+/-22.9, P=0.002; CNE-2:from 84.4+/-4.3 to 278.9+/-29.7, P=0.003) and there was no significant difference in MMP-2 expression intensity either in CNE-1 or CNE-2. (3)The IL-8 concentration in CNE-2 supernatant was 1201.8+/-593.3 pg/ml after treatment with MIF for 24 h, remarkably higher than that without treatment (32.7+/-20.1 pg/ml, P=0.026). However, there was no detectable difference of IL-8 concentration found in CNE-1 (P=0.581). (4)The expression level of MMP-9 mRNA, but not of MMP-2 mRNA was significantly increased both in CNE-1 and CNE-2 after treatment with MIF. In addition, the IL-8 mRNA level was only enhanced in CNE-2 but not in CNE-1. CONCLUSION: MIF cytokine might play an important role in neoplastic cell invasion and metastasis by up-regulating the expression of MMP-9 and IL-8 in NPC cells through the pathway of activation of their gene transcription.

Loss of an XhoI-site within N-terminal region of Epstein-Barr virus LMP1 gene in nasopharyngeal carcinoma.

BACKGROUND & OBJECTIVE: It is well known that Epstein-Barr virus(EBV) LMP1 gene is involved in nasopharyngeal carcinogenesis. This research was designed to investigate the loss of an Xho I-site within the N-terminus of Epstein-Barr virus(EBV) latent membrane protein 1(LMP1) gene isolated from nasopharyngeal carcinoma (NPC) in Guangdong for further understanding the sequence variation of LMP1 gene involved in carcinogenesis. METHODS: Sixty-three fresh nasopharyngeal biopsies taken from the patients with nasopharyngeal carcinoma were collected in Cancer Center of Sun Yat-sen University. The peripheral blood mononuclear cells (PBMCs) obtained from 10 healthy EBV carriers were as control. The QIAamp DNA Mini Kits were used for extracting the DNA of biopsies and PBMCs. The N-terminus of EBV LMP1 gene was amplified using nested polymerase chain reaction (PCR) and then followed by Xho I enzyme digestion. Bidirectional solid-phase sequencing of the PCR products was performed using four-colored fluorescence terminator sequencing method. RESULTS: No loss of an Xho I-site within N-terminus of EBV LMP1 gene (wt-Xho I) was detected in PBMCs of all 10 carriers. The loss of an Xho I-site (Xho I-loss) was demonstrated in 50 cases (50/63, 79.36%) and the partial loss was demonstrated in 4 cases (4/63, 6.35%). The loss of an Xho I-site was not found in 9 cases (9/63, 14.29%). Besides loss of an Xho I-site (nt:169423-169428; GAGCTC --> GATCTC), 4 additional missense point mutations were found. CONCLUSION: According to the results obtained from this investigation, the PBMCs of 10 EBV carriers residing in Guangdong merely contain EBV variant with wt-Xho I. On the contrary, the EBV variant with XhoI-loss becomes the predominant variant detected in NPC tissues. So, the genomic variation within N-terminus (loss of an Xho I-site and other missense point mutations) of EBV LMP1 gene might be developed in the process of nasopharyngeal carcinogenesis.

Study on sero-diagnosis of nasopharyngeal carcinoma using a dual antibody test against recombinant Epstein-Barr virus antigens.

BACKGROUND & OBJECTIVE: The aim of this study was to optimize a dual-antibody assay for sero-diagnosis of nasopharyngeal carcinoma(NPC) by evaluating 4 Epstein-Barr virus(EBV) antigen-based enzyme-linked immunosorbent assays(ELISAs). METHODS: The serum samples of 57 pretreated NPC patients and 58 apparently healthy adults in Guangzhou were collected. The levels of anti-EBV antibody in the sera were tested by 4 ELISAs, which were developed using fusion proteins of glutathione transferase and EBV specific recombinant antigens, namely, EBNA1-IgA, EBNA1-IgG, Zta-IgA, and Zta-IgG. RESULTS: When evaluated individually, the sensitivity(0.9123) and negative predictive value(0.9074) of EBNA1-IgA were the highest among the 4 ELISAs tested. Zta-IgA test had the highest individual accuracy rate(pi, 0.8870) and Youden index(J, 0.7738). The dual positives for EBNA1-IgA and Zta-IgA were the highest among the 4 dual positives when paired ELISAs were evaluated. Five NPC patients with negative reaction to EBNA1-IgA showed positive reaction of Zta-IgA, and 7 NPC patients with negative reaction to Zta-IgA showed positive reaction of EBNA1-IgA. CONCLUSION: The EBNA1-IgA assay is more suitable than the other 3 ELISAs(EBNA1-IgG, Zta-IgA, and Zta-IgG) when used individually for serological diagnosis of NPC. When two assays are combined, EBNA1-IgA and Zta-IgA have complementary effect on serological diagnosis for NPC and is thus an optimal combination of serum antibody assays.

[Comparison of the Epstein-Barr virus infection and 30 bp-deleted LMP1 gene among 4 histologic types of nasopharyngeal carcinoma].

OBJECTIVE: To compare the Epstein-Barr virus (EBV) infection rates and the frequencies of wt-LMP1 and del-LMP1 EBV variants detected singly or dually among the four types of nasopharyngeal carcinoma (NPC) and to illustrate the possible role of del-LMP1 gene in nasopharyngeal carcinogenesis. METHODS: EBER in situ hybridization was performed in 117 NPCs, including 48 non-keratinizing carcinomas (NKCs), 25 keratinizing squamous cell carcinomas (KSCCs), 5 adenosquamous carcinomas (ASCs), 6 mucoepidermoid carcinomas (MECs) and 33 adenocarcinomas (ACs). Nested PCR for demonstration of EBV LMP1 gene was performed on the tissue samples collected from 99 EBER-positive carcinoma cases and the peripheral blood mononuclear cells (PBMCs) of 53 healthy adults (HAs). RESULTS: As indicated by EBER in-situ hybridization, the EBV infection rates in both of 48 NKCs and 25 KSCCs were 100%; and the infection rates of 11 ASCs/MECs and 33 ACs were 9/11 and 51.5% (17/33), respectively. Worthy to note was that most of the NKC cells were EBER-positive while only a small number of EBER-positive neoplastic cells could be found in 17 ACs. The percentage of del-LMP1 EBV variant detected singly in NKCs (85.4%, 41/48) was not only significantly higher than that in PBMCs of 46 HAs (8.7%, 4/46) but also significantly higher than those detected in KSCCs (16.0%, 4/25). The dual infection rate of wt-LMP1 and del-LMP1 variants detected in KSCCs (56.0%, 14/25) was significantly higher than that of NKCs (12.5%, 6/48). The majority of the EBV detected in AC tissues (12/17) and HAs' PBMCs (34/46, 73.7%) were of dual wt-LMP1 and del-LMP1 variants. CONCLUSIONS: The EBV infection rates are significantly different among 3 major histological categories, namely, NKC/KSCC, ASC/MEC and AC. Though NKCs and KSCCs are always consistently associated with EBV, the single del-LMP1 EBV variant detected in NKCs is predominant over that in KSCCs and most of the KSCCs contain dual wt-LMP1 and del-LMP1 EBV variants. The EBV of the del-LMP1 variant might play a crucial role in carcinogenesis of NKC.