The Epstein-Barr nuclear antigen 1 (EBNA-1) gene, plays a key role in viral infection, immortalization, viral genome replication, transcription and maintenance, and is the frequently detected gene, protein in both latent and lytic stage of Epstein-Barr virus (EBV). Based on the amino acid at position 487, EBNA-1 was classified into five subtypes, including P-Ala, P-Thr, V-Val, V-Pro and V-Leu. In Vietnam, an Asian country with a high incidence, mortality rates of nasopharyngeal carcinoma (NPC), had limited research on the EBNA-1 variation. Therefore, the aim of the current study was to identify the pattern of the EBNA-1 V-Val subtype in Vietnamese NPC patients, for its value further applied in NPC patients. Fifty-eight NPC biopsy samples were collected from local patients, analyzed by nested-polymerase chain reaction (nested-PCR), sequencing and compared to a previous B95-8 prototype sequence. Four EBNA-1 subtypes, including V-Val (35/44, 79.55%), P-Ala (2/44, 4.55%), P-Thr (5/44, 11.36%), and V-Leu (2/44, 4.55%), were observed in 44/58 samples. The sequences of the V-Val subtype were compared to the B95-8 prototype, resulting in five patterns, contained seven consensus changes, including five amino acid changes at positions 487, 499, 502, 524, 594, and two silent changes at residues 520 and 553. Of these, four of five, patterns were identified as novel patterns of the V-Val subtype, showing the different changes of amino acids at positions 492, 528, 529, 553, 585 and 588, by comparison with previous studies of V-Val EBNA-1. Those data suggested the profile of variation patterns of the EBNA-1 gene, related to geographic distribution, in Vietnamese NPC patients.

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Epstein-Barr virus (EBV) infection is the main cause of Nasopharyngeal Carcinoma (NPC). EBNA-2, one of the most important genes participating in the formation of NPC, also helps EBV evade an attack on the immune system. EBNA-2 has 4 variants including E2-A, E2-B, E2-C and E-2D, of which E2-A and E2-C are the characterized variants for NPC. This study aimed to evaluate the variations of EBNA-2 in NPC biopsy samples of Vietnamese patients. This initial study used 10 biopsy samples, which were positively confirmed to NPC, collected from Cho Ray Hospital. Nested PCR – nucleotide sequencing was applied to analyze the variants of EBNA-2. The results showed that 8 out of 10 samples, accounting for 80%, were positive to EBNA-2. Additionally, only two variants, E-2A and E-2C were detected in our study, in which, E2-A subtype was identified as the predominant subtype. These findings would provide initial data about potential contribution of EBNA-2 polymorphisms to etiology of NPC in Vietnamese population.

Background and Objective: The methylation of Ubiquitin C-Terminal Hydrolase L1 (UCHL1) gene has been reported in many human cancers including nasopharyngeal carcinoma (NPC). In Vietnam, the methylation of UCHL1 gene’s promoter in NPC has not been demonstrated yet. In this study, a systematic literature revision was carried out to summarize the current evidences about the frequencies of UCHL-1 gene’s promoter methylation in NPC for further application in Vietnamese population. Methods: A systematic literature analysis was conducted based on the comprehensive studies. Moreover, many bioinformatic tools such as Methprimer, TFsearch, IDT OligoAnalyzer 3.1 were used to predict the CpG islands, transcriptional factors, and to pick up the MSP (Methylation-Specific PCR) primers. Results: Total of three previous studies were summarized and accessed for eligibility from literature research. As the results, the average weight methylated frequencies were 72.4% and 13.0% for NPC and non-cancerous samples, respectively. The significant association between UCHL-1 promoter methylation and NPC with the OR of 10.459 (95% CI = 4.915 – 22.254, p < 0.001) and RR of 4.117 (95% CI = 1.958 – 6.645, p < 0.0001) based on the random effects model, was observed. Moreover, we were successful in predicting the CpG islands as well as identifying transcriptional factor binding sites which served as “hot spot” for ideal primer pick up and located in gene promoter. Conclusion: The methylation of UCHL-1 gene promoter was significantly associated and contributed to NPC developmentin which it could be further applied in evaluation of UCHL-1 gene promoter status in Vietnamese population.