Initial study of single nucleotide polymorphism genotyping of Epstein-barr nuclear antigen 1 (EBNA-1) from Vietnamese nasopharyngeal biopsy samples

Background: Epstein-Barr virus nuclear antigen (EBNA1), encoded by EBNA-1 gene, has been shown as one of the most frequently detected protein in Nasopharyngeal carcinoma (NPC), which the most common and highly incident cancer of head and neck cancer in Asian countries. The geographically-associated polymorphisms of EBNA-1 have been observed in East-Southern Asia, including Vietnam. The subtype V-val EBNA-1 has been demonstrated that it may contribute to the oncogenesis of NPC. This current study is initially performed to characterize the variations of EBNA-1 in NPC biopsy samples from Vietnamese patients. Methods: Nested PCR-sequencing was applied to amplify and characterize the C-terminal region of EBNA-1 gene by the designed oligonucleotide primers. Results: 10 NPC biopsy samples were enrolled, as the results, only two patterns of EBNA-1 variations: P-ala and V-val were observed. In addition, of these two subtypes, the frequency of V-val and P-ala were determined counting for 80% (8 of 10 cases) and 20% (2 of 10 cases), respectively. It indicated the V-val subtype preferentially exists in biopsy NPC samples, which collected from Vietnamese patients. Conclusion: We successfully designed the nested PCR-sequencing primer for detection of EBNA-1 variations based on the data collected from previous study. In our initial study, the sub-strain of EBV with V-val subtype of EBNA-1 infects NPC preferentially to those from biopsies of NPC patients. In further study, it is necessary for a larger number of samples and non-cancerous samples in order to confirm the characteristic of EBNA-1 variations, as well as determination of the association V-val subtype with NPC in Vietnamese patients.