Epstein-Barr virus gene polymorphism in different parts of the same nasopharyngeal carcinoma patient

In most previous studies, comparisons of Epstein-Barr virus (EBV) gene polymorphisms and genotypes were made between strains from tumors and normal throat washings (TWs) from different individuals. However, it remains controversial whether different EBV subtypes are present in different parts of the same NPC patient. In order to address this question, in this study, we compared the genotypes in sets of paired throat washings (TW) and paraffin-embedded tissues of 20 patients with nasopharyngeal carcinoma (NPC), and we found the same genotype in throat washings (TWs) and tumor cells from the same individual in most cases. The subtypes of EBER and EBNA1 genes were furthermore sequenced, and identical EBV strains were identified in tumor tissues and TWs. In conclusion, different sites of the same individual are infected by the same EBV strains, except for a few differences in occasional cases, suggesting that the EBV subtype detected in throat washings is a reasonable guide to the subtype present in the carcinoma tissue.