A comparative study of EBV genomes detected in tumors, nasopharyngeal swabs, and saliva from patients with nasopharyngeal carcinoma.

Abstract

Background: Specific genetic variations of Epstein-Barr virus (EBV) have been linked to nasopharyngeal carcinoma (NPC). Because EBV sheds through saliva, it is commonly used for EBV genotyping in studies of EBV-associated diseases. However, it remains uncertain whether infection with the same EBV strains occurs across different tissues within a host, and whether EBV detected in saliva accurately represents the strain in diseased tissues.

Methods: We conducted whole-genome sequencing of EBV from paired biopsy tissues, saliva, and nasopharyngeal swabs from 33 newly diagnosed NPC patients to determine the genetic concordance of EBV strains across different tissue types within the same individual.

Results: Phylogenetic and pairwise genetic distance analysis revealed a high degree of intra-host concordance, indicating infection with the same EBV strains among different samples within the host. Multiple EBV infections were identified in 6% of saliva samples, compared to 3% in tumor tissues. Notably, NPC tumor EBV strains were consistently detected in paired saliva and swab samples. For multiple infections in saliva and nasopharyngeal swab, EBV variants of the major strain showed higher genetic concordance with the variants detected in NPC tumors than variants of the minor strain.

Conclusion: Our study highlight the genetic consistency of EBV across tumor, nasopharyngeal swab, and saliva samples, supporting the use of saliva as a reliable source for EBV sequencing and genotyping in future epidemiological studies.