Exploring EBNA3C Genetic Variability and Recombination in Epstein-Barr Virus-Associated Cancers

Epstein-Barr virus is a globally disseminated oncovirus capable of causing various malignancies, including gastric cancer, Burkitt lymphoma, and Hodgkin's lymphoma. The influence of recombination on the EBV genome revealed limitations in the current traditional EBV classification, and the extent of these recombination events across the EBV genome is not fully understood. The nuclear antigen 3C (EBNA3C) is an indispensable gene in the oncogenesis of the virus. Despite its critical role, little is known about EBNA3C sequence variability. We examined 988 EBNA3C gene sequences extracted from EBV genomes in this context. Among the protein motifs, the interaction sites with Nm23-H1, RBP-Jk, and nuclear localization signal (NLS) 2 and 3 were the most divergent between EBV types, while NLS-1 and the leucine zipper-like showed high conservation. In our study of the impact of recombination vs. point mutations in the EBNA3C gene, we found that recombination contributed five times more to substitutions than mutation. Notably, Asian populations exhibited the highest variability and recombination rates. Importantly, our analysis revealed geographical rather than disease-specific markers. Furthermore, filtering for recombination regions did not affect the classical classification of EBV-1 and EBV-2. This finding suggests that recombination is pivotal in the architecture of EBV genetic diversity of the EBNA3C gene.