Evolutionary analysis of complete Epstein Barr virus genomes with a focus on Argentinean isolates

BLAZQUEZ, C.; BERENSTEIN, A; IZQUIERDO, A.; FELLNER D; PICCONI A; ALEJANDRO, LORENZETTI MARIO; MARIA VICTORIA PRECIADO

Congreso; 19th International Symposium on Epstein-Barr Virus and Associated Diseases.; 2021

EBV genomes from different geographic regions present a marked geographic structure. Currently, more than 1000 worldwide complete genomes were sequenced; however, South American isolates are underrepresented. Our aim was to characterize polymorphisms in EBV genomes from our region and perform a comprehensive evolutionary analysis, including isolates from several regions of the world. Forty isolates from Argentina were sequenced by NGS using EBV-custom target-enrichment probes. 198 raw NGS data from other geographies were downloaded from SRA-NCBI database. Fastq files were analysed with our custom-built bioinformatic pipeline. Reads were mapped to both EBV-type reference genomes. VCF files were used to predict EBV type and generate consensus sequences. Phylogenetic, population structure and phylodynamic studies were performed on the 238 MSA file. 208 samples were EBV1, 26 EBV2 and 4 recombinant genomes. 32 Argentinean isolates were EBV1 and 8 EBV2. Considering EBV1 genomes, phylogenetic analysis segregated Asian sequences independently. In Principal Component Analysis, PC1 confirmed Asian segregation while PC2 allowed Asian genomes discrimination into three subgroups. Argentinean sequences segregated with African and European genomes. Asian sequences contained more variants compared to NC_007605.1, but presented lesser intragroup variability. Variability of Argentinean genomes didn't differ from that of Europe, Africa, Australia and North America. Discriminant Principal Component Analysis detected four informative regions that were responsible for geographic segregation. The entire genome evolution rate was estimated at 9.09e-6_s/s/y. Genes coding for immune-evasion and non-structural proteins presented higher evolution rates than structural and replication-related ones. We expanded data on EBV genomes from Argentina. The history of colonization and migration of our country was reflected in the phylogenetic and population analysis. Genomic regions that contributed to the independent segregation of the Asian clade were identified. The estimated evolution rate for the entire EBV genome suggests that the coevolution of EBV and humans may not be fully acerted.