[Seminar] "The hidden world of dsDNA viruses in eukaryotes: diversity, host associations, and cryptic lifestyles" by Mr. Hongda Zhao

Speaker: Mr. Hongda Zhao, Kyoto University, Japan [website]

Title: The hidden world of dsDNA viruses in eukaryotes: diversity, host associations, and cryptic lifestyles

Abstract:

The evolutionary history of eukaryotes is deeply intertwined with that of their viruses, among which double-stranded DNA (dsDNA) viruses play a crucial role. Studies on giant viruses suggest that viruses may have contributed to the origin and early evolution of eukaryotic cells, while advances in metagenomics have uncovered vast numbers of previously unknown dsDNA virus groups. Because viral DNA can integrate into host genomes through both functional life cycles and incidental integration events, eukaryotic genomes serve as a genomic archive of past virus–host interactions. Here, we analyzed over 37,000 eukaryotic genome assemblies and observed that double stranded DNA virus derived sequences are widespread but unevenly distributed across host lineages. These sequences were notably abundant in certain groups, such as protists, cnidarians, arthropods, and mollusks, where viral elements constitute over 10% of total genomic content in some species. Overall, our findings expand current knowledge of host virus associations and highlight the need to further explore why viral DNA accumulates differently across lineages and how these sequences relate to viral lifestyles.