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The epigenetic cost and benefit balance of giant virus endogenizations

Project description

Novel insight into genome evolution

Some viruses have the capacity to permanently embed their genome into that of the host. This process, known as endogenisation, is well documented for small viruses. However, it has not been extensively studied for giant viruses carrying thousands of genes. Understanding how such large-scale integrations occur could provide important insight into genome evolution. The ERC-funded ENDOGIANT project investigates how giant virus DNA integrates into host genomes and how chromatin regulation mediates this process. Using model species from distant lineages, researchers will study how these integrations are epigenetically silenced, potentially repurposed for immunity and distributed across animal lineages. Collectively, ENDOGIANT work will shed new light on the mechanism of exchange of genetic material between giant viruses and eukaryotes.

Objective

Giant viruses, renowned for their exceptionally large genomes with thousands of genes, are increasingly being identified as integrated elements within eukaryotic genomes. This seemingly paradoxical process of endogenization is significant, as it represents a pathway for large-scale lateral gene transfer in eukaryotes. However, the initial integration of viral DNA can impose severe evolutionary costs, potentially being lethal for the host. The overarching hypothesis of this proposal is that the genetic conflict between giant virus and host genome merging is mediated at the chromatin regulation level.
Giant virus endogenizations are often epigenetically silenced and evolutionary dynamic. This rapid evolutionary pattern could imply benefits for the host. To test this, we will explore potential roles in immunity and gene family expansions.
Giant viruses, in turn, have their own set of chromatin regulation genes, which could be involved in hijacking host chromatin. To test this, we will characterise molecular interactions with host chromatin during infection and the role of captured eukaryotic transcriptional regulators encoded by giant virus.
Among eukaryotes, the animal kingdom is exceptional for its lack of reported giant virus endogenizations. However, our data reveal that all Hydra genomes contain giant virus integrations, hinting at an overlooked phenomenon. We will establish Hydra as a tractable model system for investigating the epigenetic regulation of these giant virus integrations in animals, and we will systematically survey giant virus endogenizations across diverse animal phyla.
Giant Viruses are ancient, having exchanged genetic material with eukaryotes since before the last common ancestor of modern eukaryotes to this day. Understanding the mechanisms and consequences of giant virus endogenization thus sheds light on an extraordinary and old source of genome innovation, and can illuminate the evolution of eukaryotic chromatin.

Fields of science (EuroSciVoc)

Keywords

Programme(s)

Topic(s)

Funding Scheme

HORIZON-ERC - HORIZON ERC Grants

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Call for proposal

(opens in new window) ERC-2025-COG

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Host institution

QUEEN MARY UNIVERSITY OF LONDON
Net EU contribution
€ 1 999 997,00
Address
327 MILE END ROAD
E1 4NS LONDON
United Kingdom
Activity type
Higher or Secondary Education Establishments
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Total cost
€ 1 999 997,00

Beneficiaries (1)