Exploring the role of copper as as a driver of Vibrio aestuarianus emergence and niche specialisation as an oyster pathogen

Project Information

VibOysCopper

Grant agreement ID: 101107909

DOI

10.3030/101107909

Project closed

EC signature date 21 April 2023

Start date 3 June 2024

End date 2 June 2026

Funded under

• Marie Skłodowska-Curie Actions (MSCA)

Total cost

No data

EU contribution

€ 211 754,88

Coordinated by

INSTITUT FRANCAIS DE RECHERCHE POUR L'EXPLOITATION DE LA MER
France

Periodic Reporting for period 1 - VibOysCopper (Exploring the role of copper as as a driver of Vibrio aestuarianus emergence and niche specialisation as an oyster pathogen)

Reporting period: 2024-06-03 to 2026-06-02

Summary of the context and overall objectives of the project

Aquaculture is one of the fastest-growing food production sectors worldwide and plays a key role in ensuring future food security. However, infectious diseases remain one of the main constraints to sustainable fish and shellfish production. In Europe, the emerging bacterial pathogen Vibrio aestuarianus has caused recurrent mass mortality events in Pacific oysters (Magallana gigas), leading to substantial economic losses for the oyster industry. At the same time, coastal ecosystems are increasingly exposed to environmental changes, including metal pollution, which may influence the interactions between pathogens and their hosts. Despite its importance, the role of environmental copper in oyster health and disease remained largely unknown.

The VibOysCopper project aimed to investigate how environmentally relevant copper exposure influences the interaction between Vibrio aestuarianus and Pacific oysters. Rather than considering copper solely as an environmental pollutant, the project explored whether it could affect bacterial virulence, oyster immune responses and the overall outcome of infection. To address this question, the project combined controlled infection experiments, bacterial and host transcriptomics, microbiome analyses and functional assays to investigate the biological responses of both the pathogen and the host.

By improving our understanding of the mechanisms driving bacterial diseases in oysters, the project contributes to the development of more sustainable aquaculture practices and provides scientific knowledge relevant for disease prevention, environmental risk assessment and shellfish health management. The results are expected to support future research and contribute to improving the resilience of European aquaculture under changing environmental conditions.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The project successfully established experimental infection models to experimentally investigate the effects of environmentally relevant copper concentrations on the interaction between Vibrio aestuarianus and Pacific oysters at laboratory scale. Experimental exposures demonstrated that copper accumulated in oyster tissues in a dose- and time-dependent manner and, unexpectedly, that moderate copper exposure consistently reduced oyster mortality following bacterial infection.

To understand the mechanisms underlying this protective effect, the project investigated both bacterial and host responses. Bacterial transcriptomic analyses revealed that copper regulates genes involved in copper homeostasis and detoxification while simultaneously reducing the expression of the only known virulence factor of V. aestuarianus. Complementary functional assays further demonstrated that copper reduced the intracellular survival of the pathogen within oyster immune cells.

Host transcriptomic analyses showed that oysters previously exposed to moderate copper concentrations developed an earlier and more effective immune response than non-exposed animals. In addition, microbiome analyses, incorporated during the project as a complementary research activity, demonstrated that copper exposure modifies the oyster-associated microbial community and reduces the relative abundance of V. aestuarianus following infection.

Together, these complementary approaches provided the first integrated assessment of how environmental copper simultaneously influences bacterial physiology, host immunity and the oyster microbiome, generating a comprehensive understanding of the factors determining disease outcome. Overall, the results show that copper plays a pivotal role in modulating the risk of V. aestuarianus infection in oysters, with its effects ranging from protective to detrimental depending on environmental conditions and the level of exposure.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The project significantly advances current knowledge of host–pathogen interactions in marine organisms by demonstrating that environmentally relevant copper concentrations influence disease outcome through multiple complementary mechanisms rather than through a simple antibacterial effect. The integration of bacterial transcriptomics, host transcriptomics and microbiome analyses within the same experimental framework provides a systems-level understanding of oyster health that was previously unavailable.

The results reveal that copper not only modulates bacterial responses and virulence regulation but also enhances host immune responses and alters the oyster-associated microbiota. These findings establish a new conceptual framework for understanding how environmental factors influence disease susceptibility in aquaculture species and open new research directions on the interaction between pollution, host immunity and infectious diseases.

Beyond the scientific advances, the project provides valuable knowledge for researchers, aquatic animal health specialists and the aquaculture sector. The results may contribute to the development of improved disease management strategies and support future studies aimed at strengthening the sustainability and resilience of shellfish production under changing environmental conditions. The datasets, methodologies and integrated experimental approaches generated during the project also constitute a valuable resource for future research in marine microbiology, environmental microbiology and aquatic animal health.