New case study: pathogen diagnostics for shellfish (feasibility study)

Demonstrated the ability of a new non-invasive diagnostic process

Disease is a threat to oyster farming and restoration. Current UK measures to stop the spread of oyster diseases in the UK rely on the prevention of animal movement from disease-positive to disease-free sites. This is not foolproof and can lead to the spread of pathogens. Existing diagnostic options are costly, slow, destructive, and only test small samples, making proactive testing impractical for most farmers.

This project aimed to develop a portable, affordable, and non-invasive diagnostic tool that allows oyster farmers to test large batches on-site before moving stock. Such a system would enable proactive disease management, reducing risk and supporting sustainable aquaculture. Valued at almost £55k, the project was led by the University of Edinburgh’s Roslin Institute. It was funded by the Seafood Innovation Fund with support from SAIC.

Two experimental challenges were conducted:

• OsHV-1 (Oyster Herpesvirus) in Pacific oysters
• Bonamia ostreae in native oysters

Oysters were held in tanks or buckets for 24 hours, after which water and sediment samples were collected. Using portable qPCR technology alongside standard lab equipment, researchers extracted and amplified DNA from these samples. The key findings were:

• Bonamia DNA was detected in sediment from holding tanks, indicating infection in at least one oyster per tank. Water alone was less reliable.
• OsHV-1 was detected in both water and sediment from tanks with infected oysters.
• Oyster DNA was consistently detected, confirming effective extraction methods.
• Portable qPCR systems worked well in field conditions, demonstrating that on-site testing is feasible.

The process proved highly sensitive, detecting infection rates as low as 4%, with potential for even greater sensitivity after refinement. This approach could transform shellfish disease management by enabling rapid, non-invasive testing before stock movement - something previously unachievable.

Next steps include further validation and refinement through a follow-on R&D project supported by the Seafood Innovation Fund. Ultimately, this innovation could help keep farms and restoration sites disease-free, protecting livelihoods and marine ecosystems.

The full title of this project is ‘Feasibility study: pre-emptive and non-invasive pathogen diagnostics to prevent the spread of shellfish disease’.

Read the case study