The overall objective of this project is to provide useful tools for the evaluation of human viral contamination in shellfish and innovative technology for their quality control and depuration. Shellfish viral contamination is currently under 1 diagnosed, although significant epidemiological studies have linked viral illnesses to the consumption of contaminated shellfish. To answer this problem molecular typing and study of the resistance of major human enteric viruses will be investigated. Moreover, the quality of harvesting areas and shellfish depuration process will be assessed. These information will help evaluating various tools; routing methodologies, "Warning system" to prevent the contamination of harvesting areas, "Good Depuration Practices" to secure the shellfish depuration process. The project results will provide the elements for a sustainable development of European shellfish production.
The overall objective of the "Virus-Safe Seafood" project is to provide, along the food chain, useful and rapid tools for the evaluation of human viral contamination of shellfish and innovative technology for their quality control and depuration. The final objective is to assure the safety of the food supply.
The problem of shellfish contamination is currently under diagnosed and under managed, although significant epidemiological studies have linked viral illnesses to the consumption of contaminated shellfish meeting bacterial standards. Protecting the consumer will imply preventing action based on seafood specificity. Shellfish are a unique foodstuff, because of the characteristics of the animal (filter-feeder) and the way they are eaten (slightly cooked, and even raw for oysters). These animals are grown in seawater, and hydric environment is the main source of contamination. They accumulate contaminants, among them human enteric viruses, which are able to persist for a long time in the animal. If viral hydric contamination occurs in harvesting areas, shellfish could be contaminated. As bacterial indicators have now been proved not to be correlated with viral presence, regulation set up to protect consumers is inefficient. Even if EU rules recommend depuration for bacterial polluted shellfish, the efficiency of depuration process to remove viruses still needs to be demonstrated. Efficient consumer protection must take into consideration the viral contamination of growing areas (sewage input and harvesting water quality) and the viral elimination during the depuration process. The food chain is here "harvesting and depuration". All these factors are taken into account to construct and organise the project ''Virus-Safe Seafood''.
A co-operative research between multidisciplinary partners is settled to procure the competence necessary to achieve the project. Expertise from fundamental research, r & d and shellfish producers, are complementary to address the following objectives:
- Determination of viral input and shellfish contamination: the main human enteric viruses implicated in diseases linked to shellfish consumption chosen for this study will be: astrovirus (AV), calicivirus (CV), enterovirus (EV), Hepatitis A virus (HAV), rotavirus (RV). They will be searched to appreciate the role of the environment as a reservoir. The following techniques will be used:
- Extraction /concentration of viral particles and purification of nucleic acids;
- Commercial kits validation and evaluation for routine detection;
- Detection by RT-PCR, hybridisation; quantification and standardisation of the protocols;
- Molecular typing to determine the strains persisting in the environment.
These techniques will be applied to assess viral contamination of waste waters, rivers, seawater and shellfish samples. Shellfish imported or sampled from harvesting areas will be analysed. The concentration of actual and potential indicators (Escherichia coli and F+RNA specific phages) will be compared to the presence of human enteric viruses and evaluated to propose a more valuable approach for shellfish safety.
- Evaluation of the persistence of enteric viruses in the environment: Virus-like Particles (VLPs) of astrovirus, calicivirus and rotavirus will be constructed. This new technology issued from molecular research will be used to:
- simulate and compare their behaviour in seawater;
- follow viral capsid degradation and thus, obtain information on infectivity;
- evaluate the role of physical (temperature, salinity) and biological (bacterial flora) parameters on viral fate.
- Optimisation of shellfish depuration: to assess the efficiency of depuration process on viral contamination:
- VLPs-artificially contaminated shellfish will first be used;
- Different parameters will be evaluated to enhance depuration processes;
- After VLPs assays optimisation, the same depuration processes will be applied to naturally contaminated shellfish;
- Efficiency of depuration enteric viruses and indicators will be then evaluated.
These information will define various tools to evaluate the accuracy of EC standards, reducing the risk caused by seafood consumption and providing a sustainable development of shellfish production:
- Understanding of pathogen distribution and designing "viral risk months";
- Providing valuable information about viral risk for countries involved in shellfish trade; improving shellfish safety by defining "Good Depuration Practices" and a "warning system" in harvesting areas.