Validation of a Boindicator as Monitoring Tool for Oyster Norovirus Outbreak

Noroviruses are responsible for 700M of annual cases of gastroenteritis, of which 15M are directly related to the consumption of contaminated food, including oysters. Current regulations do not require control of human noroviruses in shellfish. However, an ISO standard recommended to detect their genome in high-risk foodstuffs. However, presence of viral genome doesn't testify to the presence of infectious particles. Routine application of this standard would therefore wrongly lead to the withdrawal of shellfish from market, since norovirus genomes are widely found in the environment and in food without indicating a viral risk. Given the difficulty of cultivating human noroviruses in vitro and thus of discriminating infectious particles from non-infectious particles only based on genome detection, it is necessary to identify an indicator of the infectious nature of these pathogenic viruses. To be suitable, the indicator must first be associated with the presence of norovirus genome in the environment. This is the case of fecal bacteriophage F-specific RNA. Since bacteriophages are cultivable in the laboratory, it is easy to estimate the proportion of genomes of these bacteriophages corresponding to infectious particles. To confirm this indicator, it is necessary to demonstrate a relationship between the presence of infectious bacteriophages with that of infectious norovirus. This is only estimable by the occurrence of a gastroenteritis after consumption of a contaminated food by humans. We propose this randomized controlled clinical trial to evaluate the incidence of norovirus infection after consumption of oysters free from or containing infectious F-specific RNA bacteriophages. The purpose of this study is to evaluate if norovirus infections incidence is significantly weak after the consumption of oysters free of F-specific infectious RNA bacteriophages, compared to the consumption of oysters containing these same infectious bacteriophages.