Norovirus is the leading cause of gastroenteritis and is responsible for 65% of foodborne illnesses in Canada. In recent years, norovirus outbreaks are increasingly associated with consumption of raw oysters. The largest outbreak occurred in the winter of 2016-2017, when BC-harvested oysters sickened hundreds of people across multiple provinces. The resulting farm shutdowns led to an estimated $9.1 million loss for the provincial shellfish industry.
Advanced laboratory methods like DNA sequencing are essential for linking contaminated food to human illness. However, it is difficult to apply these methods to noroviruses, since noroviruses cannot be grown in the laboratory and exist in very low concentrations in contaminated oysters. Therefore, improved laboratory methods are needed to better study noroviruses in oysters.
The UPCOAST-N (Unified Pathogen Control One Health Approach Specifically Targeting Norovirus) team aimed to develop new methods and generate genomic data to improve current surveillance and outbreak mitigation strategies.
The team developed a new probe capture sequencing method that uses pieces of DNA like magnets to capture norovirus from human and oyster samples. They also built tools to analyze the data and compared this new method with the current gold standard protocol. They found the new probe capture method generated higher quality sequence data in both human and oyster samples, allowing the detection of norovirus at very low levels. It also made it possible to tell different virus strains apart in environmental samples – a first in Canada.
Generating higher resolution genomic information from human cases or infected oysters allows for better management and prevention strategies. It allows health officials to trace outbreaks to their source and remove contaminated oysters from circulation quicker, protecting public health and BC’s shellfish industry. This predicted improvement in turn-around time for outbreak investigations will help make BC’s food supply safer, improve the health of consumers and contribute to the prosperity of our shellfish industry.