SF6025 - Development of a Rapid Microarray Based Diagnostic Assay for Detection of the Norwalk Like Virus

Researcher:

Dr. Sabah Bidawid, Health Canada

Objectives:

1. The development of rapid methods to capture and concentrate enteric viruses from foods.
   

2. The development of simple and rapid nucleic acid extraction techniques to isolate viral nucleic acid from foods.
   

3. The development of new molecular methods based on reverse transcriptase-PCR (RT-PCR) and nucleic acid microarray technology, for the rapid and sensitive detection of the NLVs in food, water and environmental samples.

Expected Benefits:

1. The development of a rapid and sensitive diagnostic tool to screen foods (and water as applicable) for the presence of foodborne viruses.
   

2. The development of rapid and sensitive diagnostic assays for the detection of foodborne viruses will increase the number of laboratory facilities in Ontario that are able to perform diagnostic testing, thereby facilitating epidemiologic investigation.
   

3. The development of rapid methods will aid in the evaluation and implementation of appropriate control strategies for viral contamination of foods, particularly in view of the fact that foodborne viruses are resistant to many of the traditional methods used to control bacterial pathogens.

Summary of Research Results:

Noroviruses (formally known as Norwalk or Norwalk-like viruses) are currently the leading viral pathogens responsible for more than 65% of non-bacterial gastroenteritis in the USA. Most Norovirus foodborne outbreaks have been reported in consequence to consuming raw contaminated oysters and other shellfish. Increasingly, Norovirus outbreaks have been attributed to other types of foods, such as fruits (strawberries), vegetables (salads), pasta and pasta salads, and ready-to eat foods (i.e., ham and beef cold cuts…etc). Foods act as vehicles for the transmission of these highly infectious viruses to consumers. Currently available methods, such as electron microscopy and the Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) have been successfully used to detect Noroviruses in stools of patients with gastroenteritis, where the Norovirus causative agent is present in high numbers which renders its detection easily accomplished by such methods. Similarly, much work has been done to detect these viruses in shellfish, where the virus can also exist in high numbers, since shellfish tend to concentrate the virus as a result of filter-feeding. However, our diagnostic capabilities in detecting this group of viruses in other types of foods, such as fruits, vegetables, and ready-to-eat products, remain very limited due to the textural complexities of the vast number and types of foods. Most of these foods contain numerous substances that can inhibit the performance of these methods.

Consequently, developing appropriate and efficient methods to detect these viruses in such foods, as well as to have the capability to conduct needed epidemiological monitoring of the food supply will be necessary to improve on the safety of the food supply and implement needed intervention strategies to control virus contamination and spread via foods. The objectives of this project were aimed at the development of three useful tools to address the challenges that face food virologists. The first two were focused at methods for isolation and concentration of viruses from various food matrices. The third objective was to develop a DNA microarray-based platform that would allow the simultaneous identification and molecular characterization of Noroviruses belonging to the various genogroups. By fulfilling these objectives, the project gives valuable tools to diagnostic laboratories, regulatory agencies, and policymakers.