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Research Project: Process efficacy investigation of infectious norovirus particle ratios and enteric viral surrogates levels in environmental and food samples

Location: Food Safety and Intervention Technologies Research

Project Number: 8072-42000-081-01-I
Project Type: Interagency Reimbursable Agreement

Start Date: Jun 1, 2014
End Date: May 31, 2019

Design and execute a series of experiments designed to assess inactivation pf human norovirus. Specifically, will work with partners in academia to: A. Identify and optimize analytical methods to determine concentrations of human norovirus accurately and precisely as described environmental samples B. Design experimental protocols to accurately and precisely determine the impact of specific process (as defined in table1 of the IAG) these include waste water treatment, chlorination, UV waste water treatment, uptake of virus by shellfish C. Provide raw and analyzed data. D. Work with collaborators to appropriately interpret and report experimental results.

Major data gaps in the quantitative risk assessment include the absence of data on the fraction of norovirus particles that are infectious at each stage of the process model and the impact of biological and mitigation/control steps on the ratio of infectious to total norovirus particles. Detection methods for norovirus are based on molecular methods that cannot distinguish between infectious and non-infectious particles Currently the draft quantitative risk assessment model uses viral surrogate data, where available, to evaluate the impact of a given process on the infectious particle concentration. However, such data rarely include complementary molecular measurements that would inform changes in the infectious to total particle ratio. This latter information is needed to link molecularly-based measurements of norovirus to public health metrics. The research supported by the interagency agreement will serve to fill these data gaps by providing a suite of measurements of norovirus and critical viral surrogates before and after environmental or mitigation/control steps that include (1) Quantitative measures of the number of norovirus particles present, the numbers of norovirus particles that bind porcine gastric mucin, and the numbers of particles that do not bind porcine gastric mucin. The ability of a norovirus particle to bind porcine gastric mucin is a surrogate measure of the potential of the particle to be infective. (2) Quantitative measures of the number of Male Specific MS2 (phage MS2) particles by qRT-PCR and conventional culture techniques. (3) Quantitative measures of Murine Norovirus or other appropriate norovirus surrogate by qRT-PCR and conventional culture techniques. Together, these measurements will enable FDA to more accurately describe norovirus survival in the environmental and in food and as a result, provide more accurate measures of the risk reduction provided by different risk mitigation/control steps.