Occurrence and accumulation of potentially infectious viruses in process water and impact of water disinfection practices to minimize viral cross-contamination

The presence of human enteric viruses like norovirus (NoV), hepatitis A virus (HAV), astroviruses (HAstV) and rotavirus (RV) in irrigation water has extensively been reported. However, the virological quality of process water used by the produce industry has received limited attention. Molecular-based methods have been used to detect human enteric viruses in water samples. However, these methods cannot discriminate between inactivated and potentially infectious viruses. Recent studies have proposed the use of viability markers incorporated into qPCR-based methods for assessing infectivity of enteric viruses in several types of water samples. Bacteriophages infecting enteric bacteria have been suggested as a viral indicators because they mimic viruses better than any other group of indicators. Somatic coliphages and F-specific RNA phages are the major groups investigated for water quality assessment. In this project, the occurrence of potentially infectious viruses will be examined by viability PCR in different process waters from whole and fresh-cut products collected from commercially facilities. Moreover, the analysis of somatic coliphages and F-specific RNA phages will be assessed using plaque assays for the potential used of coliphages as viral indicators. The risk of viruses associated to process water not only depends on their occurrence but also on their resistance to disinfectants currently used by the industry to prevent cross-contamination. As limited information is available on the efficacy of chlorine and non-chlorine based sanitizers against enteric viruses in process water, batch scale experiments and experiments using a dynamic disinfection system will be performed to establish the operational conditions and critical parameters of the washing system needed for the prevention of cross-contamination with a mix of cultivable surrogate viruses (human enteric viruses and coliphages). The implementation of selected operational conditions will be operated in the commercial facilities in collaboration with the five industrial cooperators to evaluate water disinfection practices to minimize viral cross-contamination and validate the operational limits. Our objectives are to 1) detection and quantification of potentially infectious enteric viruses and coliphages in process water used from industrial partners, 2) inactivation studies to evaluate the efficacy of chlorine and non-chlorine based sanitizers on human enteric viruses and coliphages, 3) validation of the stablished water disinfection practices in commercial facilities, 4) correlation between inactivation rates and occurrence of enteric viruses and somatic coliphages and F-specific RNA phages. As a result, the risk of virus contamination by fresh produce process water will be identified. The results of this proposal will contribute to the prevention of viral cross-contamination through water disinfection practices, helping producers and processors to establish the operational standards in process water when using chlorine and non-chlorine based sanitizers.