Fruits and vegetables are major vehicles for transmission of food-borne enteric viruses since they are easily contaminated at pre-and postharvest stages and they undergo little or no processing. However, commonly used sanitizers are relatively ineffective for removing human norovirus surrogates from fresh produce. In this study, we systematically evaluated the effectiveness of surfactants on removal of a human norovirus surrogate, murine norovirus 1 (MNV-1), from fresh produce. We showed that a panel of surfactants, including sodium dodecyl sulfate (SDS), Nonidet P-40 (NP-40), Triton X-100, and polysorbates, significantly enhanced the removal of viruses from fresh fruits and vegetables. While tap water alone and chlorine solution (200 ppm) gave only <1.2-log reductions in virus titer in all fresh produce, a solution containing 50 ppm of surfactant was able to achieve a 3-log reduction in virus titer in strawberries and an approximately 2-log reduction in virus titer in lettuce, cabbage, and raspberries. Moreover, a reduction of approximately 3 logs was observed in all the tested fresh produce after sanitization with a solution containing a combination of 50 ppm of each surfactant and 200 ppm of chlorine. Taken together, our results demonstrate that the combination of a surfactant with a commonly used sanitizer enhanced the efficiency in removing viruses from fresh produce by approximately 100 times. Since SDS is an FDA-approved food additive and polysorbates are recognized by the FDA as GRAS (generally recognized as safe) products, implementation of this novel sanitization strategy would be a feasible approach for efficient reduction of the virus load in fresh produce.

Human norovirus (HuNoV) is the leading causative agent of foodborne disease outbreaks worldwide. HuNoV is highly stable, contagious, and only a few virus particles can cause illness. However, HuNoV is difficult to study because of the lack of an efficient in vitro cell culture system or a small animal model. To date, there is very limited information available about the biology of HuNoV, with most data coming from the study of surrogates, such as HuNoV virus-like particle (VLP), murine norovirus (MNV), and feline calicivirus (FCV). High-risk foods for HuNoV contamination include seafood, fresh produce, and ready-to-eat foods. Currently, there is no effective measure to control HuNoV outbreaks; thus, development of food-processing technologies to inactivate HuNoV in these high-risk foods is urgently needed. Although a VLP-based vaccine induces humoral, mucosal, and cellular immunities in animals and currently is in human clinical trials, development of other new vaccine candidates, such as live vectored vaccines, should be considered. Recent evidence suggests that blockage of virus-receptor interaction may be a promising antiviral target. To enhance our capability to combat this important agent, there is an urgent need to develop multidisciplinary, multi-institutional integrated research and to implement food virology education and extension programs nationwide.

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