|DICAPRIO, ERIC - The Ohio State University|
|PHANTKANKUM, NUTTAPONG - The Ohio State University|
|CULBERTSON, DOUG - The Ohio State University|
|MA, YUANMEI - The Ohio State University|
|HUGHES, JOHN - The Ohio State University|
|URIBE, ROBERT - Kent State University|
|LI, JIANRONG - The Ohio State University|
Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/20/2016
Publication Date: 6/15/2016
Citation: Dicaprio, E., Phantkankum, N., Culbertson, D., Ma, Y., Hughes, J.H., Kingsley, D.H., Uribe, R.M., Li, J. 2016. Inactivation of human norovirus and Tulane virus in simple mediums and fresh whole strawberries by ionizing radiation. International Journal of Food Microbiology. 232:43-51.
Interpretive Summary: Viruses are very difficult to inactivate using nonthermal technology. In this publication, the potential of ionizing irradiation (E-beam and gamma) are evaluated for virus stocks and for artificially-contaminated strawberries. The two viruses evaluated are the culturable norovirus surrogate, Tulane virus and a non culturable GII.4 human norovirus strain. The later was evaluated using the PGM-MB binding assay developed by the USDA ARS for human norovirus viability. Results indicate that very high doses of irradiation, which are well above currently approved levels, would be required to inactivate these viruses. This research confirms for the first time that human norovirus, the number one cause of foodborne illness, is relatively resistant to irradiation. Results reported here are consistent with previous work demonstrating that hepatitis A virus and murine norovirus, another human norovirus surrogate virus, are highly resistant to irradiation as well.
Technical Abstract: Human norovirus (NoV) is a major cause of fresh produce associated outbreaks and human NoV in irrigation water can potentially lead to viral internalization in fresh produce. Therefore, there is a need to develop novel intervention strategies to target internalized viral pathogens while maintaining fresh produce quality. In this study electron beam (E-beam) and gamma radiation were evaluated for efficacy against a human NoV GII.4 strain and Tulane virus (TV). Virus survival following ionizing radiation treatments was determined using direct quantitative reverse transcriptase PCR (RT-PCR), the porcine gastric mucin magnetic bead (PGM-MB) binding assay followed by RT-PCR, and plaque assay. In simple mediums a high dose of E-beam treatment was required to completely abolish the receptor binding ability of human NoV (35.3 kGy) and TV (19.5-24.1 kGy) as assessed using the PGM-MB binding assay. Both human NoV and TV were more susceptible to gamma irradiation than E-beam, requiring 22.4 kGy to achieve complete inactivation. In whole strawberries, no human NoV or TV RNA was detected following 28.7 kGy of E-beam treatment using the PGM-MB binding assay. Overall, human NoV and TV are highly resistant to ionizing radiation and therefore the technology may not be suitable to eliminate viruses in fresh produce at the currently approved levels. In addition, the PGM-MB binding assay is an improved method to detect viral infectivity compared to direct RT-PCR.