Submitted to: Journal of Food Protection
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/30/2010
Publication Date: 2/1/2011
Citation: Gogal, R.M., Kerr, R., Kingsley, D.H., Granata, L.A., Leroith, T., Holliman, S.D., Dancho, B.A., Flick, G.J. 2011. High hydrostatic pressure processing of murine norovirus 1-contaminated oysters inhibits oral infection in STAT-1 -/- deficient female mice. Journal of Food Protection. 74:209-214. Interpretive Summary: High pressure processing (HPP) is being investigated as a means to non-thermally pasteurize raw oysters and clams. Previous work with oysters contaminated with the human norovirus surrogate, murine norovirus (MNV-1), showed that HPP can inactivate the virus directly with the shellfish meats as judged by extraction of the virus and infectious tissue culture assay. In this publication, we use a mouse animal model to assess inactivation of the human norovirus surrogate directly within live MNV-susceptible mice. The virus was mixed with sterilized oyster homogenate and then fed to live mice with, or without, high pressure treatments. The novel use of live mice demonstrated that HPP not only blocks the virus’ ability to infect host cells in vitro but it destroys the ability to initiate infection within the digestive tract of mice in vivo; effectively demonstrating that in vitro blockage is equivalent to in vivo blockage of infection. Also we characterize the pathologic effects of the systemic MNV infection observed for positive control groups in this study.
Technical Abstract: We have previously demonstrated that high pressure processing (HPP) is effective in preventing in vitro replication of murine norovirus strain 1 (MNV-1), a human norovirus surrogate, in a monocyte cell line following extraction from MNV-1-contaminated oysters. In the present study, the efficacy of high pressure processing to prevent in vivo replication within mice fed HPP-treated MNV-1-seeded oyster extracts was evaluated. Oyster homogenate extracts seeded with MNV-1 were given 5-min, 400-MPa (58,016 psi) treatments and orally gavaged into immunodeficient (STAT-1 -/-) female mice. Mice orally gavaged with HPP-treated MNV-1 showed significant (p = 0.05) weight loss and morbidity, whereas those given 100 and 200 plaque-forming units of HPP-treated MNV-1 were comparable to uninfected controls. MNV-1 was detected, via real-time PCR, within the liver, spleen and brain of all mice fed non-HPP-treated homogenate, but was not detected in the tissues of mice fed HPP-treated homogenates or in uninfected control mice. Hepatocellular necrosis and lymphoid depletion in the spleen were observed in non-HPP-treated MNV-1 mice, only. These results clearly show that HPP prevents MNV-1 infection in vivo and validates that viral inactivation by HPP either in vitro or in vivo are essentially equivalent. Further, the data suggest that HPP may be an effective food processing intervention for norovirus-contaminated shellfish.