|Abdulhafid, Gwen M.|
|Seitz, Scot R.|
Submitted to: Journal of Infectious Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/9/2011
Publication Date: 8/1/2011
Citation: Leon, J., Kingsley, D.H., Montes, J., Richards, G.P., Lyon, G., Abdulhafid, G., Seitz, S., Fernandez, M., Teunis, P.F., Flick, G.J., Moe, C.L. 2011. Human norovirus inactivation in oysters by high hydrostatic pressure processing: A randomized double-blinded study. Journal of Infectious Diseases. 77(15):5476-82. Interpretive Summary: High pressure processing (HPP) is a promising technology which can inactivate pathogens in uncooked foods. Norovirus is the most frequent cause of food-borne illness. In this study, we evaluated the potential of HPP to inactivate human norovirus as a possible means to prevent food-borne illness associated with oysters was examined. Since there are currently no suitable laboratory animals and no methods for laboratory propagation, human volunteers were used to assess virus inactivation. The study finds that pressures of approximately 88,000 pounds per square inch (psi) at refrigeration temperatures for 5 minutes, were sufficient to inactivate 99.99% of norovirus injected into oysters. However, lower pressures of approximately 59,000 psi, administered for 5 minutes at either refrigeration, or room temperatures, were not sufficient to inactivate the virus. The pressure required to inactivate human norovirus is considerably higher than pressures currently used for commercial processing of raw shellfish. The 88,000 psi of pressure required to inactivate norovirus does appear to alter the character of raw oysters, suggesting that HPP may have limited utility as an intervention for raw on the half-shell type oysters. Presumably, the moderate character changes to oyster meat observed in this study would be insignificant for oysters that were subsequently cooked. Currently, it is unknown whether alternate HPP conditions can be identified such as, using temperature or pH, which will inactivate norovirus at pressures more suitable for commercial processing.
Technical Abstract: This randomized, double-blinded, clinical trial assessed the effect of high hydrostatic pressure processing (HPP) on genogroup I.1 human norovirus (HuNoV) inactivation in virus-seeded oysters when ingested by subjects. The safety and efficacy of HPP treatments were assessed in three study phases with healthy, secretor-positive adults, randomized into two groups. Subjects received HuNoV (8FIIb, 1.0 × 104 genomic equivalent copies) in seeded oysters with or without HPP treatment (400 MPa, 25 deg C; 600 MPa, 6 deg C; 400 MPa, 6 deg C, 5 min). The primary endpoint of HuNoV infection status was determined by RT-PCR detection of HuNoV RNA in subjects’ stool or vomitus. Forty-four subjects were enrolled in this study. 600 MPa, but not 400 MPa (at 6 deg or 25 deg C), inactivated at least 4-log10 of HuNoV in seeded oysters. A white blood cell (granulocyte) shift (WBC shift) occurred in 92% of those infected and was significantly associated with infection (p=0.0014). This is the first demonstration of human NoV HPP inactivation by HPP within HuNoV-contaminated whole oysters and suggests a potential intervention for the commercial shellfish industry. This study also indicated that a WBC shift is an early predictive indicator of HuNoV infection.