The purpose of this research study is to the effectiveness of high hydrostatic pressures processing (HPP) treatment on norovirus infected shellfish. Norwalk virus can survive in shellfish and still be able to cause sickness. HPP inactivates microorganisms living both on the surface and on the interior of the food. The goal of the study is to determine whether HPP treatment on oysters spiked with norovirus will reduce infection rates in people consuming raw infected oysters.