High-hydrostatic-pressure inactivation of GI.5 and GII.4 human norovirus and effects on the physical, chemical, and taste characteristics of oyster (Crassostrea virginica)

Human norovirus (HuNoV) can cause acute gastroenteritis. Oyster is important vector for HuNoV transmission. Aiming to evaluate the inactivation effect of high-hydrostatic-pressure (HHP) on GI.5 and GII.4 HuNoV, we placed GI.5 and GII.4 HuNoV in oyster (Crassostrea virginica) digestive gland (DG) homogenate and phosphate -buffered saline (PBS) under the pressure of 200, 300, 400, and 500 MPa at 5 degrees C for 5 min. Propidium monoazide (PMAxx)-RT-qPCR and transmission electron microscopy (TEM) were used to evaluate the inactivation effect. The physical, chemical, and taste characteristics were also analyzed to evaluate the sensory quality of oysters. The results showed that PMAxx-RT-qPCR could effectively distinguish infectious HuNoV. The tolerance of GI.5 HuNoV to HHP was higher than that of GII.4. DG homogenate had a certain protective effect on HuNoV to tolerate higher pressure. Two types of HuNoV in homogenate and buffer all decreased below the detection limit (500 MPa/5 min). The pH, hardness, springiness, and chewiness of oysters treated by HHP were enhanced. Therefore, HHP treatment under 500 MPa at 5 degrees C for 5 min can effectively eliminate HuNoV and maintain oyster quality. The data could inform the development of methods to control HuNoV in oysters and the safety of raw oysters for consumption.